"Science, Faculty of"@en . "Chemistry, Department of"@en . "DSpace"@en . "UBCV"@en . "Embree, William Howard"@en . "2012-03-27T22:38:27Z"@en . "1947"@en . "Master of Arts - MA"@en . "University of British Columbia"@en . "1. The effect of pH on flotation has been shown. 2. The establishment of a good colourimetric analysis for the collector has been achieved. 3. The amount of adsorption of the collector has been shown. 4. The absence of Bromide on the silica surface has been shown which seems to indicate a metathetic reaction has occurred. 5. A very approximate calculation of the adsorption of T. M. C. A. B. per square cm. has been given."@en . "https://circle.library.ubc.ca/rest/handle/2429/41814?expand=metadata"@en . "SURFACE REACTION\" WITH CATIOFIC COLLECTORS IN SILICA FLOTATION. Submitted to the Department of Chemistry, the University of Brit i s h Columbia, in partial f u l -fillment of the requirements for the Degree of Master of Arts, by W. H. EMBREE.. ACKNOWLEDGMENT. I wish to express my sincere appreciation to the late Dr. William Ure and to Dr. G. H. Hooley, for the assistance they have given me in the carrying out of the work. INDEX. Page. 1. I n t r o d u c t i o n . 1. a. Previous work. 2. b. Nature of work to be undertaken. 3. Prep a r a t i o n of . s i l i c a samples. 5. Influence of pH on f l o t a t i o n . 5.\u00E2\u0080\u00A2 a. Apparatus and m a t e r i a l s , b. Procedure 8. A n a l y t i c a l methodB f o r the c o l l e c t o r . 9. a. Micro-Kheldahl a n a l y s i s . 9. - Apparatus, and s t a n d a r d i z a t i o n . 13. - A n a l y s i s of Trimethyl G e t y l Ammonium Bromide (T.M.C.A.B.) 16. - P o s s i b l e a p p l i c a t i o n of the method. 18. - Summary of the Kheldahl process. 18. b. C o l o u r i m e t r i c a n a l y s i s . 18. - Procedure 19. - S t a n d a r d i z a t i o n 22. - A p p l i c a t i o n to adsorbed c o l l e c t o r . 2.8. - Summary of Colourimetric: a n a l y s i s . 29. c. Bromide a n a l y s i s 31. - Method and s t a n d a r d i z a t i o n . 31. - A n a l y s i s f o r adsorbed c o l l e c t o r . 33. General d i s c u s s i o n of a n a l y t i c a l r e s u l t s . 34. Determination of adsorption per u n i t area of the s i l i c a surface. 36. Summary. 36. Future Work. 37. B i b l i o g r a p h y . ABSTRACT. 1. The effect of pH on flotation has been shown. 2. The establishment of a good colourimetric analysis for the collector has been achieved. 3. The amount of adsorption of the collector,has been shown. 4 . The absence of Bromide on the s i l i c a surface has been shown which seems to indicate a metathetic reaction has occurred. 5. A very approximate calculation of the adsorption of T. M. C. A. B. per square cm. has been given. INTRODUCTION. Collectors used in the flotation industry are sub-stances that cover the mineral particle, or part of the particle with an air avid coating, that is one which permits the a i r to displace at least part of the water. Collectors a l l contain polar and non polar groups and a l l collectors must be adsorbed in order to be effedtive. It has been found ( Ref. 1, P. 95) that there are three main classes of collectors; (a) Oils. (b) Acids containing a hydrocarbon group and the potassium and sodium salts of these acids. (c) Bases containing a hydrocarbon group and the salts of these bases, usually chlorides or halides. The most important members of the (c) group are derivitives of the amines, and certain organic analogues. It is a member of this group, trimethyl cetyl ammonium bromide ( in future, this w i l l be referred to as T. M. C. A. B.) which is to be dealt with in this thesis. T. M. C. A. B. is one of the most interesting members, of the series. (Ref. 1, P. 104). Previous Work. The majority of the experimental work in connection 2. with the use of T. M. C. A. B. as a flotation reagent has been done by Wark (2). Wark has used this collect-or in the flotation of galena, rhodonite, cassiterite, quartz and other minerals. He has experimented with flotation in acid, alkaline or neutral solutions and found T. M. C. A. B. to be a collector for quartz in a l l mediums (Ref. 1. P. 248). In connection with the surface reactions between collectors and mineral sur-faces two main theories have been advocated. Taggart (3) postulated a chemical theoryof the adsorption process in which he stated that the flotation reagent must react metathetically with the mineral surface in order to form a water repellent coating. .Wark believes s