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Surface reaction with cationic collectors in silica flotation Embree, William Howard 1947

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SURFACE REACTION" WITH CATIOFIC COLLECTORS IN SILICA FLOTATION.  Submitted to the Department of Chemistry, the University of B r i t i s h Columbia, i n p a r t i a l f u l f i l l m e n t of the requirements f o r the Degree of Master of A r t s , 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 i n the carrying out of the work.  INDEX.  Page. 1. 1. 2.  Introduction. a. P r e v i o u s work. b. Nature of work to be u n d e r t a k e n .  3.  Preparation  5. 5.•  I n f l u e n c e of pH on f l o t a t i o n . a. A p p a r a t u s and m a t e r i a l s , b. P r o c e d u r e  8. 9. 9. 13. 16. 18.  of . s i l i c a  samples.  A n a l y t i c a l methodB f o r the c o l l e c t o r . a. M i c r o - K h e l d a h l a n a l y s i s . - Apparatus, and s t a n d a r d i z a t i o n . - Analysis of Trimethyl Getyl Ammonium Bromide (T.M.C.A.B.) - P o s s i b l e a p p l i c a t i o n of t h e method. - Summary o f the K h e l d a h l p r o c e s s .  18. 18. 19. 22. 2.8.  b. C o l o u r i m e t r i c a n a l y s i s . - Procedure - Standardization - A p p l i c a t i o n t o adsorbed c o l l e c t o r . - Summary o f C o l o u r i m e t r i c : a n a l y s i s .  29. 31. 31.  c. Bromide a n a l y s i s - Method and s t a n d a r d i z a t i o n . - 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  34.  D e t e r m i n a t i o n of a d s o r p t i o n silica  36.  Summary.  36.  F u t u r e Work.  37.  Bibliography.  surface.  results.  per u n i t area of the  ABSTRACT.  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 colourimetric  analysis  f o r the c o l l e c t o r 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 i n the f l o t a t i o n industry are substances that cover the mineral p a r t i c l e , or part of the p a r t i c l e with an a i r avid coating, that i s 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 c o l l e c t o r s must be adsorbed i n order to be effedtive.  I t has been found ( Ref. 1, P. 95) that  there are three main classes of c o l l e c t o r s ; (a) O i l s . (b) Acids containing a hydrocarbon group and the potassium and sodium s a l t s 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 d e r i v i t i v e s of the amines, and certain organic analogues. It i s a member of this group, trimethyl c e t y l ammonium bromide ( i n future, this w i l l be referred to as T. M. C. A. B.) which i s to be dealt with i n this thesis. T. M. C. A. B. i s one of the most i n t e r e s t i n g members, of the s e r i e s . (Ref. 1, P. 104). Previous Work. The majority of the experimental work i n connection  2. with the use of T. M. C. A. B. as a f l o t a t i o n reagent has been done by Wark ( 2 ) . Wark has used this c o l l e c t or i n the f l o t a t i o n of galena, rhodonite, c a s s i t e r i t e , quartz and other minerals.  He has experimented  with  f l o t a t i o n i n acid, alkaline or neutral solutions and found T. M. C. A. B. to be a c o l l e c t o r f o r quartz i n a l l mediums (Ref. 1. P. 248). In connection with the surface reactions between c o l l e c t o r s and mineral surfaces two main theories have been advocated. Taggart (3) postulated a chemical theoryof the adsorption process i n which he stated that the f l o t a t i o n 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 i n the adsorption theory and that the essential differences between adsorption and chemical reaction i s that the chemical reaction proceeds throughout the entire p a r t i c l e unless hindered by formation of a f i l m , 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 i n which the c o l l e c t o r i s attached to the surface of quartz. As noted above there has been some controversy over the point.  i  3. It i s a well established f a c t that the surface of s i l i c a becomes hydrated, forming the acid of the structure Si02» xHgO, which i s sometimes written f o r the purpose of equations as H^SiO^.  A" possible surface reaction may  then be H Si0 t(CH ) C H N-Br —> (CH ) 2  3  3  3  1 6  3 3  3  G^HggN-HSiO^ HBr  3  However data on this s p e c i f i c reaction was not encountered by the author so i t was necessary to attempt to throw further l i g h t on the process of adsorption through a n a l y t i c a l methods. Preparation  of S i l i c a Samples.  It was desirable to obtain s i l i c a i n the purest form possible and this was done i n the following way. c r y s t a l i n e s i l i c a was obtained, ble traces of impurities. was done by heating and  then plunging  which contained  Some  no v i s i -  The preliminary breaking up  the s i l i c a to quite a high temperature  i t into cold water.  was then set up to cause considerable  Sufficient strain shattering.  It  was also found much easier to carry out the grinding a f t e r this treatment.  The quartz, was ground by hand with  a large mortar and pestle.  Preliminary s i z i n g was done  with 60 to 150 mesh brass seives.  When a considerable  quantity of quartz of this s i z e had been prepared, i t was. washed with sulphuric acid to insure removal of any metallic impurities that may have accumulated from the  2iG*i.  F-Tft.T.  s  T  150 ineak sieve.  1111  ii II  to tap. L  4. sieves.  In respect to the m e t a l l i c impurities: Wark makes  this statement (Ref.l. P  179)  "the a c t i v a t i o n 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 t y p i c a l instance of adsorption." By '"activation" he i s here r e f e r r i n g to the fact that a permanent change in the surface c h a r a c t e r i s t i c s of quartz can be produced by an a c t i v a t i n g cation such as iron. It i s believed that a l l possible precautions, were taken as to the elimination of m e t a l l i c impurities, and of organic, impurities. After washing with sulphuric acid, the s i l i c a  was  e l l u t r i a t e d to get r i d of p a r t i c l e s below 150 mesh. The most s a t i s f a c t o r y type of e l l u t r i a t i o n f o r particles: of this size was ing  of the design shown i n the accompany-  diagram (Pig., 1.)".  