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UBC Theses and Dissertations

Research on Wisconsin ore Dayton, William Arthur 1938

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RESEARCH ON WISCONSIN ORE - b y -William Arthur Dayton -0O0-0O0-A Thesis submitted for the Degree of MASTER OP APPLIED SCIENCE in the Department • • . of •> • '• ' ' METALLURGY. -0O0-0O0-0O0-The University of British Columbia May .- 1938. I N D E X ..j Acknowledgement • • * * * " ! * * " ^ Problem Conclusions • • • Location of Property Analysis of Ore • • 2 .2 3 3 C h a r a c t e r i s t i c s of Ore • • • • • • • 4 4 5' 8 9 10 Screen A n a l y s i s . . . . . . . . . . . . . . . . . . . Previous M e t a l l u r g i c a l Work • •. • • • • • • • • • Preparation of-Ore Previous to Testing • • * • • . Flotation • • * • • • • • • • • * • Preamble • • . • Conclusions . . . . . . . . . . . . . ... 11 Recommendations • • ! * * . ' . * 1 1 Theory and Discussion of Reagents\ • • •• • • 1 2 Methods • • • • . * . 2 2 Tests • • * • • • • • • • * • • • : * • 2 3 Gas F l o t a t i o n . . . . . . . . . . . . . . . . . 67 Tests . . . . . . . . . . . . . . . . . . 69 . . 72 Gyaniaation' *'!!.'•••'*•*!*•*'!-•* Summary * • • • •• • '• • • • * Recommendations . . . . . . . . . . . . . . . . Theory • ' • • • • • • *•• • * • • • • • Methods * • • • • • • • • • • • • • • • • 7 6 Tests . . . . . . . . . . . . . . . . . Roasting • • • • • * • • * * ' * * * • • • • Blanket Concentration • • • 73 74 75 79 96 98 Assay Methods (a) Gold and S i l v e r (b) Copper • • • (c) Iron • « • (a) Sulphur . . (e) Arsenic . . (f) Cyanide i n Pulp (g) Lime i n Pulp ; Bibliography Appendix i AOIQTOWIED&EMENTS The work on the ore was carried out by D.R. Ferguson, and • W.A. Dayton i n the Metallurgical-and Geological Laboratories of the •University of British Columbia, under the supervision of Professor G i l l i e s and'Associate Professor Forward of the Department of Metal-lurgy, and Dr. Warren of the Department of Geology. The writer wishes to thank Professor G i l l i e s for his help with the flotation tests, Professor Forward for his aid and many suggestions concerning cyanid-ation and wet assaying, Professor Warren for his supervision of the microscopic examination ©f the ore, and" of the work on the superpanner and infra-sizer, Instructor W. Bishop for his help i n the f i r e assaying, and Mr. Ferguson for his invaluable aid collaboration. For reference in"flotation, "Flotation" by A.M. Gaudin was used freely; for the Cyanidation, "Manual of Cyanidation" by Hamilton was used, while for the roasting tests, advantage was taken of Bulletins of the Australian Institute of Mining and Metallurgy. 2 • * * PROBLEM To devise an economically profitable method of treatment for the ore of the Wisconsin Mine. CONCLUSION The re stilts of the examination were generally unsatisfactory. The results of the tests and the microscopic examination established the fact that i t i s improbable that the ordinary methods of milling can give a high recovery of gold. Four principal processes were t r i e d . They were flotation, flotation followed by cyanidation, roasting and cyanidation and straight, cyanidation. Flotation, under the present circumstances, i s not practical due to the small size of the gold particles and the d i f f i c u l t y of separating arsenopyrite and pyrite. A recovery of 96% of the gold can be obtained in 62% of the feed. Flotation followed by cyanidation was not satisfactory. Low temperature roasting before cyanidation did not improve the recovery. Straight Cyanidation has greater p o s s i b i l i t i e s than any of the other methods used in these tests. While the preliminary treatment has no effect upon the recovery of the gold i t i s evident that fine grinding warrants consideration. We understand that m i l l heads can be maintained at 0.35 oz. or • $12.20 per ton, with gold at $35 per ounce. With a 59$ recovery, this gives a gross production of $7.25 per ton. If the tonnage i s s u f f i c -iently large, the property might be operated at a p r o f i t . If the recovery rose to 66% (the recovery for fine grinding), 3 the gross production would be $8.05 per ton. Whether the extra cost of installation, operation and depreciation of the additional equipment necessary would be more than $0.80 per ton should be ascertained. Smelting i s the most l o g i c a l course, but as this i s impossible under the existing circumstances, i t i s apparent that a satisfactory method of treatment has not yet been established. LOCATION OJ PROPERTY The property i s i n the Nelson Mining Division, two or three miles south-southwest from the forks of Midge Creek, which empties Into the east side of Kootenay Lake-, about 20 miles southerly from Proctor, B.C. The mine is reached from the railway at Midge Creek station. A narrow road i s practically completed for about 2g miles up the creek; from there to the mine there is a pack t r a i l which can be improved into a road. The total distance from the railway to the mine is fourteen miles. The elevation at the mine i s about 6300 feet, which is about 4500 feet above the railway at Midge Greek. ANALYSIS 03T ORE Au - 0.44 oz./ton Pb - 0.33 percent Sb - Tr. Ag - - 1.88 o z . / t o n Ie/' - 2 9..7 percent Cu - 0.43 " As - 8.50 *• Zn - 0.93 " Arsenopyrite Pyrite Galena Chalcopyrite Sphalerite Sv - 30>5 Insol* .«*• 29„5 CaO - • — MgO - — 18.5 percent 48.9 0.35 " 1.2 " 1.5 4 CHARACTER ;0F ORE The bulk of the ore was crystalline masses of pyrite and arsenopyrite which were fractured and brecciated, with chalcopyrlte form-ing veinlets along the fractures. In these veinlets were also sphaler-ite, galena, telluride mineral, tetrahedrite (?) and small particles of an unknown mineral. Part of the gold occurs in finely disseminated particles fairly evenly distributed. The presence of a gold mineral i s indicated by superpanning and infrasizing results. Microchemical tests show the presence of a telluride, and fusion on a pyrex glass shows a gold tellu-ride. In the chalcopyrite can be seen minute particles, too small to be identified, of a yellow mineral which may be gold. The principal gangue mineral i s quartz. SCREEN ANALYSIS The - 200 mesh products were sized by the Haultain Infra-si zer and microscope. 20 Minute grind, 1000 grs. ore and 1000 grs of water in Mi l l • INFRASIZING RESULTS FOR - 200 MESH MESH ~%T Wt f-65 0.0 65/100 0.1 100/150 0.2 150/200 2.4 -200 97.5 100 MESH GOLD Wt. <fo Dist. f 250 19.8 250-400 21.7 14*4 4 0 0 - 5 6 0 18.9 XV * 3 560-850 .12.3 1 9 . 5 850-1100 8 .7 7.0 1100-1700 7.9 8.4 - 1700 10.5 8.3 100. 100. 5 20 Minute grind 500 grs ore and 500 grs water i n m i l l , MESH. wt . {• 250 0 . 3 6 250-400 1 4 . 0 0 400-560 2 8 . 4 0 560-850 2 2 . 8 5 850-1100 15e04 1100-1700 7 .08 - 1700 12.20 1 0 0 . PREVIOUS METALLURGICAL WORK Previous work on the Wisconsin ore has been carried out by the Ore Dressing and Metallurgical Laboratories of the Department of Mines at Ottawa, the Consolidated Mining & Smelting Company of Canada., Limited at T r a i l , B.C., and the Ore Dressing Laboratories at the University of B.C. The results at Ottawa showed that Flotation was not practical and that by Cyanidation only s l i g h t l y over 50 percent of the gold could be recovered. Smelting was recommended as the only profitable means of treating the ore, although the f e a s i b i l i t y was not thoroughly investigated* The CM. & S. Co., tests were principally conducted.along the lines: 1 . Roasting & Cyanidation. Recovery 20% ' 2 . Roasting & Chlorination. Recovery 80$ 5« Roasting with 5% Soad Ash (McKay method)followed by Cyanidation. Recovery 82% 6 , . 4. Amalgamation. Recovery 3% 5. Tabling - Recovery depended on bulk present. 6. Direct Cyanidation. Recovery 42% 7. Flotation » Unsuccessful The roasting methods were considered by the Company to be un-satisfactory. As the temperatures varied between 780° and 1450°C this process cannot be used due to the proximity of the Wisconsin property to the American border and the large amount of sulphur and arsenic fumes that would be evolved. Flotation Tests only were made at the University. The results were not satisfactory. The series of tests indicated that (a) the. gold recovery in a concentrate depended almost entirely upon the bulk of that concen-trate and (b) that i t was not possible to separate Arsenopyrite and pyrite by selective flotation. . Two tests (6,13-) 'were selected from this series as'having the best p o s s i b i l i t i e s for satisfactory results,?served as a basis for the earlier experiments i n the present work. As the duplicate #6 was abandoned without assaying i t w i l l not be recorded, but #13 i s as follows: TEST #13 Charge to B a l l M i l l Ore ~ 1000 grs Water - 1000 grs Lime - 2#/ton KGN - ©a#/ton Time of Grinding - 20 minutes. CONCENTRATE 1 Added Aerofloat #15 - 0.079#/ton Cresylic Acid - 0.068#/ton 7 Conditioned » 2 mins ; Skimmed - 10 mins pH - 10.1 CONCENTRATE 2 Added Cu S0 4 - 1.0#. /ton Skimmed - 10 mins * CONCENTRATE 3 Added Cone. Hg S0 A - 5 ce. #301 - 0.02 #/ton Pine Oil , # 5 . ^ '©.08 #/ton Conditioned - 2 mins Skimmed - 15 " pH. - 3,9 CONCENTRATE 4 Skimmed - 10 Mins RESULTS Wt PROD. Grs. % Feed Au oz/ton Au Ag fo: az/ton Rec. , Ag fo Rec. Ou . Cu J> Rec As fo As RIC CI 30*0 3.0 2*40 21.2 ; 16.48 23.6 86.5 12.2 2.5 02 25.0 2.5 o.go 4.12 6.1 1.2 _10.2 16.6 3.1 03 330.0 33.0 0.43 42 .? 2.60 45.3 Tr 30.9' 62 ,4 04 30.0 3.0 0.40 4.8 4.00 5*2 Tr 16.0 4.3 T 585.0 58® 5 1000,0 74.3 80.2 •96:,7 72.3 It must be noted before comparing this test with similar ones described later, that the head sample for the ore used i n above 8 test ran 17.55% Arsenic and 35.7% Iron. PREPARATION Off ORE PRIOR TO TESTING Approximately £5 pounds of ore that had been ground to pass through a 10 mesh screen remained from the previous year. It was thought that there would be insufficient for the proposed tests, so a new batch weighing about 50 pounds was secured. This was stage-ground to 100% -10 mesh and mixed with the f i r s t batch, thus ensuring a supply of ore that would be consistent throughout and f a i r l y representative . Both samples had been exposed to possible' oxidation for over a year, but i t was unavoidable. By constant r i f f l i n g about 4-00 grs. of ore were obtained from the above-mixture. This amount was disc-pulverized u n t i l i t i n entirety; passed through a 100 mesh screen. It was s p l i t once more and £00 grs obtained which provided a good representative sample from which the head assays were determined,. 9 F L O T A T I O N CONCLUSIONS REC01(WENDATI0NS THEORY & TESTS -0O0-0O0-0O0-10 1 •Y P R E A M B L E The objective i n the flotation tests has been the recovery of gold in some suitable form which w i l l render I t amenable t o one or more subsequent processes. During these tests, two p o s s i b i l i t i e s have been kept i n mind, f i r s t to concentrate the gold in a sufficiently small bulk and high con-tent to warrant shipping to a smelter for further treatment. It was nec-essary to reduce the amount of metals such as arsenic t o a-quantity i n -sufficient to incur penalties. The second p o s s i b i l i t y was to obtain a concentrate containing over 30% Arsenic so that i t could be shipped as an arsenic concentrate, containing gold. Both courses were found t o be impossible. The reason for the impossibility of the concentration of the gold i n a small bulk was probably due to the very fine dissemination of the gold throughout, both as native gold and a g o l d t e l l u r i d e . The cause of failure for the second case was due to the intergrowth of the pyrite and arsenopyrite and the necessity of extremely fine grinding to unlock one from the other. Another reason i s the close similarity between pyrite and arsenopyrite i n their reactions to flotation reagents. This has been confirmed by Wark & Cox i n their research work with contact angles. In i t they show that the two minerals react i n the same manner, there being only a very slight difference i n sensitivity to depressants when the pH i s high, around 11. At this range the arsenopyrite i s slightly more reactive and can be depressed, but extreme care must be taken in the regulation of the reagents. 1. I.W. Wark & A.B. Cox - "Principles of Flotation, VI" Mining Technology, January 1938. 11 CONCLUSIONS la Arsenopyrite & pyrite cannot be separated by selective flotation, with the present reagents. This i s discussed under the previous heading. 2 . A higher percentage of arsenic i n a concentrate can be obtained when the pulp i s slightly acid. 3. Practically without exception the percentage recovery of the gold depends, in direct proportions on the bulk of the concentrate collected. 4. The use of sodium sulphite to replace potassium cyanide does not appreciably affect the recovery and has no effect i n the s e l -ective flotation of arsenopyrite and pyrite. 5. Collectors #208 and -#301 added to the b a l l m i l l and aero-float 15 to the c e l l , gave the best gold recoveries. 6. The collector 2-6 (Pentasol Xanthate) apparently was no different from the other collectors in i t s action. 7. No advantage i s to be gained by cleaning a bulk concentrate. RECOMMENDATIONS 1. Should any further work be done i n the flotation of an arseno™ pyrite concentrate, i t would be advisable to keep the pH between 5.0 and 7.0. 