t r i c t l y in the adsorption theory and that the essential differences between adsorption and chemical reaction is that the chemical reaction proceeds throughout the entire particle unless hindered by form-ation of a film, whereas adsorption ceases at the surface layer. Nature of the Work to be Undertaken. -The fundamental object of this research was to attempt to come to some conclusion as to the manner in which the collector is attached to the surface of quartz. As noted above there has been some controversy over the point. i 3. It is a well established fact that the surface of s i l i c a becomes hydrated, forming the acid of the structure Si02\u00C2\u00BB xHgO, which is sometimes written for the purpose of equations as H^SiO^. A\" possible surface reaction may then be H 2Si0 3t(CH 3) 3C 1 6H 3 3N-Br \u00E2\u0080\u0094> (CH 3) 3 G^HggN-HSiO^ HBr However data on this specific reaction was not en-countered by the author so i t was necessary to attempt to throw further light on the process of adsorption through analytical methods. Preparation of S i l i c a Samples. It was desirable to obtain s i l i c a in the purest form possible and this was done in the following way. Some crystaline s i l i c a was obtained, which contained no v i s i -ble traces of impurities. The preliminary breaking up was done by heating the s i l i c a to quite a high temperature and then plunging i t into cold water. Sufficient strain was then set up to cause considerable shattering. It was also found much easier to carry out the grinding after this treatment. The quartz, was ground by hand with a large mortar and pestle. Preliminary sizing was done with 60 to 150 mesh brass seives. When a considerable quantity of quartz of this size had been prepared, i t was. washed with sulphuric acid to insure removal of any metallic impurities that may have accumulated from the F-Tft.T. 2 i G * i . 1111 ii II s T 150 ineak sieve. to tap. L 4. sieves. In respect to the metallic impurities: Wark makes this statement (Ref.l. P 179) \"the activation of quartz cannot be attributed to the formation by double decomposition of an insoluble compound on the surface and can only be described as a typical instance of adsorption.\" By '\"activation\" he is here referring to the fact that a permanent change in the surface characteristics of quartz can be produced by an activating cation such as iron. It is believed that a l l possible precautions, were taken as to the elimination of metallic impurities, and of organic, impurities. After washing with sulphuric acid, the s i l i c a was ellutriated to get r i d of particles below 150 mesh. The most satisfactory type of ellutriation for particles: of this size was of the design shown in the accompany-ing diagram (Pig., 1.)\". It was found that in order to carry over quartz of the 60 - 150 mesh size i t was necessary for the pressure to be regulated directly from the tap. By means, of manipulation of the tap and the atop cock (S.) a constant rate of flow of water could be obtained. The s i l i c a which flowed through the tube (T) was collected in the 150 mesh sieve, the water flowing through helping to remove particles less, than 150 mesh. It was f e l t that by the above method a f a i r l y uniform range of sizing was obtained. The main object in this was to be able to get some degree of reproducibility of J&QTITI0H_APPARATUS. s m i i Flotation c e l l . Air pressure, Manometer Skiaimar Frotk c e l l e c t e r Gr \u00C2\u00A9und j o i n t Rubber connection S^intered plate r e s u l t s when the determination of the amount of c o l l e c t o r adsorbed was c a r r i e d out. Influence of pH on F l o t a t i o n . There has been a considerable amount of data i n the l i t e r a t u r e on the i n f l u e n c e of pH on f l o t a t i o n , i n con-n e c t i o n w i t h many minerals and types of c o l l e c t o r s ( l ) but the m a j o r i t y of experiments were c a r r i e d out on a much l a r g e r scale, than was p o s s i b l e w i t h the apparatus and m a t e r i a l s a v a i l a b l e to the author. I t was t h e r e f o r e necessary to t e s t r e s u l t s on a smaller s c a l e . Apparatus and Materials.. In the a c t u a l f l o t a t i o n a c e l l of the accompanying design was used ( F i g . I I ) . I t had been found w i t h pre-vious types of c e l l s which had a l i p to c a r r y o f f the overflow, that s i l i c a tended to c o l l e c t on the upper w a l l of the c e l l thus preventing 100% c