THE SUCCESSFUL COMMERCIAL IMPLEMENTATION OF THE COMBINED LEACH ION EXCHANGE SOLVENT EXTRACTION - ELECTROWINNING PROCESS AT THE BUCIM COPPER PROJECT

Transcription

1 THE SUCCESSFUL COMMERCIAL IMPLEMENTATION OF THE COMBINED LEACH ION EXCHANGE SOLVENT EXTRACTION - ELECTROWINNING PROCESS AT THE BUCIM COPPER PROJECT By 1 Tdr Angelv, 1 Gergi Savv, 1 Aleksander Tsekv and 2 Ivan Nishkv 1 Intech 2000 JSC, Bulgaria 2 University f Mining and Gelgy St. Ivan Rilski, Bulgaria Presenter and Crrespnding Authr Tdr Angelv tdr_ang@abv.bg ABSTRACT Bucim Cpper Prject is situated near the village f Bucim and in the suth brders f Plachkvitsa Muntain in the Republic f Macednia. Territrially and administratively the Prject belngs t the municipality f Radvis. It is 95 kilmeters away frm the Skpje capital, and 170 kilmeters frm the nearest prt Thessalniki (Republic f Greece) at an altitude f 620 m abve sea level. Cmmissined in January 2012 and reached steady cpper prductin in August 2012, Bucim Cpper Prject, became the first cmmercial peratin using cmbined Intech s hydrmetallurgical prcess t treat lw grade and higher grade xide cpper res and t prduce LME grade cpper cathdes. The Intech s Leach-In Exchange Slvent Extractin- Electrwinning prcess cmbines in exchange and slvent extractin t extract and cncentrate the cpper frm pregnant leach slutin, befre the final prduct - cpper cathdes is btained by electrwining. The prcess is suitable fr recvery f cpper frm PLS with metal cncentratins, varying n a brad range as well as fr treatment f slutins in the decmmissining f spent cpper heaps and dumps, acid mine drainage /AMD/ аnd ammniacal etch slutins. Furthermre, cmbining the in exchange and slvent extractin allws (1) winter peratin withut trubles - slvent extractin wrk prperly i.e. with gd phase disengagement times, even at lw temperatures (this is due t high temperatures f in exchange regenerate used as a slvent extractin feed), (2) strngly reduces rganic lsses and crud frmatin, (3) cntrl f metal/acid rati, which is very imprtant fr slvent extractin prcess and (4) lead t slvent extractin plant sizes reductin. In rder t imprve the whle plant perfrmance, t expand the prductin capacity and t prvide prper management f the excess drainage waters in 2014 was decided t expand the Bucim Cpper Prject. The expansin will be cmpleted in 2015, with the cmmissining f newly cnstructed leach fields, the expanded in exchange circuit as well as with ttal replacement f extractant riginally used in slvent extractin circuit. This paper highlights the successful implementatin f Cmbined Leach-In Exchange Slvent Extractin-Electrwinning prcess at the Bucim Cpper Prject, while prviding the riginal peratins descriptin as well as the changes and additins within the plant, which will lead t imprved verall perfrmance. 1

