ABSTRACT

Organic canplexing agents have received special attentioo over the pastfew decades in the search for reagents for improved flOiatioo separationof minerals, especially non-sulphides. The majority of such reagents thathave been proposed over the past few decades have remained largely a\al)(ntory curiosity, excep pemaps allcyl hydroxarnates, because theirselea.ioo is seldom based 00 canmercial viability. In this regard, thechoice of canplexing agents such as oximes may be more realisticbe£ause of their widespread use in solvent extractioo of copper. Ourearlier studies have cmfmned that they are also effective as colleClors forcopper oxide minerals, including chrysocolla which is the most difficultcopper mineral to beneficiate.

The flotation behaviour of chrysocolla for several structurally-relatedhydroxyoximes were studied as a ftmctioo of pH and oxime coocentrationand the role of structural features examined. The structural changesstudied included substitutioos in ~ chelating and non-chelating parts ofthe molecule. The results indicated that, cootrary to expectations, manyof the structural changes in the basic molecule, salicylaldoxime, do nothave a positive effeCl 00 collector efficiency. The reduction in collectorefficiency is ratiooalised on the basis of possible steric factors affectingcanplexation and packing of the collector species 00 the mineral surfaceas well as effects due 10 changes in electron density brooght about bysubstituents. Introductioo of alkyl substituents on the oximic carbon ofsalicylaldoxime yielded the highest collector efficiency.

INTRODUCTION

Over dte past six decades or so, since dte advent of solublesurfactants as collectors in flotation, dtere has been a relentlesssearch for new chemistries for improved separation of minerals,bodt sulphides and non-sulphides. Whedter it is for flotation ordepression, organic-<:omplexing agents or chelating agents. havereceived special attention (Barbezy et al, 1977; Drzymala andLaskowski, 1981; Fuerstenau and Pradip, 1984; Gutzeit, 1946;Holman, 1930; Marabini et al, 1971, 1974, 1973, 1976; Nagaraj,1987; Sornasundaran and Nagaraj, 1984; Taggart. 1930). This islargely driven by dte success of these reagents in analyticalseparations. While in principle it is logical to expect metalspecificity observed in analytical separations to translate intomineral specificity, in practice this is far from a straight forwardtransfer. Neverdteless, an assumption is made in dte majority ofswdies dtat complexing agents oosorb on minerals by formingmetal complexes on mineral surfaces under conditions mostfavorable for metal complexation in solution as observed inanalytical separations, and dtat such metal complexes areresponsible for imparting hydrophobicity to dte solid. While avariety of complexing agents are already in large scale use insulphides flotation, this is not dte case in oxides flotation. Fattyacids and arnines still dominate dte industry though numerouscomplexing agents have been Jroposed. Perhaps dte onlysignificant commercial utility in the non-sulphides area can beattributed to dte alkyl hydroxamales (Fuerstenau and Pradip,1984) in the former Soviet Union at least until a few years ago.Current usage of dtis is not known. Limited application can alsobe found for certain phosphonic acids (Nagaraj, 1987). Theprohibitively high cost and high dosages required of many of dteproposed complexing agents are certainly major factors. Theunderlying factor, however, may be the choice of a complexing

agent. Complexing agents have been chosen invariably on thebasis of success in analytical separation rather than on the basisof commercial viability. Thus many of the proposed structuresfall into the category of 'exotic' chemistry and remain largely alaboratory curiosity. h1 this regard the choice of cornplexingagents such as oximes may be more realistic. The commercialviability of oximes has been well established because of theirwidespread use in solvent extraction of copper.

One of the early references to the proposed use of oxirnes isthat of Vivian in 1927. Dimethylglyoxime (DMG) was proposedfor floating nickel oxide ores. Delitsina et aI (1954. 1956)recommended the use of DMG for the flotation of chalcopyrite.bornite, malachite. pyrite and electrolytic copper and nickel.They concluded that the increase of hydrophobisation of themineral was greater with DMG than with xanthate. which is anintriguing result, especially for sulphide minerals. Their fmdingscontradict those of Peterson el at (1965) who found lack offlotation of chrysocolla with DMG and of Drzymala andLaskowski (1981) who found lack of flotation of syntheticmillerite and other nickel minerals with DMG and otherdioximes. It should be noted here that DMG forms water-solublecopper chelate. Usoni et at (1971) showed that a hydrocarbon oilwas necessary to obtain acceptable flotation of niccolite withDMG. Teoh et aI (1982) used several homologous dioximes forthe flotation of nickel bearing minerals. Optimum flotation wasobtained with 2.3-nonanedione dioxime. Peterson et aI (1965)also suggested the use of alpha-benzoin oxime for chrysocollaflotation.