o l l e c t i o n . In t h i s type a glass, rod w i t h a skimmer attached to the top was used to scrape the SiO\u00C2\u00A3 o f f the edge of the c e l l . I t w i l l be n o t i c e d In the diagram that the s c i n t e r e d g l a s s f i l t e r funnel which was used to create the bubbles of the process was attached to the upper s e c t i o n of the c e l l by a rubber connection. This method was used to enable the changing of the volume of water i n the c e l l , i f i t were necessary, and at the same time keep the same hei g h t of f r o t h zone. In order to assure that the rubber would not affect'\" the f l o t a t i o n process., tfce. connections were made by g r i n d i n g the surfaces so that a t i g h t ground glass connection r e s u l t e d . T e r p i n i o l was used as a f r o t h i n g agent, i t s concen-t r a t i o n being .250 g r s / c c . T. M. G. A. B. was prepared i n s o l u t i o n form having a c o n c e n t r a t i o n of .0001 g r s / c c . Procedure. In the f o l l o w i n g experiments the method was as f o l l o w s : s 2 grams of s i l i c a were put i n t o the f l o t a t i o n c e l l . The a i r pressure was turned on s l i g h t l y so that when the water and c o l l e c t o r were added, none would be l o s t by running through the p l a t e . The pH of the f l o t a t i o n so-l u t i o n was adjusted by means, of HC1 and NiaOH, w i t h c o l l e c t o r and t e r p i n i o l added. The s o l u t i o n was poured-i n t o the c e l l and the pressure increased to insure suf-f i c i e n t roughing of the s i l i c a and c o l l e c t o r . The pressure was then f u r t h e r increased u n t i l the f r o t h zone was h i g h enough to c a r r y the s i l i c a over. The c o l l e c t i n g of the s i l i c a was c a r r i e d on f o r one minute. I t was n o t i c e d that the great m a j o r i t y of the s i l i c a was c a r r i e d over w i t h the f r o t h i n the f i r s t few seconds of the run. The f r o t h was q u i t e watery and a t the end of one minute the f r o t h zone was c o n s i d e r a b l y h i g h e r . This, however, was considered p r a c t i c a l l y a n e g l i g i b l e f a c t o r . At the end of the c o l l e c t i o n time, the SiOg was. 7. washed i n t o a weighed Gooch c r u c i b l e , having an asbestos f i l t e r . The c r u c i b l e and s i l i c a were then d r i e d a t 1 1 0 \u00C2\u00B0 C f o r s e v e r a l hours and again weighed. The d i f f e r e n c e i n weight gave the weight of c o l l e c t e d s i l i c a . The f o l l o w i n g t a b l e gives the r e s u l t of t r i a l s u s i n g d i f f e r e n t amounts of c o l l e c t o r a t va r y i n g pH's. Table I. 10 cc Terpineol Roughing Time s 2 min. C o l l e c t i n g Time \u00E2\u0080\u00A2 1 min. Concentration of c o l l e c t o r . 0 0 0 1 gral/cc Press. cms.Hg V o l KgO pH i i C o l l e c t o r Crs. Vol.fcc) S i l i c a In C e l l In P r o t h of Colle< 6-7 2.00 cc 1.9 . 0 0 0 2 2 2 .136 0 6.8 it i t 2.98 it n 2 .8690 4 3 . 4 i i II 3 . 9 6 t i i t 2 1 . 7 1 1 0 8 5 . 6 II i t 4 . 4 7 5 tt. \u00C2\u00AB\u00C2\u00BB 2 1 . 8 9 7 1 9 4 . 8 II: II: 5.21 l l It; 2 1 . 9 5 2 7 9 7 . 7 6-7 I t 2 . 9 2 5 . 0 0 0 4 4 2 1 . 2 4 5 2 6 2 . 2 5 i i II 3 . 4 1 w t t 2 1 . 7 5 8 9 88 i t II ' 4.04 n l l 2 1.9672: 9 8 . 3 it II 4 . 6 1 ' i t i t 2. 1 . 9 7 2 5 9 8 . 7 6-7 II 2.06 . 0 0 0 6 6 2. . 3 4 7 3 1 7 . 3 5 it t l . 2 . 8 7 5 \u00C2\u00ABi i t 2 1 . 4 1 4 2 7 0 . 6 it It 3.6 i t I I 2 1 . 9 5 6 1 9 7 . 8 II II 3.96 l l II; 2 1 . 9 2 4 1 9 6 . 4 8. The results shown on the graph (Pig. I l l ) check qualitatively with the results of previous workers.on the subject and may be summarized as follows.: 1. Increase in pH causes, rapid increase in float-a b i l i t y up to 86% and 90%, 2. The slope of the curve increases, as the quantity of collector in the flotation pulp increases. Further discussion on possible interpretation of pH stati s t i c s w i l l be given in a f i n a l discussion of experi-mental results of thesis. Analytical Methods for the Collector. As i t was to be attempted to determine the nature of the surface reaction between the collector and s i l i c a , one of the essential factors, was to find a method of analysis for the collector. It was thought possible to work at the problem from two points of view: either (a) find the amount of collector adsorbed directly on the surface by displacing i t from the surface and analyzing i t , or else (b) measure the amount l e