2 INTRODUCTION Bucim Cpper Prject started t perate in January 2012 at the Bucim Mine Site in the Republic f Macednia by applying cmbined Intech s hydrmetallurgical prcess with heap leaching, in exchange, slvent extractin and electrwinning at a small scale f 2400 tns f cpper cathdes per year. The cmbined Intech s Leach-In Exchange Slvent Extractin- Electrwinning (ION/L- IX-SX-EW) prcess was selected as the best available technlgy fr the site nt nly due t the fact that the final prduct is with extremely high quality, but als due t its ability t achieve the stringent envirnmental demands. Based n a successful start up, despite the extended cmmissining, related largely t mechanical issues, a decisin t expand prductin t a rate f 3000 tns f cpper cathde per year was taken in the The Bucim Cpper Prject cmprises a leach peratins fr treatment f xide cpper re, tgether with assciated in exchange, slvent extractin, and electrwinning circuits t separate and recver cpper disslved frm the res. New develpments, changes and additins t a number f the riginal peratins like new leach fields cnstructin, in exchange circuit expansin and SX reagent replacement has led t prject recvery and availability levels rutinely abve 95%. IONTECH/ LEACH-ION EXCHANGE-SOLVENT EXTRACTION-ELECTROWINNING (ION/L-IX-SX-EW) PROCESS Develpment Hystry Intech began develping the cmbined prcess in 2002, with the main purpse f develping a new hydrmetallurgical prcess t recver cpper frm cpper pregnant leach slutins. The successful results f the initial bench scale tests initiated the design and cnstructin f a fully integrated pilt plant at the Tzar Asen Cpper Prject /TACP/, with prductin capability f 960 tpy (r 2.6 tpd) f cpper cathde. The TACP is lcated adjacent t the mining village f Tzar Asen in Bulgaria s central parts at an elevatin f abut 300 m abve sea level, apprximately 120 km sutheast f Sfia, the cuntry s capital city. The TACP invlves treatment f the PLS stream, riginating frm the dump leach peratin with the in exchange facility fr cpper extractin and cncentratin, and the subsequent recvery f the cpper as a high purity cathde prduct by slvent extractin and electrwinning, t prduce sheets f 99.99%-pure cpper cathdes (1). Operatins f the TACP pilt plant cnfirmed the metallurgy f the ION/L-IX-SX-EW prcess and gave enugh engineering, design and peratinal data t minimize the scale-up risk in rder t implement the cmbined prcess in fully cmmercial peratins fr cpper recvery (2). Prcess Descriptin The ION/L-IX-SX-EW prcess is very succesful in the recvery f cpper frm different cpper cntaining slutins. Figure 1 depicts the verall prcess. As the name suggests the prcess invlves fur majr stages: Leaching - the prcess by which cpper is remved frm the re using chemical agents called lixiviants, mstly sulfuric acid slutin. When lixiviant slutin is applied t the re, it disslves the present cpper t prduce a pregnant leach slutin(pls); In Exchange - the prcessin which the cpper cntaining PLS is passed trugh the resin laid in the clumns and cpper is adsrbed n the resin. The clumn is then regenerated with sulfuric acid slutin t btain highly purified cpper slutin, suitable fr the further treatment via slvent extractin prcess; Slvent Extractin the prcess in which an rganic extractant that binds cpper but nt impurity metals is disslved in an rganic slvent (diluent) and is mixed with the cpper cntaining aqueus slutin. The cpper-laded rganic slutin is separated frm the aqueus slutin in a settler tank. The barren aqueus slutin, called raffinate is sent back 2

3 t the leaching. Sulfuric acid slutin, mstly spent electrlyte returned frm the EW tankhuse is then added t the laded rganic mixture, which strips the cpper int an electrlytic slutin ready fr electrwinning; Electrwinning - the prcess by which cpper ins within strng electrlyte slutin, prduced in SX prcess are plated nt the cathde t prduce cpper sheets with % purity. Figure 1: ION/L-IX-SX-EW Prcess basic flwsheet Key Findings The key findings f the ION/L-IX-SX-EW prcess are: 1. The Prcess is suitable fr recvery f cpper frm slutins with metal cncentratins, varying n a brad range; 3