It was  found that i n order to  carry over quartz of the 60 - 150 mesh size i t was necessary for the pressure to be regulated d i r e c t l y 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. was  The s i l i c a which flowed through the tube (T)  collected in the 150 mesh sieve, the water flowing  through helping to remove p a r t i c l e s less, than 150 mesh. It was f e l t that by the above method a f a i r l y range of s i z i n g was was  obtained.  uniform  The main object in t h i s  to be able to get some degree of r e p r o d u c i b i l i t y of  smii  J&QTITI0H_APPARATUS.  Flotation  cell.  A i r pressure, Skiaimar Frotk  cellecter  Gr ©und j o i n t Rubber connection S^intered p l a t e  Manometer  r e s u l t s when the d e t e r m i n a t i o n o f the amount o f c o l l e c t o r adsorbed was c a r r i e d o u t . I n f l u e n c e of pH on F l o t a t i o n . There has been a c o n s i d e r a b l e amount o f d a t a i n t h e l i t e r a t u r e on the i n f l u e n c e o f pH on f l o t a t i o n , i n conn e c t i o n w i t h many m i n e r a l s and types of c o l l e c t o r s ( l ) but t h e m a j o r i t y o f experiments were c a r r i e d out on a much l a r g e r scale, t h a n was p o s s i b l e w i t h t h e a p p a r a t u s and m a t e r i a l s a v a i l a b l e to t h e a u t h o r .  I t was t h e r e f o r e  n e c e s s a r y t o t e s t r e s u l t s on a s m a l l e r s c a l e . A p p a r a t u s and M a t e r i a l s . . In  the a c t u a l f l o t a t i o n a c e l l o f t h e accompanying  d e s i g n was used  ( F i g . I I ) . I t had been found w i t h p r e -  v i o u s types o f c e l l s w h i c h had a l i p t o c a r r y o f f t h e o v e r f l o w , t h a t 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 p r e v e n t i n g 100% c o l l e c t i o n .  In this  type a glass, r o d w i t h a skimmer a t t a c h e d t o the top was used to s c r a p e the SiO£ o f f the edge o f t h e c e l l . I t w i l l be n o t i c e d I n the diagram t h a t t h e s c i n t e r e d g l a s s f i l t e r f u n n e l w h i c h was used to c r e a t e the bubbles of  the process was a t t a c h e d to t h e upper s e c t i o n o f t h e  c e l l by a rubber c o n n e c t i o n .  T h i s method was used t o  enable the changing of the volume o f water i n the c e l l , if  i t were n e c e s s a r y , and a t the same time keep t h e same  h e i g h t o f f r o t h zone.  I n o r d e r to a s s u r e t h a t t h e  rubber would n o t a f f e c t ' " 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 s u r f a c e s so t h a t a  t i g h t ground g l a s s c o n n e c t i o n T e r p i n i o l was t r a t i o n being  .250  resulted.  used as a f r o t h i n g agent, i t s concengrs/cc.  i n s o l u t i o n form h a v i n g  T. M.  G. A. B. was  prepared  a c o n c e n t r a t i o n of .0001  grs/cc.  Procedure. In the f o l l o w i n g experiments the method was  as  follows:  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 The  a i r p r e s s u r e was  turned  cell.  on s l i g h t l y so t h a t when the  w a t e r and c o l l e c t o r were added, none would be l o s t running  through the p l a t e .  l u t i o n was  The pH of the f l o t a t i o n  a d j u s t e d by means, of HC1  c o l l e c t o r and  t e r p i n i o l added.  i n t o the c e l l and the p r e s s u r e  The  so-  and NiaOH, w i t h s o l u t i o n was  poured-  i n c r e a s e d to i n s u r e s u f -  f i c i e n t r o u g h i n g of the s i l i c a and c o l l e c t o r . The was  by  pressure  then f u r t h e r i n c r e a s e d u n t i l the f r o t h zone was  enough to c a r r y the s i l i c a s i l i c a was  over.  The  c o l l e c t i n g of  c a r r i e d on f o r one m i n u t e .  I t was  t h a t the g r e a t m a j o r i t y of the s i l i c a was  q u i t e w a t e r y and a t the end  f r o t h zone was considered  considerably higher.  the  noticed  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 r u n . f r o t h was  high  The  of one minute  the  T h i s , however,  was  practically a negligible factor.  A t 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 , h a v i n g an a s b e s t o s filter.  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 ° C  f o r s e v e r a l hours and a g a i n weighed. w e i g h t gave the w e i g h t o f c o l l e c t e d The f o l l o w i n g  The d i f f e r e n c e i n silica.  t a b l e g i v e s 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 o f c o l l e c t o r a t v a r y i n g pH's. Table I. 10 cc T e r p i n e o l Roughing Time 2 min. C o l l e c t i n g Time • 1 m i n . Concentration of c o l l e c t o r s  P r e s s . V o l KgO cms.Hg 6-7  2.00  cc  pH  iC o l l e c t o r iC r s . Vol.fcc)  1.9  it  it  ii  II  II  it  II:  II:  5.21  It  2.925  6-7 ii  II  it  II  it  II  6-7  II  it  tl.  it  It  II  II  2.98 3.96 4.475  3.41 '  4.04 4.61'  2.06 2.875 3.6 3.96  .0001  gral/cc  Silica In C e l l  of  In P r o t h Colle<  .0002  2  2  .1360  it  n  2  .8690  ti  it  2  1.7110  85.6  tt.  «»  2  1.8971  94.8  ll  It;  2  1.9527  97.7  4  2  1.2452  62.25  w  tt  2  1.7589  88  n  ll  2  1.9672:  98.3  it  it  2.  1.9725  98.7  6  2.  .3473  «i  it  2  1.4142  70.6  it  II  2  1.9561  97.8  ll  II;  2  1.9241  96.4  .0004  .0006  6.8 43.4  17.35  8.  The r e s u l t s shown on the graph (Pig. I l l ) check q u a l i t a t i v e l y with the r e s u l t s of previous workers.on the subject and may  be summarized as follows.:  1. Increase  in pH causes, rapid increase i n f l o a t -  a b i l i t y up to 86% and  90%,  2. The slope of the curve increases, as the quantity of c o l l e c t o r in the f l o t a t i o n pulp increases. Further discussion on possible interpretation of pH s t a t i s t i c s w i l l be given in a f i n a l discussion of experimental results of t h e s i s . A n a l y t i c a l Methods f o r the C o l l e c t o r . As i t was  to be attempted to determine the nature of  the surface reaction between the c o l l e c t o r and s i l i c a , of the e s s e n t i a l factors, was for the c o l l e c t o r .  