De Win and Batchelder (1939) investigated the collectorfunction of salicylaldoxirne (SALO). its meta- and para- isomers.and its mono methyl ether, for chalcocite, covellite, azurite.malachite and cuprite. Only SALO was found to function as acollector. The meta- and para- isomers could not function ascollectors since their structure does not permit chelate formation.It was also proposed that if the phenolic hydroxyl is replaced by amethoxy group. the resulting monomethyl ether of SALO wouldnot be a collector. Mukai and Wakamatsu (1976) also usedSALO as a promoter of xanthate adsorption for the flotation ofchrysocolla. Adsorption of xanthate increased with the additionof SALO. while a complete coating of SALO on chrysocollaadversely affected xanthate adsorption. No effort was made toinvestigate the collector action of SAW alone. It is not clearwhat the mechanism of this coadsorption is and why a xanthate isrequired in addition to SALO.

Barbery el aI (1977) and Cecile et aI (1981) investigated thecollector function of oxirnes for malachite and chrySOcolla. Theystudied adsorption of SAW on malachite with supportinginformation derived from IR analysis. Multilayers of copperchelate were observed on the mineral surface.

Nagaraj and Somasundaran have conducted many systematicstudies on the adsorption of oximes on copper oxide minerals andtheir flotation (1979a. 1979b. 1981). The collector pro~rty ofcommercially used solvent extractants of the UX type 'wereevaluated for the flotation of chrysocolla and cuprite. Theseinvestigators also conducted a fundamental study of the systemtenorite-SALO in order to elucidate the mechanism of collector

The terms 'complexing' and 'chelating' will be usedinterchangeably in this paper since all of the discussion appliesequally to both, and since 'chelation' is but a special case of'complexation'.

1. Henry Krumb School of Mines, Columbia University, NewYork, NY 10027, USA

2. American Cyanamid Company, Stamford cr 06904, USA.

XVIII International MnefaI Proc»ssing C«'Ig(ess Sydney, 23 - 28 May 1993 577

TABLE 1TIte stnICtlD"U and ~Ur solubility of hydroxyoximes.

Structure Name Mol.\Vt.

$ALO

WaterSolu-bility, M

2.0 x 10-1(Salicylaldoxime) 137.1

OHAPO (O-Hydroxy Acet0-phenone Oxime) 4.5 x 10-3151.2

OHBuPO (o-Hydroxy Butyro-phenone Oxime) 5.0 x 10-4179.2

Q-: HC"-It

aiM»f

~V',c,'0f0

aiM»f

Q-: ai,of.aisC""II<»IM»fQ-~ ~

~C-J! ::::JIIailQ{QI.

OHBePO (O-Hydroxy Benzo-phenone OxIme) 1.5 x 10-4213.2

2H5MeAPO",,0\

CII

C»IPQt

~

3.0 x 104(2.~roxy 5-Methyt

Acetophenone Oxime) 166.2

2HSMBAO (2-Hydroxy 5-MethoxyBenzaldoxime) 5.0 x 10.3168.2

OHNAO (2-Hydroxy 1-NaphthaJ-doxlme) 1.0 x 10-4189.2

OHCI-K) (o-~roxy Cyclo-hexanone Oxime) 129.0 -1.0

OMeAPO (o-Methoxy keto-phenone Oxime) 165.0

OHAPOMeO (o-Hydroxy Aceto-phenone o.methylOxime 165.0

Generalized Structure ..

.,..R,CII

OH~

The structure of a complexing agent and, dterefore, itsproperties. can be changed by incorporating substituents in eidIerthe chelating part or dIe non-(;helating part of the molecule. Theeffect of such changes on dte collector efficiency of a number ofstructurally-related hydroxyoximes for chrysocolla as a functionof pH and reagent concentration is discussed in this paper.Information on structure-activity relationships is important fromdte point of view of not only understanding fundamentalmechanistic aspects, but also for dIe commercial viability of

action of hydroxyoximes. Aliaga and Somasundaran (1987)found an interesting correlation between dte UV spectta ofseveral struCttlrally-related oximes. dteir copper chelates and dteircollector properties.