4 2. The Prcess is capable t perate effectively with very lw-graded cpper-bearing slutins. This results in prlnged prjects life, cmpare t slvent extractin recvery nly; 3. The cnstructin f large pnds fr pre-filtratin f the PLS is nt necessary. In this case, very sensitive slvent extractin prcess can be wrk prperly even at intensive rainfalls and with turbid slutins and slutins cntaining large quantities f suspended slids; 4. Winter peratin withut trubles. SX can be wrk prperly i.e. with gd phase disengagement times, even at lw temperatures. This is due t high temperatures f IX regenerate used as a SX feed; 5. Cmbining f in exchange and slvent extractin strngly reduces rganic lsses and crud frmatin; 6. Integratin f the IX prcess in SXEW scheme can be used fr cntrl f metal/acid rati as well as Cu/Fe rati, which are very imprtant fr SX prcess; 7. Cmbining f in exchange and slvent extractin reduces EW rganic prblems and thence imprved cpper cathdes quality; 8. In Exchange - Slvent Extractin - Electrwinning technlgical apprach lead t SX plant sizes reducing. Thus, minimizes the flr space requirements fr SX ftprint ; 9. The IX-SX cmbinatin is characterized with similar capital cst and lwer perating cst cmpare t slvent extractin prcess nly; 10. The Prcess generates n effluents and minimal emissins; 11. The Prcess ffers shrt cnstructin times. Pssible Applicatins The bjective f the ION/L-IX-SX-EW prcess develpment was t prvide an ecnmically attractive and envirnmental friendly alternative fr cpper recvery frm different prcess streams in rder t prduce high quality final prduct. The ION/L-IX-SX-EW prcess: is capple t treating variety f pregnant leach slutins riginating frm: dump leach peratins heap leach peratins agitatin leach peratins vat leach peratins allws the ecnmic treatment f lw-grade cpper cntaining streams like: slutins frm the decmmissining f spent cpper dumps and heaps acid mine drainage (AMD) ther cntaminated waters and prcess streams COMMERCIAL IMPLEMENTATION OF IONTECH/ LEACH - ION EXCHANGE - SOLVENT EXTRACTION - ELECTROWINNING (ION/L-IX-SX-EW) PROCESS The Intech/Leach-In Exchange-Slvent Extractin-Electrwinning (ION/L-IX-SX-EW) Prcess has been under develpment fr ver 9 years. In the late 2010 the cnstructin f an industrial 4

5 scale plant, with start-up scheduled fr early 2012, began at the Bucim mine site in the Republic f Macednia. This was the beginning f the Bucim Cpper Prject - the first peratin cmmercially using the ION/L-IX-SX-EW Prcess. The Bucim Cpper Prject is situated near the village f Bucim and in the suth brders f Plachkvitsa Muntain, in Republic f Macednia. Dminating tp in the immediate surrunding is Versnik, n 720 meters abve the sea level, while 620 meters is the average abve the sea altitude f the re depsit (3). Figure 2: Bucim Cpper Prject Lcatin Bucim Cpper Prject territrially and administratively belngs t the municipality f Radvis. It is 95 kilmeters away frm the Skpje capital, and 170 kilmeters frm the nearest prt Thessalniki (Republic f Greece). Cpper prductin at the Bucim Cpper Prject started at a level f 2400 tns f cpper cathdes per year, treating xide re t recver cpper and t prduce LME grade cpper cathdes.the dwnstream prcessing f the cpper-rich slutins, prduced by the leach prcess includes in exchange and slvent extractin circuits t extract and cncentrate the cpper, befre the final prduct-cpper cathdes is btained by electrwining. The prject includes heap leach facilities with separate pregnant leach slutin pnds, events pnd, sediment cntrl pnds, cpper recvery plant, rads, man camp, and miscellaneus facilities t supprt the main peratins. The Bucim Cpper Prject has been successful in achieving its prductin gal, btaining high quality cathdes since start up. Hwever, after twelve mnths f peratin was desided t increase its prductin t 3000 tns f cpper cathdes per year by the cmmissining f new leach fields and the in exchange circuit expansin. Bucim Cpper Prject Original Operatins The Buchim Cpper Prject includes the fllwing peratins: Heap Leaching, In Exchange, Slvent Extractin and Electrwining (4). The prcess flwsheet is shwn in Figure 3. The piping netwrk fr heap leaching cmprises main lines at grund level and heap supply header pipes alng the heaps, which distribute slutin ver the surface thrugh a series f dripper lines. All piping netwrks are HDPE thrughut, and are installed manually using special equipment.in the leaching peratin the barren slutin frm the in exchange facility ( filtrate ) and slvent extractin plant ( raffinate ) which has a high acid cncentratin is applied t the surface f the dump at rates f eight litters per square meter each hur. Pregnant leach slutin (PLS) frms as the slutin perclates thrugh the pile and disslves cpper minerals int the aqueus slutin as cpper sulphate. The PLS flws dwn thrugh the entire heap until it reaches the drainage layer where it enters the lined PLS pnd. A highly permeable material separates the tw liners and leak, if detected is remved by a pump. Cntrl-emergency pnd, designed t accmmdate the excess flw frm leaching and the runff frm majr strms is als cnstructed at the site. 5