It was  one  to f i n d a method of a n a l y s i s  thought possible to work at  the problem from two points of view: either (a) find  the  amount of c o l l e c t o r adsorbed d i r e c t l y 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 i n the o r i g i n a l solution f i n d  the  amount adsorbed. It seemed quite l o g i c a l 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 i n (a) the amount adsorbed would be small and in (b) the difference  9. between the amount adsorbed and the amount i n solution would be small. Micro KheldahlAnalysis. Because the c o l l e c t o r i s 3.85$ nitrogen the micro Kheldahl test was considered. The lower l i m i t claimed for nitrogen detection is. about .067 mg ( 8 ) .  As. w i l l  be seen l a t e r the maximum amount of T. M. C. A. B. analyzed f o r was below .0008 grs. 3.04 xlO  grs. of nitrogen.  This amounts, to  As this maximum figure i s  below the lower l i m i t of Kheldahl accuracy i t was f e l t that insofar as detection was concerned under conditions used i n the experiments, the micro Kheldahl process was; not very p r a c t i c a l .  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 c o l l e c t o r 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 r e p r o d u c i b i l i t y that could be obtained.  I t was decided  to use G.uanidine carbonate to standardise the apparatus. It, was from a well known source and i t s purity was  10. considered r e l i a b l e . A\ solution of Guanidine carbonate was prepared .03ET with respect to nitrogen. ((NHgJgP  =  N H  ^2* 2 3 H  G 0  W  i  t  h  a  The formula f o r G. C. i s m  o  l  e  c  u  l  a  r  weight of 180.14.  The nitrogen equivalent of this i s 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 S 0 2  4  and 3. parta of C.uS0 *5H 0 with 1 Hengar 4  2  selenized granule. 2cc of concentrated H 2 S O 4 were used for digestion(5). The G. C. w$s  introduced into the digestion f l a s k by  means of a micro burette.  The catalyst and H 2 S O 4 were  then added and the mixture heated for 2. hours.  I t was.  found that short digestion times recommended i n the l i t e r ature were i n s u f f i c i e n t to insure Once digestion was completed  reproducible results.. i t was necessary to  consider the best way of c o l l e c t i n g the d i s t i l l e d ammonia. The Boric acid c a l i b r a t i o n curve system (6) was  tried.  Thiq was based on a c a l i b r a t i o n curve of quantity of jRH^OH added to a constant volume of 4^ Boric acid, plotted against pH readings.  I t was found very d i f f i c u l t to use  with any precision as even changes in the pH of d i s t i l l e d water used in the process were s u f f i c i e n t to change the results. The method f i n a l l y decided upon was found in a text on micro-analysis ( l l ) .  The ammonia was d i s t i l l e d f o r  6 minutes into lOcc of A.% Boric acid into which had been  11. put 4 drops o f a m i x t u r e of lOcc o f b r o m c r e s o l green and 2 cc of m e t h y l r e d i n d i c a t o r . s o l u t i o n s of the s o l i d d y e s t u f f  B o t h i n d i c a t o r s were »1$ i n 95$ a l c o h o l .  The  c o l o u r change was from b l u i s h p u r p l e , to b l u i s h g r e e n 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 p i n k shade. The method was found to g i v e p r e c i s e  end p o i n t s .  I n the t a b l e which f o l l o w s t h e r e i s shown the volume of s t a n d a r d HC1 used t o t i t r a t e the ammonia from the d i g e s t i o n of the Guan&dine c a r b o n a t e .  The volume o f HC1  used has been t r a n s f o r m e d to .03N ( t h e n o r m a l i t y  of the  G. C.) from w h i c h 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 . H C l . t o n e u t r a l i z e d .03N .008826M .  $ error 6-5.82. x 100 =3$) 6 6-5.82 x 100 zZ%)  1  6cc  19.8  5.82  2  6  19.8  5.82  3  8  26.1.  7.675  4  8  26.3  7.74  5  3  9.82.  2.89  6  3  9.7  2.85  7  1  3.65  1.075  8  1  2.7  1.087  1.075-1x100=7.5$ ) 1 ) 1.087-1 xl00=8.7$J  9  1  3.6  1.06  1-1.06 xlOO r 6 $  10  .5  1.85  11  .5  1.85  .546 .544  8-7.675X 100-4.06)  ~ ( 8-7.74x100 =3.25^(low ~~8 ) 3-2.89x100 =3.67$) 3 ) 5-2.85x100 =5$ ) 3  [high  .547-.5x100 9 4 $ j —75 ) .544-.5x100 =88$ ) .5 =  12. B l a n k s were r u n w i t h the apparatus, i n w h i c h a l l the c h e m i c a l s used i n the d i g e s t i o n process, were i n t r o d u c e d i n t o the d i g e s t i o n f l a s k and t h e amount o f ammonia p r o duced from these a l o n e was d e t e r m i n e d . 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 u s i n g the NH3 from r e a g e n t s , d i f f e r e n t volumes: o f G. G. . 00882611 . 05F 6cc 8cc 5cc l c c .5cc 1  .2cc  .0588  2  .25cc  .073  .98  .735 1.95  5.88  11.7  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 6 Table  IQQ Z  .98$  Ilia  V o l . o f G. C. 8  Y  .  Average  error.  .823$ h i g h  6  1.098$ h i g h  3  2.16$  high  1  6.59$  high  .5  13.1$ When  high  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 t o t h e  r e u l t s o f t r i a l s 7 to 11, i t was found t h a t t h e m i c r o K h e l d a h l method gave an a c c u r a c y of about 2$ f o r samples of G u a n i d i n e Carbonate c o n t a i n i n g 2.52 mg. o f 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 t h a t these r e s u l t s , had an a c c u r a c y of somewhat low o r d e r b u t as s o u r c e s o f e r r o r were n o t  13.'  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 j u 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 f a c t o r s . Analysis of Tri-Methyl Getyl Ammonium Bromide. The analysis of T.M.C.A.B. was  carried out i n con-  centrations much above those that can be used in f l o t a t i o n . The reason f o r this was mentioned in a previous section. The samples of c o l l e c t o r to be analysed were prepared from Eastman Kodak material, at a concentration of .005011 grs/cc or .01373N in nitrogen. Conditions f o r the analyses were as follows: 5cc of .01373U T.M.C.A.B. were put i n digestion flask, digested with SejCuSO.jKpSO. catalyst and.2cc H S 0 f o r 2 hours. 2  Distilled  4  into lOcc Boric acid f o r 6 minutes.  Titrated with standard  HC1.  In the table following, the volume of standard . 0088671T HC1 HC1.  