Kiersmicki et al (1981) swdioo dte effect of alkyl chain lengdtin 5-aikyl SALO in dte flotation of sphalerite. smithsonite anddolomite and suggested dtat a propyl group gave optimumresults.

578 Sydney. 23 - 28 May 1993 XVIII International MnefaJ Pro<»ssWlg Congress

~.

>-Q::~0<.)w~

Z0

~~

§

INITIAL CONCENTRATION, M

FKJ 1 - ~ of cluy~. as . fulK:lioo of ~ of hmKIIOIues oximes: SALO; OHAPO; OHBuPO.

oximes in flotation. auoysocolla would be a logical choiceamong the oxide-type cower minerals because it is one of memost difficult to float. Its flotation aspects were reviewedrecently (Laskowski el ai, 1985).

(Xmfirmed by IR 8Id T1..C teclmiques. Water solubility of dieoximes wlS measured by derennining die aRk)\D1t dissolved aftershaking the oxinte in 10 ml of biply distilled water for d1ree daysat 25 - 26°C. The values are given in Table 1. These solubilitiesare expected to be close to die equilibrium values.

Stock solutions of oxintes in triply distilled water wereJrepared by adding one per cent acetone to ensure adequatesolubility. This amount of acetone was also beneficial in flotationtests because it Jroduced small. uniformly sized bubbles; aseparate frolher WIS, ~fore, not n«:essary.

EXPERIMENTAL

Mineral

Chrysocolla, CuSiO3, obtained as high-grade lumps from BlackHills Minerals. was crushed. hand-sorted, and crushed again 10.14 mesh. The -14 + 100 mesh fraction was passed dlrough a drymagnetic separator. ground in an agate mortar 10 -48 mesh. The-48 + 100 mesh fraction was passed dlrough a magnetic separatoragain, deslimed and cbied. It analysed 24 per cent Cu. X-raydiffraction indicated mioor amounts of quartz impurity.

Fk)tation

95 ml of the oxime solution at the desired concenb'ation wasstirred in a 150 m1 cyfuder. After pH adjUStmen1 to the desiredvalue. 0.7 g of the mineral was added aJ¥i conditioned fCK the~uired period with continuous COOb'ol and recording of the pH.pH was adjusted with KOH and HN03 to within :t: 0.05 unit.After conditioning. the mineral was floated in a modifiedHallimom tube for one minwe with 20 cchnjn nib'ogen.

OximesThe oximes used are shown in Table 1. SALO obtained from LaChat Chemicals was purified by ~rallisltion from petroleumedler-benzene mixture. 2-hydroxy-l-cyclohexanone oxime wasprepared by the met/X)d described by Nmz el al (1964). All ocheroximes w~ p-epared from their respective ketones or aldehydesby the medtods described by Blatt (1955) and Kohler aid Bruce(1931). All the oximes except OHAPOMeO were purified byrecrystallisltion. OHAPOMeO was obtained as a liquid and itwas purified by etha- ex~oo. The stnK:nIres and pJrities wa-e

RESULTSRotation data for Chrysocolla at pH 4.8 as a f\DK:tion ofconcentration of d1e duee homologous oximcs - SAW, OMAro,and OHBuPO . are shown in Figure 1. pH 4.8 was se1«;ted forthese tests b«:ause preliminary work with UX type of reagentshad indicllai that flotation was opirnum around pH 4.8. The

XVIII k1~ma~ *er8I ~ Congress Sy«IeY. 23 . 28 .-y 1 ~ 579

(ie 2H5MBAO, see Table 1) as well as methyl substitution in the5-position of OHAPO (ie 2H5MeAPO) decreased die collectorefficiency (more so widt 2H5MeAPO), dtough bodt 2H5MBAOand 2HSMeAPO had lower water solubility compared with theirparent molecules.

