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Optimum conditions for the flotationa of sphalerite by iso amyl xanthate Harrison, T. Allan 1942

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OPT IHUM FOE SHE  C OICOIEIOITS  FLCffiAMGI 01? SPHALBBIf Til Bf  .  IS© A i l L  submitted f o r olio decree of :  MAS513H OF ARES'  - • ' -w • •  Department of •GhmrlstTj U n i v e r s i t y of B r i t i s h ColraiMa 1948  It is. a  t q t j  great pleasure  to aclmowledge the help and guidance of Br* W» Tfre®, xmH&T  wkos© diasetioit, t h i s  worli was eaa?3?ie& out* •  Introduction l^QzlmCTtt^L. work jlateriels Apparatus Flotation tests w i t t e t collector ELot&tion t e s t a v a r j i a g c o l l e c t o r f l o t a t i o n t e s t s T&sfyitig pH Dec opposition of scant Iiate E f f e c t of decomposition on c o l l e c t i o n Abstraction Discussion of abstraction  References  .  results  In esperiiaontal investigo.-!;ion o f the f l o t a t i o n ox minerals* two teehniqtiQS are i n general use: the "contact angle" method as developed "by i?ark end Cox, and tiie* d i r e c t f l o t a t i o n mo tho a, i n which an expsriraontal c o l l i s rtscd, operating on the same p r i n c i p l e &s those uoocl coiamereiallyc doing ths second method, the Dehaviotrc of -fotassinra  othyl jtanthats as a c o l l e c t o r o f s p h a l e r i t e has  "boon i n v e s t i g a t e d i n t h i s 1 ah oratory f o r tho paot several '/oars.  I t was desired,, hor/ever, to compile  gos'-'O data as t o the hohsviour of soma other c o l l e c t o r s v/ith tho osse ore and under the sane conditions., i7ith t h i s i n trim the present tvoid-i was iiridertalcen, using potassium iso-arayi stanthate as osseiople® general opinion seems to be that pure aphalo r l t o v / i l l not f l o a t unless a c t i v a t e d , Oaudind) however, states that w i t h c o l l e c t o r s containing an a l k y ! Group of f i v s carbon3 or more,  f l o t a t i o n i s posoihle  v/lthcml; a c t i v a t i o n and submits data i n d i c a t i n g that uitJi  ranthates containing the e t h y l , n-aciyl and n-  hoptyl groups,, col l o o t ion of s p h a l e r i t e increases i n that order.  He  also f i n d s a groat v a r i a t i o n of  recovery o f nnaetivated s p h a l e r i t e at constant pli (S.S) v.nlnr; potaeolna n-exn^l saathat© at ooiiesiitratioBs ranging from soro to .6 Ib./ton r;ith a Bayissinvi Ghent 46,J at ths l a t t e r .  of  C«H«M» del Girl dice ( 2 ) quo-ces  a»a sodorses §a«din.* Hoyass and Haas, to^he e f f e c t that using arayl xsatfcat©the aaslinaa recovery o f u i i a c t i vated sphalerite eomos i n the pE range from 3.4- t o 5«4, but does not state what recovery v/as obtained»  Swains©n  and ^ndorson (3) however, express the b e l i e f that comparing various Kanthates as c o l l e c t o r s , t h e i r a c t i v i t y reaches a Haxinran at four carbon atoms and that f o r any number o f carbons, the secondary compound i s best, • followed by i s o - and noivial.  C h a i r data era based on  copper and lead ores however, not OH sphalerites i'/arls and Cox (4) express the view* based on t h e i r aeasursments of contact angles, that i n concentrations  of S5Eg»/l« iao-arayl scant hat© w i l l not B  f l o a t (inactivated s p h a l e r i t e *  I n a l a t e r a r t i c l e (5)  they state that i n higher concentrations (up to. 300 1  nig./ - J or i n acid s o l u t i o n , ( c r i t i c a l pH 5.5), eon* e  tact  i s possible*-, With regard t o possible decomposition o f the  orayl xamtliste i n use, a v a i l a b l efiata#6)„(?)indicato extensive decomposition o f e t h y l xanthate I n eeicl solution*  S i m i l a r behaviour on the part o f the arayl  Kanthate eould b© expected and was investigated the  OO-jv'GO  of  the  motIc*  in  Materials rp&Q d i f f e r e n t samples o f