Novel redesign of a pressure leach autoclave by a South African platinum producer

Transcription

1 Univesity of Wollongong Resech Online Fculty of Engineeing nd Infomtion Sciences - Ppes: Pt A Fculty of Engineeing nd Infomtion Sciences 2009 Novel edesign of pessue lech utoclve by South Aficn pltinum poduce Joseph O. Roux Impl Pltinum Limited Mdeleine du Toit Univesity of Wollongong, mdt@uow.edu.u Dvid Shklz Engineeing Systems, South Afic Publiction Detils Roux, J. O., Du Toit, M. & Shklz, D. (2009). Novel edesign of pessue lech utoclve by South Aficn pltinum poduce. Jounl of the South Aficn Institute of Mining nd Metllugy, Resech Online is the open ccess institutionl epositoy fo the Univesity of Wollongong. Fo futhe infomtion contct the UOW Liby: esech-pubs@uow.edu.u

2 Novel edesign of pessue lech utoclve by South Aficn pltinum poduce Abstct The Impl Pltinum Limited Bse Metls Refiney in Spings, South Afic, efines conveto mtte contining bse metls nd PGM's (pltinum goup metls) using hydometllugicl pocess. In ddition to PGM-ich concentte tht is futhe efined, the Bse Metls Refiney poduces nickel (in powde o biquette fom), coppe cthodes nd coblt powde. Five leching stges e utilized to emove the bse metls nd impuities fom the PGM concentte. The poject descibed in this ppe involves dicl edesign of the second stge lech utoclve with the im of educing mintennce costs nd downtime, incesing thoughput nd ensuing sfe woking envionment. The second stge lech pocess t the Bse Metls Refiney, poduces PGM-ich esidue though the extction of coppe nd ny emining bse metls fom the fist stge lech solid esidue mteil. Leching is pefomed in n utoclve opeting t pessue of 600 kpg nd tempetue of 140 C to 150 C. Concentted H 2 SO 4 is dded to the feed to poduce solution with fee cid content between 10 nd 30 g/ L nd ph of less thn 2. Oxygen is pssed into the 1st nd 2nd comptments of the utoclve. As esult of the ggessive, highly oxidizing conditions within the utoclve, the oiginl design utilized hevy wll cbon steel shell with led lining nd two lyes of cid bicks. The bicks cted s we esistnt mteil nd ensued low sufce tempetue t the skin of the led lining, whees the led lining cted s coosion bie to potect the steel shell. These bick lined utoclves wee hevy, mintennce intensive nd pone to ctstophic filue. A dicl utoclve edesign ws needed to educe the high costs of mnufctuing, instlltion nd opetion. Finite element modelling ws used to optimize the design nd vious high lloy mteils wee investigted fo the ppliction. Bsed on extensive test wok, the cbon steel shell ws eplced with duplex SAF 2205 stinless steel in the new design. The use of this highly coosion esistnt mteil, elimintes the need fo the led nd bick linings nd educes the wll thickness equiements substntilly, esulting in n incese in the vilble volume fo the sme extenl shell dimensions. The vessel is welded in cicul sections to fom n elongted, impemeble, cylindicl body, with sevel gitto nozzles nd comptments. The fist new duplex stinless steel unit hs been in continuous opetion fo moe thn 24 months nd its pefomnce hs exceeded the highest expecttions. The design ws so successful tht ptent hs been egisteed. The mjo benefits of the new stinless steel design include incesed thoughput, impoved pefomnce, less downtime nd sfe woking envionment. Led hs been eliminted nd eplced with moe envionmentlly sfe mteil, nd the totl lifespn of the vessel hs been extended. In ddition, the utoclve poject hs mde significnt developments in dvncing the field of welding nd optimizing the integity of welding qulity stndds in South Afic. Keywods pltinum, ficn, south, utoclve, pessue, poduce, lech, novel, edesign Disciplines Engineeing Science nd Technology Studies This jounl ticle is vilble t Resech Online:

3 Publiction Detils Roux, J. O., Du Toit, M. & Shklz, D. (2009). Novel edesign of pessue lech utoclve by South Aficn pltinum poduce. Jounl of the South Aficn Institute of Mining nd Metllugy, This jounl ticle is vilble t Resech Online:

4 Novel edesign of pessue lech utoclve by South Aficn Pltinum poduce by J.O. Roux*, M. du Toit, nd D. Shklz J o u n l Synopsis The Impl Pltinum Limited Bse Metls Refiney in Spings, South Afic, efines conveto mtte contining bse metls nd PGM s (pltinum goup metls) using hydometllugicl pocess. In ddition to PGM-ich concentte tht is futhe efined, the Bse Metls Refiney poduces nickel (in powde o biquette fom), coppe cthodes nd coblt powde. Five leching stges e utilized to emove the bse metls nd impuities fom the PGM concentte. The poject descibed in this ppe involves dicl edesign of the second stge lech utoclve with the im of educing mintennce costs nd downtime, incesing thoughput nd ensuing sfe woking envionment. The second stge lech pocess t the Bse Metls Refiney, poduces PGM-ich esidue though the extction of coppe nd ny emining bse metls fom the fist stge lech solid esidue mteil. Leching is pefomed in n utoclve opeting t pessue of 600 kpg nd tempetue of 140 C to 150 C. Concentted H 2 SO 4 is dded to the feed to poduce solution with fee cid content between 10 nd 30 g/l nd ph of less thn 2. Oxygen is pssed into the 1st nd 2nd comptments of the utoclve. As esult of the ggessive, highly oxidizing conditions within the utoclve, the oiginl design utilized hevy wll cbon steel shell with led lining nd two lyes of cid bicks. The bicks cted s we esistnt mteil nd ensued low sufce tempetue t the skin of the led lining, whees the led lining cted s coosion bie to potect the steel shell. These bick lined utoclves wee hevy, mintennce intensive nd pone to ctstophic filue. A dicl utoclve edesign ws needed to educe the high costs of mnufctuing, instlltion nd opetion. Finite element modelling ws used to optimize the design nd vious high lloy mteils wee investigted fo the ppliction. Bsed on extensive test wok, the cbon steel shell ws eplced with duplex SAF 2205 stinless steel in the new design. The use of this highly coosion esistnt mteil, elimintes the need fo the led nd bick linings nd educes the wll thickness equiements substntilly, esulting in n incese in the vilble volume fo the sme extenl shell dimensions. The vessel is welded in cicul sections to fom n elongted, impemeble, cylindicl body, with sevel gitto nozzles nd comptments. The fist new duplex stinless steel unit hs been in continuous opetion fo moe thn 24 months nd its pefomnce hs exceeded the highest expecttions. The design ws so successful tht ptent hs been egisteed. The mjo benefits of the new stinless steel design include incesed thoughput, impoved pefomnce, less downtime nd sfe woking envionment. Led hs been eliminted nd eplced with moe envionmentlly sfe mteil, nd the totl lifespn of the vessel hs been extended. In ddition, the utoclve poject hs mde significnt developments in dvncing the field of welding nd optimizing the integity of welding qulity stndds in South Afic. Intoduction Bckgound The Impl Pltinum Limited bse metls efiney in Spings pocesses oe contining bse metls nd pltinum goup metls (PGM s) souced fom mines in the Rustenbug e nd supplied to the efiney in the fom of conveto mtte. At the BMR, hydometllugicl pocess is used to efine the mtte. The min poducts of the BMR include: PGM-ich concentte, which is futhe efined t the Pltinum Metls Refiney nickel in biquette o powde fom coppe cthodes nd coblt powde. Duing the efining pocess, five septe leching stges e used to emove the bse metls nd impuities fom the PGM-ich concentte. This epot will focus on complete edesign of the utoclves used in the 2nd stge leching step. The second stge lech pocess t the Bse Metls Refiney poduces PGM-ich esidue though the extction of coppe nd ny emining bse metls fom the fist stge lech solid esidue mteil. A PGM-ich esidue is poduced, which is futhe pocessed in the 3d stge leching step. The second stge leching pocess is pefomed in numbe of utoclves (n utoclve is defined s hevy vessel fo chemicl pocessing unde high pessue) opeting t pessue of 600 kpg nd tempetue of 120 C to 140 C. Concentted H 2 SO 4 is dded to the feed to poduce * Impl Pltinum Limited, Bse Metls Refiney, South Afic. Deptment of Mteils Science nd Metllugicl Engineeing, Univesity of Petoi, South Afic. Engineeing Systems, South Afic. The Southen Aficn Institute of Mining nd Metllugy, SA ISSN X/ This ppe ws fist published t the SAIMM Confeence, Bse Metls, July P p e The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 109 NON-REFEREED PAPER NOVEMBER