i s shown as the equivalent volume of .01373^  i . e . , as the same normality with respect to nitrogen  content as the c o l l e c t o r .  If 5cc of the c o l l e c t o r were  used and calculations indicate that 5cc of .01373F HC1  .14. were required to neutralize the ammonia, then 100$ y i e l d of ammonia- would be indicated. Table IV T r i a l Vol.T.M.C.A.B. V o l . of HCl. .01373N .008867F .01573N  $ Y i e l d of 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 f a r as precision was. concerned the above results of the analysis came out very well.  However the  very low y i e l d indicated something r a d i c a l l y wrong with the method.  I t was thought that a possible explanation  was that as the water solution of the c o l l e c t o r evaporated and the H2SO4  became more concentrated that the  consequent increase i n temperature might be s u f f i c i e n t to cause v o l a t i l i z a t i o n of the compound.  As conditions  were carried out i d e n t i c a l l y as. f a r as the author was able to discern, the precision would be accounted f o r . Further experiments were carried out with i d e n t i c a l l y the same conditions except f o r the f a c t that the t o t a l period in the digestion f l a s k ( including time f o r the water solution to evaporate) was decreased somewhat. The results were as follows:  .15. Table.V. Trial  Vol.  T.M.C.A.B.  Vol. HCl .009129  .01373N  % Y i e l d 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 t r i a l s , seemed to j u s t i f y the assumptions based on the previous t r i a l s , the increased y i e l d being accounted f o r by the decrease i n time i n contact with the H 2 S O 4 at the higher temperatures.  It .  was born in mind however that the v o l a t i l i z a t i o n must have taken place between the time when the majority of water had evaporated o f f and the decomposition compound occurred.  There may have been  of the  other v o l a t i l e  products: containing nitrogen that were formed i n the preliminary stages of digestion but this i s thought unlikely. It was deemed advisable to carry out a few more t r i a l s before deciding whether or not to endeavor to use the Kheldahl method of analysis.  A. v a r i a t i o n in the  technique was now introduced;' to place a cap over the digestion f l a s k just at the moment when a l l the water had evaporated or j u s t 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. T r i a l Vol.T.M.C.A.B. .01373N  Vol. HCl .009129  .01373  % Y i e l d 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 v o l a t i l i z a t i o n that causes the discrpancy  in results.  Reference to Table I l i a indicated  that the yields above are i n error by about 1% due to ammonia i n reagents. It was decided here, that to use the micro Kheldahl for  the precise analysis required f o r the adsorption  study would be rather f u t i l e . to to t r y  Some work was done however  develop a process by which the adsorbed amount  of c o l l e c t o r on the s i l i c a could be determined. Possible Application of the Kheldahl Method. One of the processes t r i e d was to put 26 grams of s i l i c a i n a beaker with 45cc of water and 5cc of T.M.C.A.B. of concentration  .005 grs/cc.  s t i r r e d f o r several minutes.  The mixture was mechanically The solution was then poured  into the digestion f l a s k , the SiO washed withl5cc of 2 water and the washing added to the f l a s k . I t was noticed  17. that 15cc of water did not appear to be enough to thoroughly wash the S i 0  2  as the c l o s e l y 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 c o l l e c t o r was to put in the digestion f l a s k . out here.  too much  Digestion was not c a r r i e d  The s i l i c a , itarelf was washed with a large but  i n d e f i n i t e 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 thoroughly; the area of the surface of the f i l t e r  being  s u f f i c i e n t l y large to insure that a l l the s i l i c a p a r t i c l e s came in contact with fresh wash water.  The s i l i c a  was  then washed into the digestion f l a s k with 150 cc of water. 2cc of H2SO4 Were added along with the c a t a l y s t s .  I t was  assumed that the c o l l e c t o r would not evaporate off with the water as what was l y attached. was  not washed off would be quite firm-  The d i f f i c u l t y encountered by this method  that bumping occurred  so vigourously that the  shot r i g h t out of the f l a s k .  Even when extreme care  taken to prevent bumping, by using very gradual and the volume was  silica  heating,  obtained where digestion could take  place, then the H2SO4 was  soaked up by the s i l i c a  and  there was  not s u f f i c i e n t acid to contact the complete  surface.  A solution  to the problem may  use a larger quantity of acid, but i t was  have been to felt  that  inaccuracies introduced by this would not j u s t i f y i t s use.  was  18. Summary o f K h e l d a h l P r o c e s s . I t had been hoped t h a t a check on the a n a l y s i s c o u l d have been made by d e t e r m i n i n g the amount o f 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 p l a c e and the amount adsorbed  on t h e s i l i c a . ,  the t o t a l which would  e q u a l 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 t o a p p l y t h e K h e l d a h l t o 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 n o t c o n s i d e r e d p r a c t i c a l t o c a r r y on any f u r t h e r with i t . Colourimetric  Analysis.  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 o f 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 ( 1 2 ) . The method had been a p p l i e d to many of such compounds b u t a s far  as c o u l d be determined  T.M.C.A.B. in  i t has n o t been a p p l i e d t o  An o u t l i n e of the method o f a n a l y s i s as g i v e n  the r e f e r e n c e i s as f o l l o w s :  Procedure.  In a separating  f u n n e l take 50 mis o f 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 compound.  Use s t a r c h - g l y c e r o l s t o p c o c k g r e a s e .  Add 5 m i s .  