2. Any attempt to separate the two should be made at a pH of 11.0. 12 THEORY" Off FLOTATION only -While this paper is not concerned with f l o t a t i o n , / i t i s thought advisable to presdnt a short review showing the relationship and imp-ortance of the various factors* HISTORY Flotation has passed through many stages in the evolution of the modern process. The f i r s t attempt in modern times was the separation of sul-phides from earthy matter by means of o i l y agents. Later results were 2 improved by the use of modifying agents such as acids and acid salts A further stage was the introduction of gas as the buoyant medium, re-suiting in a decided reduction of the amount of o i l s used. It was not u n t i l 1924 that Perkins 3 patented the use of Xanthates, thus marking the beginning of the modern trend of flotation by chemical collectors. • • . Many discoveries in the use of inorganic salts have had far-reaching results in the flotation of and concentration of minerals that could not be treated previously, and they have advanced the process of selective flotation considerably. The accurate classification of the reagents i s d i f f i c u l t , but for ordinary purposes i t i s desirable to discuss them largely i n terms of their functions. They w i l l be discussed under the headings of; (1) Frothers ( 4 ) Depressants (S) Collectors or promoters (5) Sulphidizing Agents (S) Activators (6) Regulators 2 . Rickard, T.A.- "History of Flotation". Mining Sc. Press, 114. Pgs 365 -•:. 369; 401 - 406. 3. U.S. Patent #348,157. 1 3 FROTHERS A frothing agent must c r e a t e a f r o t h c a p a b l e o f bearing non-wetted particles denser than water to the surface, but may or may not possess t h e p r o p e r t y o f making t h e minerals l e s s w e t t a b l e by water. P u r e liquids do n o t f r o t h , as only substances w h i c h have different surface tensions are capable o f foaming. Organic compounds are used almost i n -variably, as s m a l l amounts dissolved, i n water l o w e r t h e surface tension very appreciably. T h i s may be understood from a consideration o f G i b b s adsorption equation -07" a r ' W . 7 in w h i c h " a " is t h e amount o f material adsorbed on the interface, T i s the absolute temp., R i s a constant, C the concentration in the b u l k of t h e l i q u i d and ™ t h e r a t e o f change of the surface t e n s i o n w i t h concen-dc - t r a t i o n . In organic-compounds, where surface tension is low and oap-dr i l l a r y active substances are easily adsorbed, ~ i s large, therefore small concentrations cause a considerable drop in surface t e n s i o n . In -organic s u b s t a n c e s however, w h i c h tend to raise the surface tension and be poorly adsorbed, — w i l l be small and the concentration would have dc to be large to produce much change in the tension. The extent to which the organic substances affect the surface tension of water i s closely related to their structure. The length of the hydrocarbon chain has a definite effect, as pointed out by Traube. In a homologous series each higher homologue has a solubility 1/3 that ' of the proceeding one, while the surface tension i s depressed three times, with the result that the best results are obtained with a homo-logue midway in the series. 14 Frothing compounds have structural formulae that are composed of two constituents having opposite properties; one part of the molecule i s polar, which*is water avid, the other non polar, which repels i t . The latter part consists of a hydrocarbon chain, while the polar section may consist of oxygen in the (GO), (COOH), or (OH) forms, or nitrogen in the amino (NHg), or n i t r i l e (CN) form. The last two are avoided where frothing only is desired,- as they ionize and therefore- have collecting properties. Taggart, Taylor and Ince 4 have come to the conclusion that a l l good frothers contain one polar group only. The mechanism of the bubble may be represented by a cross section of a portion of a bubble . To understand i t one must remember the char-acter of the molecules with one water repellent and one water avid por-tion. The non-polar part i s represented by "R" and the polar part by "X" or any polar solvent. As a result of these a f f i n i t i e s the molecules arrange themselves as indicated, with the polar group dissolving i n water and the non-polar part sticking out into.the a i r . Consequently the bubbles are lined with a monomolecular sheath of water repellent and 'chemically inactive groups 4. Taggart, Taylor & Ince, "Experiments with Flotation Reagents" A.I.M.M.E. 68 (1923) 5. "The Story of the Bubble", C.I.M.M. Bulletin, July 1935. Pg..349. .-G.A. Gillies.. 15 oriented outwards, thus preventing coalescence of the bubbles and pro-ducing a more permanent froth. The effect of the dissolved substances on frothing may b,e b r i e f l y explained by a consideration of the film of the solution. As the f i l m i s stretched the liquid comes from the bulk of the pulp and dilutes the film, thereby increasing the surface tension and counteracting the stretching force. This gives the film a greater e l -a s t i c i t y than that obtained from pure liquids whose surface tension can-not be Increased by a stretching of the surface. Therefore by constant adsorption and changing of the surface tension an equalibrium can be quickly reached in which the stretching force balances the surface tension and ensures the s t a b i l i t y of the froth. The principal requirements of a froth are; 1. It must be an organic substance. 8. It's molecules should be heteropolar and consist of one or more hy-drocarbon radicals attached to one polar group. 3. There should be only one polar group and i t should contain oxygen in the form of the hydroxal (OH), carboxyl (COOH), or carbonyl (GO); or nitrogen in the amine (NHg) or n i t r i l e (ON) form. 4 . It must not ionize materially. 5. Must be readily available at reasonable cost. In practice, the most widely used frothers are cresylic acid and pine o i l , with the former gradually replacing the pine o i l . Locally used frothers, such as camphor o i l in Japan and eu-calyptus o i l in Australia, are excellent frothers and are usually less expensive than the two more important ones. COLLECTORS The term collecting agent goes back to the days of o i l f l o t -16 ation, at which time i t was used to designate certain o i l s capable of .bringing sulphide minerals i n the froth to greater abundance. There are two types, (a) collecting o i l s , which are not used in modern plants, and (b)chemical collectors which act by adhering to the surface of certain mineral particles either in their natural state or i n , some altered chemical form, producing a non-polar coating that repels water but attaches i t s e l f to gas bubbles. They may be divided into two varieties, those that form definite compounds by metathesis with the surface of the minerals, and those that do not. Xanthates, which play an important part in modern practice, appear to b e an example of the f i r s t variety. They act on base-metal sulphides by double decomposition between an oxidised coating and the reagent, followed b y later decomposition so that the f i n a l coating need not be a base-metal Xanthate. CHARACTERISTIC STRUCTURE OF COLLECTORS The promoter molecules, lik e those of the frothers are com-posed of two parts, polar and non-polar. Unlike the frothers, however, the collectors ionize and the polar part of the molecule reacts with the mineral to form an Insoluble compound or cause adsorption on the surface. As in the case of frothers increased length of the hydrocarbon chain results in an increased effectiveness of the collector. The op-timum for the number of carbon atoms has not yet been established, a l -though at present five i s thought to be the most satisfactory.' ACTION OF COLLECTORS Many theories regarding the attachment of a particle to a bubble have been advanced, but not one has been generally accepted. It i s possible that, when the bubble i s in the pulp, the 17 p o l a r p a r t o f t h e c o l l e c t o r u n i t e s w i t h t h e m i n e r a l , p r o v i d i n g a monomol-. e c u l a r s u r f a c e w i t h t h e h y d r o c a r b o n c h a i n o r i e n t e d o u t w a r d s . T h i s u n i t e s w i t h t h e p o l a r p a r t o f t h e b u b b l e , c a u s i n g a u n i o n o f t h e p a r t i c l e and b u b b l e . Some o t h e r a d d i t i o n a l s u p p o r t must a l s o be n e c e s s a r y . T h i s may be due t o . t h e s i n k i n g o f t h e p a r t i c l e i n t o t h e b u b b l e w a l l u n t i l a de-f i n i t e c o n t a c t a n g l e i s r e a c h e d . ' • F o r u n i o n i n t h e ' f r o t h , ; a d i f f e r e n t e x p l a n a t i o n i s r e q u i r e d . A t h e o r y advanced by Dr. C h r i s t m a n n ^ i s t h a t o f d i s s o l u t i o n o f t h e h y d r o -c a r b o n o f t h e f r o t h f i l m , so t h a t a m i n e r a l f r o t h w o u l d be c o n s t i t u t e d a s shown -I t i s n o t l i k e l y t h a t t h e two h y d r o c a r b o n s m u t u a l l y d i s s o l v e , b u t r a t h e r t h a t t h e r e i s a d s o r p t i o n between t h e two, r e s u l t i n g i n t h e adh e r e n c e o f t h e p a r t i c l e t o t h e b u b b l e . 6. Transactions of A.I.M.M.E. Vol. 112 Pg. 239. 18 SELECTION IN GAS - SOLID ATTACHMENT The gas s o l i d attachment-pictured as r e s u l t i n g from the en-counter of bubbles and p a r t i c l e s must be s e l e c t i v e between minerals having d i f f e r e n t surfaces, consequently the p o l a r i t y of the surfaces i s important. I f a p a r t i c l e having a non-polar surface (1) encounters an a i r bubble the contact angles at the s o l i d surface i n d i c a t e a tendency f o r the gas to displace the water at the s o l i d s surface. S i m i l a r l y i f a. p a r t i c l e having a polar surface (8)encounters an a i r bubble the contact angles i n d i c a t e a tendency f o r the water to displace the gas at the s o l i d s surface • CONTACT ANGLES Much work has yet to be done on the contact angles between 8 gasses, l i q u i d s and s o l i d surfaces. Recent research has indicated that a great deal of valuable information, which can be used i n the i n t e r -p r e t a t i o n of f l o t a t i o n phenomena may be obtained by measuring the angles formed between various mineral surfaces and bubbles. So/Sc/ - 7. Gaudin, A.M. "Flotation'?, page 99. 8, .f.w. Wark, A.B. Cos - "Transactions of A.I.M.M.E. V o l , 112 19 FROTH FOiMATlON As the bubbles move upward there i s a downward draining of the water and the suspended substances in the water. As the draining proceed the walls of adjacent bubbles.come in contact at one point and gradually assume a definite polygonal shape as the pulp drains. The particles suit ably prepared adhere to the bubble surfaces and as they are close to-gether have a filtering-action which traps some of the gangue. COLLECTORS USED IN PRACTICE (a) Fatty Acids and "Soaps &:£ov non-metallic minerals. (b) Xanthates and their oxidation products. (c) Organic hydrosulphides (mercaptans) and their oxidation products. (d) substituted thioureas , (thioearbonilid), dithiophosphates, amines, a azo compounds. FLOTATION; ACTIVATING AGENTS Agents which through their effect upon the surface of otherwise non floatable or poorly floatable minerals make them amenable to f l o t a -tion with the usual collecting agents. Generally speaking they are compounds which are capable of pro-ducing less soluble salts with the collecting agents than any of the metal compounds at the surface of the minerals to be floated. They must also be capable of f i r s t reacting with the mineral surface to form com-pounds whose solubility is less than that of the metal compounds at the surface of the minerals. The metals whose organic salts and oxides are the least soluble are Cu, Hg. Consequently they are, i n salt form, the most effective activating agents. The best example i s copper sulphate in connection with sphalerite 20 / Copper sulphate changes the surface of the blende to covellite (CuS) which i s readily floated by the regular promoters. DEPRESSANTS The function of'depressors i s to prevent', either temporarily or permanently as desired, the flotation of certain mineral constituents of complex ©res.subjected,to selective flotation without preventing the primarily desired mineral or minerals from being readily floated. Among the more, common depressants are: LIME - has a depressing action on gold and a l l sulphides, particularly pyrite. KCN - has a depressing action on pyrite, arsenopyrite and sphalerite BICHROMATES - specially for galena SULPHIDIZING AGENTS These compounds are capable of changing the surfaces of oxidized^ minerals by coating with a sulphide fil m . They are used rarely and ev-idence i s increasing which shows that they are of l i t t l e use i n f l o t a -tion, even with oxidized ores. The most common agent i s sodium sulphide. It was found9 that sodium sulphide i s detrimental i n the flotation of precious minerals. REGULATORS . The function of the regulator i s to modify the alkalinity or acidity (pH) of a solution. The action of the regulator may be said to be three-fold. (I) It precipitates soluble gaits from the solution (II) Depresses certain sulphides by affecting the mineral surface 9. U.S. Bureau of Mines "Report of Investigations" Metallurgical Division • June, 1935. 