f t in the solution from which the adsorption takes place and hence by subtraction from the known quantity in the original solution find the amount adsorbed. It seemed quite logical to assume that the amount to be adsorbed would be very small and would thus require a sensitive test for either (a) or (b), as in (a) the amount adsorbed would be small and in (b) the difference 9. between the amount adsorbed and the amount in solution would be small. Micro KheldahlAnalysis. Because the collector is 3.85$ nitrogen the micro Kheldahl test was considered. The lower limit claimed for nitrogen detection is. about .067 mg ( 8 ) . As. w i l l be seen later the maximum amount of T. M. C. A. B. analyzed for was below .0008 grs. This amounts, to 3.04 xlO grs. of nitrogen. As this maximum figure is below the lower limit of Kheldahl accuracy i t was f e l t that insofar as detection was concerned under conditions used in the experiments, the micro Kheldahl process was; not very practical. However as i t was thought to be of possible use in future work involving larger quantities of materials, i t was decided to attempt to standardise the Kheldahl method with respect to the organic collector being used here. \" Apparatus and Standardization. The apparatus used was. similar to the type described in the Journal of Ind. and Eng. Chem. (4). As: the apparatus had not been previously used by the author i t was necessary to check the accuracy and reproducibility that could be obtained. It was decided to use G.uanidine carbonate to standardise the apparatus. It, was from a well known source and its purity was 10. considered reliable. A\ solution of Guanidine carbonate was prepared .03ET with respect to nitrogen. The formula for G. C. is ((NHgJgP = N H^2* H2 G 03 W i t h a m o l e c u l a r weight of 180.14. The nitrogen equivalent of this is 180.14. 6 There have been a number of catalysts recommended for digestion but i t was f i n a l l y decided to use a mixture of 1 part K 2S0 4 and 3. parta of C.uS04*5H20 with 1 Hengar selenized granule. 2cc of concentrated H2SO4 were used for digestion(5). The G. C. w$s introduced into the digestion flask by means of a micro burette. The catalyst and H2SO4 were then added and the mixture heated for 2. hours. It was. found that short digestion times recommended in the l i t e r -ature were insufficient to insure reproducible results.. Once digestion was completed i t was necessary to consider the best way of collecting the d i s t i l l e d ammonia. The Boric acid calibration curve system (6) was tried. Thiq was based on a calibration curve of quantity of jRH^ OH added to a constant volume of 4^ Boric acid, plotted against pH readings. It was found very d i f f i c u l t to use with any precision as even changes in the pH of d i s t i l l e d water used in the process were sufficient to change the results. The method f i n a l l y decided upon was found in a text on micro-analysis ( l l ) . The ammonia was d i s t i l l e d for 6 minutes into lOcc of A.% Boric acid into which had been 11. put 4 drops of a mixture of lOcc of bromcresol green and 2 cc of methyl red i n d i c a t o r . Both i n d i c a t o r s were \u00C2\u00BB1$ s o l u t i o n s of the s o l i d d y e s t u f f i n 95$ a l c o h o l . The colour change was from b l u i s h purple, to b l u i s h green i n the presence of ammonia.. When d i s t i l l a t i o n was complete the s o l u t i o n was t i t r a t e d w i t h HC1 to a f a i n t pink shade. The method was found to give p r e c i s e end p o i n t s . In the table which f o l l o w s there i s shown the volume of standard HC1 used to t i t r a t e the ammonia from the d i g e s t i o n of the Guan&dine carbonate. The volume of HC1 used has been transformed to .03N (the n o r m a l i t y of the G. C.) from which c a l c u l a t i o n s were s i m p l i f i e d . Table I I T r i a l Vol.G.G. V o l . HCl.to n e u t r a l i z e d $ e r r o r .03N .008826M . 1 6cc 19.8 5.82 2 6 19.8 5.82 3 8 26.1. 7.675 4 8 26.3 7.74 5 3 9.82. 2.89 6 3 9.7 2.85 7 1 3.65 1.075 8 1 2.7 1.087 9 1 3.6 1.06 10 .5 1.85 .546 11 .5 1.85 .544 6-5.82. x 100 =3$) 6 6-5.82 x 100 zZ%) 8-7.675X 100-4.06) ~ ( 8-7.74x100 =3.25^(low ~~8 ) 3-2.89x100 =3.67$) 3 ) 5-2.85x100 =5$ ) 3 1.075-1x100=7.5$ ) 1 ) 1.087-1 xl00=8.7$J 1-1.06 xlOO r6$ [high .547-.5x100 =94$ j \u00E2\u0080\u0094 7 5 ) .544-.5x100 =88$ ) .5 12. Blanks were run w i t h the apparatus, i n which a l l the chemicals used i n the d i g e s t i o n process, were introduced i n t o the d i g e s t i o n f l a s k and the amount of ammonia pro-duced from these alone was determined. Table I I I T r i a l Vol.HOT to n e u t r a l i z e $ E r r o r i n v o l v e d using the NH3 from reagents, d i f f e r e n t volumes: of G. G. . 