of 10$ sodium c a r b o n a t e s o l u t i o n , 1 m l o f 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 m i s 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 b l u e powder i n lOOmls o f water c o n t a i n i n g 1 m l of .lftUodium h y d r o x i d e . s o l u t i o n s t e a d i l y f o r 2.5 t o 3 m i n u t e s ,  Shake the  l e t the l a y e r s  19. separate roughly (20 to 30 sec.) and then swirl the funnel contents. separated.  Let stand several minutes or u n t i l well  Rinse a 15ml  centrifuge with a portion of  the aqueous layer, discard the layer e n t i r e l y and then run the coloured benzene layer into the tube. the tube and centrifuge at about 1000 to c l a r i f y .  rpm.,  Stopper  i f necessary  Read using f i l t e r 60 i n a.Klett-Summerson  colourimeter tube. Limit of error 2% with occasional errors of b%. Some modifications of the method were found necessary. ' The a r t i c l e 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 i n place of 50cc. A K l e t t photo-electric colourimeter wa3 used without a f i l t e r . 5 tandard izatioru In much of the preliminary work with the K l e t t i  colourimeter, no r e p r o d u c i b i l i t y 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 samples 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  same l i g h t transmission within one d i v i s i o n on the colourimeter.  the  20. I t was found v e r y d i f f i c u l t t o g e t r e p r o d u c i b i l i t y of r e s u l t s u s i n g Benzene.  The g e n e r a l shape o f the curve  o b t a i n e d is. g i v e n i n the accompanying graph F i g . IV, b u t the  i r r e g u l a r i t y of the p o i n t s i s to be n o t e d .  the g r a p h s i s i n the f o l l o w i n g  Data f o r  table.  Table V I I C o n c e n t r a t i o n of T.M.C.A.B. a .00005 g r s / c c 20 cc Benzene S h a k i n g time 3 minutes 1 c c 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 . Crs.  V o l . H C(cc) 2  K l e t t Reading  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 d e f i n i t e l y unsatisfactory, so i t was decided that another solvent, ethylene d i c h l o r i d e , that was recommended i n the l i t e r a t u r e , be t r i e d (9). Table VIII. 20 cc ethylene dichloride Concentration of T.M.C.A.B. = .00005 grs/cc. Shaking time = 3 min. Trial  T.M.C.A.B. Vol. Grs.  Vol. H 0 2  K l e t t Reading.  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 c o l l e c t o r was l e f t i n contact with the indicator f o r about 10 minutes before the ethylene dichloride was added.  This was to see i f rate  i  i r  •  -41  F  1 I  V  Calm ifI'm etr(c Ca.fi h fa~tion C  £ thy  C  It  —t_i  rrcy  /ot~jc/<t  •  / ZO Cr  V  S rvj  too  *>° •  40  A3. .  O00<  O-Z. ti"  . 00  O3  .aot 3<T  o  ;o60&  22. of f o r m a t i o n As  of the s a l t had any  e f f e c t on the  results.  the r e s u l t s i n d i c a t e , i t does not appear to do I t was  decided  so.  t h a t the a c c u r a c y of the method j u s t -  i f i e d g o i n g ahead w i t h the problem of d e t e r m i n i n g problem of a d s o r p t i o n  on the  the  silica.  A p p l i c a t i o n o f C o l o u r i m e t r i c A n a l y s i s to  the  A d s or b e d C o l l e c t o r . Procedure i n A n a l y s i s . I t had  been observed by the a u t h o r t h a t  r e s u l t s of the a n a l y s i s c o u l d be o b t a i n e d  reproducible  on the same  c a l i b r a t i o n c u r v e u s i n g t o t a l volumes of w a t e r f r o m to 260  cc.  In the e x p e r i m e n t a l  and X. f l o t a t i o n was and  210  50  r e s u l t s shown i n Table IX  c a r r i e d out i n the volumes of 50  cc of w a t e r .  Washing was  cc  done w i t h 50 cc of w a t e r  i n each case, the a n a l y s i s then b e i n g c a r r i e d out on lOOcc and  260  cc r e s p e c t i v e l y .  Method |U To the volume of water to be used i n the was  flotation  added the r e q u i r e d amount of c o l l e c t o r so t h a t  t o t a l volume was added as i t had  50 cc or 210 c c .  T e r p i n e o l was  the  not  been found to i n t e r f e r e w i t h the  colour-  i m e t r i c t e s t and a l s o the a c t i o n of the c o l l e c t o r a l o n e was  desired.  The  pH of the s o l u t i o n was  adjusted  a pH meter,O.2 g r s . of s i l i c a were put i n t o the cell, added.  the a i r p r e s s u r e The  pressure  was  was  turned  on and  with  flotation  the s o l u t i o n  k e p t h i g h enough to i n s u r e  com-  23. plete mixing of the s i l i c a with the solution, but not high enough for the f r o t h to be carried over the edge of the ing,  cell.  The roughing time was 3 minutes . -  A f t e r rough-  the solution was drawn off into a separating funnel. •  The c e l l and s i l i c a were washed with 50 cc of water, the washing being carried out i n the c e l l and the water added to the rest of the solution.  The analysis was then  carried out as described under the section dealing with the  preparation of a c a l i b r a t i o n curve.  The reading ob-  tained on the colourimeter was compared with the curve, from which the amount adsorbed was determined.  This  reading was the amount adsorbed by the s^intered plate of the  c e l l and the s i l i c a .  I t was therefore necessary to  run  a blank on the apparatus without using s i l i c a . Proced-  ure was the same as i f s i l i c a were used. The r e s u l t s of the analyes under the varying conditions are shown i n Table IX.  (See Page 24.)  24.  Table I X . Method A.  Collector. Flotation Vol. H 0 Klett Grs. o f C o l l e c t r VoLcc. Grs-. F l o t - Wash- Reading In S o l n . Adsorbed PH ation ing  Trial  2  1 Plate 3 i 0  2  Plate  4  .0002  '6.04  50  50  68  .0001075 .0000925  4  .0002  6.04  50  50  92  .000147  .0000395  SiO?.  2 Plate S i 0  2  4  .0002  6.08  50  P l a t e - u s i n g same f a c t o r s as i n t r i a l Si0  50  70  (1)  .000111  .000089  .000147  .000053 .000036  o  3 Plate S i 0  2  Plate  6  .0003  6.06  50  50  119  .0002025 .0000975  6  .0003  6.06  50  50  134  .00025  SiOp 4 Plate S i 0  .000053  .0000500 .0000475  2  6 •  .0003  6.08  50  50  122  .00021  .00009  Plate  .00005  SiO^  .00004  5 Plate S i 0  2  8  .0004  1.96  50  50  158  .000354  .000046  Plate  .00005  S.i.Pa  .00000 -?  