21 CONCLUSION' The tremendous strides made in the last few years can be re-cognized when-it i s noted that, apart from the metallic sulphides that were originally floated, the more d i f f i c u l t ores such as; native metals, phosphates, some carbonates and oxides, can now be concentrated. 22 , ; • - METHODS The charges of ore were ground i n a c y l i n d r i c a l rod m i l l with a watertight cover. The m i l l was rotated f o r a s p e c i f i e d time at 41 R.P.M. The pulp was then transferred to the f l o t a t i o n c e l l and d i l u t e d to the required density. The reagents were added i n the desired q u a n t i t i e s and the pulp agitated. The c e l l used was a Denver Sub-aeration with with b e l t drive and a capacity of 1000 grs of ore. Skimming was done by hand with a metal scraper. The concentrates and t a i l s were drie d and assayed at the end of the run. The reagents used, excepting soda ash, lime, cyanide, zinc sulphate, and f r o t h e r s were made up i n aqueous solutions so that 1 cc. equalled 1#/ton of ore when 1000 grs of ore were used. The pH was determined by the Leeds & Northrup i n d i c a t o r . The reagents used, weight of ore, pulp density, time of grinding and general conditions p e r t a i n i n g to the I n d i v i d u a l t e s t s are given with the assays and recoveries of each. A l l r e s u l t s are tr a n s f e r r e d to the ^appendix.in table form and eire also, shown on graphs, both i n - • d i v i d u a l and composite. Recovery c a l c u l a t i o n s are based on the equation -Wt of element i n concentrate x 100 = % Recovery sum of weights of element i n concentrates 4 t a i l s 2> TEST I . To D u p l i c a t e T e s t 6 o f l a s t y e a r . Charge t o B a l l M i l l Ore Water KCH N a 2 C 0 3 Z11SO4 Time o f g r i n d i n g -1000 g r s . 1000 g r s . 0.5 ft/ton, 2.5 f / / t o n . 0.5 #/ton. 20 m i n u t e s . C e l l . Added C o n c e n t r a t e I . P i n e O i l #5 C r e s y l i c A c i d A e r o f l o a t #25 0.24 # / t o n . 0.54 # / t o n . 0.06 ft / t o n . C o n d i t i o n e d 2 m i n u t e s Skimmed 20 m i n u t e s pH. - 6.85. A t f i r s t t h e b u b b l e s were t o u g h and h e a v i l y m i n e r a l i z e d . A f t e r 5 m i n u t e s t h e y were s m a l l e r and v e r y c o p i o u s . A f t e r 15 m i n u t e s t h e b u b b l e s became c l e a n . Then t h e f r o t h t u r n e d d a r k e r and c o n c e n t r a t e IB s t a r t e d . C o n c e n t r a t e I B . Added ( K - E t . X a n t h a t e ( ( C u S 0 4 (5% s o l . ) C o n d i t i o n e d 2 m i n u t e s Skimmed 48 " pH. - 7.0. 0.197 # / t o n . 2.00 # / t o n . ,24 The b u b b l e s were s m a l l and c o p i o u s and t h e . f r o t h was good. ' C o n c e n t r a t e . 2. Added JK-Et. X a n t h a t e 0.197 # / t o n . (CuSO (5% s o l . ) 2.00 # / t o n . 4 C o n d i t i o n e d - 2 m i n u t e s Skimmed - 12 • " . . ' pH - 7.02 The f r o t h was composed o f s m a l l and c o p i o u s b u b b l e s c a r r y i n g f e w s u l p h i d e s * T h i s t e s t was n o t a s s a y e d , as a new b a t c h , o f o r e a r r i v e d and i t was t h o u g h t t h a t b e t t e r r e s u l t s c o u l d be o b t a i n e d witlfo t h e f r e s h o r e . 25 TEST 2. To D u p l i c a t e T e s t 15 o f P r e v i o u s T e a r 8 Charge t o - B a l 1 M i l l Ore Water KCN Lime Time of g r i n d i n g - 20 m i n u t e s * 1000 g r s . 1000 g r s . 0.10 # / t o n . 2.0 # / t o n . C e l l . C o n c e n t r a t e 1. Added C r e s y l i c A c i d A e r o f l o a t #15 0.108;# / t o n . 0.438 # / t o n . C o n d i t i o n e d - 2 m i n u t e s . Skimmed - 16 m i n u t e s pH - 7.2 The b u b b l e s a t f i r s t were l a r g e , t o u g h and w e l l -armored, b u t a f t e r t h r e e m i n u t e s became s m a l l and c o p i o u s . The s m a l l b u b b l e s were d i r t y , b u t soon c l e a r e d . C o n c e n t r a t e 2. Added : C U S O 4 1.0 # / t o n . C o n d i t i o n e d - 2 m i n u t e s Skimmed - 10 " pH - . 7.2 The p e r s i s t e n t f r o t h was composed o f s m a l l , l i g h t l y m i n e r a l i z e d b u b b l e s . C o n c e n t r a t e 5A. Added P i n e O i l 0.8 # / t o n . c #301 0.02 # / t o n 26 ^ ' C o n d i t i o n e d 2 m i n u t e s Skimmed 15 " • P : 7.2 The f r o t h was f a i r l y p e r s i s t e n t , t h e b u b b l e s were s m a l l and more m i n e r a l i z e d t h a n t h o s e o f p r e v i o u s t e s t . Skimming was c o n t i n u e d 15 m i n u t e s t o d u p l i c a t e l a s t y e a r ' s r e s u l t s , b u t as m i n e r a l was s t i l l coming up, skimming was c o n t i n u e s i n t o a n o t h e r p a n . C o n c e n t r a t e 5 B. Skimmed 9 m i n u t e s pH 7.4 T h i s i s a c o n t i n u a t i o n o f 3A. Skimming was c o n -t i n u e d u n t i l t h e b u b b l e s were c l e a n . .The froth was t h e same as 3 A. C o n c e n t r a t e 4. Skimmed 13 m i n u t e s . pH 6.8 i! T h i s c o n c e n t r a t e was t a k e n t o d u p l i c a t e l a s t y e a r ' s r e s u l t s . The f r o t h was t h e same as i n 3B, and l i t t l e m i n e r a l was c a r r i e d o v e r . C o n c l u s i o n . Mote. The c o n c e n t r a t e o f t h i s t e s t were n o t ^assayed as a new b a t c h o f o r e a r f i v e d and i t was t h o u g h t t h a t b e t t e r r e s u l t s c o u l d be o b t a i n e d w i t h t h e f r e s h o r e . 27 V . TEST 5. To d u p l i c a t e T e s t 15 w i t h t h e Hew M i x t u r e o f Ore. Charge t o B a l l M i l l Ore - 1000 grs® Water - 1000 " KCN Lime  O . l f / t o n 2.Of/ton G r i n d i n g Time 20 m i n u t e s . C e l l C o n c e n t r a t e 1. Added G r e s y l i c A c i d 0.108 # / t o n . A e r o f l o a t #15 0.438 *# / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 10 n pH » 7.0 S m a l l and p o o r l y m i n e r a l i z e d b u b b l e s . They were d i r t y f o r f i r s t 5 m i n u t e s , t h e n c l e a n f o r r e m a i n d e r o f t i m e . C o n c e n t r a t e 2« Added Copper S u l p h a t e 1.0 # / t o n C o n d i t i o n e d 2 m i n u t e s Skimmed 10 " pH 7.0 F r o t h was v e r y s i m i l a r t o p r e v i o u s c o n c e n t r a t e b u t l e s s m i n e r a l i z e d . C o n c e n t r a t e 3. Added . . P i n e O i l 0.68# / t o n #301 0.02 # / t o n 28 H 2 § 0 4 (1:1) 5 o c . C o n d i t i o n e d 2 m i n u t e s Skimmed -- I S pH — 4.4 A t f i r s t , a few l a r g e b u b b l e s t h a t were v e r y h e a v i l y m i n e r a l i z e d , came up. A l m o s t e n t i r e s u r f a c e o f c e l l was c o v e r e d w i t h a s i l v e r y ' scum t h a t w a s v e r y p e r s i s t e n t . A f t e r a s i x m i n -u t e p e r i o d t h e : b u b b l e s became s m a l l e r and more c o p i o u s . M i n e r a l i z a t i o n was heavy b u t l e s s t h a n a t s t a r t . Skimmed 15 m i n u t e s t o d u p l i c a t e l a s t y e a r ' s t e s t , b u t as m i n e r a l was s t i l l b e i n g b r o u g h t up, c o n t i n u e d skimming i n t o a n o t h e r pan. C o n c e n t r a t e 5 B. Skimmed- - 12 m i n u t e s pH - 4.4 C o n t i n u a t i o n o f #3. F r o t h was same as 3, e x c e p t t h a t t h e b u b b l e s were l e s s m i n e r a l i z e d . C o n c e n t r a t e 4. Skimmed - 13 m i n u t e s pH - 4.6 A f o u r t h c o n c e n t r a t e was t a k e n t o d u p l i c a t e l a s t y e a r ' s t e s t . The f r o t h was weak and b u b b l e s were d i r t y and p o o r l y m i n e r a l i z e d . 3 C - 6 o ao 30 30 7 z o 4 o 4c? 2 0 2,0 & u N, 0 k 6 6 111 (j) ^ ^ 5^ O  O O 4-0 si o to K M K 0 o o 4 O o zo 3 29 RESULTS. P r o d u c t Wght. Feed Au o z / t o n Cu % •': Fe As % Au Rec. Cu Rec. Fe Rec. As Rec •L 17.6 •1.7 2.68 3.17 33.9 6.8 11.9 12.9 1.9 1.3 2 21.1 2.0 1.24 2.02 31,5 7.0 6.6 10.9 2.0 1.7 5 424.3 40.6 0.40 0.35 36.6 13.2 42.6 33.8 48.1 62.8 3b 175.3 16*8 0.48 • 0.43 39.2 9,3 21.3 16.4 21.2 18.3 4 33.7 ; 3.2 • 0.32 0.53 36.5 8.5 2.9 4.1 3.8 3.2 T 368.5 35.7 0.16 0.26 20.2 3.1 14.7 21.9 23.1 12,8 1040.5 100.0 100.0 ioo.o 100.0100,0 % FeAsS _ . % CuFeS2 % . F e S 2 FeAsS C u F e S 2 F e S 2 14.8 9.1 49.5 1 © 3 12.9 1.9 15.2 5.8 46.4 1.7 10.9 2.1 28.7 1.0 48,0 62.8 33.8 44.4 20.2 X e 2 60.2 18.3 16.4 23.0 13.5 1.5 59.2 3.2 4.1 4.3 6.7 0.7 30.0 12.8 21.9 24.3 100.0 , 100.0 . 100.0 C o n c l u s i o n s . The g o l d and a r s e n i c r e c o v e r i e s c h e c k e d g a i r l y w e l l w i t h t h o s e o b t a i n e d i n T e s t 13 o f l a s t y e a r . The c o p p e r and a r s e n i c g rades a r e d i f f e r e n t , b u t t h i s due t o t h e d i f f e r e n c e . i n t h e heads o f t h e two b a t c h e s . 3 D -TEST 4t To d u p l i c a t e T e s t 5 u s i n g l e s s s u l p h u r i c A c i d . B a l l M i l l Ore - 1000 g r s . Vtfater - 1000 g r s . • ECU - 0.1 # / torn Lime - 2 . 0 f / t o n G r i n d i n g Time - 20 m i n u t e s . C e l l C o n c e n t r a t e 1» Added C r e s y l i c A c i d 0,108 # / t o n A e r o f l o a t #15 0.438 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed 10 11 pH - 7.2 The bubble's were s m a l l and not w e l l m i n e r a l i z e d . They were d i r t y f o r t h e f i r s t f i v e m i n u t e s and t h e n f a i r l y c l e a n t o end of- s k i m . The p e r s i s t e n c e o f f r o t h was good. ' C o n c e n t r a t e 2. Added C u S 0 4 1.0 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 10 " pH - 7.2 The f r o t h was v e r y s i m i l a r t o #1, b u t t h e b u b b l e s were p o o r l y m i n e r a l i z e d . C o n c e n t r a t e 3. Added P i n e O i l #208 .08 # / t o n .02 # / t o n 31 1:1 H 2 S 0 4 S c . c . C o n d i t i o n e d - 2 m i n u t e s Skimmed - 15 " pH - 5.2 • O b t a i n e d a good f r o t h o f t o u g h and h e a v i l y armored b u b b l e s , t h o u g h n o t as h e a v i l y armored as i n c o n c e n t r a t e 5, t e s t 3. C o n c e n t r a t e 3b. pH • - 5.2 Skimmed - 13 m i n u t e s The f r o t h was' same as c o n c e n t r a t e 3, b u t b u b b l e s became g r a d u a l l y c l e a n e r . C o n c e n t r a t e 4. pH - 5.4 Skimmed - 13 m i n u t e s O b t a i n e d p o o r f r o t h o f weak, d i r t y b u b b l e s , , c a r r y i n g l i t t l e m i n e r a l . RESULTS. Conc-e n t r a t e Weight P e r c e n t o f f e e d Au A s s a y o z / t o n Cu Fe % As fo Au Rec Cu Rec Fe Rec As Rec 1 13.4 1.3 2.96 4.45 5.5 10.4 13.5 1.4 0.8 2 20.2 2.0 1.16 1.94 28.3 7.1 6.2 8.9 1.9 1.6 3 452.2 45.0 0.48 0.43 36.3 13.2 56.8 43.6 55.1 70,3 3b 146.9 14.6. 0.36 0,31 39.1 8.0 13,8 10.3 19,4 13.7 4 19.8 1.9 6.32 0.67 30.0 6.4 1.7 2,9 1,9 1.5 T 354.0 35.2 0.12 0.26 17.1 2.9 11.1 20.8 20.3 12.2 1006.5 100.0 100.0 100.0 100.0 100.0 FeAsS GUFeSg F e S P FeAsS GuFeS 2 FeS2 Conc-e n t r a t e Grade A r s e n o -p y r i t e Grade C h a l c o -p y r i t e Grade P y r i t e R ec. A r s e n o -p y r i t e R ec. C h a l c o -p y r i t e R e c . P y r i t e 1 11.9 12.7 46.0 0.8 13.5 1.5 2 15.4 5.5 • 40.5 1.6 8.9 2.0 3 28.7 1.2 43.0 70.3 . 43.6 47.6 3b 17.4 0.9 62.0 13.7 10.3 22 • 3 4 13.9 1.9 46.6 1,5 2.9 2.3 T 6.3 0.7 27.9 12.2 20.8 24.3 100.0 100.0" 100.0 C o n c l u s i o n 9 The a d d i t i o n o f l e s s s u l p h u r i c A c i d t h a n i n t h e p r e v i o u s t e s t , does n o t m a t e r i a l l y a f f e c t t h e grades o f t h e c o n c e n t r a t e s . The s l i g h t l y h i g h e r r e c o v e r y i s due t o i n c r e a s e d b u l k of t h e c o n c e n t r a t e s . Prom t h e r e s u l t s f o r c o n c e n t r a t e 3 it i s e v i d e n t t h a t t h e d e c r e a s e i n s u l p h u r i c a c i d made no d i f f e r e n c e i n t h e grade p e r c e n t a g e o f a r s e n i c p r e s e n t . s i * _ •• \ ; • TEST 5. To D u p l i c a t e T e s t s 5 and 4, b u t u s i n g Ho S u l p h u r i c A c i d . Charge t o B a l l M i l l . . Ore - 1000 gms. Water - 1000 " KCK - 0.1 # / torn Lime - 2.0 # / t o n G r i n d i n g t i m e — 20 m i n u t e s C e l l Go n o e n t r a t e 1. Added - • C r e s y l i e a c i d 0.108 # / t o n A e r o f l o a t 0.438 * # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed 10 " pH - 8.65 O b t a i n e d f a i r f r o t h , w h i c h c o u l d have b e e n s t r o n g e r . B u b b l e s were Tfeak and d i r t y . C o n c e n t r a t e 2. Added - C u S 0 4 1.0 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 10 " ' pH - :8.37 ; F r o t h was weak and d i r t y . B u b b l e s were l a r g e r . C o n c e n t r a t e 3. Added - P i n e O i l .08 # / t o n #301 .02 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 15 " pH - 8.20 A F r o t h was composed o f s m a l l , weak, d i r t y b u b b l e s , w h i c h were n o t n e a r l y as h e a v i l y armored as t h o s e i n t h e t e s t s -where HgSO^ was added. C o n c e n t r a t e 5 .B. Skimmed - 12 m i n s . pH - 7.98 F r o t h was same as 5, composed o f s m a l l , weak, d i r t y b u b b l e s , w h i c h were n o t h e a v i l y armored. C o n c e n t r a t e 4. Skimmed - 13 n i i n s . pH - 8.00 • F r o t h was a g a i n weak and d i r t y , and was composed o f s m a l l b u b b l e s c a r r y i n g l i t t l e ' m i n e r a l . RESULTS. Conc- Weight P e r c e n t G o l d Cu Fe As Au Cu Fe As ent r a t e . o f Feed o z / t o n % of 7° % Rec Rec Rec Rec 1 25.3 2.84 5.0 39.0 6.9 17.9 29,3 3,1 2.1 2 11.1 i . i 1.44 2.06 36,0 7,3 4,0 5.5 1.3 1.0 3 109.1 10.8 0.84 1.01 29.4 9.0. 