00882611 . 05F 6cc 8cc 5cc l c c .5cc 1 .2cc .0588 .98 .735 1.95 5.88 11.7 2 .25cc .073 1.216 .912 2.43 7.3 14.6 Sample c a l c u l a t i o n f o r e r r o r : .0588 Y IQQ Z .98$ 6 Table I l i a V o l . of G. C. Average e r r o r . 8 . .823$ h i g h 6 1.098$ h i g h 3 2.16$ hig h 1 6.59$ h i g h .5 13.1$ h i g h When t he c o r r e c t i o n f a c t o r was a p p l i e d to the r e u l t s of t r i a l s 7 to 11, i t was found that the micro Kheldahl method gave an accuracy of about 2$ f o r samples of Guanidine Carbonate c o n t a i n i n g 2.52 mg. of n i t r o g e n and 5$ f o r samples c o n t a i n i n g 1.26 mg. of n i t r o g e n . I t was r e a l i z a e d that these r e s u l t s , had an accuracy of somewhat low order but as sources of e r r o r were not 1 3 . ' apparent, i t was decided to go ahead and carry out the analysis of T.M.C.A.B. and see what results could be obtained. If the results obtained in the previous t r i a l s are to be trusted, and the f a i r precision obtained seemed to ju s t i f y the conclusion, then the micro Kheldahl apparat-us used does not seem to give very good accuracy when used on samples below 1.26 mg. of nitrogen as below this burette errors w i l l become major factors. Analysis of Tri-Methyl Getyl Ammonium Bromide. The analysis of T.M.C.A.B. was carried out in con-centrations much above those that can be used in flotation. The reason for this was mentioned in a previous section. The samples of collector to be analysed were prepared from Eastman Kodak material, at a concentration of .005011 grs/cc or .01373N in nitrogen. Conditions for the analyses were as follows: 5cc of .01373U T.M.C.A.B. were put in digestion flask, digested with SejCuSO.jKpSO. catalyst and.2cc H 2S0 4for 2 hours. Di s t i l l e d into lOcc Boric acid for 6 minutes. Titrated with standard HC1. In the table following, the volume of standard . 0088671T HC1 is shown as the equivalent volume of .01373^ HC1. i.e., as the same normality with respect to nitrogen content as the collector. If 5cc of the collector were used and calculations indicate that 5cc of .01373F HC1 .14. were required to neutralize the ammonia, then 100$ yield of ammonia- would be indicated. Table IV Tr i a l Vol.T.M.C.A.B. Vol. of HCl. $ Yield of .01373N .008867F .01573N Nitrogen. 1 5 4.255 2.75 55. 2 5 4.3 2.77 55.4 3. 10 8.4 5.42 55.2 4 10 8.6 5.55 55.5 As far as precision was. concerned the above results of the analysis came out very well. However the very low yield indicated something radically wrong with the method. It was thought that a possible explanation was that as the water solution of the collector evapor-ated and the H2SO4 became more concentrated that the consequent increase in temperature might be sufficient to cause volatilization of the compound. As conditions were carried out identically as. far as the author was able to discern, the precision would be accounted for. Further experiments were carried out with identically the same conditions except for the fact that the total period in the digestion flask ( including time for the water solution to evaporate) was decreased somewhat. The results were as follows: .15. Table.V. T r i a l Vol. T.M.C.A.B. Vol. HCl .009129 .01373N % Yield of Nitrogen. 1 6 5.13 3.41 56.8 2 5 4.45 2.96 59.2 3 5 4.425 2.94 58.8 4. 5 4.45 2.96 59.2 The results, of these trials, seemed to j u s t i f y the assumptions based on the previous t r i a l s , the increased yield being accounted for by the decrease in time in contact with the H2SO4 at the higher temperatures. It . was born in mind however that the volatilization must have taken place between the time when the majority of water had evaporated off and the decomposition of the compound occurred. There may have been other volatile products: containing nitrogen that were formed in the preliminary stages of digestion but this i s thought unlikely. It was deemed advisable to carry out a few more tr i a l s before deciding whether or not to endeavor to use the Kheldahl method of analysis. A. variation in the technique was now introduced;' to place a cap over the digestion flask just at the moment when a l l the water had evaporated or just when the f i r s t trace of charring appeared. Evaporation and digestion were carried out. 16. for exactly two hours as before. Table VI. Tri a l Vol.T.M.C.A.B. .01373N Vol. HCl .009129 .01373 % Yield of Nitrogen. 