I. ABSTRACT~..

~

or the reagent from the .IJn;i..:; of tll~ !j'liJier~l.Important factors goveiDh"1g flcta,itl:1 "veredetermined to be the rapper ';c)u)ili.y of themineral as weD as the adht.,::~ -:!f ~h< chelate orthe ~agent to the surf:.rp. of i~:~ fi'.::erAl. Vihil~maximum flotation as a [\".,;tiom c.;i ?H ~\.:;inversely related to solubility ,,"1:3 was f.~' ~tyaccouflt.cd for by the chemica] :.:,.\..; of thech~lating agent. the maxJ;..1um as a fianction (,f'Z,)!)ditioning time was found to be B!Jvemed byboth so~u~iJity and the detachment of th~ ::helateor 1:Jle \~,,~~nt from the s~Tface. The effe.~:s ofj:lc,'e'~e of ionic strength and COi't'Ct' .ddition indecreasing notation have further confimled therole of copper solubility or the solution copper inthe flotation of oxidized copper minerals.

Ch~](Jti"g agents {hat can fonn insoluble,hydrophobic chela1ts on the surface of mineralscould b~ poter.!jaj coll.;~tors for selective flotation0... milltrals. ~jl this stlJdy it was found thilt Ux@serif:5 of reagents, which are highly selectivecoiM\ercial r;opp",r-c:hel~~~g soivent extractants,flJllctiol1 as colJect'"rs for the o:cidized coppermii'\~ra1s. F11)~,,~icln of cllprite and cJ1l"jsocolla hasbeen ~rrle.1 ou: ':'lith LiX\5jN as a function ofUX concentration, pH, conditioning time, ionic$ir:ngth, ;laid ;:~!'Jtion c.:.opper cOnC~1\'fation.FiO1ntion was fO'i.i!'\U \0 've si~ir;antiy .fftcted byconditions U'\3t t>ermit det'.'.t:;b,tltnt of t,e ~hei~i~

~

Recent Developments in Separation Science82

"i-(Q)II. INTRODUCTION

(Q)-.HON OH

Compounds with this chelating group form charac-teristic green insoluble chelates with CU2+.

LlX65N is a substituted 2-hydroxy benzo-

phenone oxime:

C.H..

~C~~ .JII T

nON OH2-hydJoxy-S-nonyl-benzopllenone oxime

It has the same chelating group as 2.hydroxybenzophenone oxime (i.e., 2HBPO):

IQ1- c r61II -'-YHON OH

or salicylaldox.ime (i.e. SALO)

H'cIIHON OH

LIX65N forms a yellowjsh-brown chelate withCU2+.

The chelating agents must meet certain require-ments to function as collectors. The most impor-tant requirement is that they should form insol-uble chelates (or inner complexes) with the metalcation on the surface of minerals. There is nodirect proof for this requirement, but it hasgenerally been found to be true..,2 ,S-7 A few

other requirements are (a) the chelating agentmust form a surface chelate that is bound to thesurface of the mineral sufficiently strongly; (b) theligand, or the chelate, must induce sufficienthydrophobicity tQ the mineral to facilitate favor-able bubble attachment to the mineral; (c) thechelation must be specific over a wide pH range;and (d) common requirements such as ease of

Chelating agents have received attention in thepast for their potential as collectors with highselectivity for minerals. As early as 1927, Vivian I

reported the use of cupferron, a well knownanalytical chelating agent, as a collector for theflotation of cassiterite. Since then, there have beenseveral reports2-7 of the use of chelating agents as"flotaids" (either as collectors or as promoters) forminerals. An obvious advantage of using chelatingagents lies in the selectivity or the specificity thatthey possess for metal cations. Of course, thisadvantage is based on the assumption that they doadsorb or form a chelate on surfaces of mineralswith selectivity or specificity similar to what theyexhibit in aqueous solutions. In almost all cases oftheir use as flotaids, the choice of a particularchelating agent has been made on the basis ofknowledge in the area of analytical chemistry. Inother words, chelating agents used in the past haveall been well-known analytical reagents. Someexamples are: dimethylglyoximel,6 for nickelminerals, cupferronl,6 for iron and tin minerals,and salicylaldoxime2 for copper minerals. It is alsoa fact that such analytical reagents have now madeit possible for the process of solvent extraction tobe one of the most attractive techniques of metalsseparations and concentration. For example, amodification of o-benzoin oxime (cupron) wasintroduced by General Mills over a decade ago,under the trade name LlX63, as the first chelatingextractant for use in commercial solvente xt raction processing.8,9 Later, severalmodifications of salicylaldoxime were introducedas aromatic LlX reagents.8 ,I 0 At present, these