o%& were used-*. A«  Source:  Pari: i n c o l o r sad when ground f i n e retained  this  color- ffho esact composition was not determined, hut rough analysis indicated appr o:ci Kate 1 y 1 'I of copper i n the ore*  2 M s would, i n d i c a t e that the ore was  prohably activated,, at l e a s t p a r t i a l l y • 15* Source: Ottawa County, Olda* largo p i e c e s  9  Dark colored when i n  hut r/hen hroken up had a resinous ap-  pearance and when "ground f i n e was creamy white i n c o l o r . * J!o copper could he detected. Potassium 4so~sia;yl saethate was zaade hy the usual method i r o n C  i-aioj/1 a l c o h o l , carbon a i -  oulphide and potassium hyftrozido. i n Bcetoa®, c r y s t a l l i s e d twice from  I t was diosolved bensea©, d r i e d  and stored over sulphuric a c i d i n a desiccator* i'erplneol was used as f r o t h o r i n e l l toe t o , a stock s o l u t i o n of 250 Mg./l, "being made up and amounts froia 10 to 25 u l . as reouiracl .v*ers placed i n tho c e l l along w i t h the oro. varied  Hie amount recjuired  considerably with the pE at which the t e s t  was made, strongly haoic solutions r e q u i r i n g more t©j'pineoi.  0  Apgarattig  The ore was ground  P&WI& r a i l l w i t h p o r c e l a i n  was  2b,t  i n a laboratory  ana, f l i n t pebbles* I t  sized i n an. e l u t r i a t o r as- described by Her&O).*  the ore.having a s e t t l i n g rate between 8 and 16 cm* per aiirote being use a f o r a l l tests*- 2Ha s e l l used f o r f l o t a t i o n t e s t s was a m o d i f i c a t i o n of the design by Sennet'  a pyres f r i t t e d glass f i l t e r being sealed  to'a piece of pyres tubing of the same the f i l t e r and SI os® long-  diameter as  A l i p v&& formed at the  top o f the tube t o provide f o r an overflow*  9Jwo pli  meters were used j an i n d u s t r i a l model Beoiinan w i t h glass and ealorael electrodes f o r mD&surement of pH; and  a research model Beclcnan w i t h platinum and  calomel electrodes i o r t i t r a t i o n s , f l o t a t i o n Tests I without C o l l e c t o r  Gaudin (10} and Taggart, d e l  Oividlee and iSionl 111), state that s p h a l e r i t e has no native f l o a t - a b i l i t y , that i s * i t v^.11 not f l o a t i n the presence of f r o t h e r alone.  In order to t e s t the char-  a c t e r i s t i c s , of the c e l l and also the o r e  6  both# ore  samples \7©re tested by the f o l l o w i n g method*  To a  weighed* dry sample of the ore i n a beaker, about 200 ml. o f water and 5 ml* o f 81? ammonium acetate were added*' pii w»ts adjusted on the meter by additions of r  HOI or KOH as required* fha water used  i n .oil tects  and o i l s o l u t i o n s throughout t h i s Y/orlr was d i s t i l l e d , the only exception being e l u t r i a t i o n of the ore.  flie  5 ammonium acetate iiras foti^fl necaosary sine© xrithout i t pH d r i f t e d considerably during the test-,, and p r e l i a i n as^r t e s t s indicated that i t had no. appreciable effect' on the f l o t a o i l i t y o f the ore*  Shis aistttgs was then  placed i n the c e l l 10-8S ml« t e r p i n e o l . were added ae 9  needed and the volume t/as made up to 800 ml.  A i r was  turned on and adjusted to a pressure o f 34 OBI, o f mercury, which pressure .seemed to work "beat wit& t h i s c e l l , • 5?he overflow was caught i n a bealcer and wben the f r o t h had become clean, the overflow was f i l t e r e d tlirongli weighed gooeh. c r u c i b l e .  She weight of heads was  pared the the sample weight t o give  a  com-  a measure of the  recovery obtained, expressed as per cent* . j^.arge maah s r of t e s t s were made over a large pii range w i t h ore A, the rc3P.lt3 of some of which are given  i n Sable  I*  yhere i s no regular v a r i a t i o n w i t h pH noticeable« Also„ some f a c t o r not under c o n t r o l hae a l a r g e e f f e c t on the recovery at any one ol-U A s i m i l a r set of t e s t s on Ore 3  gave an  i n d i c a t i o n of r e g u l a r i t y with pH, tliongii not enough t e s t s were Hade t o walre such a conclusion d e f i n i t e , Hesnlts of thSL s e t o f t e s t s are given i n Table 11 and F i g * 1*.  '  2A3LI3  1  Bscovery without c o l l e c t o r - Osfa.fut •% recoverjr  pH  sample weight  '•2,2  5.001  2*7  5.000  4,00  3.6  6.001  5,30  4.5  S.004  §.84  5*001  8»1  -.5.5  1*000  »8  7*5  5*001  *74  9*0  S.000 -  .06  5*000  1.2  4*5  •  5.0*9  e  g 1.16  Recovery without c o l l e c t o r - Ors B pH  . sample weight -  2.0'  g.00  4*0  &»  5*0  a&-  .6*0  -fie  6*0 8*0 10*0 '13*0  $ recovery  ...  . ' _  18..4 ... S2#4 •  44*6  to  0.5.*9  -do  18*5  dO'  17*2  do  12*6  7 I I ' O o f f l J l ^ ^ ^ L ^ t & l ^ l a S , aaou-nts of cojj.ecto^r SMs  .series of -teste was  eondactefl only  with  Ors A* Procedure- was as outlined above, except, that just "before a i r was "blown i n t o -the c e l l , a measured amount of a standardised.solution  of the xanthate  was added» i a -Tolumes corresponding to the amounts of c o l l e c t o r shows i s  the t a b l e *  fh©.volum© was  300  ft  s i . * ' i s a l l oases*.- Basalts*' are shown f o r two complete s e r i e s at p i 4 and 8*5 shoxfii are  i n ' t a b l e I I I sad Irig* 2*  .Also  a few r e s u l t s obtained at ,pH..2*0 and 2*8  'though these s e r i e s ar© not complete*  As soon as a  f r o t h head formed, when c o l l e c t i o n was good* th© became very h e a v i l y mineral!sed*  ,  froth  Shis formed a heavy  cafe© on top of the c e l l which had. .to he scraped o f f * f his  behaviour was expected since i t had been B O B -  t i o n s t as a c h a r a c t e r i s t i c of amyl xsiithat.e hy Saudis •{12} and Balston and Barfesr-flS}* . f  Wzm$ tho  curves-of f i g * 2.* i t i s -seen-, tnat  l a f a i r l y acid .solution* the colleeto-r i s e f f e c t i v e i n very small fU-autitiss,. shout 1 Big.* being a l l . that i s required to produce raaxiiaurg recovery*. range however* .more c o l l e c t o r i s required,, -5 mg*  In tho nearly  "being reached- "before the -eurro l e v e l s o f f *  basic  8. 2ABLE 111 C o l l e c t i o n Of 0l*3 A'- varying amounts of c o l l e c t o r pH  sain pie  pH  tag. coll...  sample  heads  .5  si.2  5..02  *5  44*2  .3  65.G  5*04  1.0  46*4  .5  81*5  5*00  1.5  51*6  2.0  92.5  3*0  58.2.  £5.0  94.5  5*04  5*0  65*9'.  4,0  9S»0  •5*04  4*  0'  §6*-@  5*0  95.4  5:»00  4*0  78 *-6 . 2.6  S.O '  77.1  5.01  6*0  74*5  5.04  5*5 •  71*7  5*01'  7.0  74.0  3„0  5*00  heads  8.5 5..02  • 5,01  4.0  mg* coll, .1  5*00  .66  91*0  .70  9s*e 00*7  5,00 *SS  88*9  I h i s s e r i e s .was' carried' out on hoth ores*. The .collector was f i x e d at 5rag.«ncf was added' iiamediately Before Mowing*  i l l ' samples mm  5 grams* -Salils 1?  and Pig*. B give the resuit8 phtained w i t h ore A*  i  SABES XI • C o l l e c t i o n of C pH  recover^'  varying pH pH  recovery  pH  88.0  9.5  recovery  x~:us  94.??  g-  94.4  6.5  90-.5  10*5  60 c 8  95^0  6.5  9.1 e 5  10.5  G8.2  01.4 89,7  ii.n  75  o  n  94*4 0  4*5  94.0  4*5  95.4  0.5  5® 5  91.8  9.5  i i ,f)  27,0  73.7  12.0  4.24  76.0  12.5  1.79  5?J» f o l l o w i n g reeiilts for Ore 5 were obtained during the work 011 abstraction (see "below). A f t e r treatment w i t h the rsanthate s o l u t i o n , which was f i l t e r e d o f f , th© ore was oividedjlnto spproalraataly f i r e grara sample.?. About 800 ml. of water was adaed to each and the pK was adjncrtod to that required. 2'hio was placed i n the c e l l , ''terpineol added, TOIIMS  the  was made up to SOO l a l * and the c e l l woo blown.  