22.8 25.4 LO.O 12.1 3b 37.5 •3.7 0.44 0.54 37.0 10.2 :• 4.1 • 5.6 : 4.4 4.7 4 41.7 4.1 0.42 0.66 35.5 10.8 .4*4 6.8 4.6 . 5.6 T 783.3 77,8 0.24 0.15 31.3 ; 7.7 46.8 2Z.4 76.6 74.5 ) 1008.0 100 100 100 ieo 100 Z8f<?o 4o fo 3 3 K H X IP 0 fcr to 0 0 CO Q G. . Q lO 30 9 35 6 6-5 20 a 33 4- 8-3 3 I I 5 o 6 Z9 o 73 FeAsS CuFeS 2 FeSp FeAsS CuFeSp F e S 2 Conc- Grade Grade Grade Rec. Rec. Rec. e n t r a t e A r s e n o - C h a l c o - P y r i t e A r s e n o - C h a l c o - P y r i t e * p y r i t e p y r i t e P y r i t e ' p y r i t e 1 15-.0- 14.3 54.0 2.1 29.3 3.0 2 15.9 5.9 54.3 1.0 :5.-5- 1.3 3 19.6 2.9 26.4 12,1 25.4 6.4 3b 2 2 © 2 1.5 46.9 4.7 5.6 3.9 4 2.3.5 1.9 41.0 5.6 6.8 3.8 T •16.7 0.4 47.0 74.5 2.7.4 81.6 100.0 100.0 100.0 C o n c l u s i o n . The absence o f s u l p h u r i c a c i d d e f i n i t e l y a f f e c t e d t h e a r s e n i c p e r c e n t a g e p r e s e n t i n c o n c e n t r a t e 3. I t i s .evidentt. , f r o m t h e l a s t t h r e e t e s t s , t h a t t h e pH s h o u l d be s l i g h t l y b e l o w 7 f o r t h e b e s t r e c o v e r y o f a r s e n o p y r i t e . 3.6'. T e s t 6. lo D u p l i c a t e T e s t 3, B u t U s i n g More S u l p h u r i c A c i d . Charge t o B a l l M i l l Ore - 1000 gms. l a t e r - 1000 gms. KCK - \ 0 . 1 # / t o h Lime - 2.0 # / t o n G r i n d i n g Time 20 m i n u t e s . 0.108 # / t o n 0.438 '# / t o n C o n d i t i o n e d pH-Skimmed C e l l C o n c e n t r a t e 1. Added — . C r e s y l i c A c i d A e r o f l o a t #15 • 2 m i n u t e s 8.68 10 m i n u t e s The f r o t h was weak? h u b b i e s were d i r t y - and n o t s t r o n g . The f r o t h , was s i m i l a r t o t e s t #5, C 1, e x c e p t t h a t b u b b l e s were c l e a n e r a t t h e end. C o n c e n t r a t e 2. Added - C u S 0 4 1.0 # / t o n C o n d i t i o n e d - 2 m i n u t e s pH - 8.18 Skimmed - 10 m i n u t e s The f r o t h was weak a n d : d i r t y , s i m i l a r . t o T e s t #5, C 2. C o n c e n t r a t e 3. Added C o n d i t i o n e d Skimmed P i n e O i l #208 1:1 H2SO4 2 m i n u t e s 15 " 0.08# / t o n 0.02 # / t o n 10. c . c . pH - 3,67 .57-A t f i r s t , o b t a i n e d f r o t h o f b i g , h e a v i l y armored b u b b l e s , b u t a f t e r two m i n u t e s , t h e b u b b l e a became s m a l l e r , even, w e l l -armored and p e r s i s t e n t . T h i s was t h e most p e r s i s t e n t f r o t h so f a r o b t a i n e d i n t h e t e s t s . * C o n c e n t r a t e 5 B. Skimmed - 12 m i n u t e s .. pH - 3.67 G-ot a t o u g h , p e r s i s t e n t f r o t h , o f s m a l l , h e a v i l y armored b u b b l e s a t f i r s t , b u t i t g r a d u a l l y and r a p i d l y weakened, and a t t h e end was v e r y weak. C o n c e n t r a t e 4. Skimmed - 13 m i n u t e s pH •' - 4 The f r o t h was p o o r . The b u b b l e s were s m a l l , weak and d i r t y , and c a r r i e d l i t t l e m i n e r a l . RESULTS. Au Cu Fe As Au Cu Fe As Cone- Wght. e n t r a t e #nof Feed Au o z / t o n Cu % Fe % As Rec Au Rec Cu Rec Fe Rec As Rec. 1 31.6 3 i l 2.64 5.8 38.7 6.8 20.2 39*2 4.0 2.6 2 17.5 1.7 -> 0.80 0.8 33«3 7.1 3.4 3.0 1.8 1.4 3 602.2 58.9 0.44 0.32 37.1 11.7 64.8 41.0 71.1 83.1" 3b 55.2 5.4 0.32 0.40 35.8 8.8 4.4 4,7 6,3 5.8 4 11.9 1.1 0.32 0.83 28.8 5.1 1.0 2.2 1.1 0.7 T 304.1 29.8 0.08 0.15 16.3 1.8 6.0 9,9 15.7 6.4 1022.5 100.0 100.0 100.0 1,100.0 FeAsS CuFeS„ FeS; , FeAsS CuFeS,, F e S 2 Cone- Grade Grade Grade Rec. Rec. Rec. e n t r a t e A r s e n o - C h a l c o - P y r i t e A r s e n o - C h a l c o - P y r i t e p y r i t e p y r i t e p y r i t e p y r i t e 1 14.8 16.6 54.1 2.6 39.2 3,6 2 15.4 2.3 51.7 1.4 3.0 1.9 3 25.4 0.9 53.2 83.1 41.0 68.5 3b 19.1 1.1 54.5 5.8 4.7. 6.5 4 11.1 2.4 45.8 0.7 2.2 1.2 T 3.9 0.4 28.1 6.4 9.9 18.3 100.0 100.0 100.0 C o n c l u s i o n . I t i s e v i d e n t t h a t a r e l a t i v e l y h i g h amount o f s u l -p h u r i c a c i d i s n o t s a t i s f a c t o r y . F o r t h e b e s t r e c o v e r y o f a r s e n i c t h e pK should, n o t drop b e l o w 4.0. • An e x a m i n a t i o n o f t h e No. 3 c o n c e n t r a t e f o r t h e l a s t t h r e e t e s t s shows t h a t g o l d i s d e p r e s s e d i n an a c i d c i r c u i t i n p r o p o r t i o n t o t h e i n c r e a s i n g a c i d i t y . hi' TEST 7. To T e s t C o l l e c t o r s # 206 and #-501, and F r o t h e r P i n e O i l . Charge t o B a l l M i l l Ore 1000 gms. ~ ~ : Water 1000 gms. K a 2 C 0 3 4 # / t o n KCN o . l # / t o n #208 0.05 # / t o n . G r i n d i n g Time - 20 m i n u t e s . Cell C o n c e n t r a t e 1. Added - Pine. O i l 0.68 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed 30 " pH - 7.82 F o r t h e f i r s t m i n u t e , t h e h u b b i e s were s m a l l , and t h e . f r o t h weak and d i r t y . Then g o t a " ' f r o t h o f l a r g e and s m a l l b u b b l e s , w h i c h were o v e r - m i n e r a l i z e d . A f t e r f i f t e e n m i n -u t e s , t h e f r o t h ?/as much. b e t t e r ; i t had j u s t t h e r i g h t p e r -s i s t e n c e , t h e b u b b l e s were o f medium s i z e and n o t t o o h e a v i l y m i n e r a l i z e d . C o n c e n t r a t e 2. Added - #361 . 0.07 # / t o n C o n d i t i o n e d - 2 minutes Skimmed - 15 " pH - 7.68 The b u b b l e s were n o t a s a l r g e as in C o n c e n t r a t e b u t were w e l l m i n e r a l i z e d . The f r o t h had t h e r i g h t c o n s i s t e n c y . TES' r 7 \ \ V T o l d \ e 0 (SO 7 €C > \ A r s e n i c \ \ \ L \ p H \ '!, T r o n 9 \\ B u l k 1 V \ \ \ \\ Copp er d \ ' A 11 V Nl o Vl 0 V Hi R) c \\ .0 s. VI \ \ K V 1 ttl , \ \ _\_ ?c )_ r Zc $ ) 1. i \ \ • i / >\ / i s •* C o c o « o V p E \ \ \ \ I \ \ \ i 1 \ \ \ \ < D- 4a a 7 <3<S \ V \ » A \ \ \ i \ 1 i N '—\ • 9 \ \ in Q 1 Hi > L s 1 0. 0 VI M \ 0 ( k. o >c "v. G \ N \ 1 1 \ V \ I c -). s 1 \ V < 1 V \ \ V c ) t Q z J r 7^ r IR ATTR,C 1 ! 40 * C o n c e n t r a t e 5. %dded 1:1 H 2 S O 4 3 c . c . . P i n e O i l 0.34 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed • * 6 " pH - / 4.82 The f r o t h was good; t h e b u b b l e s were s m a l l b u t d i d n o t c a r r y much m i n e r a l . RESULTS. A.B' C O ' . '• 'A<< ' v> U A1 A Conc-e n t r a t e Wght. • % o f Feed Au o z / t o n Cu % , Fe % ' .. As •* Au Rec Cu Rec Fe Rec As' Rec 1 438.1 42.3 0.52 0.77 34.9 11.4 67.8 76.0 50.9 60 .8 ; 2 .232.4 22.4 0.52 0*14 36.6 8.8 22.0 7.6 . 28.3 24,9 3 31.7 3.1 Q.24 0.09 33 « 3 9.3 2.3 0.7 3 a 5 3 © 5 T 332«3 32.2 0.08 0.21 15.8 2.7 7.9 •15.7 17.3 10.8 1034.5 100.0 LOO.O 100.0 100.0 100.0 C o n c l u s i o n . C l o o e c t o r # 208 i s a b e t t e r c o l l e c t o r t h a n 301 f o r gold> c h a l c o p y r l t e , and t o a l e s s e r e x t e n t , f o r a r s e n o p y r i t e . I t has no e f f e c t on p y r i t e . . • & TEST 8. , **•-" To D u p l i c a t e T e s t %, U s i n g C r e s y l i c A c i d as a F r o t h e r . Charge t o B a l l ' M i l l . .Ore - 1000 gms. Water - - 1000 gms„ ¥a 2C0g - 4 # / t o n KCN - 0.1 # / t o n -.. #208 - : 0.05 # / t o n G r i n d i n g Time - 20 m i n u t e s . C e l l C o n c e n t r a t e 1. Added - C r e s y l i c A c i d 0.11 f / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed 30 " ; p H - 9.74 For t h e f i r s t m i n u t e , t h e b u b b l e s were d i r t y ; t h e n f o r t h e n e s t t e n m i n u t e s , . t h e f r o t h was e x c e l l e n t . The b u b b l e s were o f medium s i z e , and n o t t o o w e l l m i n e r a l i z e d , w h i l e t h e f r o t h Jtiad j u s t t h e r i g h t p e r s i s t e n c e . A f t e r t e n m i n u t e s , t h e f r o t h g r a d u a l l y weakened and t h e b u b b l e s became l e s s m i n e r a l i z e d . C o n c e n t r a t e 2. Added - #301 0.07 # / torn ' ' C o n d i t i o n e d - 2 m i n u t e s Skimmed 15 " p H - 8.03 . For?th'e f i r s t m i n u t e , a t h i c k s i l v e r y scum was formed. Then got a f r o t h composed of l a r g e , m i n e r a l i z e d b u b b l e s , w h i c h g r a d u a l l y became l e s s m i n e r a l i z e d . The b u b b l e s a t f i r s t , were l a r g e , b u t g r a d u a l l y became s m a l l e r , t h e n i n c r e a s e d i n s i z e t o w a r d s t h e end, and became v e r y weak. RESULTS. AU . CU FE A§ AU. CU FE AS Conc- Wght. % o f G o l d , Cu Fe As Au Cu Fe As e n t r a t e Feed O z / t o n % % % Rec Rec Rec Rec 1 355.4 35.3 0.88 0.98 35.1 11.3 76.0 83.5 . 41.5 48.9 2 288.0 28.6 0.24 0.07 35.8 9.2 16.8 5,2 35.2 32.2 T 363.5 36.1 0.08 0.13 18.7 4.3 7.2 11.3 23.3 18.9 1006.9 100.0 100.0 100.0 100.0 100.0 FeAsS CuFeS 2 FeSg FeAsS OuFeBg F e S ? •Conc-e n t r a t e P e r c e n t A r s e n o -p y r i t e P e r c e n t C h a l c o -p y r i t e P e r c e n t P y r i t e R e c o v e r y A r s e n o -p y r i t e R e c o v e r y C h a l c o -p y r i t e R e c o v e r y P y r i t e 1 ^ 2 4 * 6 2.8 ; 48.6 48.9 83.5 39.7 2 . 20.0 0.2 54.5 32 • 2 5.2 36.0 • T 0.4 29.1 18.9 100.0 11.3 100.0 24.3 100.0 C o n c l u s i o n . There i s l i t t l e d i f f e r e n c e between P i n e O i l and C r e s y l i c A c i d as f r o t h e r s , but t h e l a t t e r i s a c o l l e c t i n g power f o r g o l d and c o p p e r . -43.'-TEST 9. To D u p l i c a t e T e s t 7, U s i n g A e r o f l o a t # 15 as a F r o t h e r . Charge t o , B a l l M i l l ' Ore 1000 gms. Water 1000 gms. - ¥a 2COs 4-f / t o n : KCN 0.1 # / t o n ..# 208 0.05 # / t o n C e l l ^ r i n d i n g Time 20 m i n u t e s . C o n o e n t r a t e 1. Added ' A e r o f l o a t # 15 0.088 #•/ t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed • 30 m i n u t e s pH : - 8.83 F o r t h e f i r s t m i n u t e t h e b u b b l e s w e r e s m a l l and weak; t h e n a t o u g h , o y e r - p e r s i s t e n t f r o t h f ormed. The b u b b l e s were o v e r - m i n e r a l i z e d , and g r a d u a l l y -i n c r e a s e d i n s i z e u n t i l , a f t e r f i f t e e n m i n u t e s , t h e y were t h e r i g h t s i z e . A t t h i s p o i n t , b o t h t h e f r o t h and b u b b l e s were good, and s t a y e d t h a t way u n t i l t h e end o f skimming. However, t h e b u b b l e s g r a d u a l l y became l e s s m i n e r a l i z e d . C o n c e n t r a t e 2. Added # 301 .07 # / £on C o n d i t i o n e d 2 m i n u t e s Skimmed 15 m i n u t e s pH - 8.05 I I ' .* I n t h e f i r s t m i n u t e , a t h i c k scum o f m i n e r a l formed, t h e b u b b l e s g r a d u a l l y formed, some o f them l a r g e and h e a v i l y m i n e r a l i z e d . The f r o t h was over p e r s i s t e n t . The b u b b l e s r e d u c e d i n s i z e u n t i l o f medium s i z e , and m i n e r a l i z a t i o n l e s s e n e d , b u t t h e f r o t h was t o o t o u g h t h e whole t i m e . RESULTS. Conc-e n t r a t e Wght. % of Au Feed o z / t Cu on % Fe As % % Au Cu . Rec Rec Fe Rec As Rec 1 358.4 34.8 0.56 1.05 35.0 11,. 9 56.5 '. 91.8 42.3 50.2 2 248.1 24.1 0.08 0.07 37.4 9.5 5.5 3.6 31.4 27.6 T T422.0 41.1 0.32 0.05 18.6 4.5 38.0 4.6 26.3 22.2 1028.5 100 .0 100.0 100.0 100.0 100.0 •FeAsS CuFeSp Fe*S, FeAsS CuFeSp FeS„ Conc-e n t r a t e Grade A r s e n o -p y r i t e Grade C h a l c o -p y r i t e Grade P y r i t e Rec. A r s e n o -p y r i t e R ec. C h a l c o -p y r i t e Reo. P y r i t e 1 25.9 3.0 47.7 50.3 91.8 39.5 2 20.7 0.2 57.0 27.6 3.6 32.6 T 9.8 0.2 28.7 2 2 • 2 100.0 4.6 100.0 27.9 100.0 C o n c l u s i o n . A e r o f l o a t # 15 does n o t ap p e a r t o be as s a t i s f a c t o r y a f r o t h e r c o n c e r n i n g o n l y t h e c o l l e c t i n g power, b ut as a f r o t h e r . " o n l ^ i t was c o n s i d e r e d b e t t e r t h a n e i t h e r P i n e O i l o r C r e s y l i c A c i d , due'to t o u g h n e s s . o f b u b b l e s and g e n e r a l b e h a v i o u r . TEST 10. To Add # 501 to the B a l l M i l l I n s t e a d o f # 208 Charge t o B a l l M i l l G r i n d i n g Time Ore Water : •Na2003 : ICON # 501 20 m i n u t e s . 1000 gms . 1000 gms. 4 # / t o n 0.1 #•/ t o n 0.05 # / t o n C e l l C o n c e n t r a t e 1, Added -C o n d i t i o n e d -SEimmed. -P H . -A e r o f l o a t # 15 2 minutes 50 minutes 8.82 0.088 # / t o n F o r t h e f i r s t m i n u t e , t h e b u b b l e s were s m a l l , weak and d i r t y . F o r t h e r e s t o f t h e t i m e t h e f r o t h and b u b b l e s w e r e , on t h e w h o l e , good, a l t h o u g h t h e •bubbles were s l i g h t l y o v e r -m i n e r a l i z e d . . . . C o n c e n t r a t e 2. Added A e r o f l o a t # 1 5 # 208 H 0,44 f./. t o n 0.07 f / t o n C o n d i t i o n e d Skimmed : pH 2 m i n u t e s 15 " - •• ' 8.4 . The f o r t h had t h e r i g h t p e r s i s t e n c e , t h e b u b b l e s were of medium s i z e and l i g h t l y m i n e r a l i z e d . RESULTS. Conc-e n t r a t e Wght. P e r c e n t o f F e e d Au Cu o z / t o n % Fe % As % Rec Au Rec Cu Rec Fe Rec As 1 206.2 20.1 0.78 1.64 35.2 9.4 52.7 77.0 24.1 25.7 2 82.8 8.1 0.32 0.43 33.3 9.9 8.7 8.0 9.2 10.7 T 757.0 71.8 0,16 0.09 27.3 6.6 38.6 15.0 66.7 63.6 1026.0 100.0 100.0 100.0 100.0 100.0 FeAsS CuFeS F e S P FeAsS CuFeSg FeS Conc- Grade — A Grade Brade Rec. R e c . : & R e c . e n t r a t e A r s e n o - C h a l c o - P y r i t e A r s e n o - C h a l c o - P y r i t e p y r i t e p y r i t e p y r i t e p y r i t e 1 20.5 4.7 50.0 25,7 77.0 23.3 2 21.5 1.2 48.3 10.7 8.0 9.0 T 14.4 0.3 40.5 63.6 15.0 67.7 100.0 100.0 100,0 C o n c l u s i o n . The g o l d a n d copper c o n t e n t s were i n c r e a s e d i n t h i s t e s t and t h e r e was l e s s g o l d i n t h e t a i l i n g s . T h i s i n d i c a t e d t h a t % 301, when u s e d i n t h e Sail M i l l i n p l a c e o f # 208, i s a b e t t e r c o l l e c t o r f o r g o l d and c h a l c o p y r i t e , b u t n o t f o r a r s e n o p y r i t e . TEST 11. To A t t e m p t To Get a B u l k . C o n c e n t r a t e , Charge t o B a l l M i l l . G r i n d i n g Time Ore Water.. N a 2 C 0 3 WE # 2 0 8 # 3 0 1 20 m i n u t e s . 