5 Novel edesign of pessue lech utoclve solution with fee cid content of between 10 nd 30 g/l nd ph of less thn 2. Oxygen is pssed into the 1st nd 2nd comptments of the utoclve. As esult of the ggessive, highly oxidizing conditions within the utoclve, the oiginl utoclve design fo the 2nd stge lech pocess utilized thee-lyeed configution, consisting of hevy cbon steel shell (with wll thickness of 40 mm), followed by led lining nd two lyes of cid bicks. The bicks ct s we esistnt mteil nd ensue low sufce tempetue t the skin of the led lining, whees the led lining cts s coosion bie to potect the steel shell fom cid coosion. The lyes of bicks e positioned one on top of the othe with mot to ensue tht the bicks e held fimly in position, while peventing the penettion of the coosive solution between the bicks. The totl thickness of the led lining nd the two lyes of bicks is between 200 mm nd 250 mm. The bicks nd the led line, if dmged, must be eplced immeditely s contct between the cidic solution nd the cbon steel shell esults in pid, coosive ttck. The utoclve lso utilises veticl ptition wll mde up of two bick lyes which cete fou buffe zones (comptments) fo the diffeent stges of the pocess. An gitto is instlled inside the utoclve to ensue pope gittion, which inceses the lech efficiency. Duing the gittion pocess, vibtions e ceted in the utoclve shell, which cn cuse dmge to the bicks nd lines. Vessels of this type hve become the industy stndd fo this ppliction nd hve been in use in the pltinum industy fo mny yes. Limittions of the oginl 2nd stge lech utoclve design The oiginl utoclve design, descibed bove, exhibits sevel poblems which cuse educed poductivity levels nd efficiency in opetion. The min concens e s follows: 1) The utoclves equie extensive mintennce due to bicks collpsing t the nozzles nd ptition wlls, which necessittes fequent mintennce intevls to void deteiotion of the min shell nd unde pefomnce due to the collpse of the ptition wlls. 2) As esult of the fequent collpse of the bick lining, the bick composite mteil contmintes the finl poduct, theeby futhe educing poductivity. 3) Ech vessel is exceedingly costly to mnufctue, which equies the outly of substntil cpitl investment. 4) The dution of mnufctue is lengthy, which is futhe excebted by the need to hve the bick lining constucted in situ. This is both time consuming nd equies skilled lbou, mnged by suitble poject mnges. Futhemoe, it equies hevy lifting nd hndling equipment, s well s stoge nd wehousing fo the bick nd mot mteils. 5) Due to its hevy design, which consists of thick cbon steel shell, led lining nd bicks, suitble foundtions nd hevy lifting equipment e equied. This ises the instlltion costs of the vessel considebly. 6) Bick lying involves mnpowe woking in confined spces unde hzdous conditions which necessittes the implementtion of specil pecutions, the use of bething pptus nd specil equipment to comply with the Occuptionl Helth nd Sfety Act nd othe sttutoy equiements. 7) Wokes lying the led lining in the wokshop e exposed to extemely hzdous conditions, such s fumes, led vpous nd high isk of poisoning. The use of led is govened by specific egultions, nd is esticted in sevel counties ound the wold. South Afic hs pomulgted Led Regultions which stipulte the use nd ppliction of led in the Ntionl Occuptionl Helth nd Sfety Act. 8) When the vessel is decommissioned, stict egultions hve to be dheed to when disposing of the vessel. Due to the extemely hevy weight of the utoclve nd the bick lining, it is not fesible to lift the vessel s whole unit. The bicks hve to be emoved, following which the vessel hs to be otted nd heted bove the melting point of led to llow the molten led to flow out though the nozzles. This equies specilized nd highly skilled wokfoce. As well s the inconvenience of hving to suspend poduction, the dnges ssocited with the hndling of the led e plentiful, including contmintion, fumes nd the need fo sfety zone fo pesonnel who hve to be dessed in pesonl, sfety potection ge. 9) Poblems exist elting to mnufctuing tolences cused by the bick lining. Since the bick lining tends to swell, it is essentil to ensue tht the mnufctue mintins vey stict out-of-ound contol to ensue tht the pemissible tolences e not exceeded. It is common to hve 0.5% out-ofound on the bick lining, whees the code of constuction on pessuized equipment limits the out-of-ound to 1% of the dimete size. This necessittes dditionl mnufctuing jigs, spides nd tempoy bcing to mintin ciculity within pemissible tolences. 10) The vessel contins fou comptments with lge gitto to mix the poduct duing pocessing. It is common fo this gitto to hve un-out which induces sevee vibtions, theeby wekening nd ccking the mot nd cusing the bickwok to collpse. 11) Finlly, the vessel hs to be plced on hevy foundtion, which must withstnd the hefty mss of shell, led lining nd the two lyes of bick lining. A dicl utoclve edesign ws, theefoe, needed to educe the high costs of mnufctuing, instlltion nd opetion. Solving the poblems ssocited with the oiginl 2nd stge lech utoclve design: To enginees who hd been opeting these utoclves fo yes, it ws evident tht solution to the poblems, descibed bove, hd to be developed. This solution hd to be innovtive, with view to poviding sfe woking 678 NOVEMBER 2009 VOLUME 109 NON-REFEREED PAPER The Jounl of The Southen Aficn Institute of Mining nd Metllugy