X!ha;a the f r o t h had cleared, both heeds and t a i l s were  c o l l e c t e d i n weighed gooohes and the  scrapie weight  was obtained by a d d i t i o n of the two weight 9 » J?he R  f i r s t s i s r e s u l t s i n the •cable are preliminary teste made on welched samples and treated as shown, and indicated that -this v a r i a t i o n i n teehiiiqite vj&shlng w i t h santbate  } has  { pre-  no appreciable e f f e c t  on the f l o t a t i o n y i e l d . Basnlts i n Table V awti Fig.4*  10 EABO ' ?' C o l l e c t i o n of ore B pl-l v/ash  varying pH  pH oell  sample  heads  5*0  5.000  4.974  99.5  5 Bg. c o l l e c t o r i n o e l l  7.0  5*000  4.928  98.6  do  treatment  yj  11 #0 • 5,000  4.695  3*0 .5*000  4.975  99.5 ' prswashed with 5 ag. c o l l .  7*0  5.000  4.957  99.3  do  11,0  5.000  4.750  95,0  do.  5-..0  5*0  G»607  6.447'  96*5 . f pr swashed w l t i i 20 rag.  5.0  5.0  4»S64> '  4*200  5,0  15 »0  5.0  5.0 0  O » •J  11.0  do  )  6.243  .98,5  S.999  S,367  99. g do  5.3.3 5'  Be IBS  98«8  do  5 ® 0 .' # 0 4,864  4.754  97.8  do  5*0  &j  do  5«-0  7*0  5.48?  5.202  .95.0' do  5,0  7.0  5.717  5*520  do  8.0 •4.315  4*212  • y / * o do  IS . 0 12 .0 •4.970  3.684  74.1  9,0  0*644  • 6.344'  13,0  5,000  3..7-42  74.8  5*000  .441  8*8  8,0  12.0  ......  ssnthate -20 fjy.oie  do  9S:*4 do 5- mg» c o l l e c t o r i n c e l l do *  Another v a r i a t i o n t?as made possible Iry the above technique*  I t w i l l ho noted that several of the samples  were "blown i n tb©. c e l l ' at a d i f f e r e n t pH t o that at which they were treated w i t h santhate, tn.it that t h i s  treat-  ,  - --  >  o  o  m :o  :D  ID  C  -  1  >  > k  o DC  •  %n  •••  t  :>  •  «  *  \  si  -  "v . •  M '  —*<*—  O  «w  Pi  11 meat seomlmgly has no ©ffeetsince the r e s u l t s agree within  the experimental l i m i t s w i t h the r e s u l t s of nor-  mal treatment* Ehis would d e f i n i t e ' -manner  appear t o indicate i n a rather  that whatever the c o n t r o l l i n g  effect  of pH- i s , i t exercises•that control during tho reaction "between the c o l l e c t o r and the ore, and not at the attaeb.'. meat "of- the mineral to the. a i r bubble« SecoapositlOB of Santhate As. mentioned on page2 decomposition of the atayl r  "xanthat© was expected i n the acid range,  Snsyefor© i t  "was rather s u r p r i s i n g t o f i n d t t e c o l l e c t o r "behaving 'very e f f i c i e n t l y - as f a r up the pH scale as pH l»{?ig«5)» "She decomposition talcing place "was followed by a method s i m i l a r t o that applied to ethyl'rant hate by Keraper (?}• • Samples of rcanthate s o l u t i o n w i t h oufxer added, were adjusted to the desired pH, allow©a to .atana f o r 10 :  •minutes, then returned to gH 6«i> ??hich seemed t o work f  h©st„ -and t i t r a t e d e l e c t r O m e t r l c a l l y w i t h standard -iodine- solution®, She- r e s u l t s are shown i n Sable VI and i n gra^h'fonii i n f i g u r e 5* ''  ••  IS • fABLS ? I  Decomposition  of  mg» Xantiaate Oxl ge final 1*6  .0099  2,0. 2 .0'  0^0  Xauiiiate yl. decosip.  .0004  9& Q  - .0004  96.0  V  .0108  ,00051  .0108  .0005  8*5  ,0104 •  .0005  2.75  ,0099  .0005  .5.0  .0099  .0018  s.o  .•0099  .0021 •'  2..25  ,0099  .0056  Si 5  ,0050? •  .00508 .  •39.2  3.9  *0099 -  *O081  18.2  -4,5  *00507  -.00493  2.75  •5*0  -.0114.  .0112 '  1.75  S.5  .©0507  ,00507  6»0  13*0  '•95. S  95.2 :  94.8  81*8  6So7  .0114 ."  ;  •00507  .00507  v0114  *0114  — -  *0105  -.0105  ———  «01o8  *01O3  Bftgeofr of Peooapogltlon In an o f f e r s  t o f i n d some reason f o r the higli  recovery l a v & t j strong aeicl ptilp  9  ta© f o l l o w i n g v a r -  ...  ,,,„.„  " l a . •• S -  ) e c o m p o s / t i o n of > - a.myl Xawtlia.t'e.  Of,  Left** ;  '  .:  '  AA t •  '  9e\  :  O  ;  • •  i, i  y- '\J\J  •  i  i f : —  .  .  .  •• ...... .  i\  , . , .  