Solvent extraction in copper metallurgy has been the first major application for producing nonferrous metals beyond the production of rare earths/nuclear metals. With the advent of solvent extrac-tion (SX), several lean grade, complex, rnultimetal and pocket deposits including

byproducts could be processed to produce copper economically. Though, the SX technology is proven internationally, it has yet to find an industrial application in the Indian context. This paper outlines the possibility of using solvent extraction in copper metallurgy particularly in the Indian scenario. Specific example of the processing of copper bleed stream has also been mentioned. Some of the details and the flowsheet

coven here shows how the sulphuric acid can be recov-ered from the copper bleed stream for recycling in the system. Besides, the recovery of copper and nickel in convenient form like metal sulphates and electrolytic grade metal

cathodes can be taken u

Agrawal, A

Kumar, Vinay

Pandey, B D

Premchand,

English

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S EM INAR... ON-' RE`C OVERY OFVALUAB LE BY-PRODUCTS,FROM INTERMEDIATE.SECONDARIES IN'.NON-FERROUS INbUSTRIES;c :C^I,I )1';N J1117^I1,1',l', YI',AL2 19960J' G/\N ISEU BYTHE INDIAN INSTITUTE OF METALSGHATSILA CHAPTERINDIAN COPPER COMPLEXHINDUSTAN COPPER LIMITED= 29th. Sept., 1996 Staff Club, Mosaboni Mines(-SEMINAR ON RVBIB 1SOLVENT EXTRACTION IN COPPER METALLURGYRECOVERY OF ACID AND METALS FROM COPPER BLEED STREAMArchana Agarwal , B D Pandcy, V Kumar and PremchandNora-Ferrous Process Division National Metallurgical Laboratory, Jamshedpur 831007.ABSTRACTSolvent extraction in copper metallurgy has beenthe first major application for producing non-ferrous metals beyond the production of rareearths/nuclear metals. With the advent of solventextrac-tion (SX), several lean grade, complex,rnultimetal and pocket deposits includingbyproducts could be processed to producecopper economically. Though, the SX technologyis proven internationally, it has yet to find anindustrial application in the Indian context. Thispaper outlines the possibility of using solventextraction in copper metallurgy particularly inthe Indian scenario. Specific example of theprocessing of copper bleed stream has also beenmentioned. Some of the details and the flowsheetcoven here shows how the sulphuric acid can berecov-ered from the copper bleed stream forrecycling in the system. Besides, the recoveryof copper and nickel in convenient form likemetal sulphates and electrolytic grade metalcathodes can be taken upINTRODUCTIONSolvent extraction is considered as the turningpoint in the history of copper metallurgy, whichresulted in the exploitation of oxidic ores thatwere considered unsuitable earlier for eco-nomicproduction. This was also applicable for leangrade sul-phidic ores which could be processedthrough purely hydrometal-lurgical routes. Theapprehension of economic viability of anycommon non-ferrous metal production, otherthan those of rare earths/nuclear metals, wasproved otherwise with the operation of firstsolvent extraction plant(I) for copper by the year1968. Since then more than 25 plants came in[2 11M Ghol silo Chapletto being using leaching-solvent extraction (SX}:'i`eleclrowinning (EW) route with a share of about15% copper metal produced world over through;this technolo-gy. The domain of the processapplicable in the copper metallurgy is widespread(2,3), startlnq from primary metal productionfrom different leach liquors, to recovery of thtmetal from various secondaries like dross,wires, rods, electronic components, boards etc,and even effluent treatment. It is interesting tonote that the metal of high purity (above 99.9%)could be direct-ly produced by SX-EW technologywhich is largely suitable for most of theapplications envisaged for the primary metal. Ithas also been possible to extract several othernon-ferrous metals on industrial scale in the lastthree decades.INDIAN SCENARIOIn our country, Hindustan Copper Ltd., operatestwo plants at Khetri and Ghatsila using thesmelting-refining technology. The basicingredients of the smelter come from theconcentrator plan(s , where the ore is enriched toa desired level. There are two more plants slatedto start production soon in the private sectorfrom the imported concentrates using the smeltingroute. The application of solvent extraction hasyet to start In our countrys' copper plants due tovarious reasons other than techno- logicalproblem,though there Is tremendous scope.Some of the possible applications of the solventextraction in copper indus-try may be inumeratedbelow:(i) Possibility of taping pocket deposits locallyby agitated tank / heap / dump/ bioleachingfollowed by SX-EW, without producingconcentrate of desired specificationsPage No3t')InL S,titii^^ ^^ ON RVDISparticularly with respect to grade and purity.