reagents, together with a substitutedg.hydroxyquinoline8,ll produced by AshlandChemicals under the trade name Kelex@, arecommercially available.

LIX63 is a substituted aliphatic o.hydroxy.oxime:

C,H. C,H.I ICH, (CH,),CHC-CHCH (CH,),CH,

. IHON OH

S,8-diethyl-7-hydtoxy-dodecan-6-one oxime

It has the same chelating group as o:.benzoinoxime (i.e., cupron):

~~--,

83

chelating agents for copper and their applicationfor copper minerals.

III. MATERIALS

synthesis of the chelating agent. low cost, lowtoxicity, high stability, etc.

A perusal of the published literature of the LIXreagentsl2-14 indicated that they do meet severalof the above requirements and, accordingly, theymust function as collectors for copper minerals.

The present study marks, to our knowledge, thefirst attempt to investigate the application of theUX reagents as collectors. Flotation tests werecarried out using LIX65N and LIX63. The resultsof flotation using LIX63 are discussed else.where! 3 This paper describes the Hallirnond cell

flotation of cuprite and chrysocolla using LIX65N,which forms a (very) stable and insoluble chelatewith cupric ions. Flotation tests were carried outunder varying conditions of pH. concentration ofthe reagent, etc. It was suspected, as also indicatedby a few initialttsts, that under certain conditionsthere was a preference for LIX to exist in the formof a copper chelate in the bulk aqueous phaserather than on the mineral, thereby affecting theflotation. This prompted an investigation into theeffect on flotation of the copper in solution (or ofsolubility of the mineral), and of the parameterssuch as conditioning time and ionic strength whichinfluence the solubility.

The present study confirmed the predictionsthat LIX reagents will function as collectors forcopper minerals and that the solubility of themineral will influence the flotation. The studydiscusses the results in the light of the availableknowledge of the nature of cuprite and chryso-colla and of the properties of LIX reagents andtheir chelates with copper. The study also en.visages the recent and future developments of

The two oxidized minerals, cupritt and chryso-colla, used for this study were obtained fromWard's Natural Science Establishment (New York)and Black Hills Minerals (South Dakota), respec.tively. The minerals, received in the form oflumps, were hand-crushed to approximately lA.in.pieces, and the hand-picked pieces from theSt wereground to the desired size range in a porcelainmortar and dry-stored in polythene bags. Theminerals prepared in this way wert appreciablypure (see Table I). Tablt I also gives the sizefraction and the amount of mineral UStd for aflotation test, both of which were Stlected on thebasis of the specific gravity of the mineral.

The sample of commercial.grade LIX65N usedwas supplied by General Mills. The as.receivedsamples invariably contain an inert diluent (pos.sibly up to 40%) which is added to facilitatehandling. 1 5,16 Because they might also containimpurities, the flotation test results obtained usingcommtrcial reagents might be difficult to inter.pret. However, the initial tests were carried outwith the as-received sample of LIX65N; but,subsequently, it was purified by the procedureused by Ashbrookl6 and Atwood and Miller.'3The commercial UX65N was reacted at ambienttemperature with 10 M NaOH to precipitate thepure LIX65N in the form of a ye!low-orangegelatinous substance, leaving the diluent and theimpurities untouched. The precipitate was then

TABLE 1

Minerals

ChrysocoUaCuprite

AppearanceS.G.Chemical analysis

Blue to blueish green-2.536% Cu; 44% silica

X-ray analysis

Reddish-brown crystalline6.184~ CD; 1.9% insolubles;

-2% iron9S~ Cu, 0; CuO not detec-

ted; - 2% a-q uartz.5-10% o-quartz; rest

cllrysocoDa .ith a sma])OJ, of malachite

Size fraction usedfor notation

Amount used foreach notation test

-6S + ISO mesh -35 .. 65 mesh

0.711..,

I...