1000 gms. 1000 Gms, 4 # / t o n 0.1 # / t o n 0.05 # / t o n 0.05 # / t o n C e l l C o n c e n t r a t e 1. Added •C o n d i t i o n e d Skimmed pH A e r o f l o a t # 15 2 m i n u t e s 30 " 8.63 .088 # / t o n A t f i r s t t h e h u b b i e s and f r o t h were good, t h e n t h e b u b b l e s became t o o l a r g e and o v e r m i n e r a l i z e d , and t h e f r o t h t o o t o u g h . The f r o t h g r a d u a l l y weakened so a f t e r f i f t e e n m i n u t e s , one drop of A e r o f l o a t # 15 was added. The f r o t h and b u b b l e s were good u n t i l t h e end o f skimmimg. RESULTS. Conc- WgWfc % of G o l d Cu Fe As Au Cu Fe As <• e n t r a t e Feed o z - t o n % % Reo Rec Rec Rec 1 580.1 58 0.54 0.65 36.8 1140 90.3 89.9 71.0 76.3 T 423.7 42 0.08 0.10 20.3 4.7 9.7 10.1 29.0 23.7 1003.8 100.0 100.0 100.0 100.0 Conc-e n t r a t e Grade A r s e n o -p y r i t e .Crade C h a l c o -p y r i t e Grade P y r i t e , Rec. A r s e n o -p y r i t e R e c . C h a l c o -p y r i t e R ec. P y r i t e 1 23.9 1.5 53.2 76.3 89.9 69.8 T 10.2 0.2 31.5 23.7 10.1 30.2 100.0 100.0 100.0 C o n c l u s i o n . T h i s t e s t showed t h a t a b u l k c o n c e n t r a t e c o n t a i n i n g 90.3 % o f t h e g o l d can be o b t a i n e d i n a c o n c e n t r a t e vri.th 58 %o£ t h e f e e d . TEST 12. To T e s t The E f f e c t Of H i g h A l k a l i n i t y . Charge t o B a l l M i l l , G r i n d i n g Time Ore Water NaOH # 208 20 m i n u t e s 1000 gms. 1000 gms . 6 # / t o n 0.05 # / t o n C e l l C o n c e n t r a t e 1. Added C o n d i t i o n e d -Skimmed pH A e r o f l o a t # 15 2 m i n u t e s 30 " 12.0 0.044 # / t o n A t f i r s t a v e r y t o u g h d i r t y f r o t h o f t i n y h u b b i e s , f o r m e d . The b u b b l e s s l o w l y became l a r g e r and more m i n e r a l -i z e d , u n t i l t h e y w e r e o f medium s i z e . The f r o t h a t f i r s t , was o v e r p e r s i s t e n t ; l a t e r i t im p r o v e d , b u t was n o t s a t i s -f a c t o r y a t any t i m e . C o n c e n t r a t e 2. Added - #301 . l x l H 2 S 0 4 C o n d i t i o n e d Skimmed pH . 0.07 # / t o n - s u f f i c i e n t t o b r i n g down t h e pH. 2 m i n u t e s 25 " 9.42 A s i l v e r scum c o a t e d t h e s u r f a c e o f t h e p u l p . L i v e r b u b b l e s c o m p l e t e l y c o a t e d w i t h m i n e r a l f o r m e d , and t h e f r o t h was o v e r p e r s i s t e n t . B u b b l e s g r a d u a l l y d e c r e a s e d i n s i z e , and became l e s s m i n e r a l i z e d u n t i l a f t e r e i g h t m inutes t h e m i n e r a l -i z a t i o n was s a t i s f a c t o r y . •'50-RESULTS. Conc-e n t r a t e Wght. . % o£ G o l d Feed o z / t o n Cu % F e % As Au % Rec Cu Rec Fe Rec As Rec 1 254.4 24.8 0.64. 1.45 315 © 3 10.4 45.6 82.3 29.8 30.8 2 447.4 43.7 0.32 0.14 37.1 10.7 40.0 14.1 55.0 55.5 T 321.9 31.5 0.16 0.05 14.2 3.7 14.4 3.6 15.2 13.7 1023.7 100.0 100.0 100.0 100.0 100.0 FeAsS CuFeS? F e S 0 FeAsS CuFeSp F e S 9 Conc-e n t r a t e Brade A r s e n o -p y r i t e Grade C h a l c o -p y r i t e Grade P y r i t e Rec. A r s e n o -p y r i t e Rec. C h a l c o p y r i t e R ec. P y r i t e 1 22.6 1.8 51.Q) 30.8 82.3 29.4 2 23.3 0.9 . 54.5 55.5 14.1 55.2 T 8.1 0.4 21.1 13.7 100.0 3.6 100.0 15.4 100.0 C o n c l u s i o n . T h i s i n d i c a t e s t h a t a f a i r l y h i g h a l k a l i n i t y does n o t a f f e c t t h e s e l e c t i v e s e p a r a t i o n o f p y r i t e and a r s e n o p y r i t e . TEST 13 To C l e a n A B u l k C o n c e n t r a t e . Charge t o B a l 1 M i l l . C e l l Ore Water 1000 gms. 1000 gms. G r i n d i n g Time Na2C0 3 4# / t o n # 208 0.05 # / torn # 301 0.05 # / t o n 20 m i n u t e s . C o n c e n t r a t e 1. Added C o n d i t i o n e d Skimmed p l l A e r o f l o a t # 1 5 2 m i n u t e s 30 " 8.63 0.088 # / t o n ( t o t a l ) The f r o t h was weak and d i r t y f o r t h e f i r s t m i n u t e ; t h e n l a r g e , o v e r m i n e r a l i z e d b u b b l e s and an o v e r p e r s i s t e n t f r o t h f o rmed. The f r o t h g r a d u a l l y weakened and t h e b u b b l e s became l e s s m i n e r a l i z e d . A f t e r f i f t e e n m i n u t e s , • o n e drop o f A e r o -f l o a t # 15 was added, and a good f r o t h o f l i g h t l y armored b u b b l e s o f medium-size was o b t a i n e d . C l e a n e r C o n c e n t r a t e 1. Added Pulp d i l u t i o n 4:1 ( r o u g h l y ) Skimmed .6 m i n u t e s pH 7.7 • L a r g e , t o u g h , h e a v i l y - m i n e r a l i z e d b u b b l e s formed, b u t t h e y g r a d u a l l y decreased i n s i z e and load of m i n e r a l . C l e a n e r C o n c e n t r a t e 2. Added A e r o f l o a t # 15 0.044 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - . 4 " pH 8.0 The f r o t h wa.s f a i r l y t o u g h j t h e h u b b i e s were s m a l l , and n o t n e a r l y as h e a v i l y m i n e r a l i z e d as t h o s e o f t h e p r e v i o u s c o n c e n t r a t e . C l e a n e r C o n c e n t r a t e 3. Added A e r o f l o a t ^ 15 ; 0.044 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 6 m i n u t e s pH - 7.80' A good f r o t h of s m a l l , l i g h t l y m i n e r a l i z e d b u b b l e s was o b t a i n e d . RESULTS. Conc-e n t r a t e % o f Wght. Peed G o l d o z / t o n Fe % As of /" Au Rec. Fe Rec. CI CC1 236.2 23.1 0.76 34.8 8.0 46.2 28.6 CC2 72.8 7.1 0.60 31.5 11.2 8.0 CC3 52.1 5.1 0.48 33.9 6.4 6.3 CCT 68.6 6.7 0.32 30.8 5.7 7.4 T 591.6 58.0 0.20 24.1 30.5 49.8 1021.3 100.0 100.0 100.0 Conclusion-. R e s u l t s o b t a i n e d i n t h i s a t t e m p t t o s e p a r a t e t h e p y r i t e and a r s e n o p y r i t e by c l e a n i n g a b u l k c o n c e n t r a t e , were n o t s a t i s f a c t o r y . These r e s -u l t s bear o u t t h e f i n a l c o n c l u s i o n r e a c h e d t h a t p y r i t e a n d a r s e n o p y r i t e r e a c t s i m i l a r l y t o a l l r e a g e n t s and c a n n t be s e p a r a t e d s a t i s f a c t o r i l y . TEST ;it To Get A B u l k C o n c e n t r a t e U s i n g 2-6 ( P e n t a s o l X a n t h a t e )  as a C o l l e c t o r . . Charge to B a l l M i l l Ore 1000 gms. Water 1000 gms. ' . H a 2 C 0 3 4 # / t o n C e l l C o n c e n t r a t e 1. Added Z-6 0.12 # / t o n A e r o f l o a t # 15 0.088 # / t o n ( t o t a l ) C o n d i t i o n e d - 2 m i n u t e s Skimmed - 28 " pH - 8.98 A good f r o t h o f w e l l m i n e r a l i z e d b u b b l e s was o b t a i n e d . R1SULTS. Conc-e n t r a t e Wght. % o f Feed G o l d o z / t o n Fe % As % Rec Au Rec Fe 1 456.5 45.2 0.62 34.3 8.9 76.4 55.8 T 554.3 54.8 0.16 2 2 f 4 23.6 44.2 1010.8 100.0 100.0 100,0 C o n c l u s i o n . T h i s c o l l e c t o r was n o t s a t i s f a c t o r y as i t p r o d u c e d a c o n c e n t r a t e c a r r y i n g o n l y 76.4 % of t h e g o l d i n 45.2^ of t h e b u l k . 55.' TEST 15, To Get A B l a n k e t C o n c e n t r a t e . Charge t o B a l l M i l l . Ore 1000 gms Water 1000 gms Time of G r i n d i n g - 20 m i n u t e s . The charge f r o m t h e - h a l l m i l l was washed o y e r a c o r d u r o y b l a n k e t . Cone. Wht. f Feed Au. o z / Au. t o n Recov. 1 .179.8 18 0.44 18.0 C o n c l u s i o n . T h i s t e s t showed t h a t b l a n k e t c o n c e n t r a t i o n o f t h i s o r e i s n o t s a t i s f a c t o r y . From t h e r e s u l t s o b t a i n e d i n t h i s t e s t and t h e f o l l o w i n g one, i t i s e v i d e n t t h a t t h e r e i s no c o n c e n t r a t i o n , t h e r e c o v e r y depending e n t i r e l y on t h e b u l k r e m a i n i n g on t h e b l a m k e t . * TEST 16. To Get a B l a n k e t C o n c e n t r a t e and Then F l o a t t h e B l a n k e t T a i l i n g s . "Charge t o B a l l M i l l Ore 1000 gms. Water 1000 gma. l a 2 C 0 3 4 # / t o n KCK 0.10 # / t o n Time o f g r i n d i n g - 20 m i n u t e s . C o n c e n t r a t e 1. The charge f r o m the b a l l m i l l was washed o v e r a c o r d u r o y b l a n k e t . The t a i l i n g s were f i l t e r e d , p u t i n t o t h e c e l l and d i l u t e d 4 s 1 . C e l l C o n c e n t r a t e 2. Added - # 3 0 1 0.10 # / t o n A e r o f l o a t # 15 0.088 # / t o n 1:1 B 2 S 0 4 0.7 c . * f . ( t o l o w e r t h e pH) C o n d i t i o n e d - 2 m i n u t e s Skimmed 15 " pH . - 6.9 One d r o p " o f A e r o f l o a t # 15 produced a weak f r o t h , so one more drop was added. T h i s p r o d u c e d l a r g e , h e a v i l y m i n e r a l i z e d b u b b l e s a t f i r s t , b u t t h e y l e s s e n e d i n s i z e and m i n e r a l b u r d e n u n t i l a f t e r t h r e e m i n u t e s , t h e f r o t h was good. C o n c e n t r a t e 3. Added - C u S 0 4 1 # / t o n # 301 0.05 # / t o n A e r o f l o a t #15 0.044 # / t o n C o n d i t i o n e d - 2 m i n u t e s . Skimmed - . 1 2 " ' pH - 6.78 57-• A good f r o t h o f s m a l l , w e l l - m i n e r a l i z e d b u b b l e s a t f i r s t , was o b t a i n e d . The b u b b l e s remained s m a l l , b u t s l o w l y weak-ened and became d i f - t y . RESULTS. Cone. Wt.' % Feed G o l d o z / t o n Fe % • As % Au '•vReofo'. Fe As Rea% C - l 236.5 24.5 0.44 -27.3 C-2 285.7 ' 30,0 0.68 38.8 11.3 48.5 39.1 41.4 C-3 114.9 12.1 0,38 38,7 9,0 10.7 15.7 T 317.3 954.4 33.4 0.16 13.5. 100.0 C o n c l u s i o n . • These r e s u l t s show t h a t f l o a t a t i o n o f b l a n k e t t a i l i n g s does n o t g i v e a b e t t e r r e c o v e r y t h a n s t r a i g h t f l o t a t i o n . TEST 17. To Use Sodium S u l p h i t e ( Ha ?SO g) I n s t e a d o f X.GN i n t h e B a l l M i l l , Charge t o B a l l M i l l Ore 1000 g r s . Water 1000 g r s . Wa2C0 5 I # / t o n f 208 0.05 # / t o n 301 0.05 # / t o n K a 2 S 0 3 0,10 # /' t o n 20 m i n u t e s . Time o f G-rinding C e l l C o n c e n t r a t e 1. Added C o n d i t i o n e d Skimmed PH O.I3'2 # / t o n A e r o f l o a t # 15 2 m i n u t e s 30 " 7.98 The f r o t h was good, as were t h e b u b b l e s , A e r o f l o a t # 1 5 b e i n g added whenever t h e f r o t h g o t weak.. ,... .,. . ... i, RESULTS. Cone. Wt. Feed Au o z / t o n Fe % As 7° Au : R e c ^ Fe Rec . As Rec . 1 510.7 51.0 0.68 39.2 10.8 81.1 66.2 70,8 T 507.0 49.0 0.16 18.9 1007.7 100.0 1 00.0 6 C o n c l u s i o n , There i s no a p p r e c i a b l e d i f f e r e n c e between t h e s e r e s u l t s and t h o s e o b t a i n a b l e f o r t e s t #11, showing t h a t sodium s u l p h i t e has l i t t l e e f f e c t . TEST 18. - - - - - ..%> • ,• To D u p l i c a t e T e s t # 1 7 , But U s i n g More Sodium S u l p h i t e . Charge t o B a l l M i l l . C e l l Added Ore Water K a 2 C 0 3 Wa 2S0g # 208 # 3 0 1 C o n c e n t r a t e 1. A e r o f l o a t # 15 1000 gms. 1000 gms. 4 # / t o n 1.0 # / t o n 0.05 # / t o n 0.05 # / t o n 0.132 # / t o n ( t o t a l ) C o n d i t i o n e d . Skimmed pH '2 m i n u t e s ' - 30 " 8.42 . The "bubbles were s m a l l and d i r t y a t f i r s t , t h e n became w e l l m i n e r a l i z e d . They i n c r e a s e d i n s i z e u n t i l q u i t e l a r g e . Whenever t h e . f r o t h became weak, A e r o f l o a t # 15 was added. RESULTS. Cone. Wght. 589.4 425.7 1015.1 Peed 58.0 Au o z / t o n 0.64 0.14 Fe As 38.3 Au Rec 10.6 86.5 15.5 100.0 Fe Rec As Rec 75.1 79.8 C o n c l u s i o n . O t h e r t h a n an i n c r e a s e d b u l k , t h e a d d i t i o n o f more s o l u t i o n o f sodium s u l p h i t e had no e f f e c t . 60-TEST 19. To S e p a r a t e P y r i t e and A r s e n o p y r i t e a t a Low pH. Charge t o B a l l , M i l . B e l l Time o f G r i n d i n g . C o n c e n t r a t e . 1. Ore 1000 gms. 'Water 1000 gms. H a 2 0 0 3 4 # / t o n NagSOg 1 # / t o n 20 m i n u t e s , Added A e r o f l o a t # 15 #301 H 2 S 0 4 (1:1) 0.088 # / t o n 0.10 #n/ t o n 3.2 c . c . C o n d i t i o n e d Skimmed pH 2 m i n u t e s 7 " 5.6 A good, p e r i s t e n t f r o t h o f l a r g e , w e l l - m i n e r a l i z e d h u b b i e s was f o r m e d . The b u b b l e s became s m a l l e r , a t end o f s i x m i n u t e s , m o r e . A e r o f l o a t # 15 was added. I n a n attempt t o g e t a h i g h grade c o n c e n t r a t e t h e t i m e o f skimming was c u t down. C o n c e n t r a t e 2. Added 0.044 # / t o n 0.05 # / t o n 1.0 # / t o n A e r o f l o a t # 15 # 208 C u S 0 4 2 mi n u t e s 5 minutes 5.12 The f r o t h was t o u g h and composed o f s m a l l , f a i r l y w e l l m i n e r a l i z e d b u b b l e s , w h i c h soon became c l e a n . C o n d i t i o n e d Skimmed pH 6 2 -TEST l:9sL RESULTS, Cone. Wght. % Feed Au F e As Au Fe As o z / t o n # # Reo, R e c . Rec. 1 150.7 15.0 0.86 40.2 10.5 30.6 20.2 20,2 2 144.3 . 