(ii) Processing of lean grade and complex sulphideores scattered In the country as the recoveriesduring concentration may be poor andindividual concentrate production may not beviable. Under such conditions, pyro-hydro-metallurgical treatment followed by SX-EWcan be the ideal solution.-Recovery of copper from the processing ofmixed oxide - sulphide Malanjkhand depositby SX-EW route.-Processing of dirty ore /concentrate fromSikkim-Way out can be found for problems in theexisting plant at Ghatsila with respect toprocessing of certain Intermediates andbyproducts like converter slag, dump slag,anode slime for precious metal recovery,anode slag residue containing nickel andcopper etc.,-Recovery of sulphuric acid and copper andnickel metals from the copper tank housebleed solution by SX technology. This canavoid producing poor quality copper beinggenerated In the decopperisation step whichburdens the smelting/melting shop duringrecycling.R&D WORK AT NMLProcessing of copper bleed stream:At the instance of Indian Copper Complex,Ghatsila, a systematic R&D work was Initiatedto develop a suitable process to treat copperbleed stream. The aim of this study was to workout the details for recovery of acid, iron, nickeland copper in suitable form producing useful endproducts. It was also expected to be applicableunder the conditions projected for recovery ofthese metals from the liquor of nickel rich anodeslag residue. The literature search on thesubject shows that several solvent extractionprocesses were developed to recover the metalsn IIM GhoW!oChopterfrom copper bleed stream . Japanese researchersdeveloped (4,5) and implemented the SX andIon exchange based recovery systems in someplants . Similarly, several others from copperplants of western companies (6-8) have alsoapplied the SX technology for the puri1ose Itwas thus considered worthwhile to develop ascheme specially suitable in Indian context. Thetypical composition of the bleed solution was 40g/L Cu, 20 g/L Ni, I g/L Fe and 180 g/L.. I I ,SO4.The Initial experiments were carried out to ex-tract sulphuric acid by organic reagent viz thetertiary amine . These were Alamine 336, asolvent produced by M/s Henkel Corporation(USA) and Tri- isoorkyl amine (TIDA) diluted inKerosene 10% isodecanol (ID) was added as thethird phase modifier.The results of the acid extraction 110111 011aqueous feed containing 167.6 g/L sulphuricacid by 25* Alamine 336 at different orcianicto aqueous ratio (0/A) are given In Figure-1 ` It isapparent that 50% acid was extracted at O/A 2and 90% extraction at O/A 4 It also showsthe quantitative acid extraction in single contactat O/A 6. Figure - 2 shows the extraction ofsulphuric acid in different contacts at O/A 1 Dataclearly reveal the drop In acid content of aqueousfeed with the simultaneous extraction in Alamine336. In four contacts the acid left in the aqueousraffinate was found at 17 g/L.In order to see the rate of acid extraction, thekinetics experiments were also carried out andresults are shown In Figure-3. At O/A of unity,the kinetics was found to be very rapid andfavourable. In 30 seconds also, the acid extractionwas fairly high with no major effect on extractionby increasing the mixing time. The rapid rate ofacid transfer to the organic phase is thereforeideal for running any mixer-settler unit to achievethe ob)ecllve of acid recovery from suchaqueous solutions. Loading of Alamine 336 withsulphuric acid at two different phase ratios wasstudied for a contact time of 5 minutes andresults are depicted in Figure-4. In two contacts,maximum acid loading was observed at 0/A 4whereas five contacts resulted in maximumI! II'I''I III na^t^p^pmen^pn^^ill^f ^1 - ^ "°T"^v,,rr "^'[ n SEMINAR ON RVBIloading at O/A 8. These results are critical fromthe point of extracting and