1 5 7.2 4.78 95.75 2. 5 6.55 4.36 87.2 3 5 7.25 4.82 96.4 4 5 7.25 4.82 96.4 5 5 7.2 4.78 95.75 The results seemed to prove f a i r l y conclusively that i t was some type of volatilization that causes the discrpancy in results. Reference to Table I l i a indicated that the yields above are in error by about 1% due to ammonia in reagents. It was decided here, that to use the micro Kheldahl for the precise analysis required for the adsorption study would be rather f u t i l e . Some work was done however to to try develop a process by which the adsorbed amount of collector on the s i l i c a could be determined. Possible Application of the Kheldahl Method. One of the processes tried was to put 26 grams of s i l i c a in a beaker with 45cc of water and 5cc of T.M.C.A.B. of concentration .005 grs/cc. The mixture was mechanically stirred for several minutes. The solution was then poured into the digestion flask, the SiO washed withl5cc of 2 water and the washing added to the flask. It was noticed 17. that 15cc of water did not appear to be enough to thor-oughly wash the S i 0 2 as the closely packed s i l i c a tended to adsorb most of the wash water . The amount of water required to remove a l l the excess collector was too much to put in the digestion flask. Digestion was not carried out here. The si l i c a , itarelf was washed with a large but indefinite amount of water, the method being to put the s i l i c a on a large s^intered glass f i l t e r and wash thor-oughly; the area of the surface of the f i l t e r being sufficiently large to insure that a l l the s i l i c a particles came in contact with fresh wash water. The s i l i c a was then washed into the digestion flask with 150 cc of water. 2cc of H2SO4 Were added along with the catalysts. It was assumed that the collector would not evaporate off with the water as what was not washed off would be quite firm-ly attached. The d i f f i c u l t y encountered by this method was that bumping occurred so vigourously that the s i l i c a shot right out of the flask. Even when extreme care was taken to prevent bumping, by using very gradual heating, and the volume was obtained where digestion could take place, then the H2SO4 was soaked up by the s i l i c a and there was not sufficient acid to contact the complete surface. A solution to the problem may have been to use a larger quantity of acid, but i t was f e l t that inaccuracies introduced by this would not jus t i f y its use. 18. Summary of Kheldahl Process. I t had been hoped that a check on the a n a l y s i s could have been made by determining the amount of c o l l -e c t o r i n s o l u t i o n a f t e r c o l l e c t i o n had taken place and the amount adsorbed on the s i l i c a . , the t o t a l which would equal the amount i n the o r i g i n a l s o l u t i o n . An attempt has been made to apply the Kheldahl to t h i s a n a l y s i s . As no f u r t h e r m o d i f i c a t i o n i n the method was r e a l i z e d . ^ i t was not considered p r a c t i c a l to c a r r y on any f u r t h e r w i t h i t . C o l o u r i m e t r i c A n a l y s i s . An a r t i c l e d i s c u s s i n g the a n a l y s i s of q u a t e r n a r y ammonium compounds was found i n the l i t e r a t u r e (12). The method had been a p p l i e d to many of such compounds but as f a r as could be determined i t has not been a p p l i e d to T.M.C.A.B. An o u t l i n e of the method of a n a l y s i s as given i n the reference i s as f o l l o w s : Procedure. In a separ a t i n g funnel take 50 mis of water c o n t a i n i n g 50 to 75 micrograms of the q u a t e r n a r y comp-ound. Use s t a r c h - g l y c e r o l stopcock grease. Add 5 mis. of 10$ sodium carbonate s o l u t i o n , 1 ml of aqueous.04$ Bromphenol blue i n d i c a t o r s o l u t i o n and e x a c t l y 10 mis of Benzene. The i n d i c a t o r s o l u t i o n i s made up as f o l l o w s : D i s s o l v e 40mg of Bromphenol blue powder i n lOOmls of water c o n t a i n i n g 1 ml of .lftUodium hydroxide. Shake the s o l u t i o n s t e a d i l y f o r 2.5 to 3 minutes, l e t the l a y e r s 19. separate roughly (20 to 30 sec.) and then swirl the funnel contents. Let stand several minutes or u n t i l well separated. Rinse a 15ml centrifuge with a portion of the aqueous layer, discard the layer entirely and then run the coloured benzene layer into the tube. Stopper the tube and centrifuge at about 1000 rpm., i f necessary to c l a r i f y . Read using f i l t e r 60 in a.Klett-Summerson colourimeter tube. Limit of error 2% with occasional errors of b%. Some modifications of the method were found necessary. ' The article above recommended the use of 50 micrograms of sample (.00005 grs.) It was desired to be able to analyze up to .0004 grams so i t was decided to use 20cc of Benzene instead of lOcc. lOOcc of water were also used in place of 50cc. A Klett photo-electric colourim-eter wa3 used without a f i l t e r . 