6 Figure 3: Bucim Cpper Prject flwsheet Frm the PLS pnds, slutins are directed t IX facility with a design feed flw rate f apprximately 650 m 3 /h. The facility cnsists f 8 in exchange clumns - 4 IONTIX units (Intech Design) (5). The btained IX regenerant is pumped t plant feed pnd, where it is mixed with pregnant leach slutin frm the leach peratin. Feed slutin frm the plant feed pnd flws int a cnventinally designed slvent extractin plant (SX) at arund 30 m 3 /h. The SX plant using a 3E x 2S cnfiguratin, with cnventinal flw design. The feed is depleted f cpper and returned t leaching as a raffinate slutin alng with the filtrate frm IX facility, thus frming a very envirnmentally respnsible prcess by nt allwing any discharge int the envirnment. The use f a selective cpper extractant (LIX 84-I), which perates in a clsed circuit inside the plant, allws the cpper t be transferred t an electrlyte perating in a clsed circuit with the electrwinning plant. The cpper is captured frm the strng electrlyte in the electrwinning plant. The electrwinning prcess uses a cmmn design. Cells are cnnected in series t a current transfrmer rectifier with hydraulic feeding f electrlyte t cells cnnected in parallel. Scavenger cells are nt included. The peratin uses stainless steel permanent cathdes and Pb/Ca/Sn ally andes, assembled in cmbinatins f 25 and 26 units per cell, respectively, cntained in a ttal f 24 cells. The cathdes are remved frm the cells and transprted fr manually stripping by hammer and chisel in rder t separate the depsited cpper frm the mther plate. The cpper cathdes with % purity are weighed and banded and the mther plates are rinsed and returned t the cells fr the next lading cycle. The main peratinal parameters are summarized in Table 1. Table 1: Bucim Cpper Prject riginal peratinal parameters Leaching Applicatin Rate - 8 l/h/ m 2 PLS Flwrate 650 m 3 /h PLS Cpper Grade g/l Cu IX resin 64 m 3 (H + frm); Lewatit TP 207 M+ SX feed 28 m 3 /h; 7-8 g/l Cu, g/l H + Organic 45 m 3 /h; 20 v/v% LIX 84-I diluted in ShellSl D100 Lean Electrlyte 22,5 m 3 /h, 37 g/l Cu,175 g/l H + Strng Electrlyte 110 m 3 /h, 49 g/l Cu,160 g/l H + Electrwinning Permanent cathdes, 280A/ m 2, 24 cells, 92%Current efficiency Prduct Quality LME (High Purity Grade) Cpper 6