recovering acid sothat the condition can be implemented in acontinuous operating system.The kinetics of stripping of loaded acid from, the25% Alamine 336 Is shown in Figure-5. Data onstripping showed the requirement of about 2minutes at O/A 1 at room temperature whichis also suitable for a continuous extractor. Furtherstudies were carried out to strip the loaded acidfrom the solvents and results are listed in Table 1.Tnble - 1 Stripping of acid from the LoadedOrganicExtractionOrganic phaseAq. feedO/A-1 1- 5Stripping:25% Alamine 336/TIOA and10% isodecanol (ID) in Keroserie170.58 g/L HISO4min No of Contact - 1Acid loaded Alamines 336 =47.04 g/LAcid loaded In TIOA -49.08 g/LO/A -I t- 5 min Temp. 30° CSI Cont- Alamine 336 T10ANo act No ci Ac n- c AcidStripped Stripped Stripped(%) (g/L ) (%) (g/L)1 1 31.25 32 . 34 31.50 33.642 2 41.04 27.73 42 . 90 28.053 3 46 . 25 25 . 28 49 . 20 24.964 4 49 . 49 23 . 76 53 . 50 22.835 5 52 . 06 22 . 54 56 . 70 21.256 6 54 . 53 21.39 59 . 10 20.057 7 56 . 32 20 . 54 61.20 19.03The conditions for extraction and waterstripping with 25% Alamine 336 and 25%, TIOAare also given- The stripping at room temperature(30" C) in different contacts for Alamine showthat 56.32% acid was recovered with 20.54g/Lacid being still attached to the solvent in sevencontacts. Acid recovered by water stripping ofn IIMGhoI flcCnnplorthe acid from TIOA was 61.2% with 19.03 g/Lacid left in the solvent due to equilibrium effect.As some amount of acid remained attached withthe solvent, It was considered worthwhile toexamine the recycling characteristic of theregenerated solvent. The results given in Table.2clearly Indicate that the loading of acid in Alamine336 as well as in TIOA in 4 cycles was almost thesame, the acid extraction being slightly higherfor the latter. Thus, two solvents can be usedconveniently to recover acid and recycle the samein the plant if desired.Table- 2 :Recycling of the regenerated solvent(Alamine 336/TIOA)Extraction :-Loading : 25% TIOA/Almamine 336I and 10% ID in KeroseneAq. feed 176.4 g /L H,SO4O/A-1 t- 5 min No of Contact - 1StrippingO/A -1 t- 5 min No of Contacts - 4Recycle T10A Alamine 336Acid Aci d In Aci d ci dloaded regenerated Loaded re-g(neraterl(g/I) Solvant (g/L) (g/l) solvent (g,Cycle 1 50.96 24.38 47.04 23.76Cycle 2 53.78 26.85 53.16 29.25Cycle 3 55.27 28.10 56.69 27.48Cycle 4 56.52 29.66 52.96 25.58As regards extraction and separation of Iron,copper and nickel from the raffinate obtained inacid extraction, the iron may be first precipitatedout at 3.5 '- 4 pH by neutralisation and aeration.The studies on copper extraction from acidicsolution by partially saponified Napthenic acid(sodium salt) were carried out and results aregiven in Table 3.1'nkc Nn 38UU SEMINAR ON RVBISTable- 3Extrc:ctfon of Copper By Naphthenlc Acidof Different pHAq. feed :4.86 g/L CuOrg Phase. : 25% Naphthenic Acid, 101AID Kerosene.0/A=1 t. 10 min No of Contact = 1SI No Cu Loaded Loading!ruUa -Equi^Ifbrfu n q/L (%j1 3.8 2.6 0 . 09 1852 3.8 3. 0 0.87 17903 3.3 3.15 2.73 56.174 3.3 38 3.89 80145 3.8 4, 0 43.48 92.18It thus shows the possibility of copperextraction without major nickel loading underthe conditions optimised. The nickel could thenbe extracted at still higher pH. The pregnantsolutions of copper and nickel sulphates couldbe used to produce the respective metals byelect rowinning or metal sulphate crystals asdesired by conventional technology. Anindigenous solvent viz. di-2ethyl hexylphosphoric acid (D2EHPA) now available wasalso found quite suitable for recovery of copperand nickel as discussed above. The bench scaleand continuous facilities on large scaleavailable at the NML can be used to test theprocess described earlier. A flowsheet is given InFigure-6 which shows the scheme for separationand recovery of acid and metals in respect ofprocessing copper bleed stream. The scheme canalso be applicable for treating the sulphatesolution of nickel rich anode slag residue.CONCLUSIONThe solvent extraction-electrowinning - a stateof the art technology opens up the possibilityof exploiting several low grade complex andpocket deposits in our country which may notrequire the concentration plant or the bulkconcentrate can be treated. Even the dirtyconcentrates like those produced in Sikkim and11 11M GholsuoChoptermixed oxide-sulphide ore that is available