14.3 0.56 "38,1 6.8 19.0 18.4 12.5 T 711.9 70.7 0.30 - 50.4 100*6.9. 100.0 100.0 C o n c l u s i o n . T e s t u n s a t i s f a c t o r y as t h e r e i s no s e p a r a t i o n o f p y r i t e and a r s e n o p y r i t e . TEST 20. T o t r y f s e l e c t i v e f l o t a t i o n b y T a k i n g a P y r i t e c o n c e n t r a t e and . t h e n an a r s e n o p y r i t e c o n c e n t r a t e . P r o c e d u r e - To f l o a t t h e p y r i t e w i t h a s m a l l amount o f P o t a s s i u m E t h y l X a n t h a t e f o l l o w e d b y a more p o w e r f u l ' c o l l e c t o r f o r t h e a r s e n o p y r i t e . Charge t o B a l l M i l l Ore 1000 gms. Water 1000 gms. HagCOg, 4 # / t o n Time o f G r i n d i n g - 20 m i n u t e s . C o n c e n t r a t e 1. Added - P i n e O i l #5 - 0.069 % / t o n -P o t . E t h y l X a n t h a t e 0.01 # / t o n C o n d i t i o n e d - 2 m i n u t e s Skimmed - 35 " pH - 8.17 Got a,good f r o t h o f w e l l - m i n e r a l i z e d b u b b l e s . C o n c e n t r a t e 2. Added -, P i n e O i l # 5 - 0,069 # / t o n ' Z-6 0.40 # / t o n C u S 0 4 1.5 # / t o n C o n d i t i o n e d - 2 m i n u t e s . Skimmed 10 " pH - 8.15 A p e r s i s t e n t , d i r t y f r o t h w i t h s m a l l , f a i r l y m i n e r a l i z e d b u b b l e s was o b t a i n e d . RESULTS. Cone. Wght. Feed Au pz/ton Fe % As 7° Au Rec Fe Rec As Rec 1 320.0 32.0 0.62 40.4 10.5 63.2 • 40.1 47.3 2 20.9 2.1 0.44 36.1 9.7 3.0 2.4 3.6 T 660.4 65.9 0.16. 28.0 5.3 33.8 57.5 49.1 100.0 100)0} 100.0 C o n c l u s i o n . The T e s t was a f a i l u r e as t h e r e was no s e p a r a t i o n o f t h e p y r i t e and a r s e n o p y r i t e . 65' TBBT 2 1 . Tp Get A; B u l k 0 o n e e n t r a t e And G l e a n I t i n a H i g h A l k a l i n e C i r o - u l t . C h arge.to B a l l M i l l Ore 1000 gms. Cyan i d e 0.1 # / t o n N a 2 G 0 3 4.0 f / t o n Time o f G r i n d i n g - 20 m i n u t e s . B u l k C o n c e n t r a t e Added - A e r o f l o a t # 15 - 0.088 # / t o n # 208 - 0.05 # / Ton # 501 - 0.05 # / t o n C o n d i t i o n e d - 2 mi n u t e s Skimmed - 19 pH - 8.65 A t f i r s t t h e b u b b l e s were t o o l a r g e , b u t soon i m p r o v e d , p r o d u c i n g a good f r o t h o f o v e r - m i n e r a l i z e d b u b b l e s . C l e a n i n g o f B u l k C o n c e n t r a t e . -: The c o n c e n t r a t e o f 582.0 gms. was t r a n s f e r r e d t o t h e 500 gm. c e l l and d i l u t e d t o 4:1 p u l p d e n s i t y . Sodium h y d r o x i d e was added t o r a i s e t h e pH t o a p p r o x i m a t e l y 11.0. I t was f o u n d t h a t t h e f i r s t a d d i t i o n b r o u g h t t h e pH t o 12.5-*- . As t h i s was t o o h i g h , a few drops o f # s u l p h u r i c a c i d were added. T h i s was a g i t a t e d f o r one m i n u t e and t h e pH was fo u n d t o be 11.5. E v i d e n t l y t h e a g i t a t i o n was i n s u f f i c i e n t as a t t h e c o n c l u s -i o n o f t h e r u n t h e pH was 9.10. ' ' C o n c e n t r a t e 1 - C l e a n e r . Added - NaOH & H 2 S 0 4 ( l : l ) pH - 9.10 C o n d i t i o n e d 1 - 1 m i n u t e Skimmed - 8 m i n u t e s The f r o t h was good and t h e b u b b l e s were w e l l m i n e r a l i z e d . . 66 C l e a n e r C o n c e n t r a t e 2. "* Skimmed - 35 m i n u t e s pH - 8.92 T h i s i s a c o n t i n u a t i o n of 1. . The skimming was c o n t i n u e d u n t i l t h e h u b b i e s were c l e a n . C l e a n e r C o n c e n t r a t e ' 5. Added - A e r o f l o a t # 15 0.044 # / t o n # 3 0 1 . 0.01 # / t o n C o n d i t i o n e d - 2 m i nutes Skimmed -T h i s t e s t was abandoned due t o m e c h a n i c a l t r o u b l e , b u t t h e f r o t h was y e r y s i m i l a r ' t o - 1 and 2. RESULTS. Cone. Wght. Feed Au o z / t o n Cu : % Fe % As % Au Rec Cu Rec Fe Rec Au Rec CI 582.0 61.5 CC1 114.4 12.1 0.78 1.44 38.5 12 .8 28.8 40.2 15.7 20,0 CC2 149.5 15.8 0.64 0.95 38.9 13.5 30.8 34.8 20,8 27.7 CC3 CT 318.1 33.6 0.36 40.5 9,2 36,9 46.1 40.2 T 365.5 38.5 0.03 13.1 2.4 3.5 17.4 12.1 947.5 100.0 100.0 1 00.0 100.0 C o n c l u s i o n . T h i s t e a t produced t h e h i g h e s t f r a d e o f a r s e n o p y r i t e o b t a i n e d . T h i s i n d i c a t e s t h a t a h i g h a l k a l i n i t y i s n e c e s s a r y f o r t h e sep-a r a t i o n o f p y r i t e and a r s e n o p y r i t e . T h i s a g rees w i t h t h e f i n d -i n g s of Wark <x Cox w h i c h a r e summarized e l s e w h e r e . A l t h o u g h t h e a r s e n i c c o n t e n t was 13.59 i t was n o t a c o m m e r c i a l a r s e n i c c o n c e n t r a t e . 6 7 G A S f I 0, T A T I 0 N 6 8 i GAS FLOTATION These tests were not successful so the remarks in the conclusion for each tetet w i l l be sufficient. There was not enough time to make a thorough investigat i n n so the matter was dropped when the second test was finished. The hydrogen sulphide gas was generated i n the usual manner and introduced into the c e l l through the ordinary a i r passage. Carbon dioxide was made by the action of 1:1 H„ SO on lumps of Soda Ash. The gas entered the pulp through the same a i r passage. for the results, see tests # 2 2 and 23. TEST 22. To D u p l i c a t e T e s t # 4, U s i n g Hgf f as t h e g a s Phase. Charge t o B a l l M i l l . Ore . 1000 gms. Water 1000 gms. Lime 2 # / ton KCI O.IDO # / t o n Time of G r i n d i n g - 20 m i n u t e s . C o n c e n t r a t e C e l l C r e s y l i c A c i d 0.109 # / t o n A e r o f l o a t # 15 0.044 # / t o n # 3 0 1 $.05 # / t o n C o n d i t i o n e d - 2 m i n u t e s . As: a n o n - m i n e r a l i z e d f r o t h was o b t a i n e d , 1.0 # / t o n , CuSO^ was added. T h i s had no e f f e c t so a n e x t r a 0.15 # / t o n o f # 301 was added. ;The f r o t h , w a s s t i l l n o n - m i n e r a l i z e d , so t h e t e s t was abandoned. C o n c l u s i o n . The HgS f o u l s t h e p u l p b y p r e c i p i t a t i n g s u l p h u r w h i c h la.^s' t h e m i n e r a l p a r t i c l e s . T h i s i s e x p l a i n e d by a c o n s i d e r a t i o n o f t h e l a w o f mass • a c t i o n w h i c h i s shown by t h e equation-:-( H ) 2 (S) K H 2S " * As t h e i o n i z a t i o n c o n s t a n t . K i s lowm an i n c r e a s e o f t h e hydrogen i o n c o n c e n t r a t i o n due t o an a c i d c i r c u i t n e c e s s i t a t e a p r o p o r t i o n a l d e c r e a s e i n t h e s u l p h u r i o n c o n c e n t r a t i o n . T h i s , f o r c e s t h e s u l p h u r t o p r e c i p i t a t e f o r m i n g a s u l p h u r c o a t i n g on t h e m i n e r a l w h i c h i n h i b i t s t h e f l o t a t i o n . TEST 23. To D u p l i c a t e T e s t # 4 , U s i n g C 0 ? as t h e Gas Phase. Charge t o B a l l M i l l Ore W a ter Lime EOT Time o f G r i n d i n g C o n c e n t r a t e 1. 20 m i n u t e s , 1000 gms. 1000,gms. 2 . 0 f / t o n 0) .10 # / t o n C e l l 0.11 # / t o n ' 0.044 # / t o n 0.05 # / t o n C r e s y l i c A c i d A e r o f l o a t ^ 15 # 301 2 mi n u t e s - 10 " ' 6.67 The f r o t h was weak and d i r t y w h i l e t h e b u b b l e s were s m a l l and l i g h t l y m i n e r a l i z e d . C o n c e n t r a t e 2. Added : -C o n d i t i o n e d Skimmed C o n d i t i o n e d Skimmed pH C u S 0 4 2 minutes 10 » 6.60 1.0 # / t o n The b u b b l e s w e r e s m a l l and l i g h t l y m i n e r a l i z e d j t h e f r o t h was weak and d i r t y . C o n c e n t r a t e 3. Added C o n d i t i o n e d P i n e O i l #301 H 2 S 0 4 2 m i n u t e s . 0.08 # / t o n 0.02 # / t o n 3 c . c . o f 1:1 TEST 2 3 O CZ <?3 C4 T GRADES ( T e s t 23 - c o n ' t . ) Skimmed - 15 mi n u t e s pH - 3.30 A good p e r s i s t e n t f r o t h w i t h f a i r l y w e l l - m i n e r a l i z e d b u b b l e s was o b t a i n e d . M i n e r a l i z a t i o n l a s t e d o n l y a s h o r t t i m e . C o n c e n t r a t e 4. Added - C r e s y l i c A c i d - 0.218 # / t o n B a r r e t t # 6§4 - : ±0.25 # / t o n Soap - - 1 4.0 # / t o n C o n d i t i o n e d - . 2 m i n u t e s Skimmed - 7 m i n u t e s , pH - 5.78 A t f i r s t t h e b u b b l e s / w e r e l a r g e and h e a v i l y m i n e r a l i z e d . A f t e r 5 minutes t h e y changed r a p i d l y p r o d u c i n g a good f r o t h o f s m a l l c l e a n b u b b l e s . The c o n c e n t r a t e had a p e c u l i a r app-e a r a n c e as i f some f l o t a t i o n was t a k i n g p l a c e . Gone. Wght, % o f Feed .-. Au o z / t o n Fe % As % Au Rec . Fe Rec. As • Rec, 1 4.6 :' .45 0.88 33.0 5.65 1.1 0.5 0.5 2 1.8 .17 31.3 5.8 0.3 0.2 3 11.0 1.09 e.<44 35.9 7.9 . 1.3 . 1.3 1.5 4 24.8 2.47 0.33 26.8 5,1 2.2 2.1 2.1 T 967.0 95.82 0.36 30.0 7.1 95.4 95.8 96.7 1009.2 100.0 100,0 100.0 100.0 C o n c l u s i o n . 'The c o n c e n t r a t e s produced %vhen c a r b o n - d i o x i d e was used as t h e gas phase were l o w e r i n grade t h a n t h e s e o f t e s t 4. T h i s i s due t o t h e f o r m a t i o n o f c a r b o n i c a c i d i n t h e s o l u t i o n and t h e p r o b a b l e r e s u l t a n t c o a t i n g o f c a r b o n a t e on t h e m i n e r a l s u r f a c e s , t h e r e b y r e d u c i n g t h e f l o a t a b i l i t y . 72 0 Y A H I :B A, T I 0 N CONCLUSIONS RECCW1ENDATTONS THEORY & TESTS - o O o - o ' O o - o O o -73 SUMMARY OF RESULTS OF CYANIDATION , ., — • . _ _ The r e s u l t s are summarized i n the following items. Further par-t i c u l a r s i J a n be found i n the descriptions f o r each t e s t . I t i s concluded (1) That no matter what type of preliminary treatment the ore receives excepting f i n e grinding, the percent recovery of the gold by cyanid-: a t i o n i s p r a c t i c a l l y the same. (2) That the consumption of lime and cyanide can be lowered eonsider-. ably by the use of l i t h a r g e . This appears to be an example of a chemical oxidizing'agent proving b e n e f i c i a l . (3) That bromocyanide i s not necessary. ( 4 ) That f i n e grinding w i l l increase the gold recovery and at the same time increase the consumption o f the lime and cyanide. (5) That 48 hours are s u f f i c i e n t f o r a g i t a t i o n and that a longer period i s unnecessary and increases the reagent consumption. (6) The following r e s u l t s were obtained from the t a i l s of t e s t 37, which was a d i r e c t cyanidation experiment. /Size S i z e Wt. Gold 'Gold ' Mesh ' ' u . Grs Wt. oz/ton Dist»h •f 250 #56 • 0.5 0.36 250-400 56-40 19.4 14.00 0.22 12.80 400-560 '40-28 39.3 28.40 0.19 22.45. 560-850 28-20 31. 6 22.85 0.20 18.'95/ 850-1100 20-14 20.8 -.15.04 0.26 16.22 1100-1700 14-10 9.8 - 7.08 0.28 8.23 . -1700 -10 .16.9.- ,12.20 - 0.42 21.30' 138.3 100.0 100.0 A recommendation f o r further work i n connection with cyanide t a i l s can be found under heading "Recommendations f o r Further Work". See No. 4. 74 ( 7 ) ; •, The following results were obtained from the infresizing of test 34, which was straight cyanidation after fine grinding. Size '"S.ize'-\ Wt ""It Gold Gold Mesh u Grs. Wt. oz/ton Dist'n f 250 '• f 56 . 0.1 : 0.07 250-400 56-40 0.2 • 0.13' 400-560 40-28 0.5 0.33 560-850 28-20 3.3 2.20 0.10. 1.44 850-1100 •20-14 - 21.8 14.54, •0*18 16.92 1100-1700 14-10 40.1 26.75. 0.18 31.02 -1700 : .-10 • 83.9 56.00 0.14 50.62 100.0 100 The results show that the gold remaining in the very finest grind i s the c h i e f source of loss. RECOMMENDATIONS FOR FUTURE WORK If at any time fu r t h e r tests are made on the Wisconsin Ore, the following suggestions might be of some help. (1) The p o s s i b i l i t i e s , o f very fine grinding should be examined. A l -though the gold recovery i n test 38 was 72.7$, the grinding was be-yond the present practical range. (2) The use of bromocyanogen should be studied. Although in these test's the addition d i d hot ma t e r i a l l y increase the recovery, i t should be noted that there was no excess at the end of the test, although there had been midway thru' the run. (3) Fresh ore should be used as much as possible, as i t was found that oxidation lowered the recovery. (4) An analysis of the t a i l s from a standard cyanidation test on the ore was made and reported elsewhere. It is suggested that a similar t e s t be made by i n f r e s i z i n g t h e r e s i d u e and s e p a r a t i n g e a c h tube p r o -d u c t i n t o p y r i t e and a r s e n o p y r i t e and a s s a y i n g each c o n c e n t r a t e . T h i s w o u l d show, t h e e x t e n t o f t h e a c t i o n o f t h e c y a n i d e upon each m i n e r a l . THEORY OP CYANIDATION * CHEMISTRY OF PROCESS: The u s u a l r e a c t i o n g i v e n f o r t h e d i s s o l u t i o n o f g o l d and m e t a l l i c s i l v e r i n c y a n i d e s o l u t i o n s i s known as E i s n e r ' s e q u a t i o n 2 Au f,- 4 KCN |r. 0 f, HgO — 2 K A u ( 0 N ) g f. 2 K OH The a c t i o n o f c y a n i d e on s i l v e r s u l p h i d e i s n o t as w e l l known, b u t i t m i g h t be w r i t t e n a s A g g S f 4KCN f. 0 f HgO — A g CNS. KCN fr. K Ag (CN)g f 2 K OH FUNCTION OF OXYGEN Oxygen a p p e a r s t o be an i n d i s p e n s i b l e f a c t o r , e i t h e r d i r e c t l y o r i n d i r e c t l y , i n t h e d i s s o l u t i o n o f g o l d & s i l v e r by c y a n i d e s o l u t i o n s . The most g e n e r a l l y u s e f u l agent f o r t h i s p u r p o s e i s a t m o s p h e r i c oxygen and u s u a l l y a s u f f i c i e n t amount i s a b s o r b e d by t h e s o l u t i o n s i n t h e i r c i r c u l a t i o n . •Chemical o x i d i z i n g a g e n t s , a r e g e n e r a l l y n o t s a t i s f a c t o r y as t h e y o x i d i z e t h e c y a n i d e t o c y a n a t e , w h i c h i s u s e l e s s i n t h a t form. Two a g e n t s t h a t were u s e d i n t h e t e s t s w ere, however, s u c c e s s f u l , l i t h a r g e o r l e a d o x i d e , and, t o a l e s s e r e x t e n t , bromocyanogen. The l i t h a r g e was v e r y u s e f u l f o r r e d u c i n g t h e l i m e and c y a n i d e c o n s u m p t i o n , and bromocyanogen f o r r a i s i n g t h e r e c o v e r y s l i g h t l y . J u l i a n and.. Smart 3 0-say. t h a t t h e a c t i v i t y o f t h e l a t t e r i s n o t due t o t h e l i b e r t y o f t h e cyanogen, though t h a t p r o b a b l y o c c u r s , b u t t o a l i b e r a t i o n o f oxygen. 