Flotation of chrysocolla widt 2H5MBAO and 2H5MeAPO aregiven in Figure 4 as a function of pH. Rotation behavior with2H5MBAO is very similar to dtat widt SALO, while that with2H5MeAPO is quite different and unusual compared widt dtat ofOHAPO. Two flotation maxima are observed for 2H5MeAPO,one at pH 4 and die other at pH 8.

Rotation obtained with the remaining oximes - OHBePO,OHNAO, OMeAPO, OHAPOMeO, and OHCHO at pH 4.8 areshown in Figure 5 as a function of concentration and in Figure 6as a function of pH. Flotation data widt SALO (from Figure 1)are also plotted in Figures 5 and 6 for comparison. Most of theoximes tested in dtis group were characterised by very lowcollector efficiency at pH 4.8 compared with that obtained withSALO. Thus substitution of a phenyl group for Rl (ie OHBePO,Table 1) decreased collector efficiency at pH 4.8. The pH foroptimum flotation with this oxime, however, was at pH 6, not at4.8. A fused aromatic ring (naphthalene) instead of the benzenering in SALO resulted in a very large lowering of collectorefficiency at pH 4.8 (dtOUgh it was optimum at approximatelythis pH). Thus OHNAO was inferior to all the other closelyrelated oximes. Similarly, methylation of the phenolic OH inSALO almost completely destroyed the collector property. Onthe other hand, methylation of the oximic OH of SALO (ie

maximum amount of oxime that could be used in flotation waslimited by its solubility.

It is evident from the results given in Figure 1 that an increasein the chain length of R, (see generalised strucwre, Table 1)while keeping R2 = H results in an increase in the flotationefficiency in the order -H « -CH3 < -C3H7. Ackiing the fustcarbon in R, resulted in the largest increase. Thus theconcentration of OHAPO required to obtain about 60 per centflotation is about half that of SALO and the water solubility islowered by almost two orders of magnitude. Increase in thechain length of R, by two more carbons (to give OHBuPO)further imlX'oved the coll~tor efficiency, but not to the extentobserved by introducing the first carbon. The water solubility ofOHBuro was only an order of magnitude less than that ofOHAPO.

Flotation data for the three homologous oxirnes are given inFigure 2 as a nmction of pH. Less-than-optimwn concentrationswere chosen deliberately in order to obselVe the features offlotation behaviour vs pH and to discern differences betweenoximes. These data, in general, support the results discussedabove. The collector efficiencies of OHBuM and OHAPO werehigher than that of SALO at all pH values, though theconcentrations used with the former two oximes was lower thanthat used with SALO. Flotation of chrysocolla was maximum atpH 5.0. The effect of substitution on the benzerte ring on theflotation of chrysocolla as a function of concentration of oximesat pH 4.8 is shown in Figure 3. Flotation data for SALO andOHAPO (from Figure 1) are replotted here for comparison. Itcan be seen that methoxy substitution in the 5-position in SALO

100

90 SAlO

CHAPa

OHBuPO.0~~

~

0::

W

~:Uwa:::

~0-~

~(:)

g

70

80

50

40

[30

20~~

Q-~S ~ 1 n

'~LXV M KNO3

;0:~:L 4 9 8 10 ,

12 4

qQNP.lTtO~fNG pHFIG 2 - R«alioo of chrylOOOI1a as a functioo of pH with hanologues oxirnes: SALO; OHAPO; OHBuPO.

S«) Sydney. 23.28 May 1993 XVllllntemalionaJ Mineral Promssing Ccx98Ss

~.

>:--~w

~Q4f(k:,

z0~<~0-J~

~~0 o~ 10-3

INITIAL CONCENTRATION, MFKJ 3 . Rotation of chrysocoUa as a function of coocentration of oximes: SAW; OHAPO; 2H5MBAO; 2H5MeAPO.

OHAPOMeO) only reduced the collector efficiency withoutdestroying it completely. pH for optimum flotation with thisoxime was at approximately 8.

The case of OHCHO is a special one because it belongs to theclass of alpha-acyloin oximes, though dte oxime is distinctbecause of the cyclic alkane. OHCHO was found to have anappreciable solubility in water (dte highest of the oximes tested).Its copper chelate was soluble in mildly acidic pH range andprecipitated in the basic pH range. In accord with d1is OHCHOexhibited extremely low collector efficiency even at very highCOncentrations.