84 .~~«RI Dellelopmenls in Separation Science

The conditioning method consisted of de.sliming the mineral twice with triply distilledwater (roW) in a 100-ml volumetric flask, fillingthe flask with 100 ml of row whose pH and/orionic strength has been adjusted to required values,introducing I ml of an acetone solution of LIX ofrequired concentration, filling the flask nearlycompletely with more of the TDW, securelystoppering the flask, and tumbling at IS rpm forrequired time. Instantaneous emulsification wasobserved when the acetone solution of L(X cameinto contact with the aqueous phase.

After conditioning. the mineral with the solu.tion was transferred into the Hallimond cell, andflotation was carried out for the required length oftime by passing nitrogen at 20 cc/min, while themineral was kept in suspension by a magneticstirring bar.

treated with ,everal portions of hexane to removethe organic matter. Finally, the pure oxime wasreleased from the precipitate by treating it with25'1 H2'504 in the presence of a layer of hexanewhich collected the free oxime. After severalcontacts with fresh H2 504, the pure oxime in thehexane phase was washed with water to removetraces of acid and vacuum-desiccated for about 8hr to obtain the pure LlX65N as a mixture ofcrystals and a yellow-brown liquid, correspondingto the two isomers! 3 ,16 of LlX6SN. No attempt

was made to isolate the isomers. Table 2 gives thephysical properties of the two reagents, LlX63 andLlX65N, and Table 3 gives information on theisomers of LlX65N. It is to be noted that pureLlX65N contains about 8~ of the active (anti-)

\

isomer .16

No frother was used in the Study. KOH andHNOJ were used for changing the pH, and KNOJwas used to maintain ionic strength. All thechemicals were of reagent grade. Acetone was ofspectroscopic grade. TABLE 2

The LIX~ Reagents (Oletating Solvent ExtractionReagents by General Mills)

IV. METHOD

As noted in Table 2, the LlX reagents areinsoluble in water. Ashbrook' gives a saturationsolubility of less than 10-5 M for both LlX63 andLlX65N. One way to introduce such reagents intothe conditioning solution would be in the fom1 ofan emulsion in water. However, it was found to bemore convenient in this case to introduce thereagent as an acetone solution.

CommercialLIX63(1963)

Pure UX63Commercial

LIX65N(1970- 71)

Pure UX65N(active)

Ligltt yellow-brown liquid;S.G. 0.92 (up to 70';; inert diluent)insoluble in water

Off-white wa.,}" materialAmber liquid(containing up to 40';{ napoleum4708); S.G. 0.9; insoluble in ~'ater

YeUo--brown viscous liquid

TABLE 3

The Isomers or Pure LIX6SN@200/"Inactive isomer

(syn-)White crystalline

80'"Active isomer(anti. )

Yello~'-bro~-n viscousliquid

Rapidly forms a bro.-n-colored complex~ith Cu +2

No complex with Cu ..

C "'f C.H'9

~~C II,N

cIIN

""

OHOHHO/

f

,

85

--

CUPRITE - LIX65N

10 MIN. CONDITIONING

pH 5.5-6.4so'

MIN. FLOTATION

0UJ 60.f- '~0-JLA.. 40

~0I-

20

~.Ovr

.00032 ' ., .. .

CONCENTRATION OF LIX65N. GPLFlotation of cuprile as a function of con.;emration of LIX6SN .FIGL:RE

v. RESULTS AND DISCUSSION~

.59>COPPERMINERAL ~

\Q)""R

OH\N=C

--

;u,i 0-<1;

/.I

".

/

".

;

,".