iations  oa? f l o t a t i o n teehnig.ii© were introduced. 10 ml*  { 5 iag») of the c o l l e c t or were d i l u t e d ml.  s  teffer  to about 200  was added and pH adjusted -as required. Shis  Eiisctnre was allowed t o stand f o r 10 iainntes, a f t e r which i t was poured onto the ore sample i n the c e l l * Serpinsol as added and the o e l l was blown, ffihis proaediirs., since i t allows the c o l l e c t o r to decompose aa ••determined above before i t comes in' contact w t i h t h © ore.  should  r e s u l t i n a diminution of recovery, provided the prodnets of decomposition are i n a c t i v e as c o l l e c t o r s .  A  •few t e s t s were made w i t h axayl alcohol i n concentrations l i k e l y to be found,* w i t h no c o l l e c t i o n rasttlting* and carbon disnlphids i n small amounts has no c o l l e c t i n g ' • action* .It w i l l be seen from Sable • T i l .(a,b,e)» that t h i s I s the case, i n d i c a t i n g - t h a t any other possible products of decomposition have very little„ I f any, effect*. Bierefore.j, .the high, c o l l e c t i o n i n the strong a c i d rangej as Indicated on Pig,. g . aiiat be due to e  the a c t i o n of. the zaathate ' i t s e l f ,  Shorn  f o r compasses  atlve•purposes,• imowing the amount of teeospoaition {trow F i g * 5)* another few t e s t s were made -adding the  "effective", amount of c o l l e c t o r present i n the above t e s t s . ' 2he.se are shown i n f a b l e T i l {&,e)• She c o l * l e c t o r was added immediately before blowing the o e l l .  14 ¥11 Sffeet of decomposition on r e c o v e r pH a.  C o l l e c t o r added (jug.)-  o.  E f f e c t i v e -collector  e.  C o l l e c t i o n {#)  a.  C o l l e c t o r added  ©.  C o l l e c t i o n (fl}  2.5  S.O  'S.5  5.0  5*0  5.0  1.0  8-7  .225  1*  6.08  2.  4.5  _  39.9  • 92.S  S7.2  .225 12*5  1-.0  2*7  S9.8  88*6  At ta© sarao time another few t e s t s war© made i n which the ore and c o l l e c t o r mid water  were allowed  to stand at a d e f i n i t e pB. f o r ton minutes "before a i r was admitted* wer© 94*6  Ehe rosnlte of two aneh testa  at pE S and  93*7 ;f at gS 3*5*  i h a t i s , a l i e n i n g santhat© to stand f o r ten minutes i n acid pE i n the proaenee of tho ors r e s u l t s •- i n only a very s l i g h t reduction^of recovery, .nowhere near that to he exp©eto& i f ths posecU  santliato were aooou-  Apparently, then, the ©rs coating,  Br^pna'bly  sine aayl scant hate is' formed ana remains, regardless of the pH* Ahj3tra^ion In view of the faot that potassium l»amyl santhate lias "been shmn to he d e f i n i t e l y e f f e c t i v e "in f l o a t i n g hoth#  samples of sphalerite used,, an .attempt tt  rt  was Baa© to show that the ore ai».strsetea the c o l l e c t o r  from s o l u t i o n .  I n the following worlc one sample B  was used e n t i r e l y * Previous attempts have bean made I n t h i s l a b oratory to measure a b s t r a c t i o n w i t h s p h a l e r i t e and e t h y l scauthate w i t h no success{14).  9  the d i f f i c u l t y  being one of t i t r a t i o n of the r e s i d u a l 2nanthate  9  She general procedure followed wao to s t i r the ore w i t h an eiccesa of sant.hate. i n s o l u t i o n f o r 10 rain, at the. required pH* fhe l i q u i d was then f i l t e r e d o f f the ore and attempts were made t o f i n d  either the amount  of scant hate remaining on the ore or the amount remaining I n the l i q u i d *  P i l t r a t l o n s ware performed w i t h  the arrangement described by Semper C7)-, except that 9  the f i l t e r used wao a pyres f r i t t e d glass funnel of 10 cm* diameter*  Several  v a r i a t i o n s of'procedure  were t r i e d as' outlined below* 1«  She- f i l t r a t e was t i t r a t e d e l e c t r o i a e t r i e a l l y w i t h  standard iodine solutions . ffihis method, as found by other workers.,, gave r e s u l t s much too high, i n d i c a t i n g e i t h e r no abstraetica.,'or I n d i c a t i n g saore'reducing material i n the f i l t r a t e than had been placed there o r i g i n a l l y i n the form of .