7 Bucim Cpper Prject New Develpments After apprximately tw years f successful leaching peratins, in the secnd quarter f 2014 the pregnant leach slutin chemistry has changed dramatically - slutin cpper grade decreased (frm g/l t belw 0.3 g/l) and acidity inreased. In rder t imprve the verall perfrmance f leaching peratins and t increase cpper grade in pregnant leach slutins new leach fields at the xide heap leach are designed, cnstructed and cmmissined in the middle f 2014 with ttal area fr leach f m 2. Mrever, an rderly leach management plan, which includes prperly, designed applicatin perids fllwed by rest perids, during which aeratin and xidatin f cpper minerals will cntinue and applicatin rates are develped and enfrced. Cmpliance with the plan has lead t the restratin f cpper grade and the ph f slutin t the ptimal levels g/l Cu and ph In Nvember 2014 Bucim Cpper Prject imprved its in exchange peratin at plant scale by applying tw new in exchange clums, within the existing in exchange facility. The new in exchange clumns have the same design and bigger size as the riginal nes. In the meanwhile new flw cnfiguratin fr maintaining the ptimal pressure lss in the clumns and t give mre flexibility t treat feed slutins with variable cpper cncentratins was applied successfully at the in exchange facility. The riginal flw cnfiguratin was kept. The new flw cnfiguratin differs frm the riginal flw cnfiguratin, as the exiting the first clumn slutin enters the tp, instead f the bttm f the secnd clumn. As a result apprximately 25 percent in the cpper prductin rate was reached. The slvent extractin plant started t perate with ketxime reagent LIX 84-I. Fr the purpse f make up nly this reagent had been used in its standard versin LIX 84-I. In 2013 a slvent extractin reagent called Acrga M5640 was successfully tested and the replacement f LIX 84-I reagent inventry gradually thrugh make up quantities f Acrga M5640 was decided in the middle f In Octber 2013 Bucim started t use Acrga M5640 as make up reagent t the slvent extractin plant. The main characteristics f the new reagent are increased reagent stability, higher rganic lading as % f maximum lad and imprved cpper net transfer. The cnversin f the Bucim Cpper Prject plant rganic frm a ketxime LIX 84-I reagent t a strng ester-mdified aldxime Acrga M5640 reagent, has directly resulted in significant imprvement in the verall perfrmance f the slvent extractin circuit as well as in the plant rganic health. The main peratinal parameters after new develpments at the Bucim Cpper Prject are summarized in Table 2. Table 2: Bucim Cpper Prject new develpments peratinal parameters Leaching Ttal area fr leach m 2 Applicatin Rate 8-10 l/h/ m 2 PLS Flwrate 650 m 3 /h PLS Cpper Grade 0.7 g/l Cu IX resin 84 m 3 (H + frm); Lewatit TP 207 M+ SX feed 42 m 3 /h; 8-10 g/l Cu, 15 g/l H + Organic 46 m 3 /h; 21 v/v% Acrga M5640 diluted in ShellSl D100 Lean Electrlyte 25 m 3 /h, 35 g/l Cu, 180 g/l H + Strng Electrlyte 110 m 3 /h, 50 g/l Cu, 160 g/l H + Electrwinning Permanent cathdes,300 A/ m 2, 24 cells, 92% Current efficiency Prduct Quality LME (High Purity Grade) Cpper 7

8 CONCLUSIONS Successful cmmercial peratins at the Bucim Cpper Prject using Intech/Leach-In Exchange- Slvent Extractin-Electrwinning (ION/L-IX-SX-EW) prcess have shwn that cpper can be recvered selectively int saleable high-grade prduct frm lw grade leach slutins and that n effluents are prduced fr envirnmental discharge, because all streams are returned t the site where they riginated, namely the heap. In general the Buchim Cpper Prject prvides a valuable case study in all aspects f plant peratins fr future implementatins f this type f technlgy. There are a number f cpper depsits wrldwide that are amenable t treatment by this type f circuit and the lessns learnt will be valuable in eliminating sme f the issues that will be fact f life during the design, cmmissining and peratin. ACKNOWLEDGMENTS The authrs wuld like t thank the staff and management f the Bucim Cpper Cmpany fr their cllabratin and prvisin f data t prepare this paper. The views f the authrs d nt necessarily present thse f the Cmpany. REFERENCES 1. Tsekv V., Savv G., Kanev V., Garvanv T., Angelv T., Kvacheva-Ninva V., Prductin f Cpper Cathde by Leaching-SX/EW Methd in Tzar Asen, Prc. f X th Balkan Mineral Prcessing Cngress, Varna, Bulgaria, , Tsekv V., Savv G., Angelv T., Kvacheva-Ninva V., Practical Aspects f Ecnmically Prven Cpper Cathde Prductin by In Exchange Technlgies, Prc. f XI th Balkan Mineral Prcessing Cngress, Durres, Albania, , Tabakv B., Feasibility Assessment and Develpment f a main Technical Design fr Water Prtectin Measures, Bucim Mine (Minicipality f Radvis), Draft Reprt, UNDP, Savv G., Angelv T., Tsekv V., Grigrva I., Nishkv I., Heap and Dump Leach Prcess at the Buchim Cper Prject Metallurgical Testwrk, Prc. f XXII Wrld Mining Cngress, Vl. II, Istanbul, Turkey, , Savv G., Angelv T., Tsekv V., Nishkv I., Develpment and Applicatins f Intech In Exchange (Intix) Prcess, Prc. f XXII Wrld Mining Cngress, Vl. II, Istanbul, Turkey, ,