"'Cu

a

A. Effect of LIX ConcentrationFlotation of cuprite and chrysocolla was carried

out as a function of LIX65N concentration at thenatural pH of the system. Only the results ob-tained for cuprite flotation are given in Figure I. Itis seen that the flotation curve is the familiars-shaped one, found commonly for flotation sys-tems. The collector action of LIX65N can bevisualized as the result of a surface chelation,shown in the simple schematic picture, Figure 2(which is drawn on the assumption that UX65Nforms a surface chelate).

When cuprite is contacted with the aqueoussolution, there will be a spontaneous concentra-tion of Cu. ions in the interfacial region. Cu. ions,being unstable in the absence of stabilizers such aschloride, thiocyanate, etc., will be oxidized jm-mediately to CU2+ ions; consequently, the mineralwill largely expose a distribution of Cu' and Cu2+ions. The LIX molecules will now be able to form

flGLJRE 2. Sch~malic dia!!ram sho\\ing a possibl~ surfaccchclalCSlrUClurc.

t', ..,;J;!-

,Cu,,.-.-.-,,, \

Recnrt ~/opmellts in SepQration Sc;enct"86

(C>;,'::=.JB1-0

\'" "N

CuC:N""

\ "O-H

R-t, :C

\O-<Q)-R

R

Cu2+ + ~C/f:t1

II OHHONLIX65N

~'Q ~ ORG

ORG

CuILIX65NI:z CHELATE INTHE BULK AQUEOUS PHASE

s..'h..'IlI",i.. diill'rillll ~h(\"iny ..lru.:lurc of c~lalc fom1cd in Ihc bull. pha-c a"a~ from Ih..11<..l kL .'m",..-,;,' ..url..,

be accounted for partly by its formation. in thebulk phase and partly by the peeling off of thechelate from the surface (Processes 2 and 4). Itmight be pointed out here that the LlX.cucomplex was in fact observed in the bulk aqueouspha~ during prolonged conditioning. for 10 minor longer; and correspondingly. a stain (yellowishgreen or brown) was observed on the filter paperthat was used for filtering the floated solids. It isto be noted that the LIX appearing in the bulk inthis manner becomes essentially unavailable forflotation. Also, if either or both of these t~.oprocesses (2 and 4) occurs to any significantextent, the flotation can be expected to beaffected by the solubility of the minerals or by theamount of copper species in the bulk aqueouspha~, and, therefore, by the extent of condi-

tioning.

.,t-1

the

addl

fTnl1

ring

incr

sta~

and

(1('11

lite

wit

B. Effect of ConditioningThe flotation of cuprite as a function of

conditioning time was carried out at differentconcentrations of LIX6SN. The results are shownin Figure 4. At very low concentrations of LIX (-0.0064 g/l), conditioning time has little influence.At higher concentrations (0.016 g/1), flotationrecovery appears to be going through a maximumas a function of conditioning time. At very highconcentrations (0.026 g/l), not only is there amaximum, but it appears to have been shifted to alonger conditioning time.

During the initial stage of conditioning, LIXcan undergo adsorption (process I), while, simu1.taneously, copper ions will be released from themineral. These ions can then fonn a comp1ex with

\

a chelate by deprotonation with either or both ofthe ions, depending both on the prevailing elec-tronic configurations and on the stereochemicalrestraints. It may be recognized that this chelatented not be identical to the chelate fonned withCU2+ ions in aqueous solutions which is rtpre-sented as follows in Figurt 3. Once fonned. thesurface chelate can expose a hydrophobic surfaceand a long chain, both of which favor attachmentof tht bubble to tht mineral surfact.

During tht conditioning of chrysocolla withlIX65N, tht color of tht particles was observed tochange from blue to a dull green. A similar resulthas been reported with hydroxamate as a col-lector.s It was not possible to observe such a colorchange on cuprite. Also, dark yellowish-green tobrown globules very much resembling tht LIX.cucomplex colltcted at the surface of the solutionduring conditioning of cuprite or chrysocolla. .Insome cases, even the tntire aqutous phast turnedmort turbid with a yellowish-gretn or brown tinge,tht color change or amount of globules being morenoticeable for prolonged conditioning and higherionic strtngths and LlX concentrations.