10. C y a n i d i n g G o l d and S i l v e r O r e s , pg. 81 7 6 2 B r CN $ KCN f 4 KOH ~ 2K B r f 2 KCN KCNO •$> 2 HgO f 0 S h o u l d an o r e c o n t a i n a r e d u c i n g agent s u f f i c i e n t e x t r a oxygen and c y a n i d e must be added t o make p o s s i b l e t h e p r o p e r d i s s o l u t i o n o f t h e p r e c i o u s m e t a l s . An i n c r e a s e i n t e m p e r a t u r e i n c r e a s e s t h e r a t e o f d i s s o l u t i o n o f t h e m e t a l s . STRENGTH OF THE SOLUTION IN CYANIDE There i s no advantage g a i n e d b y i n c r e a s i n g t h e s t r e n g t h o f t h e s o l u t i o n beyond t h a t w h i c h i s a c t u a l l y needed f o r t h e d i s s o l u t i o n o f th e p r e c i o u s m e t a l s . A f u r t h e r i n c r e a s e l e a d s t o c h e m i c a l and m e c h a n i c a l l o s s e s o f t h e c y a n i d e w h i c h a r e u n n e c e s s a r y . METHOD OF CYANIDATION The charge was p l a c e d i n t h e r o d m i l l w i t h an e q u a l amount o f w a t e r , and ground f o r 20 m i n u t e s . The p u l p was f i l t e r e d t o r e d u c e t h e w a t e r c o n t e n t and pu t i n t o a n i n v e r t e d b o t t o m l e s s a c i d b o t t l e . A i r a t a l o w p r e s s u r e was p a s s e d i n i n s u c h a manner t h a t i t e n t e r e d t h e p u l p f r o m t h e b o t t o m and k e p t t h e c o n t e n t s i n c o n s t a n t m o t i o n . The r e a g e n t s were added a t t h i s p o i n t . , The l i m e and c y a n i d e c o n t e n t s were checked, s e v e r a l t i m e s d u r i n g each r u n t o a s s u r e an ex c e s s o f each. A t t h e end o f t h e r u n a f i n a l a n a l y s i s was made o f the r e a g e n t s and t h e s o l u t i o n , f i l t e r e d o f f . The r e s i d u e was d r i e d and a s s a y e d f o r g o l d . The r e c o v e r y was c a l c u l a t e d f r o m t h e r e l a t i o n 100 x A s s a y o f R e s i d u e - n t l o g s o f g o l d . Head A s s a y * TEST 24. To Cyanide The Ore. ge t o B a l l M i l l Time p f G r i n d i n g Ore 500 gms. ••Water 500 gms. Lime 19 i f / t o n o f o r e Cya n i d e 5 # / t o n o f s o l u t i o n 20 m i n u t e s . C y a n i d a t i o n P u l p D e n s i t y 3:1 Time of C y a n i d a t i o n 48 h o u r s Lime Consumption. Lime added 2*5 gms, Lime R e c o v e r e d gms« gms. T i t r a t e d , 25 c . c . a t 0.035 % — 0.00875 gms. " , 25 c . c . a t 0.028 % — 0,007 gms. L e f t a t f i n i s h , 1450 c . c . a t 0.029^ - 0.402 1500 c . c . 0.417 Lime l o s t — 2,5 - 0.42 — 2 . 0 8 gms. Lime c o n s u m p t i o n / t o n o f ore — (2000)(2.08) — 8.32# 500 C y a n i d e Consumption. KCN added KCN r e c o v e r e d 5 gms 5 " 10 gms, T i t r a t e d , 25 c . c . a t .005 % — .00125 gms, " , 2 5 c . c . a t .285 % — .071 gms, L e f t a t f i n i s h , 1 4 5 0 c . c . a t .19 % — 2.755 gms, 1500 c . c . 2.837 gms. KCN l o s t -- 10 - 2 . 8 4 — 7.16 gms. .*.. KCN consmmption — 7.16 # / t o n o f s o l u t i o n . A u ; r e c o v e r y — 5951 % 78 • Conclusion. * This indicates that s t r a i g h t cyanidation of the ore w i l l give a 5 9 % recovery of the gold with a moderately low reagent consumption. 79 T E S T 25. To R o a s t t h e Ore a t a Low Temperature and Then Cyanide> R o a s t i n g . Temperature o f R o a s t i n g 47 5 ° C. Time o f R o a s t i n g 2 hours Weight o f charge b e f o r e r o a s t i n g 500 g r s . " " a f t e r «. 437.8 g r s . P e r c e n t l o s s i n •weight 12.4$ The r o a s t e d c h a r g e was t h o r o u g h l y mixed w i t h l i m e ( 1 6 # / t o n ) , m o i s t e n e d , and a l l o w e d t o s t a n d f o r f o r t y - e i g h t hours Then i t was c y a n i d e d * C y a n i d a t i o n . • P u l p D e n s i t y 3:1 Time o f C y a n i d a t i o n 48 h o u r s Lime Consumption. Lime Added Lime Rec o v e r e d 4.0 g r s . ; n T i t r a t e d , 25 c . c . a t 0.004$ 0 2.2 g r s . " 25 c . c . a t 0.041$ 0.0102 g r s . 2.2 g r s . L e f t a t f i n i s h , 1263 c . c . a t 0.040$ 0.5052 g r s . 8.8 g r s . 1313 c . c . 0.5154 g r s . Lime co n s u m p t i o n 8.4 - 0.52 *= 7.88 g r s . Lime co n s u m p t i o n / t o n ore (,2000)(7.88) _ ^ 437.8 80 C y a n i d e Consumption KCN Added KGN R e c o v e r e d .. 4.4 g r s . T i t r a t e d , 25 c .c. a t 0.0$ 0 8.6 g r s . " ; 25 c.c. a t 0.40$ 0.100 g r s . 13.2 g r s . L e f t a t f i n i s h , 1 2 6 3 c c . a t 0.18$ 2.318 g r s . 2.418 g r s . KCN consumed 13.2 - 2.42 = 10.78 g r s . ZCN c o n s u m p t i o n / t o n o f o r e (2000)(10.78) = 12.32 # 1751 G o l d R e c o v e r y 61.4 $ C o n c l u s i o n The s l i g h t i n c r e a s e i n r e c o v e r y does not w a r r a n t r o a s t i n g b e f o r e c y a n i d a t i o n , n o r the i n c r e a s e d c o s t o f l i m e and c y a n i d e . • 8 V TEST 26. To Make A B u l k C o n c e n t r a t e and Then Cyanide I t . Charge t o B a l l M i l l Time o f g r i n d Ore Water NagCOg KCK f 205 ••# 501 20minutes ieee gms. 1000 gms. 4 # / ton;. 0.10 # / t o n 0.05 # / t o n 0.05 # / t o n F l o t a t i o n C e l l C o n c e n t r a t e Added C o n d i t i o n e d Skimmed pH :: 0,152 # / t o n A e r o f l o a t # 15 2 m i n u t e s 50 m i n u t e s • : 8.63 A g o o d ^ p e r s i s t e n t f r o t h o f w e l l - m i n e r a l i z e d b u b b l e s was o b t a i n e d . G o l d r e c o v e r y » 88,3 % C y a n i d a t i o n Time o f C y a n i d a t i o n - 48 h o u r s P u l p D e n s i t y - 3:1 Consumption - Lime - 8.1 # / t o n K8N - 3.05 # / t o n G-old R e c o v e r y f o r C y a n i d a t i o n 61.3 % O v e r a l l g o l d r e c o v e r y - 54.0 % C o n c l u s i o n . R e s u l t s o b t a i n e d i n d i c a t e t h a t t h e d e c r e a s e d g o l d r e -c o v e r y w o u l d n o t w a r r a n t c o n c e n t r a t i o n by f l o t a t i o n b e f o r e c y a n i d a t i o n . TEST 27 To Make A B u l k C o n c e n t r a t e f o r a F u t u r e C y a n i d e T e s t , Charge t o B a l l M i l l Ore Water Na^COg KCN # 208 #'301 1000 gms. 1000 gms. 4 # / t o n 0.10 # / t o n 0.05 # / t o n 0.05 # / t o n TlSe" o f G r i n d 20 m i n u t e s C e l l C o n c e n t r a t e Added - : C o n d i t i o n e d -Skimmed pH A e r o f l o a t # 15 2 m i n u t e s 30 ". 8.63 0.132 C o n c e n t r a t e - 670.0 g r s . T a i l i n g s - 355.2 g r s . 1025.2 g r s . Gold R e c o v e r y 89.0 % as:-TgST'i: 28£ To T e s t t h e . E f f e c t o f L i t h a r g e on C y a n i d a t i o n , Charge i n B a l l M i l l Ore W a t e r ;.; KCN . . Lime L i t h a r g e iEime 0of,.pGg$ndingg - 20 m i n u t e s . Time o f C y a n i d a t i o n - ; 48 h o u r s P u l p D e n s i t y - 3:1 Consumption Lime KCN G o l d R e c o v e r y C o n c l u s i o n . I t I s e v i d e n t t h a t l i t h a r g e r e d u c e s c o n s i d e r a b l y t h e l i m e and c y a n i d e c onsumption w i t h o u t i n c r e a s i n g t h e g o l d r e c o v e r y . The r e a g e n t c o n s u m p t i o n d e c r e a s e i s p r o -b a b l y due t o t h e weak o x i d a t i o n power o f t h e l i t h a r g e . S h o u l d a c y a n i d a t i o n p l a n t be e r e c t e d , t h e use o f l i t h -a r g e t o r e d u c e t h e c o n s u m p t i o n of t h e l i m e and c y a n i d e , f r o m a n e c o n o m i c a l s t a n d p o i n t , s h o u l d be c o n s i d e r e d . 500 gms. 500 gms. 5 # / t o n of s o l . 15 # / t o n o f o r e l . & j f / t o n o f o r e 9.64 # / t o n 1.72 # / t o n 56.8 % •84, TEST 29 To T e s t The E f f e c t o f L i t h a r g e on C y a n i d a t i o n u s i n g  L e s s Lime t h a n T e s t 24. . Charge t o B a l l M i l l Ore - 500 gms. Water - 500 gms. Lime g 5 # / t o n o f o r e KCH - 5 # / t o n of s o l . ' L i t h a r g e 1.5 # / t o n o f o r e Time o f G r i n d i n g - 20 m i n u t e s . Time of C y a n i d a t i o n - 48 h ours P u l p D e n s i t y 5:1 Consumption Lime - 3.12 % / t o n o f ore KCH - 0.54 #./ t o n o f s o l u t i o n G o l d R e c o v e r y - 5 4 . 6 ^ C o n c l u s i o n . The c o n s u m p t i o n o f l i m e and c y a n i d e was a g a i n l o w e r e d .through t h e use o f l i t h a r g e . The d i f f e r e n c e i n l i m e c o n t e n t made l i t t l e d i f f e r e n c e . JB5* TEST 50. To R o a s t t h e Ore i n P r e s e n c e o f Lime and t h e n C y a n i d e , R o a s t i n g . Temperature - 550° G. Time o f r o a s t - 2 hours Charge t o f u r n a c e - . 500 gms. Wght. a f t e r r o a s t i n g - 452.8 gms;. ' • ' L o s s i n w e i g h t - 47.2 gms. P e r c e n t l o s s • . - 9.4 % Lime added - 5 # / t o n ore The o r e was d i s c v p u l v e J ? i z e d t o -100 mesh and t h e l i m e added b e f o r e r o a s t i n g i n a r e d u c i n g atmosphere. B e f o r e c y -a n i d a t i o n t h e l i m e was washed o u t and t h e ore: r e g r o u r i d f o r 10 m i n u t e s i n a b a l l m i l l w i t h 500 gms. o f w a t e r . C y a n i d a t i o n Time o f C y a n i d a t i o n - 48hours... P u l p d e n s i t y - 5:1 Consumption Lime - - 10.5 -jf /' t o n o r e KCN - - 3.7 s # / t o n s o l u t i o n G o l d R e c o v e r y - - 56.9 % C o n c l u s i o n . R e s u l t s o b t a i n e d a g a i n show t h a t r o a s t i n g b e f o r e c y a n -i d a t i o n ' does n o t improve r e c o v e r y . I t i s i n t e r e s t i n g t o n o t e t h a t r o a s t i n g i n t h e p r e s e n c e o f l i m e d e c r e a s e s t h e consumption o f b o t h l i m e and c y a n i d e . P o r c o m p a r a t i v e r e s u l t s c o n s u l t T e s t 25. 8 6 ' . TEST 31... To Roast t h e Ore i n P r e s e n c e o f More Lime t h a n T e s t 26'and Then C y a n i d e . R o a s t i n g , Temperature 550° C. Time o f R o a s t 2 hours Charge t o f u r n a c e - 500 gms. Weigh t a f t e r r o a s t - 460 gms. Lo s s i n w e i g h t 40 gms. P e r c e n t l o s s - 8.0 % ; Lime added - . 25.0 # / t o n The ore was d i s c p u l v e r i z e d t o -166 mesh and t h e l i m e added b e f o r e r o a s t i n g i n s. r e d u c i n g atmosphere. B e f o r e c y a n i d a t i o n t h e l i m e was washed out and t h e o r e f e g r o u n d f o r 10 g d n u t e s i n a b a l l m i l l with 500 gms. w a t e r . Time o f C y a n i d a t i o n - 45 h o u r s P u l p d e n s i t y - 3;1 . NOTE. Due t o an a c c i d e n t , t h e b o t t l e was b r o k e n and t h e t e s t was n o t f i n i s h e d . TEST 32. To T e s t t h e E f f e c t of Bromocyanide on t h e Ore. Oharge t o B a l l M i l . Ore - 500 gms. Water - 500 gms. G r i n d i n g Time - 20 miniates S y a n i d a t i o n Time o f G y a n i d i n g .- 48 h o u r s P u l p D e n s i t y - 3:1 The o r e was c y a n i d e d f o r 24 hours w i t h KGN and t h e n f o r 24 h o u r s more w i t h BrCM and K 8 H . The l a t t e r was added a f t e r t h e s o l u t i o n was r e d u c e d w i t h HgSO^ u n t i l an e x c e s s a l k a l -i n i t y o f 0.008 % OaO v/as r e a c h e d . Consumption. : . Lime - 5.88 # / t o n o r e . BrCN . - 1.26 # V t o n o f s o l u t i o n . KCN - . 5.0 # / t o n " " G o l d R e c o v e r y - 63.6 % HOTE. When end o f t e s t was r e a c h e d , t h e r e was no BrCN l e f t . T h i s t e s t was r e r u n as T e s t 35, C o n c l u s i o n . The g o l d r e c o v e r y was s l i g h t l y i n c r e a s e d . T h i s i s p r o b a b l y due t o t h e i n c r e a s e d l i b e r a t i o n o f f r e e c y a n i d e f r o m t h e bro m o c y a n i d e . 88, TEST 33. To T e s t the: E f f e c t o f O x i d a t i o n . Charge -to B a l l M i l l . • to Ore - 500 gms. '; Water - 500 gms, Time o f G r i n d i n g - 20 m i n u t e s . A f t e r g r i n d i n g , t h e w a t e r Was f i l t e r e d , o f f and t h e o r e l e f t s t a n d i n g i n a m o i s t c o n d i t i o n f o r 5 d a y s . C y a n i d a t i o n . Time o f C y a n i d a t i o n - 48 h o u r s P u l p D e n s i t y - 3:1 . Consumption. Lime - 7.64 # / t o n o r e ICN - 4.07 -#/ t o n o f s o l u t i o n G o l d R e c o v e r y - 45.5 % C o n c l u s i o n . The low r e c o v e r y i n t h i s t e s t i s p r o b a b l y due t o o x i d a t i o n of one o f t h e s u l p h i d e s , and t h e o x i d i z e d m a t e r i a l c o a t i n g t h e g o l d . 89 TEST 34. To T e s t The E f f e c t Of F i n e G r i n d i n g Charge t o B a l l M i l l Time of G r i n d i n g Ore Water 500 gms, 500 gms, 1 h o u f 30 m i n u t e s , Cyanidation Time o f C y a n i d a t i o n  P u l p D e n s i t y 48 hours 3 s l Consumption. Lime ; "\ KCN Gold R e c o v e r y C o n c l u s i o n . 