5 tandard izatioru In much of the preliminary work with the Klett i colourimeter, no reproducibility of a standard could be obtained at a l l . It was f i n a l l y discovered that the ordinary test tubes that had been used to hold the sam-ples were not of uniform thickness or colour. Test tubes, were therefore made from glass tubing of the required size and i t was found that a l l these test tubes, had the same light transmission within one division on the colourimeter. 20. I t was found very d i f f i c u l t to get r e p r o d u c i b i l i t y of r e s u l t s using Benzene. The general shape of the curve obtained is. given i n the accompanying graph F i g . IV, but the i r r e g u l a r i t y of the points i s to be noted. Data f o r the graphs i s i n the f o l l o w i n g t a b l e . Table V I I Concentration of T.M.C.A.B. a .00005 grs/cc 20 cc Benzene Shaking time 3 minutes 1 cc of i n d i c a t o r f o r below .0003 g r s . 2 cc of i n d i c a t o r used f o r above .0003 g r s . T r i a l T.M.C.A.B. V o l . H 2C(cc) K l e t t Reading V o l . Crs. 1 2 .0001 100 48 2 2 .0001 100 40 3 2.5 .000145 100 55 4 4 .0002 100 77 5 4 .0002 100 98 6 4 .0002 100 88 7 5 .00025 100 104 8 6 .0003 100 93 9 6 .0003 100 93 10 6 .0003 100 125 11 6 .0003 100 126 12 7 .00035 100 120 \" 13 8 .0004 100 124 14 8 .0004 100 132 15 8 .0004 100 138 16 8 .0004 100 138 2.1. This was definitely unsatisfactory, so i t was decided that another solvent, ethylene dichloride, that was recommend-ed in the literature, be tried (9). Table VIII. 20 cc ethylene dichloride Concentration of T.M.C.A.B. = .00005 grs/cc. Shaking time = 3 min. Tri a l T.M.C.A.B. Vol. H20 Klett Reading. Vol. Grs. 1 1 .00005 lOOcc 23 2 2 .0001 lOOcc 65 3 3 .00015 lOOcc 94 4 4 .0002 lOOcc 118 5 5 .00025 lOOcc 134 6 6 .0003 lOOcc 148 7 7 .00035 lOOcc 156 8 8 .0004 lOOcc 161 9 1 .00005 lOOcc 64 10 4 .0002 lOOcc 117 11 6 .0003 lOOcc 148 12. 8 .0004 lOOcc 161 Reproducibility of results shown in \"Fig. V. from the above table was found to be almost 100%. In t r i a l s 9 to 12 the collector was l e f t in contact with the indicator for about 10 minutes before the ethylene dichloride was added. This was to see i f rate i i \u00E2\u0080\u00A2 r -4-Calm if I'm etr(c F 1 1 I V Ca.fi h fa~tion C C \u00C2\u00A3 thy It \u00E2\u0080\u0094 t _ i rrcy /ot~jc/\u00C2\u00B0 \u00E2\u0080\u00A2 40 A3. o . O00< O-Z. ti\" . 00 O 3 .aot 3 HgSiOg + 2NaN0 \u00E2\u0080\u00A2A The p r e c i p i t a t e was thoroughly washed f r e e of any i m p u r i t i e s and the g e l was shaken up wit h s e v e r a l cc of the c o l l e c t o r of concent r a t i o n .0001 grs/ c c . The mixture was then f i l t e r e d and washed w i t h d i s t i l l e d water. Half of the s i l i c i c a c i d was placed i n an evaporating d i s h which had been c a r e f u l l y t r e a t e d to insure removal of a l l organic m a t e r i a l , and the other h a l f placed i n a f u s i o n bomb. On heating the s i l i c i c a c i d i n the d i s h , a charred residue was obtained which i n d i c a t e d the presence of the organic p a r t of the c o l l e c t o r at l e a s t . On t e s t i n g the residue from the bomb f o r bromide, no i n d i c a t i o n was found. General D i s c u s s i o n of A n a l y t i c a l Results.. Prom the r e s u l t s shown' i n the previous experimental work there appeared to be a probable metathetic r e a c t i o n , of some nature o c c u r r i n g between the c o l l e c t o r and the s i l i c a s u r f a c e . Reference to the pH - f l o t a t i o n curve ( P i g . .DX i n d i c a t e an increase of c o l l e c t i o n or adsorption of c o l -l e c t o r with increase i n pH. This may p o s s i b l y j u s t i f y the f o l l o w i n g type of r e a c t i o n : ( C H 3 ) 3 C 1 6 H 3 3 K - B r + H 2 S i O \u00E2\u0080\u0094 ( C H 3 ) 3C 1 6H 3 3N-H-Si0 3+HBr I f i t can be assumed