^anthato*  She end-point  was not good, the p o t e n t i a l tending t o ' d r i f t  badly,  making the t i t r a t i o n very tedious and not very accurate. 2* .She f i l t r a t e was t i t r a t e d w i t h iodine an before but using s t a r c h as I n d i c a t o r * 'Shis gave  high r e s u l t s  a l s o , and had the further -disadvantage that the d.isan%fe  16 thogen forced •o'bseured the "bin® starch c o l o r . S.  Elie d r i f t i n g  of p o t e n t i a l in(l«) above seemed  to i n d i c a t e that tlx© reaction causing the interference was a slov? one.  This .suggested the p o s s i b i l i t y of b-ack-  t i t r a t i o n , c a r r i e d out ciuicM.y, t o remove the e f f e c t . M s  was t r i e d by adding an excess of the iodine s o l -  u t i o n to-the  f i l t r a t e and then 'bads-titrating with  e i t h e r sodium thiosnlphate or soSlitm arsenate,, using starch i n d i c a t o r near the end-point,  again  Ehls,  however, gave a very poor endpoint. the "blue c o l o r s  returning for'about f i v e minutes a f t e r i t hafi "been f i r s t reiaovod.s  Atterapts were made - to standardise the end-  point (such as. remaining c l e a r a f t e r 2 ininntes) "trat t h i s vras not 'dependable* 4«  She next l i n o o f attack was to remove the scant hat®  from tho ore and t i t r a t e i t . .  A f t e r tho o r i g i n a l san-  thate s o l u t i o n had 'boon removed., the ore was s t i r r e d f o r 45 laiiiutes i n acetone.. Tim acetone was than f i l % tered off,, d i l u t e d with water and t i t r a t e d .  Using  starch,- the acetone was.found to decolorize tho starch iodine coisples, while electroxaetriealiy, the acetone caused the p o t e n t i a l t o d r i f t so "badly that an accurate end-point was- impossible * Even a f t e r most of the acetone hod been removed by evaporation nnder a  vacumm ,  these e f f e c t s remained* 5*  I t was noted that when  sine amjrl saint hate was  formed by addition of sine chloride t o potassium• aayl"  Kant bate  s o l u t i o n , i t redissolved on a d d i t i o n of  SOH*•' Shis suggested the p o s s i b i l i t y • t h a t the ere coating eould. be d i s s o l v ^ i n 1C0H and thon the r a s u l t i n g ^solution, t i t r a t e d .  So t h i s end an ore sample,, a f t e r  treatment with 2-anthate s o l u t i o n was washed thoroughly and thon s t i r r e d f o r  giaours i n 2H KOH* Baylor and  K n o l l (6) state that under such conditions there i s esttsnslBe decomposition of xantfaate i o n .  One sample  of san.tfe.ate s o l u t i o n was t i t r a t e d a f t e r being i n 2 1 KOH f o r S hours* /.It showed a decomposition of 6  !  p  s  which could e a s i l y be allowed f o r i n c a l c u l a t i o n of a b s t r a c t i o n . . She WB  s o l u t i o n was n e u t r a l i z e d and  t i t r a t e d , and a f t e r c o r r e c t i o n by a blank t i t r a t i o n , gave a r e s u l t I n d i c a t i n g some a b s t r a c t i o n * However as a eheMs on the refnoval of the coatings some of the or® was*- placed I n the c e l l with, water and t e r p i n e o l and blown*  I t was found to f l o a t just as well, .as I t  did before the KOH treatment* • Shis was taken as an I n d i c a t i o n that the coating had not been removed* •Further i n d i c a t i o n o f the permanence of the coating was obtained i n . an attempt to reclaim some x:anthate treated ore f o r f u r t h e r use*  This ore was s t i r r e d  f o r 10 hours In "2 IS EDI, a f t e r which I t was washed, thoroughly e l u t r i a t e d and d r i e d * A sample was .then placed I n the o e l l w i t h frother but no c o l l e c t o r , when I t was found.to f l o a t approximately  40 $ at pH 11.  