These observations could be explained by con-sidering one or more of the following processeswhich might be occurring during conditioning: (I)adsorption of LIX at the mintral-solution inter-phase. and formation of a surface chelate; (2)formation of a LIX.cu chelate in the bulk aqueousphase; (3) precipitation on the surface of mineralof the chelate fonned in the bulk; and (4)detachment of the reagent or the chelate from thesurface of the mineral.

The observed bulk phase LlX.cu complex can

H..

)-0

~

81 J

4

f.

100

.032 GPL LIX.tf

~

.GPL LIX80'

ae40016GPL LIX

CUPRITE - LIX65N

pH 5.5- 6.620 SEC FLOTATION

20

9 ~~:!:.:J:.JX

-.-0 .0032 GPL LIX . 0

~::::=~~ .00032 GPL L IX ~

300 10 20CONDITIONING TIME, MIN

Flolati"n "f ..-u"rjt~ as a function of condilionin, lim~ al djff~r~nl con.:~nlralion 1f"~I\ ofFIGL!RE 4lIX6~~ :oc

bubble size with a consequent reduced levita-tion.18 The fonner reason appears to be a remotepossibility in the system under study. On the otherhand, pH of the system, which changes slightlywith the extent of conditioning, might be partlyresponsible for the flotation behavior as a functionof conditioning time.

the yet un adsorbed UX in the bulk (Process 2). Inaddition, detachment of the reagent (:T chelatefrom the surface (process 4) might also be occur-ring following Process 1. The result is a gradualincrease in flotation to reach a maximum, at whichstage the latter two processes take over Process I,and decrease in flotation occurs. Occurrence of aflotation maximum has also been explained in theliterature by formation of a bilayer at the surfacewith the polar part of the outermost layer orientedtowards the bulk solution I 7 or by a decrease in

J.

It is seen in Figure 4 that at a higher concentra-tion (e.g., at 0.026 g/I UX) the adsorption of LIXwill be faster. and there will still be sufficient

LJ

0&&Jt-<t0...JLA..

60

.A~.~~

89

50 .-. II !.c., . ( .t

N~~ - 0 00

40 GPL LIX0

cCHRYSOCOLL..056 GPL LIX0

~...c{0-JLL

~0

A

010 MIN. CONDITIONING

1 MIN. FLOTATION10

Ol-ffo 11- I '- I I 1

0 10-4 10-3 10-2 10-1

CONCENTRATION OF KN03, MILFIGl'RE 6. fl(\13tion of ,,'urrilc and chryso.:olla usjn~ ll.X6~r-.;. as 3 function of '-NO.c(1n.:..'mr3Iion

strength can also have effects on other propertiesof the system, such as solubility of LIX in solutionand its adsorption on the mineral. At this stage, itis not possible to identify the importance of theseeffects.

C. Effect of Ionic StrengthTht solubility of a mineral is in general belitved

to play an important role in flotation.5 ,19 ,24-2 6The results discussed above indicate the possiblerole of solubility of tht mineral or tht amount ofcopper in solution in the flotation of cuprite andchrysocolla using LlX6SN. It is known thatsolubility is also influenced by changing tht ionicstrength. In this investigation, such changes weremadt using KNO). The results obtained forflotation of both cupritt and chrysocolla are givenin figure 6 as a function of KNO) concentration.An increase in the concentration of KNO) in.creases the copper released from the minera] intosolution, which in turn will increase the consump-tion of UX by bulk chelation and thereby de-crtase flotation, as is seen in figure 6. Also, theformation of globules of LlX.cu complex, and anincrease in turbidity of the aqueous phase, wereobserved to be more pronounced at higher ionicstrengths. It is recognized that an increase in ionic