that the . s l i g h t d i s s o c i a t i o n of s i l i c i c a c i d would be enough to provide a charged surface upon which the c a t i o n could be adsorbed, then i n c r e a s i n g the a c i d i t y would tend to create more un d i s -s o c i a t e d s i l i c i c a c i d w i t h consequent decrease i n adsorption power. I t thus appeared to the author t h a t whatever pecu-l i a r i t i e s , are involved on the i o n i z a t i o n of Trimethyl 34. Cetyi Ammonium Bromide, adsorptive forces are strong enough to cause some dissociation. Determination of Adsorption ger Unit Area of the S i l i c a Surface. Most flotation authorities are interested in the am-ount of adsorbed material per unit area of the mineral surface. The problem of determining surface areas of finely divided particles is very d i f f i c u l t and there have been few experimenters in the past able to reproduce results within 100 %. It has been therefore very d i f f i -cult to determine to what extent mineral surfaces are occupied by the collector and whether films of collector are monomolecular. As a very rough estimate on the amount of T.M.C.A.B. adsorbed per sq. cm. calculations have been made based on the following datas .00006 grs. of T.M.C.A.B. are adsorbed on a 2 gram sample of s i l i c a . Density of s i l i c a = 2.66 grs/cc If i t is assumed that the particles of s i l i c a came from an originally solid 2 gram sample, the volume of such a sample would be 2 = ,752cm . The s i l i c a was 2766 rs-ieved-through screens of maximum diamter equal to .246mm and of minimum diamter .104mm. The s i l i c a particles were assumed to be cubical in shape. As the irregularities in the s i l i c a surface were not accounted for, i t was f e l t that a c l o s e r approximation could be obtained by-assuming a l l p a r t i c l e s t o be of the smaller s i z e , hence the area per gram would be l a r g e r ; On these assumptions i t was c a l c u l a t e d that the t o t a l number of p a r t i c l e s ob-t a i n a b l e from a two gram sample of SiOgj. each p a r t i c l e 5 being .104 mm along the edge, would be 6.68 x 10 p a r t -i c l e s . From a p a r t i c l e count under a microscope, a 2 5 gram sample was found to c o n t a i n 3.33 x 10 p a r t i c l e s . Assuming the l a r g e r f i g u r e c o r r e c t , and as' the surface -4 2 area per p a r t i c l e is. 1.08 x 10 cm ., the t o t a l surface p area would be 72 cm . The amount of c o l l e c t o r adsorbed i s then .00006 - 8.34 x 10\" 7 grs/cm 2. 72^~ 36. SUMMARY. 1. The e f f e c t of pH on f l o t a t i o n has been shown. 2. The establishment of a good c o l o u r i m e t r i c a n a l y s i s f o r the c o l l e c t o r has been achieved. 3. The amount of a d s o r p t i o n of the c o l l e c t o r has, been shown. 4. The absence of Bromide 'on the s i l i c a surface has been shown which seems to i n d i c a t e a metathetic r e a c t i o n has occurred. 5. A very approximate c a l c u l a t i o n of the adsorption of T. M. C. A. B. per square cm. has- been g i v e n . Future Work. I t might be p o s s i b l e to apply a d i r e c t weighing method to c o l l e c t o r a d s o r ption, as i s used by H. B a r r e t i n determination of water adsorption on s i l i c a . ( 1 2 ) A photographic method of determining p a r t i c l e areas has been developed to a q u i t e accurate degree (13). A p p l i c a t i o n of t h i s method might a s s i s t i n a c q u i r i n g f u r t h e r information as to molecular s t r u c t u r e of surface f i l m s . BIBLIOGRAPHY. Reference. T i t l e . 1. P r i n c i p l e s of F l o t a t i o n . Ian W. Wark 2. J o u r n a l of P h y s i c a l Chem. 40,661, 1936 3. U. S. Bureau of Mines, B u l l e t i n 449, p. 44 4. Ind and Eng. Chem. (Anal. Ed.) 19,1294, 1927 5. Ind. and Eng. Chem. (Anal.Ed.) 14,200, 1942 6. Ind. and Eng. Chem. (Anal.Ed.) 14,437, 1942 7. Q u a n t i t a t i v e Organic Micro A n a l y s i s , P. 84, Pregle-Grant. 8. Ind. and Eng. Chem. (Anal. Ed.) 16, 12, 1944 9. Ind. and Eng. Chem. (Anal.Ed.) 15,492, 1943 10. Thorpes D i c t i o n a r y of A p p l i e d Chemistry. 11. J . A. C. S. 68, 437, 1946. 12. J.A.\" C. ;S. 63, 2839, 1940 13. Ind. and Eng. Chem. (Anal Ed.) 2, 59, 1930 "@en . "Thesis/Dissertation"@en . "10.14288/1.0062388"@en . "eng"@en . "Chemistry"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "Surface reaction with cationic collectors in silica flotation"@en . "Text"@en . "http://hdl.handle.net/2429/41814"@en .