DISCUSSION

The flotation behavior for chrysocolla with the majority of theoximes swilled was the same; optimum flotation occuned atawroximately pH 5. For UX65N (2-hydroxy-5-nonylbenzophenone oxime) two maxima in flotation occur, one at pH 5and the other at pH 10. Chrysocolla flotation with octylhydroxamate has a maximum at pH 6 (peterson et ai, 1965).AltOOugh the optimum in flotation of citrysocolla around pH 5can be explained on the basis of CuOW species on the surface(Palmer et ai, 1975), an alternative explanation would involve thepartitioning of the oxime between the mineral surf~e and thebulk aqueous phase in relation to mineral solubility, as in the caseof tenorite-SALO system (Nagaraj and Somasundaran, 1979).PKa of the oxime would also make a significant contribution tothe location of the flotation optimum.

The increase in collector efficiency observed with increase inchain length (ie SAW « OHAPO < OHBuPO, Figures 1 and 2)in the homologous series is in general agreement withobservations made in other systems. For example, Fuerstenau,Healy and Somasundaran (1964) documented this for quartzflotation with homologous amines. As can be expected,introducing the fIrSt -CH2 in SAW causes a much larger changein polarity of the molecule compared with further addition of twoCH2 groups. This is reflected in the water solubility of theoximes - SALO » OHAPO > OHBuPO - and also in thecollector efficiency. Furthermore, the increase in collectorefficiency of the higher homologues may be related to theelectron-releasing (inductive) effect of CHJ, relative to -H, whichwo~ld increase the electron density on the nitrogen. Watersolubility of homologous compounds should provide anapproximate indication of the hydrophobicity that they wouldimpart to the mineral surface assuming that their mode ofadsorption is similar. This has been observed in the case of fattyacids and arnines.

Substitution of a phenyl group in Rl (OHBePO, see Table 1)decreased the wata solubility appreciably, which is to beexpected from the less polar benzene ring. On the basis of Iowasolubility of OHBePO relative to SAW one might haverxedicted a higher collector efficiency than with SAW. Theresults, however, were quite contrary to this at pH 4.8 (Figure 5).An important reason for this is the shift of the pH of olXimumflotation for OHBePO from pH 5 with SAW to -6 withOHBePO. This shift is possibly related to a change in pK. of theoxime in going from SALO to OHBePO, which can be expected

XVIII International Mneral P~ssing Congress Sydney. 23 - 28 May 1003 581

100

90

80~

->-

f5>0<.>w~

z0

~~0-.JlJ-

70

60

50

40

30

20

0

0

CONDITIONING pHFKJ 4 - F1owioo of cluysocQla as . f\8Iaioo of pH wiIh ox--= SAW; OHAPO; 2H5MBAO; 2H5MeAPO.

me!hoxy group has reduced dte hydroPiobicity slightly becauseof dte orientation effects.

The low colleclOr efficiency of OHNAO (naphdtalene group,see Table 1), u in me cue of OHBePO, may also be related tolow hydrophobicity imparted to the surf~ after Misorpcion and~ed packing on die surf~ because of die naphd1alene rings.The very low water solubility restricted dte maximwnconcenttation snldied to -10 M.

The drastic reduction in me colleclOr efficiency associated withmemyl subsunltion for phenolic hydrogen (ie OMeAPO, Figures5 and 6) is expected because this molecule is tmable 10 form achelale widt coppa-. This result is in agreement wim dtatobserved by De Witt and Batchelder (1939) for o-methylbenzaldoxime and supports the hypothesis mat chelate formationis a JXerequisite for flotation. In mis context, dte absence ofcollector property observed by Nagaraj and Somasundaran(1979) for die syn-isomer of LlX65N is notewordty; mesyn-isomer is also incapable of chelate formation. It ca., beargued, however, mat OMeAPO could still adsorb on chrysocoUaby forming a complex (!hough not a chelate) wim cower via meoximic nittogen and function as a collector because simplealdoximes (such as R-NOH) are known 10 complex widt copper(Chakravuty, 1974). This 00es not appear to be 1he case from meflotation data obtained here, probably because the methylsubstitution on phenolic OH may impose sterlc hindrance to sucha complex formation wim oximic nittogen on the mineral surf~.