rlie c h a r a c t e r i s t i c f l o c c u l a t e d appearance of the pulp was-••no ted, i n d i c a t i n g that the f l o a t i n g was probably not just the r e s u l t of cleaning* -fheoe r e s u l t s seemed to i n d i c a t e that reiaoval of the rauihate l a y e r , at any rate Q u a n t i t a t i v e l y , was I t was then decided to return to a% wore  not p r a c t i c a l *  i n d i r e c t t i t r a t i o n met hod• 6»  SJayior and ICnoll(6) have given a method used by  the-a i n a study of abstraction of ethyl Xanthate by galena*  Since t h i s was the pethod used to obtain the  results  "below i t i s given i n d e t a i l . A weighed sample.of s i z e d ore was placed i n a  beater* a Imovm, amount of semth&t© s o l u t i o n was added* and a f t e r the addition of a few drops of atamontra?} acetate b u f f e r , pH waa adjusted to that desired*  Che  aisrfrare ( t o t a l volume about ISO ml*.) was then s t i r r e d by motor f o r ten a i i m t e s .  Ehe rant hate was Measured,  by volume of a s o l u t i o n which had been standardised by an iodine™ starch t i t r a t i o n . .  At the end of the t e n  minute p e r i o d , the l i q u i d was removed by suction i n the apparatus referred to abovo( -7)„  fhe ore. was washed  with about 100 nil. of d i s t i l l e d , water and was then sucked as dry aa possible»  She f i l t r a t e , which was p e r f e c t l y  c l e a r , was d i l u t e d to 500 nil* i n a volumetric f l a s k . 100 a l . portions were taken by pipette and treated as follows:  ;  .,  (a) t i t r a t e d as* i t was w i t h standard iodine s o l u t i o n *  19 Co), a c i d i f i e d  (pH 5) and extracted w i t h S  portions of toluene*  ,?0 »iU  Shis treatment ' remove ,e  all  santhate ae santhie acid (aolnhle i n toluene)» -She water s o l u t i o n remaining was t h e n ' t i t r a t e d a f t e r neutralisation*  She volume o f iodine t i n s obtained was  subtracted from that obtained i n (a) as a correction f o r reducing substances present^othen than santhate* gho r e s u l t i n g corrected volume '' was  used to calculate  tho santhate remaining i n s o l u t i o n and thus  gave a  measure'of the abstraction which had taken place* In the. f i r s t t r i a l of t h i s net hoc!, two more 100 ml* portions of the f i l t r a t e were treated as above except that t i t r a t i o n wao done e i e e t r o a s t r i e a l i y .  S i t r a t ion of  .Cb) was very unsatisfaotory and e n t i r e l y undefendable„* f  She reason was not determinedI t was also found "that' by using v e r y , d i l u t e iodine f -about -*3 grams per l i t e r ) and by adding,, as -.reeonmended ]  by Eaylor and S a o l l , 5 a l * - of\. a ".5 K s o l u t i o n of potassium sulphate s o l u t i o n , a very exact ©'Mr-point 'eonld bo obtained using potato starch* { l o t ' s o l u b l e s t a r c h , ) • D i l u t i o n of the 100 ml, portion of f i l t r a t e '-to about S00 K l v before t i t r a t i o n - , so reduced the density of the d i ~ xanthogen foraed i n the t i t r a t i o n that i t s opalescent blue c o l o r dies not i n t e r f e r e with' the end- point blue* .Eesults obtained by this' method are shown i n Table f i l l below*  A l l at pH 6-.0  2 0 3&BEB T i l l .Abstraction of 1-arayl.santhate  by sphalerite (3)  Xanthate In lag, Original Pinal Abstr. 15.10 19*64 4*54  fest i io 0 14  Or©  15  | 47S  80*48  18 .02  2*46  16  4,70S  2S*S0  21,05'  2,25  25.,SO  21 ..68 •  !  At*  9*562 3  17  1,62  Abstraction mg./gr.-ors. *475 . ,£80 *477 a  Averags  S01  -.408  f o s t s no» 1 - 1 3  were those uaed In methods 1  to 5 described'' above.  