D. Effect of Addition of CopperEffect of copper concentration in solution on

flotation can also be tested by adding a copper saltdirectly to the solution. Copper ions were intro-duced in the fonn of a Cu (NO])2 solution ofknown concentration, before introducing LIX.The results obtained for flotation of both cupriteand chrysocolla as a function of concentration ofadded copper are given in Figure 7. It can be seenin the figure that even small additions of coppercan markedly decrease flotation of both theminerals. The effect is seen to be more pro-nounced for chrysocolla; this is probably due to aslow adsorption of LIX on chrysocolla, thereby

J'

J

3

2

01

III

01

90 R.f'«nl Df'Mlopmenn in Sf'parDtion Science

50., 11.11.1', . 11""'1 ""'"

1 0 MIN. CONDITIONING

1 MIN. FLOTATION

40

cLLJ3Q.-~0-Ju..

~20

,CUPRITEGPL L IX6

0-

. - - - - .LA.056 GPL LIX

10

fO~II - III I I ... II ~. I I I ,. I II - I I I 1111

10.5 10.4 10.3 10-2INITIAL COPPER CONCENTRATION, MIL

FIGURE 7. Flotation of t"uprjl~ and t"hr)~ol1a using LIX6~~' as a function of initial cont"~nlration of addrdt"opprT in \Olulion.

increasing the extent of bulk aqueous phasechelation.

E. Effect of pHFrom the results discussed above, it is clear that

solubility, or amount of copper species in so1ution,has a role to play in flotation using UX. This rolecan be further examined by studying the datagiven in Figure 8 for flotation of cuprite as afunction of pH. The solubility curve shown inFigure 8 is the resu1t of leaching tests carried outin TOW at different pH values under the sameconditions as those used for conditioning ofcuprite befcre flotation, except that in theleaching tests LlX was absent. It appears fromFigure 8 that at 1ow and high pH values, solubilitycan expJain the flotation of cuprite - namely, thehigher the solubility, the lower the flotation, andvice versa. The decrease in flotation below pH 6cou1d a1so be due to a decrease, after reaching amaximum around pH 6.0, in concentration of

surface hydroxyl species such as CuOH+. The roleof such species in flotation has been previouslyreported. I 9

The decrease in flotation in the intennediatepH range of 6 to 9 is not, however, easilyexplained on the basis of the solubility data alone(Figure 8). This decrease, on the other hand, couldbe due to the fonnation of Cu(OH)1 on thesurface and the inability of LIX to fonn a chelateon this surface. Unfortunately, there is littleinfonnation available in the literature on theproperties of UX in this pH range.

The flotation increase above pH 9 again is inagreement with what is expected on the basis ofthe observed decrease in solubility. In addition,there are other contributing factors that arise fromchanges in properties of UX6SN. As discussedearlier, LIX6SN can exist as the anti- or activeisomer and the syn- or inactive isomer. The latter,which was inactive in the acidic region, is re-ported' to become very active at higher pH values,

,

~

91

CUPRITE - LJX65N

0.0096 GPL LJX

10 MIN CONDITIONING..II.II

II

1 MI" FLOTATION

fl

0ailt-o<0..J"-

a!

,,

)(

~

u

~n.n.

,I,IA,l-I

Isa...UBlLlTY,~

;..J~I(I,

AI

"~.6 A~ --- --~.6

...

.~,,I'. ,;

3 4 5 6 7pH

e 9 10 .,

FIGURE 8. FIOlation and \olubi'lt~ of c:urril~ a\ a function of "H at O.OO'K- ~"I LIX".4~

during a IO.min period cannot be expected tocorrelate with the solubility data obtained at theend of the same period.

VI. CONCLUSIONS

especial1y above pH 8. The result of this wilt be anincrease in the effective UX concentration andconsequently an increase in flotation. It is alsopossible that the surface activity of LIX65N isincreased in this pH range, since pronouncedfrothing and an appreciable decrease in bubble sizewere observed above pH 9.5, and these cancontribute to a higher flotation.

At this stage. the decrease in flotation above pH10 could only be attributed to the markedlyincreasing solubility of cuprite above that pH.