Medlylation of die oxime group (as in OHAPOMeO. Table 1)

~ause the benzate ring can alter d\e electron density on theoxime group significantly. Significanl differences betweenorientalions of adsorbed SALO and OHBcPO can also beexpected based on dieir strucnlres. which dien b'anslate intodifferences in hydrophobicity. Water contact angles. for example,on surf.:es comprising -CH2 or -CH3 are higher than diosecomprising aromatic groups (Wu, 1982). Also in the case ofOHBePO. dia-e is a JX>Ssibility d1at close packing of surfacearomatic groups is hindered. This would furdta- contribule to thelowering of contact angles.

The lower col1~tor effK:iency of oximes widi substitution indie 5-position on the rine. va 2H5MBAO am 2H5MeAPO.relative to SALO is ramer surprising (Figures 3 and 4) in view ofdie fact diat diey bodi form stable, insoluble copper chelales withcopper ions. The lower water solubility would suggest that theywould be less polar. Separate adsorption measurements (notshown here) indicated diat both substiblled compo\D1ds adsorbed. effectively as SAW. In the case of 2H5MeAPO. the pH ofoptimwn flotation is shifted (in f~t there are tWo maxima, seeFigure 4, at pH 4 and 8). This may explain the low flotation atpH 4.8. The reason for die two flotation maxima is W1known andit cannot be rationalised readily ~ all other oximes showed~ flotalioo maximum. In the case of 2H5MBAO, pH of~ flotation was 8PfX'oximately die slme . diat obtainedwidi SAW. though the medtoxy group on the ring can beexpected to alter die pK. because of the elecb'on releasing1eI¥Iency. The only explanation diat can be offa-ed at diis pointfor the lower coU~tor efficiency of 2H5MBAO is that the

Syckl8Y. 23 . 28 May 1993 XVIIlIntemaIionai aIneraI p~ ~582

is not expected to prevent chelate fonnation with copper and,therefore. its collector JropeIty should be similar to that ofOHAPO. but the results obtained here are quite contrary to thiseXpectation (see Figures 5 and 6). OHAPOMeO exhibited onlyweak collector property even at high concentrations. This can berationalised at this stage only on the basis of possible sterichindrance to complex fonnation on the mineral surface. This isnot unreasonable because steric flK:tors are much more imponantfor surface chelation than for chelation in bulk ~ueous solutions.

The very poor collector efficiency of OHCHO (see Figures 5and 6) is also rather swprising since after adsorption thiscompound should expose the cyclohexane group which should besufficiently hydrophobic. OHCHO was not only very soluble inwater (the highest among the oximes studied). but it fonnedsoluble cower chelates in mildly lK:id and neutral pH range. Theresults given in Figure 6 suggest its collector activity to increasewith increase in pH. but a very high concentration may berequired to achieve high flotation of chrysocolla.

sttuctural changes, however, made a negative conbibution to diecollector efficiency. Correlation existed between reduction inwater solubility of die oxime and increase in its collectorefficiency only for die homologous oximes.

Substitution of alkyl group on die oximic carbon ofsalicylaldoxime had die largest positive conbibution to thecollector efficiency which followed the order, o-hydroxybutyrophenone oxime> o-hydroxy acetophenone oxime »salicylaldoxime. Substitution of methoxy or medlyl in die5-position on die benzene ring in SAW and o-hydroxy~tophenone oxime, respectively, decreased die collectorefficiency. This fmding is contrary to expectations based onwater solubility and chelation of copper in solutions, and can berationalised at diis stage on die basis of steric hindrance tocomplexation and packing on chrysocolla. The medioxy group.in addition, may lead to a reduction in hydrophobicity because ofits more polar character. A fused aromatic ring (naphdialene forexample) instead of die benzene ring in SAW lowered diecollector efficiency drastically. Substitution of a phenyl group ondie oximic carbon in SAW lowered die collector efficiency atpH 4.8, but it also shifted die pH of optimum flotation to 12.Also, medlylation of phenolic group in SAW destroyed diecollector property as expected. Mediylation of die oxime group,on the oilier hand, merely lowered die collector efficiency. Thisis attributed to die negative contribution from steric factorsaffecting complexation and packing on mineral surface. Ahydroxyoxime group on a cyclohexane ring offered noadvantage. In fact dtis oxime had extremely poor collectorefficiency even at very high concentrations. This is attributed todie very high solubility of die copper chelate.