atMalanjkhand can be processed on the site byfollowing suitable leaching approach lollowedby SX-EW route. Though, It Is a thirty years oldtechnology world over, India has yet to start anduse the vast experience gained In the field at thenational laboratories to utilise the approachwherever it is possible . Some of the existingproblems of the Hindustan Copper Limited canbe directed towards this end. One such examplediscussed in the text shows how efficiently theacid, nickel and copper can be recovered in thedesired form by processing copper tank bleedstream and leach liquor of anode slag residueThough data generated showed prnntise, somemore experiments on bench and large scalesneed to be carried out to test the schemedeveloped.ACKNOWLEDGEMENTAuthors are thankful to the Director, NationalMetallurgical Laboratory, Jamshedpur for givingpermission to publish the paper.REFERENCES:1. Power, K.L., Operation of the first commercialliquid Ion -exchange arid electrowinningplant, Proc. Int. Sol. Ext. Conf.(ISEC'71),held at Hague, 19-23 April, 1991, pp 14091415.2. Rltcey , GM. and Ashbrook, A.W., SolventExtraction in Process Metallurgy , Part 11,Elsevier Science Publishers , Netherlands,1984.3. 1.o, T.C., [laird, M . 11.1, arid Hanson,C.,1 fandbook of Solvent Extraction, JohnWiley and Sons , New York. .• t'a} c N.,:?^[ n SEt+I1NAR ON RVI3I34. Shihayama, R. and Nagal, T., OnApplication of Solvent Extraction andChelatiny ion-exchange resin for purificationof copper electrolytes, Solvent Extraction1990, part B. Ed. T. Sekine, ElsevierScientific Publishers B.V., Netherlands 1992,pp. 1193- 1198.5. Nagai. T., Yama Zaki. N. and Kobayashi, M.,Purification of Copper electrolytes by solventextraction, Proc. Symp. in Fall Meeting(Muroran) MMIJ, L-1, 1976, pp 1-4.7. Abishev, D N and Stryapkov, A.V.,ExtraclionProcessing of conlaminaated copperelectrolyte, Proc. ISEC '88, Volume IV, heldat Moscow, July 18-24, 1988, pp. 305-307.8. De Schepper , A., Extraction of arsenicfrom copper electrolytes by solventextraction, paper presented at Meeting, Soc.Chem . Ind. (London ), 1979; also in DeSchepper , A., MHO Solvent ExtractionProcess for removal of arsenic from OlenCopper tankhouse bleed . InExtractionMetallurgy '85", 1985 , pii. 951-965.6. F3uttinelli, I). Glavarini, C. and Mercauti, A.,Pilot plant Investigation on H2S01 extractionby alcohols from spent electrolytes, Proc.ISEC 83, held at Denver, U.S.A., August 26-Sept. 2, 1983, p. 422-425.FIGURE I EFFECT OF 0/A VARIATION ON SULPHURIC ACID EXTRACTIONBY ALAMINE 3361 008oAq Feed = 167 . 6 g/L H; SO,ORG. PHASE = 25% ALAMINE,10% ID IN KEROSENENO OF QONTACf' S - 1 ; TIME - 15 MINT--]2 ACZ>/A F T I C> #mo'I f18 10I n IIMGhohlInCnapter n I',^^c Nn 40M SEMINAR ON RVBIBFIGURE 2 SULPHURIC ACID EXTRACTION BY ALAMINE 336 FROM COPPER BLEEDSTREAM20015010001 2 9 4 sNO c 1 CONTACTS ^^FIGURE 3 KINETICS OF ACID EXTRACTION BY ALAMINE 33649Ih*30Aq. FEED - 167.6 g/L 11,SO^ORG. PHASE- 25 % ALAMINE_AND 10 % ID IN KEROSENEO/A - I NO OF CONTACT S- I1rff--T-710 202 4 eTIME (MuN) --r-^-n IIMGholslloChopter J ra fake No 41" R1hIR1^R^"^ 1T411rA m•,.n nr w^lw^ws^n s wow lI n SEMINAR ON RVBISFIG 4 : LOADING OF H2SO4 IN ALAMINE 336 AT DIFFERENT PHASE RATIOSmAq. FEED = 170.5 g/L H2 S04ORG. PHASE= 25 3i ALAMINE10 %%, ID IN KEROSENE00/A- 4; AO/A- 8 TIME-5 MINa a 4 a 6Nc c i CONTi,^ rFIG 5 : EFFECT OF TIME ON ACID STRIPPING FROM THE LOADED ALAMINE 336oRG. PHASE - 25'K%ALAMINEAND 10 % ID IN KEROSENE(42.14 g /LHJSO,)0/A = 1 NO OF CONTACT= 11I I T T -F-t4-71 z s 4 a e 7 s 9 io 20TIME (MIN.) 11111110-N IIMGholsnoChopier I n 1'agc No 42n SEMINAR ON RVDIB 7 1iORGANIC SOLVENT(O1)ICRYSTALN.iACID STRIPH,SO, FORRECYCLEL_C u SO4CRYSTALSitCu-EWACID EXTRACTIONCu- BILEED SYSTEMpH ADJUSTMENTORGANIC SOLVENT(O,)Cu- EXTRACTIONCu-STRIPNI-EXTRACTIONINi-STRIPCu METALCRYSTALN.NISO4CRYSTALNi-EWNI-METALORGANIC SOLVENT (O,)FIG.6 SCIIEME FOR RECOVERY OF ACID, Cu AND Ni FROM COPPER BLEED STREAM.n 11Mc;hafsuc ,cr,oprd^ ^n 11' R, Nu 113I!' I II "Plot mMln^^ .^ _,* ' '^^^^ ^^ `^^ ^ ^I^IAPmutliny^aMRI1^RlnIRNN

Solvent extraction in copper metallurgy recovery of acid and metals from copper bleed stream

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Solvent extraction in copper metallurgy recovery of acid and metals from copper bleed stream

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