20 # / t o n d f p r e t o n o f s o l u t i o n 6 5 . 0 ^ F i n e g r i n d i n g i n c r e a s e d t h e g o l d r e c o v e r y s l i g h t l y , and the-. consumption o f l i m e and c y a n i d e c o n s i d e r a b l y . W h i l e t h e c o n s u m p t i o n m i g h t be l o w e r e d by t h e use o f l i t h a r g e , i t i s d o u b t f u l t h a t t h e i n c r e a s e d r e c o v e r y w o u l d w a r r a n t t h e e x t r a c o s t o f t h e f i n e r g r i n d i n g . TEST 58. To T e s t t h e E f f e c t o f Bromocyanide on t h e Ore NOTE, T h i s i s a r e p e a t o f T e s t 32 w i t h more c a r e f u l c o n t r o l o f e x c e s s l i m e and BrCN. Charge t o B a l l M i l l C y a n i d a t i o n Ore Water 500 gms, 500 gms. Time o f g r i n d i n g 20 m i n u t e s . Time o f C y a n i d a t i o n w i t h KCW " " " 11 " BrCN P u l p D e n s i t y 44 hours 4 hours 3:1 F i r s t c harge Consumption Lime S O N Second Charge - KCN BrCN Lime KCN: BrCN G o l d R e c o v e r y 6. $ / t o n o f o r e 5S / t o n . c f s o l u t i o n 5 # / t o n o f s o l u t i o n 0,23 # / t o n o f s o l u t i o n 3.84 # / t o n o f o r e 9.17 # / t o n # s o l u t i o n . 0.23 # / t o n " " " . 56.7 % C o n c l u s i o n . The u s e o f bromocyanide w o u l d n o t r a i s e t h e r e c o v e r y s u f f i c i e n t l y t o pay f o r t h e i n c r e a s e d c o s t o f r e a g e n t s . 91 i , TEST 36 To test the e f f e c t of Cyanide (KCN) on a concentrate without using any lime to give protective a l k a l i n i t y . NOTE - The concentrate from Test 23 was taken and 500 grams weighed out. No f u r t h e r grinding was done. CYANIDATION Time of Cyanidation - 48 hrs. Pulp-Density - 3 : 1 CHARGE KCN - 10#/ton of ore NOTE During the run, when samples of the solution were taken for determination of the pro t e c t i v e a l k a l i n i t y and cyanide content, i t was found that c o l l o i d a l p a r t i c l e s turned the solution a l i g h t brown color. This prevented accurate determination by titration due to the-need.for a colorless solution in the methods previously described. Consequently i t was ascertained only that there was an' excess of cyanide and that the s o l u t i o n was alkaline. . At the' end of the run the s o l u t i o n was s t i l l colored, so a f t e r f i l t e r i n g , lime was added to the f i l t r a t e to f l o c c u l a t e the ' p a r t i c l e s and give a c l e a r s o l u t i o n , s u i t a b l e f o r t i t r a t i o n . This gave two residues, one containing the main bulk of the, -.'tailings; and no lime; the other the finer p a r t i c l e s , or slimes. CONSUMPTION KCN - 8.61 #/ton of so l u t i o n PH at end of run « 11.0 Gold Recovery - 61.4% Overall gold recovery 54.6% 92 TEST 56 CONCLUSION c * Results indicate that lime i s not essential for the recovery of gold. From tests made during the run, i t was ascertained that the pulp was alkaline during the en-tir e period. The gold recovery was the same as the cor-responding test with lime while the cyanide consumption was a t r i f l e more. 9 3 TEST 37 To Cyanide the ore and float the tailings, Charge \o Bail M i l l CYAMDATION Additions Consumption. ore - 500 grs water - 500 grs Time of Grinding - SO minutes Time of Cyanidation - 48 hours Pulp Density - 3:1 •Lime 10#/ton of ore- • KCN 10# /ton of ore Lime - 9.32# / ton of ore KCN - 7.91# / ton of solution Gold Recovery - 59.0$ FLOTATION No concentrate was taken. When the tailings were transferred to a 500 gram machine and the reagents, added, i t was found that a dirty froth of small bubbles was formed. 94 TEST 38 To G r i n d E x t r a F i n e and C y a n i d e f o r f o r t y - e i g h t (48)Hours. Charge to Ba l l M i l l Ore - 200 grs Water - 200 g r s Time of g r i n d i n g - 3 h o u r s . Time o f Cyanidation - 48 hours P u l p D e n s i t y 5:1 Added - Lime - 20# /ton ore KCN - 10# /ton ore T h i s test was a g i t a t e d f o r 12 h o u r s b e f o r e any reagents were added, and the PH was found to be 10.03. Consumption Lime - 19.85# /ton o r e KCN - 9.75# /ton s o l u t i o n G o l d R e c o v e r y - 72.7% CONCLUSION The gold recovery was increased approximately 15% by the finer grinding. Should the cyanidation method of treatment be used, i t must be d e c i d e d w h e t h e r the increased cost of g r i n d i n g w o u l d be w a r r a n t e d by the increase i n the r e c o v e r y of gold. 9 5 To Grind Extra Fine and Cyanide for Ninety Six (96) hours. Charge «to B a l l M i l l - Ore 200 grs water 200 grs Time of Grinding - 3 hours. CYANIDATION Time of Cyanidation - 96 hours • Pulp Density 5:1 Added Lime - 30# /ton of ore KCN - 15# /ton of solution Consumption - Lime - 29.70# /ton ore KCN - "14.7Q#/ton of. solution Gold'Recovery - 72.7$ CONCLUSION The results indicated that an increase in time of contact between the cyanide and gold i s not necessary;, as the gold recovery was the same for both periods. The lime and cyanide consumption i s also greatly increased. 9 6 R O A S T I N G 9 7 R O A S T I N G Low t e m p e r a t u r e r o a s t i n g t e s t s were made i n an a t t e m p t t o d r i v e o f f a p a r t o f t h e s u l p h u r and expose t h e o r e more c o m p l e t e l y t o t h e a c t i o n o f c y a n i d e . The c o n c l u s i o n s r e a c h e d , however,were t h a t r o a s t i n g had no e f f e c t upon t h e f i n a l g o l d r e c o v e r y and t h a t t h e con-sumption o f l i m e and c y a n i d e was i n c r e a s e d c o n s i d e r a b l y . METHODS: 500 grs,,of o r e were t a k e n and ground i n a d i s c - p u l v e r i z e r t o p a s s a 100 mesh s c r e e n . They were p u t i n t o a s m a l l oven w i t h a p i e c e o f c h a r c o a l t o f o r m a r e d u c i n g atmosphere, and t h e f r o n t p l u g g e d w i t h f i r e c l a y . F i n a l l y t h e oven was p l a c e d i n an e l e c t r i c f u r n a c e w h i c h had been h e a t e d t o t h e r e q u i r e d t e m p e r a t u r e and l e f t i n i t f o r a s p e c i f i e d t i m e . A t t h e end o f r u n t h e charge was weighed t o d e t e r -mine t h e l o s s . See T e s t s 25 & 30. 98 99 BLANKET CONCENTRATION The r e s u l t s o f t h i s t e s t c o n f i r m e d t h e c o n c l u s i o n s p r e v i o u s l y r e a c h e d t h a t a s a t i s f a c t o r y b l a n k e t c o n c e n t r a t e c o u l d n o t be made. The grade o f t h e p r o d u c t was t h e same as t h a t o f t h e m i l l f e e d - 0.44 o z / t o n , so i t was o b v i o u s t h a t t h e g o l d r e c o v e r y depended e n t i r e l y upon t h e b u l k . The b l a n k e t c o v e r e d t h e b o t t o m o f a r e c t a n g u l a r t r o u g h s e t a t an a n g l e o f 15-20° f r o m t h e h o r i z o n t a l . The o r e , p r e v i o u s l y d i l u t e d t o a p u l p d e n s i t y o f 8:1, was added a t t h e t o p . A c o n t i n -uous s p r a y o f w a t e r washed t h e o r e down t h e s l o p e . F o r r e s u l t s , see t e s t s #15 and 16. 100 A S S A Y M E T HO D S 101 ASSAY METHODS GOLD AND SILVER: * The g o l d and s i l v e r c o n t e n t o f t h e o r e was d e t e r m i n e d by t h e n i t e r method. The m a j o r i t y o f t h e g o l d a s s a y s f o r t h e v a r i o u s p r o d u c t s was r u n b y t h e s t a n d a r d n a i l s method,, w h i c h was checked and found t o be s u f f i c i e n t l y a c c u r a t e f o r t h e p u r p o s e . S i l v e r d e t e r m i n a -t i o n s were n o t made f o r any o f the t e s t s . POPPER: S e v e r a l methods o f a n a l y s i s were t r i e d a t f i r s t , b u t a s a t i s f a c t o r y end p o i n t i n t i t r a t i o n c o u l d n ot be o b t a i n e d . T h i s was p r o b a b l y due t o t h e a r s e n i c w h i c h had n o t been e n t i r e l y e l i m i n a t e d . F i n a l l y t h e method o f p r e c i p i t a t i o n o f t h e m i n e r a l s a s s u l p h i d e s b y hydro g e n s u l p h i d e gas was t r i e d . A l t h o u g h a l o n g a n a l y s i s i t was a c c u r a t e , and c o n s e q u e n t l y was a d o p t e d f o r a l l f u t u r e c o p p e r a s s a y s . 102 C O P P E R 1.0 grs of ore in copper flask 6 grs sodium sulphate 10 cc. HgS0A Fuse thoroughly u n t i l mass i s a light yellow color. Cool sufficiently to add 30-40 cc. water. 5 drops HC1. Heat at near boiling or boiling temp, for half hour F i l t e r - Ppt. - Pb. F i l t - Fe, Cu, Sb, As. Dilute to 300 cc. and warm. Pass in HgS gas u n t i l a l l sulphides are ppted. and solution clear. F i l t e r Ppt. Cu, As, Sb, Pb, Sn. F i l t - Fe. Return ppt. to same beaker washing paper with Cone, sodium poly-sulphide solution. Digest at temp, below boiling until soln. clear and dark ppt. coagulat F i l t e r Ppt. - Cu, Pb. F i l t . - As, Sb, Sn. Return ppt. to same beaker washing with water, then hot 1:1 HNO^ , then Bromine water. Add 5 cc. cone. Hg SO^ to ppt. lead. Bake. Add water and f i l t e r out lead. 5 cc. BNOg and evaporate nearly to dryness. Make just alkaline with 1:1 NH„ OH. Boil to expell excess. 103 ; ; COPPER (Continued; Just ac i d i f y with Acetic Aoid. Cool* thoroughly. 2 grs. EE and let stand 5 minutes. Titrate with sodium thiosulphate using soluble starch soln. as indicator. 104 IRON- - Bichromate method for Sulphides. Take 0.5 grs. into 250 cc. beaker. 10 c c * water and 15 cc. HN05 Warm t i l l red fumes a l l driven off. 15 cc. HC1 and warm. 10 cc. Chlorate mixture and warm 10 cc. 1:1 H g S0^ Fume nearly to dryness. Cool and add 25 cc. water 5 cc. HC1 - b o i l While s t i l l hot, add Sn 01 drop by dron u n t i l yellow color disappears and add 1 drop i n excess. Cool quickly and add about 15 cc. Hg CI Titrate with Potassium dichromate using potassium Ferricyanide as indicator. Use white plate. End point reached when blue in drops disappears. Reagent s; . Stannous chloride - 60 cc. in 600 cc. HC1. Mercuric chloride - saturated solution Potassium ferricyanide - small crystal in 50 cc. water Potassium dichromate - To standardize - weigh up 0.7 grs ferrous ammonium sulphate, acidify with HC1, 1 drop of Sn C l 9 , excess Hg C l 9 and titrate. 105 SULPHUR: Take 0.5 grs of ore 40 cc. water and 10 cc. n i t r i c chlorate. Heat to dryness overnight 5-6 grs Na g C0 g and 25 cc. water. B o i l 10 minutes, d i l u t e to 100 cc. and b o i l . F i l t e r through: No. 1 Whatman paper. Wash twice with ho t water. Ppt. - Fe and other impurities. F i l t . - Na g S0A 20 cc. HC1 to ppt. Add excess Na g COg u n t i l get fu r t h e r ppt. Then 25 cc. water. B o i l 10 minutes, d i l u t e to 100 cc. and b o i l , F i l t e r . Add t h i s f i l t r a t e to f i r s t one. Neu t r a l i z e combined f i l t r a t e s with HC1, add 2 or 3 cc. excess, b o i l . Add hot Ba C l g and b o i l u n t i l Ba S 0 4 ppts. F i l t e r , i g n i t e and weigh as Ba S0^ Wt. of Ba S 0 A X 0.1375 . „ J _ . • 4 x 100 s f> Sulphur. Wt of sample High sulphide ore and concentrates are u s u a l l y taken down slowly or overnight with the chlorate mixture. 106 ARSENIC - D i s t i l l a t i o n Method This method was found to be more accurate than that of fusion before d i s t i l l a t i o n . The error is probably due to the volatilisation -a of some of the arsenic. Take 0.5 grs. ore i n 100 cc. beaker 25 cc, water, 10 cc. chlorate mixture, digest. 10 cc. of 1:1 HgS0A - to fumes overnight Put in d i s t i l l a t i o n flask, add some brick grape nuts, 3 grs. Ferrous Chloride or Cuprous Chloride, 2 grs. Ferric Chloride, 90 cc. HC1. Receive in 400 cc. beaker containing 100 cc. water D i s t i l l u n t i l bumping, (at 120° for half hour) Neutralize with NH^ OH. Just acid with HC1. Cool. Make alkaline with Na HC03 Add starch and t i t r a t e with Iodine Solv. REAGENTS: Iodine - 50 grs. EE i n 75 cc. water. Add 25.5 grs. of I g crystals and leave in warm place u n t i l a l l in solution. Dilute to 2 l i t r e s . To Standardize - Put 0.99 grs. As„ 0 in a 400 cc. beaker with NaOH and some water. Just acidify with HC1. Dilute to 300 cc. and cool. Make alkaline with NaHCOr,. Add starch and titrate. 107 r C y a n i d e i n P u l p . Take 25 c . c . o f p u l p F i l t e r t o c l e a r Add s e v e r a l d r o p s o f 5$ EE s o l u t i o n T i t r a t e w i t h S i l v e r N i t r a t e s o l u t i o n As soon as y e l l o w i s h p p t . i s j u s t permanent when vie w e d a g a i n s t b l a c k : b a c k g r o u n d t h e end p o i n t i s r e a c h e d . Lime i n P u l p . . Take above s o l u t i o n and add a few d r o p s o f P h e n o l p h t h a l e i n T i t r a t e a g a i n s t O x a l i c a c i d ; u n t i l r e d c o l o r d i s a p p e a r s . 108 ; BIBLIOGRAPHY I.W. Wark & A.B, Cor - "Principles of Flotation ¥11" Mining Technology; January 1938, Richard, T. A. - "History of Flotation" Mining Sc. Press, 114. Pgs. 365-369; 401-406. U.S. Patent #348,157. Taggart, Taylor & Ince - "Experiments with Flotation Reagents" A.I.M.M.E. 68 (1923) G.A. G i l l i e s - "The Story of the Bubble", C.I.M.M. Bulletin, July 1955, Pg. 349. Transactions of A.I.M.M.E; Vol. 112; Pg. 239. Gaudin, A.M. "Flotation", Pg. 99. Wark, I.W. & Cox, A.G. Transactions of A.I.M.M.E. Vol. 112. U.S. Bureau of Mines "Report of Investigations" Metallurgical Division,. Jura 1935. 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