SUMMARY

Flotation behaviour of chrysocolla as a function of pH andconcenttation of several, sparingly soluble, sttucrorally-relatedhydroxyoximes is discussed. Substimtion in both the chelatingand non-chelating parts of the basic hydroxyoxime molecule. dtesalicylaldoxime (SAW), was considered.

Rotation of chrysocolla was optimum at pH-5 with most ofthe oxirnes. The major flotation effects observed in this smdy arereadily explained by examining dte changes in slrucmral fearoresof the oximes. Conttary to what might be expected. many

100

Q~~hf.;J'$l<>.

$ALO .OHBePO .OHNAO -.-OMeAPO ~-

OHAPOMeO OHCHO -.-

90

80~

>"-'f:k::

~(:)QL.s;SCt::~

~

0.0,-

m:~

R0~~

70 Condo time = 10 min.

Flat. time = 1 min.Condo pH = 4.860

~JS = 2 x .10 M KNO350

~o,<{,

~~;30

20-v-v

""""~--410..1- -~

01'0 6 \Q~ 0-4 ~~ .1 0-2 ~~.l

;y

INITIAL CONCENTRATION, MFKI S . F1«aaioo of chrysocolla as a functioo of ooncentralioo of oximea: SALO; OHBePO; OHNAO; OMeAPO; OHAroMeO; OHCHO.

XVIII International Mneral P~ssW1g Congress Sydney, 23 - 28 May 1993 S83

~'

00

90

80~ .'0:>-a:

guw'Q:;

aE~

~

eo

pO

40

~Q

20

0'0 '

3 ($", 9 J

CONDITIONING pHFK) 6 - Halation of chrysocolla as a function of pH with oximes: SALO; OHBePO; OHNAO; OMeAPO; OHAPOMeO; OHCHO.

ACKNOWLEDGEMENT

The authors acknowledge the fInancial suppon provided by theNational Science Foundation and the Engelhard Corporation forcarrying out this work.

F~rstenau, D W, Healy, T W and Scxnasundaran, P, 1964. The Role ofHydrocarboo Otain of Alkyl Collectors in Flotation, TralLf SME,229:321-325.

Fuerslenau, D W and Pradip, 1984. in Reagenls in Minerals Industry(Eds: Jones, M J, and Oblan, R), pp 161-168 (The Institution ofMining and Metallurgy:Londoo).

Gutuit, G, 1946. OJelate-Forming Organic CcxnlX>llllds as FlotationReagents, Trans AIME, 169:272.

Hohnan, B W, 1930. Flotation Reagents, Bull Inst Min Met, 315:53.Kienzniclci, T, Majewski and Mzyk, J, 1981. lilt J Miner Process,

7:311-318.Kohler, E P and Bruce, W F, 1931. The Oximes of Onho-Hydroxy

BenlDpitenone.J Am Chem Soc, 53:1569-1574.Laskowski, J, Fuerstenau, D W, Goowez, G and Urbina, R H 1985.

Studies on the Flotation of OJrysooolla in Miner ProceR Extr MetaURev, 2:135-155.

LOOt, R W and De Win, C C, 1949. The Flotatioo of Copper Silicate fromSilica. TralLf AlME, 184:49-51.

Marabini, A M and Rinelli, G, 1913. Flotation of Pitchblende widt aOJelaling Agent and Fuel Oil, Trans IlLft Min Metall, 82:C225-228.

Mukai, S and Wakamatsu, T, 1976. Sane Problems of Copper OxideMineral Flotation ~sented at SME-AIME Fall Meeting, Denver,Co, USA.

Naguaj, DR and Scxnaslmdaran, P, 1979.. in Recent DevelopIMnis inS~[»ratio/l ScU/IC~ (Ed: N, Ii), Vol V, CRC Press, Boca Raton, Fl,017.

Nagaraj, D R, and Somasundaran, P, 1919b. Trans SME, 266: 1892-1891.Naguaj, D R and Scxnasundaran, P, 1981. Mining E/lg, September, pp

1351-1357.

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XVllllntemational Minefal PlOC»Ssing Congress Syctley, 23.28 May 1993 5M

- Sydney. 23 - 28 May 1993 XVllllntemationat Mineral P~ssing Congress