One t e s t , (Al8) was nan at pH  12*5 Instead of pH  6 w i t h the r e s u l t that an a b s t r a c t i o n  of *237 rao/gr. was foancU  Alio reason f o r choosing  these two values f o r pH'trill he found i n P i g s , 4 and 5 ...pi! 6 1B w e l l I n the range of xnaadtacsa f l o t a t i o n , r/lrile i t I s not acid enough to cause decomposition* . At pH  13.5  recovery has dropped o f f s h a r p l y * O n e would expect „ then, l e s s abstraction at pH 12*5*  ffhls  expectation Is borne  out i n the r e s u l t s • above . though In view of the. wide 9  v a r i a t i o n In r e s u l t s at pH 6, -one value at 12*5 be considered  cannot  conclusive.*  Discussion o f •abstraction r e s u l t s Fallowing the method applied by Herd (8) to galena, the- c a l c u l a t i o n s below were Bade*  Prom Stoltes Lsw  9  the average rate-of s e t t l i n g of the- p a r t i c l e s as 12 par minute, the average radius i s calculated to be  using cm.  1»75 x 10  em*  To check t h i s , a microscopic measure-  ment of SiO p a r t i c l e s was made, g i v i n g the frequency curve shown, i n P i g . 6« . where one square u n i t equals 4  256. square BJU.  C a l c u l a t i o n • of average area and radius  frora the frequency table by a method due t o l'hurstone(15) -S ,gave a value o f 1,73 x 10 era. Area per etfoic centimeter of p a r t i c l e s i s given "by the r e l a t i o n Z Area' equals volume x 0 as 1715 squ.ora. r Eaking the density of s p h a l e r i t e as 4 gia./oe* gives the area per gram o f 4-28*7 squ. osu Holaenlar volume o f 97*38 .' -3S sine snlphide™m'^^^^ - 4.o4 ac 10 e.e. -8 Holecular' diameter then i s S.4S x 10 .  The number  of Eiolecnleo per SQU»' cm* area, then I s  1 3*43 x 10  s for  15 *8S 2. 10 » She number of senthate ions then • • 15-  required  a unimoleeular l a y e r i s 1 ?7jgAlQ___ ..  from Sable T i l l , , average abstract ion  Iter gra® of ore i s  •408 ag«.  f i l l s corresponds t o 23 , .18' •408 x 6*03 s 10 - 1.22 z 10 xanthate Ions* .202 2C 10  1'hese are spread over an area o f 428*7 S Q U .  era. fhe  number of santhate ions per square era* then i s 18 ~J^?u-&-10~/! O O  D  15  =  2.84 s 10" . ~**™*~««*^**^^  )  oo •  I t i s thus seen that the nuaber of nanthote ions abstracted  i s s u f f i c i e n t to form a layer between one and  two molecules t h i c k .  She c a l c u l a t i o n s of area are  .probably l a r g e l y i n e r r o r , since the sphalerite particles' are estreiaely i r r e g u l a r i n shape, but the above r e s u l t 'would  seem to indicate a d e f i n i t e l a y e r formation. SOTSAHY •  1.  Behaviour of two d i f f e r e n t samples, of sphalerite  with potassium i s o amyl scant hate has been  investig-  ated, both with oonoentratipn of c o l l e c t o r and pH as variables • > 2® She decomposition of potassium i s o ©ayl scant hate has been investigated. 3* Evidence i s presented concerning the behaviour of the senthate as a c o l l e c t o r i n strongly acid: s o l u t i o n 4.  i'he problem of abstraction has been investigated-  and some r e s u l t s obtained*  .•  11SP131HCS3  1. Gandl'n, " F l o t a t i o n " p-204 MoGraw K i l l eo« 1932 2. 6.1.IUS©! Gttidie©, Eng., and Min* J n l * p S58 1935 e  5* Swainson and Anderson, Trans* "Sleet roehem. Soe* 60,S29,S1. 4* dark and Coz, A*I.M.I. 112,189,1954 5. ffavfc and Cos, A.I.M.B., 112§267, 1934 6. Saylor and l i o i r A j a l . S . 112, 582, 1954. 7. Kemper, 3*A* Thesis U.B.C'1940 8. Herd, M.A. S&esis, U.B.C. 1940 9. Bonnet M.A.Se. ffihesis JBB.C 1938 10. Candin, op*.eit. .p 37, 11. raggart, d e l Gnidioe, and i J e i h l , A.l.M.B. 112, MB, 19g4. 12.. Saudln, op.oit. p I I S * 13. Balaton and Barker, Erans. .lleetroehea.. Soo. 60, 319, S I . 14. Hawkes, B.A.Shesis, TJ..B.G. 1940 15 fhnrstone, "fnndaaentals. of S t a t i s t i c s " , e  quoted i n Stroud, "iMueationai .Psychology" p 73.  

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