6 Plate S i 0  2  8  .0004  2.46  50  50  153  .0003325 .0000675 .00005  Plate s i 0  .0000175  2_  7 Plate  8  .0004  1.94 •  50  50  156  .00035  .00005  8 Plate  8  .0004  2.48  50  50  156  .00035  .00005  9 Plate  8  .0004  3.55  50  50  154  .00034  .00006  T r i a l (5) shows t h a t s l i g h t l y l e s s c o l l e c t o r i s adsorbed by  25. the plate plus the s i l i c a tJian i s by the plate alone. Allowing for experimental  error i t i s believed that the  two results should be the same i . e . , at this pH no c o l l e c t or i s adsorbed by the s i l i c a .  Reference to the graph ( F i g .  IV)indicates that only mechanical f l o t a t i o n occurs at this pH and no c o l l e c t o r is seemingly adsorbed. In t r i a l s values.  7, 8 and 9, blanks were run at d i f f e r e n t pH  It was noticed that the pH did not seem to make  any appreciable difference to the amount of c o l l e c t o r adsorbed, on the s^intered plate. a l o g i c a l conclusion but i t may  This did not appear as  be that pH is not much of a  c r i t i c a l factor in adsorption on a r e l a t i v e l y smooth surface as i t is for a rough surface l i k e the ground; s i l i c a . It was decided to see what e f f e c t f l o t a t i o n i n 210 cc of solution would have on adsorption.  210 cc i s the t o t a l  volume i f 10 cc of terpineol were being used, so that concentration of the solution i s the same as in the data on  page 7. A new  due  c e l l was also used to see i f adsorption effects  to a new  s^intered plate might change the r e s u l t s .  Results are shown in Table X.  26. Table X Method A. Trial  Collector Flotation V o l . c c . Grs-. pH  Vol.HgO Klett T.M.C.A.B. F l o t - Wash- Reading G r s . i n S o l . G r s . a d s o r g ation ing • 152  .00033  .00007  50  152  .00033  .00007  50  151  .00003225  .0006775  1  Plate  8  .0004  2.22  210cc 50  2  Plate  8  .0004  5.32  210  3  Plate &Si0 Plate  8  .0004  2.25  210  2  .00007 .0000075  SiO 2 4 P l a t e S i O2  8  .0004  2.22  210  50  .00032  150  .00008  Plate  .00007  $i0  .00001  p  5 Plate &Si0  2  8  .0004  6.2  210  50  .000265  138  .000135  Plate  .00007  Si0  .000065  2  Method B. 2  .8  .0004  6.24  210  50  154  .00006  7 Sipp  8  .0004  6.2  210  50  153  .0000675  6 S'i0  T r i a l s (1) and (2) i n Table X show t h a t a d s o r p t i o n on the p l a t e i s independent v e r i f y the r e s u l t s w i t h  of the pff.  T h i s seems to  the o t h e r f l o t a t i o n  cell.  Method B. In o r d e r t o g e t f u r t h e r v e r i f i c a t i o n f o r t h e amount of c o l l e c t o r adsorbed, a new method o f approach  was  ?I0;  JSIQ.JXX.  Flotation  funnel.  "Suction,  Silica trap.  Analysis funnel,  VI  27. p l a n n e d i n which the a d s o r p t i o n f a c t o r of a s ^ i n t e r e d p l a t e c o u l d be n e g l e c t e d .  In t h i s method the s i l i c a  and  the f l o t a t i o n reagents were shaken i n a s e p a r a t i n g f u n n e l for  3 minutes..  The  s o l u t i o n was  drawn o f f , the  silica  b e i n g caught i n a t r a p c o n s i s t i n g of a p i e c e of f i n e mesh, copper gauze f i t t e d to the end of a p i e c e of g l a s s the t r a p b e i n g a t t a c h e d stopper  tube,  to the stem of the f u n n e l w i t h  i n such a manner t h a t none of the r e a g e n t s  a  could  come i n c o n t a c t w i t h the s t o p p e r and be adsorbed upon i t . The  a d s o r p t i o n c a p a c i t y of the w i r e mesh ; 1..- 3 was  sidered negligible. The  ( P i g . YI.)  f l o t a t i o n s o l u t i o n was  s e p a r a t i n g f u n n e l and  c o l l e c t e d i n another  the f l o t a t i o n f u n n e l washed, the  wash water p a s s i n g over the s i l i c a ing  con-  o f f excess c o l l e c t o r .  i n the t r a p , thus c a r r y -  The a n a l y s i s was  then c a r r i e d  out as b e f o r e , the r e s u l t s b e i n g shown i n T r i a l s 6 and  7,  Table X. A t t h i s p o i n t i n the work a check was  made as to  what e x t e n t the s i l i c a samples c o u l d be washed removing a l l the c o l l e c t o r .  The  c o l l e c t o r alone i n the c e l l ,  the s o l u t i o n was  off to  and  sample was  without  floated with then drawn  the s i l i c a washed. 200 cc more water were added  the c e l l and  10 cc of t e r p i n e o l to c r e a t the  f r o t h , which would now been removed.  The  the c o l l e c t o r was  necessary  be l a c k i n g as excess c o l l e c t o r  had  s i l i c a once more f l o a t e d showing t h a t s t i l l firmly  attached.  28. A n o t h e r p o i n t t h a t came up a t t h i s time was the f e a s i b i l i t y of c a r r y i n g out the washing of s i l i c a samples w i t h d i s t i l l e d water, as i t was thought t h a t washing w i t h a solution  of a d i f f e r e n t pH than t h a t i n which f l o t a t i o n  was. b e i n g c a r r i e d  out might d i s p l a c e some o f the c o l l e c t o r .  However t h i s was n o t c o n s i d e r e d  l i k e l y as the pH of the  d i s t i l l e d water used was around 6.3 which i s i n the r e g i o n i n which maximum c o l l e c t i o n o c c u r s and c o n s e q u e n t l y  should  not tend t o remove the c o l l e c t o r . Summary of C o l o u r i m e t r i c A n a l y s i s . (a) T r i a l s 1 to 4 Table IX i n d i c a t e  t h a t t h e r e i s an  i n c r e a s e i n the amount of adsorbed c o l l e c t o r , when the amount i n s o l u t i o n approximately  i s i n c r e a s e d and the pH m a i n t a i n e d  a. c o n s t a n t  at  value.  (b) T r i a l s 5 and 6, T a b l e I X i n d i c a t e amount of c o l l e c t o r i n s o l u t i o n  t h a t when t h e  i s k e p t c o n s t a n t the  .amount of c o l l e c t o r adsorbed i n c r e a s e s as the pH i n c r e a s e s . (a) and (b) show t h a t i n c r e a s e i n c o l l e c t i n g power i s not j u s t due to changes i n f r o t h c h a r a c t e r i s t i c s as a r e s u l t of pH changes, c a u s i n g changes i n s u r f a c e t e n s i o n . (c) Comparison of t r i a l 6 Table IX w i t h t r i a l s 3 and 4 Table X i n d i c a t e  t h a t the amount adsorbed d i r e c t l y on  the s i l i c a s u r f a c e does n o t seem to have any d i r e c t b e a r i n g on the d i l u t i o n o f the p u l p .  