It is to be noted here that while the solutioncopper concentrations reported in Figure 8 arethose obtained at the end of a total of 10 min,adsorption of LIX during reagentizing is takingplace under increasing copper concentration from0 to 10 min. Unless the UX adsorption is'onsidered a totally and instantly reversible"rocess. flotation obtained due to such adsorption

Flotation of cuprite and chrysocolla was carriedout using UX65N, which is a chelating extractantused conunercially for the solvent extraction ofcopper. The results have demonstrated its abilityto function as a collector in flotation systems. Thepresent interpretation of the results obtained isbased on the little-known nature of these UX -copper mineral systems, and of chelating agent-mineral flotation systems in general.

A simultaneous study of the solubility behaviorof the copper minerals under various conditionshas clearly shown the important role of thesolubility of the mineral in these flotation systems.

...'-

92 R~«nl ~Iopmenn in S~pil"lion Scienc~

surface, no conclusive evidence has appeared in theliterature in favor of it. It is believed that arigorous and systematic spectroscopic work isnecessary, not only to confirm the surface chela-tion but also to find out the structure andcomposition of the chelate. This information willbe invaluable in designing chelating agenu withsuitable carbon-chain substituents which offerminimum steric hinderance to the formation of achelate with the surface metal ion whose coordina-tion is already partially satisfied.

Finally, there has been a surge of interest in

new and very specific chelating agents, especiallyfor copper. Examples are the recently developedreagents such as SME@ 529.. 8 Acorga@ p I and p

17,18 OMG@ (Russian),19 and LIX 34,20 inaddition to the already existing ones such as Kelex100 and LIX 70. Data collected using suchreagents as collectors should facilitate design ofthe "best" collectors with respect to the organicmolecule in general and the chelating group in

particular.

Thus, an increase in solubility of the minerals wasfound to correspond to a decrease in the flotation,and vice versa. Similarly, increase in ionic strength(which enhances solubility of the mineral) oraddition of copper decreased flotation of bothminerals. These findings have been attributed tothe abstraction of LlX in the bulk aqueous phasein the form of a Cu-LIX chelate which may haveno collecting property. The flotation tendency ofchrysocolla was weaker compared to that ofcuprite, possibly due to the refractory nature ofchrysocolla. which is a silicate.

The flotation was maximum around pHs 5.5and 10, which is in general agreement with whatcan be predicted on the basis of the solubilitydependence on pH, and flotation was low in therange of pH 6.5 to 9.

\

-.

~I.",.

t

VII. FUTURE WORK

~

t,;.

(

ACKNOWLEDGMENTS

We wish to thank Dr. A. W. Ashbrook ofEnergy. Mines and Resources, Canada, for techni-cal information given, and Mr. Hugh Calkins forhelp with some txperiments. Support of this workby National Science Foundation, Solid and Par.ticulate Processing Program (ENG.76-80139) is

acknowledged.

The work of foremost importance to be carriedout next is the demonstration of the selectivity ofthese chelating agents for copper minerals, andtheir applicability to all the copper minerals. Theinitial tests in this study which were perfonnedusing sulfides of copper (chalcocite and chalcopy-rite) demonstrated that UX reagents were able tonoat sulfides also.

Although it has been confirmed qualitativelythat a surface chelate does fonn through theinteraction of the chelating agent with the mineral

.-:

'-'~

::\~. ~

93

REFERENCES

ift-

f.'.,.

.:

...

I. Vivian, A. C., Flotation of tin Qres. Min. Mag.. 36, 348, 1927.2. DeWitt,c. C. and Bltchetder, P. V., Chelate compoundsasflotltion relfents.I,J. Am. Chern. Soc.. 61, 1247,1939.3. Gutz~it, G., Chelate forming OJIlnic compounds as flotation mgents, Tnnl. Am. Iml. Min. MtOlaU. PtOl. Eng., 169,

272,1946.4. Ladt, R. W. and DeWitt..C. C., The Flotation of Copper Silicat~ from Silica, TrGnf. Ani. Inll. Min. M~lall. hI. En,..