This c o n d i t i o n would  l i k e l y o n l y a r i s e when,' as a r e s u l t of s u f f i c i e n t a g i t a t i o n , thorough c o n t a c t of the s i l i c a w i t h the c o l l e c t o r i s .  29 allowed  i na l l dilutions.  (d) Comparable r e s u l t s have been o b t a i n e d  using  methods A and 33 ( t r i a l s 5, 6, 7, Table X ) . (e) I t was observed w i t h r e f e r e n c e to the graph ( P i g . I l l ) t h a t 100$ f l o t a t i o n c o u l d be o b t a i n e d w i t h a l l the q u a n t i t i e s of c o l l e c t o r s c o n s i d e r e d , above pH 4. T r i a l s 1, 2, 3 and 4 T a b l e IX and T r i a l s 5, 6, and 7 T a b l e X g i v e what appears to be t h e amount o f adsorbed  collector  when 100$ f l o t a t i o n o c c u r s . Bromide A n a l y s i s . Any  work on a d s o r p t i o n would n o t be complete u n l e s s  some i n d i c a t i o n of the b e h a v i o u r  o f both i o n s o f t h e  c o l l e c t o r were, c o n s i d e r e d . In t h e a n a l y s i s o f T.M.C.A.B. p e c u l i a r i t i e s of r e a c t i o n were o b s e r v e d .  The compound from i t s s t r u c t u r e  appears t o be d e r i v e d from a s t r o n g base o r a t l e a s t compounds of a s i m i l a r n a t u r e have been found b a s i c .  How-  ever i n a normal t e s t f o r bromide i o n w i t h s i l v e r n i t r a t e on c o n c e n t r a t i o n s o f c o l l e c t o r of .002 g r s / l i t r e , no i n d i c a t i o n of t h e f o r m a t i o n o f a s i l v e r bromide p r e c i p i t a t e was n o t i c e d .  T h i s checks w i t h work .by l a r k ( 2 ) who  c o u l d g e t no p r e c i p i t a t e ing a f t e r b o i l i n g .  o f the bromide except on s t a n d -  U s i n g a h i g h c o n c e n t r a t i o n , .005 g r s / c c  a q u i t e heavy t u r b i d i t y was observed w i t h s i l v e r n i t r a t e , but p r e c i p i t a t i o n c o u l d n o t be r e a d i l y o b t a i n e d by normal  30. methods such as h e a t i n g  and u s e o f e l e c t r o l y t e s .  Wark  ( R e f . l . p 152.,) s t a t e s t h a t a t h i g h c o n c e n t r a t i o n the c o l l e c t o r forms m i c e l l e s , b e i n g an a g g l o m e r a t i o n of ionsh a v i n g a t o t a l charge equal t o t h e sums of the i n d i v i d u a l c h a r g e s ; around t h i s group a r e the o p p o s i t e o r c o u n t e r ions.  I t seemed t h a t AgNO^ m i g h t be a c t i n g i n the n a t u r e  of a c o a g u l e n t f o r the m i c e l l e s thus c a u s i n g the t u r b i d i t y . I f t h i s were t r u e then the use of o t h e r e l e c t r o l y t e s s h o u l d r e s u l t i n t h e same b e h a v i o u r .  The a d d i t i o n of  magnesium s u l p h a t e d i d n o t produce t u r b i d i t y . One  r e f e r e n c e found (10)  s a i d of the c o l l e c t o r :  " i t s mode o f a c t i o n i s n o t c l e a r , t h e compound does n o t appear to d i s s o c i a t e i n s o l u t i o n . " R e f e r e n c e to the a r t i c l e on t h e c o l o u r i m e t r i c  anal-  y s i s p r e v i o u s l y used i n t h i s t h e s i s i n d i c a t e s t h a t the e s s e n t i a l p a r t o f the procedure i s the f o r m a t i o n o f a r e l a t i o n s h i p between T.M.C.A.B. and Bromphenol b l u e a c c o r d i n g to the f o l l o w i n g  equation;  R V TM.CA.B.  31. T h i s adds some  w e i g h t t o the f a c t t h a t some i o n i z -  a t i o n of T.M.C.A.B. does o c c u r . Method and As  Standardization.  the normal AgBr t e s t was n o t p r a c t i c a l , a t e s t f o r  bromide n o t depending on the i o n i z a t i o n was Sought.  The  method f i n a l l y d e c i d e d upon and found most s a t i s f a c t o r y was  h e a t i n g of the compound w i t h C a l c i u m O x i d e .  The p r o -  cedure adopted was s t a n d a r d i z e d u s i n g d r y w e i g h t s o f T.M. C.A.B. and was as f o l l o w s : The glass  T.M.C.A.B. and C a l c i u m Oxide were s e a l e d i n a  tube.  400°C.  The tube was heated f o r 45^minutes a t about  The end o f t h e tube was then c u t o f f and t h e  c o n t e n t s washed i n t o a beaker.  The s o l u t i o n was a c i d i f i e d  w i t h n i t r i c a c i d and f i l t e r e d through a s m a l l glass was  f u n n e l to remove c a r b o n i z e d m a t e r i a l .  s^intered The f i l t e r  washed, the washings b e i n g added to the f i l t r a t e .  AgNOj was added as i n s t a n d a r d a n a l y t i c a l p r o c e d u r e s and the p r e c i p i t a t e o f AgBr c o a g u l a t e d by h e a t i n g .  The p r e c i p -  i t a t e was f i l t e r e d through a weighed Gooch c r u c i b l e an a s b e s t o s f i l t e r .  with  A f t e r a p p r o p r i a t e washing the c r u c i b l e  p l u s the p r e c i p i t a t e were d r i e d a t 120° f o r 4 h o u r s . r e s u l t a n t c a l c u l a t i o n s gave e x c e l l e n t Analysis The  quantitative  The  results.  f o r adsorbed C o l l e c t o r .  s i l i c a was f l o a t e d i n the same manner a s has been  previously  d e s c r i b e d u s i n g .0004 grs.. of c o l l e c t o r .  The  f l o t a t i o n s o l u t i o n was drawn o f f and t h e s i l i c a washed  32.  i n t o a s m a l l beaker.  The wash water was then f i l t e r e d  o f f and the s i l i c a w i t h i t s c o a t i n g of c o l l e c t o r was t r a n s f e r r e d to a. s t e e l f u s i o n bomb. was  The c a l c i u m oxide . sealed.  then added, the components mixed and t h e bomb/.  bomb was heated a t r e d h e a t f o r 45 m i n u t e s .  The  The compon-  ents were then washed i n t o a beaker w i t h t h e minimum amount of water p o s s i b l e , the s o l u t i o n was. then a c i d i f i e d and f i l t e r e d through a s ^ i n t e r e d p l a t e to remove s i l i c a and c a r b o n i z e d m a t e r i a l .  On a d d i t i o n of AgNOg no p r e c i p -  i t a t e was v i s i b l e . S e v e r a l t r i a l s o f the above n a t u r e were c a r r i e d out each g i v i n g a n e g a t i v e  t e s t f o r bromide.  I t was thought t h a t t h e s t e e l bomb was l e a k i n g so t r i a l s were c a r r i e d out i n a "sealed g l a s s tube as mentioned i n the p r e v i o u s s e c t i o n .  