184.49,1949.5. P~tenoa, H. D., Fuent~nau, M. C., Rkkard, R. S., and Mi1J~r, J. D., Chrysocolla flotation by the formation of

insoluble surfacr chelates, Trans. Soc. Min. Eng. AIME. 232,389,1965.6. Usoni, ~ Rin~Ui, G., and Marabini, A. M., Ch~/llling ag~nls Ilnd fu~/.oil: II new WilY 10 jloliltion, AIME Centennial

Annual Meeting, Ne~ York. 1971. preprint 71-8-10.7. RineUi, G. and Manbini, A. M., Flotation of zinc and lead oxjde-su1rId~ ores with chelatiJllaaents, hoc. 10th Int.

MintOn' hoc~lling Con"~ls. London, 1973,493.8. Ashbrook, A. W., Chelating reapnts in Solvent extraction pr~s: the present position. Coord Ch~m. R~f.. 16,

285.1975.9. Swanson, R. R. and Alen, D. W., A new reagent for the extraction of copper, SME-AIME Annual Meeting, New

York, February, 1964.lOa. Alers, D. W. and DeMent, E. R., LlX(!)64 as an extractant for copper-pilot plant data, SME.AIME Fall Meeting, Las

Vegas, September 1967.lOb MlttiSon, P. L. and Swanson. R. R., Process of exUactin~ copper with certain substituted 2.hydroxybenzophe.

noximes. U.S. Patent 3.655.347.1972.II. Hardage, J. A., Kelex 100 - a new copper solvent extraction reqent, SME-A1ME Annual Meeting, Salt Lake City,

September 1969.12. Adlbrook, A. W., Commercial chellting solvent extraction reapnts. 111. Oximes: spectra. structure, and properties,

H.vdrom~lllllu'g)', 1,5.1975.13. Atwood, R. L. and Miler, J. D., Suucture and composition of commercial copper chelate extrlctants. Tnnf. Soc.

Min. En,. AIME, 254,319,1973.Technical literature, UX(!)65 N rUient. General Mills International Chemicals Co., Minn~apolis, 1974.Adlbrook, A. W., private communication.Ashbrook, A. W., Commercial chelating solvent extraction reagents. I. Purification and iSomer separation of2-hYdroxyoxlrnes,J. Chromalogr.. 105,141,1975.

17. Hanna, H. S. and Somasundlran. P.. Flotation of salH)'pe minerals. in f7ollltion, A. M Gaudin Memorial Volume.I. AIME. New York. 1976. 197.

18. SomlSUndann, P. and Moudgi, B. M., The effect of dissolved hydrocarbon gases in surfactant Solutions on frothflotation ofrninerals.J. Coiloidlnl~rfllceSci.. 47,290, 1974.

19. PIlmer, B. R., Gutierrez, B. G., Fuentenau, M. c., and Aplin, F. F., Mechanisms involved in the flotation of oxidesand silicates with anionic coUectors. I and II, TranI. Soc. Min. Eng. AIME, 258,257. 1975.

- ,. Flett, D. s., Solvent extraction in copper hydrometaUurgy, Tnns. Inl'. Min. M~IIlIl. (London), 83, C30, 1974:

Discussion, 84, C60,1975.21. Zeaer, E. E., Giganov, G. P., and FednevI, E. M., Physico-chernical properties of OMG - I - extractant for

copper, Tsv~tn. Mel.. 2,24,1976.22. Kord~ky, G. A., MacKay, K. D., and Virnis, M. J., A n~w aeneration copper extractant, SME-AIME Annual

Meeting, Las Vegas, February, 1976.i. Napnj, D. R. and Somasundaran, P., Commercial chelating extractants IS collectors: flotation of copper minerals

using UXe> Reqents, SME-AIME Annual Meeting. Atlanta, March, 1977.Taam. A. F.,Hllndbook of Mineral DrtOlsing. John Wiley &. Sons, New York,I945,12.o1.

'. Glembotskii, V. A., Klasen, V. I., and Plabin, L N., f7ollllion. Primary Sources, New York, 1963.'. Gaudin, A. M.,hinciplel of Mineral DrtOlsing. McGraw-Hill, New York, 1939.

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