S e v e r a l o f these  trials,  gave no i n d i c a t i o n of Bromide i o n . A sample o f sodium s i l i c a t e was a c i d i f i e d w i t h HNO , w i t h the r e s u l t a n t p r e c i p i t a t e o f S i l i c i c a c i d , o Nag. S'i0 4-* 2HN0 —5> HgSiOg + 2NaN0 3  3  •A  The  p r e c i p i t a t e was t h o r o u g h l y washed f r e e of any  i m p u r i t i e s and t h e g e l was shaken up w i t h s e v e r a l cc o f the c o l l e c t o r o f c o n c e n t r a t i o n .0001 g r s / c c . was  The m i x t u r e  then f i l t e r e d and washed w i t h d i s t i l l e d w a t e r .  of t h e s i l i c i c a c i d was p l a c e d i n an e v a p o r a t i n g  Half  dish  which had been c a r e f u l l y t r e a t e d to i n s u r e removal of  a l l o r g a n i c m a t e r i a l , and the o t h e r h a l f p l a c e d i n a f u s i o n bomb. On h e a t i n g the s i l i c i c a c i d i n the d i s h , a c h a r r e d r e s i d u e was o b t a i n e d w h i c h i n d i c a t e d the presence o f the o r g a n i c p a r t of the c o l l e c t o r a t l e a s t . On t e s t i n g the r e s i d u e f r o m t h e bomb f o r bromide, no i n d i c a t i o n was found. G e n e r a l 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 p r e v i o u s  experimental  work t h e r e appeared to be a p r o b a b l e m e t a t h e t i c r e a c t i o n , of some n a t u r e silica  o c c u r r i n g between the c o l l e c t o r and the  surface.  R e f e r e n c e 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 i n c r e a s e of c o l l e c t i o n or a d s o r p t i o n of c o l l e c t o r w i t h i n c r e a s e 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 ) C H K - B r + H S i O — ( C H ) C H N-H-Si0 +HBr 3  If  3  1 6  3 3  2  3  3  16  33  3  i t can be assumed t h a t 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 t o p r o v i d e a c h a r g e d s u r f a c e upon which the c a t i o n c o u l d be a d s o r b e d ,  then  i n c r e a s i n g the a c i d i t y would tend t o c r e a t e more u n 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 d e c r e a s e i n a d s o r p t i o n power. It  thus appeared to t h e author  t h a t whatever pecu-  l i a r i t i e s , a r e i n v o l v e d on the i o n i z a t i o n of T r i m e t h y l  34. Cetyi Ammonium Bromide, adsorptive forces are strong enough to cause some d i s s o c i a t i o n . Determination of Adsorption ger Unit Area of the S i l i c a Surface. Most f l o t a t i o n authorities are interested in the amount of adsorbed material per unit area of the mineral surface.  The problem of determining surface areas of  f i n e l y divided p a r t i c l e s i s very d i f f i c u l t  and there have  been few experimenters  i n the past able to reproduce  results within 100 %.  It has been therefore very d i f f i -  c u l t to determine to what extent mineral surfaces are occupied by the c o l l e c t o r and whether films of c o l l e c t o r 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 i s assumed that the p a r t i c l e s of s i l i c a came from an o r i g i n a l l y s o l i d 2 gram sample, the volume of such a sample would be 2  = ,752cm . The s i l i c a was  2766 r  s-ieved-through screens of maximum diamter equal to .246mm and of minimum diamter  .104mm. The s i l i c a p a r t i c l e s were  assumed to be cubical i n shape.  As the i r r e g u l a r i t i e s  in the s i l i c a surface were not accounted  f o r , i t was  f e l t t h a t a c l o s e r a p p r o x i m a t i o n c o u l d be o b t a i n e d byassuming a l l p a r t i c l e s t o be of the s m a l l e r s i z e , the a r e a p e r gram would be l a r g e r ;  hence  On these a s s u m p t i o n s  i t was c a l c u l a t e d t h a t the t o t a l number of p a r t i c l e s obt a i n a b l e from a two gram sample of SiOgj. each p a r t i c l e 5  b e i n g .104 mm a l o n g the edge, would be 6.68 x 10 icles.  part-  From a p a r t i c l e count under a m i c r o s c o p e , a 2 5  gram sample was found to c o n t a i n 3.33 x 10 particles. Assuming the l a r g e r f i g u r e c o r r e c t , and as' the s u r f a c e -4 2 a r e a per p a r t i c l e is. 1.08 x 10 cm ., the t o t a l s u r f a c e p a r e a would be 72 cm . The amount of c o l l e c t o r adsorbed i s then .00006 - 8.34 x 1 0 " g r s / c m . 72^~ 7  2  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  e s t a b l i s h m e n t 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 a c h i e v e d . 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 s u r f a c e has been shown which seems to i n d i c a t e a m e t a t h e t i c r e a c t i o n has  5.  occurred.  A v e r y approximate c a l c u l a t i o n of the a d s o r p t i o n of T. M. C. A. B. per square cm.  has- been g i v e n .  F u t u r e Work. I t might be p o s s i b l e to a p p l y a d i r e c t  weighing  method to c o l l e c t o r a d s o r p t i o n , as i s used by H. B a r r e t i n d e t e r m i n a t i o n of water a d s o r p t i o n on  silica.(12)  A p h o t o g r a p h i c method of d e t e r m i n i n g p a r t i c l e has been developed  areas  to a q u i t e a c c u r a t e degree ( 1 3 ) .  A p p l i c a t i o n of t h i s method m i g h t a s s i s t i n a c q u i r i n g f u r t h e r i n f o r m a t i o n as to m o l e c u l a r s t r u c t u r e of surface f i l m s .  BIBLIOGRAPHY. Reference.  Title.  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 o f P h y s i c a l Chem. 40,661, 1936  3.  U. S. Bureau o f M i n e s , B u l l e t i n 449, p. 44  4.  Ind and Eng. Chem. ( A n a l . Ed.) 19,1294, 1927  5.  I n d . and Eng. Chem. (Anal.Ed.) 14,200, 1942  6.  I n d . and Eng. Chem. (Anal.Ed.) 14,437, 1942  7.  Q u a n t i t a t i v e Organic M i c r o A n a l y s i s , P. 84, Pregle-Grant.  8.  I n d . and Eng. Chem. ( A n a l . Ed.) 16, 12, 1944  9.  I n d . and Eng. Chem. (Anal.Ed.) 15,492, 1943  10.  Thorpes D i c t i o n a r y o f A p p l i e d C h e m i s t r y .  11.  J . A. C. S. 68, 437, 1946.  12.  J.A." C. ;S. 63, 2839, 1940  13.  I n d . and Eng. Chem. ( A n a l Ed.) 2, 59, 1930  

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