6 Novel edesign of pessue lech utoclve envionment nd educing the costs ssocited with mnufctuing, instlltion, opetion, downtime fo mintennce nd disposl of the unit. Combining ll these fctos is difficult, since esolving one of these pmetes hs implictions fo the othe spects, fo exmple cost sving in mnufctuing my bing bout n incese in poduction costs, o vice ves. A need ws, theefoe, identified fo solution tht would be sfe, opeble, mintinble nd disposble, nd which would not cuse pollution nd degdtion of the envionment t the end of the vessel s opeting life. This solution ws needed to ensue tht the mnufctues, s well s the opetos woking in the plnt, emined sfe nd tht the equipment opeted moe efficiently, elibly nd povided cost sving dvntges thoughout the life cycle of the vessel. In ode to stisfy these equiements, the following design citei wee stted: The solution envisged needed to be technologiclly innovtive nd comptible with the pltinum being poduced in the plnt The mteil of constuction hd to be edily vilble nd possess excellent mechnicl popeties The mteil of constuction hd to be esistnt to the high tempetues in the pocess nd t the sme time povide the coosion esistnce equied The mteil of constuction needed to be menble to the olling, foging nd welding pocesses used duing fbiction The mteil hd to be esistnt to vibtions induced by gittion in the utoclve The mteil of constuction needed to hve simil coosion esistnce to tht of the bick lining used in the oiginl design to potect the steel shell fom the ggessive solution in the utoclve. Mteil of constuction Avilble litetue suggests the use of titnium, titnium cld1,2 o supeduplex stinless steel3,4 utoclves s ltentives to bick nd led lined utoclves in pplictions involving long-tem exposue to opeting conditions simil to those within the 2nd stge lech utoclve t the BMR1,2,3. These mteils e, howeve, expensive, difficult to fbicte nd often not edily vilble. The use of moe genel pupose, duplex stinless steel, known s SAF 2205, (but lso efeed to s EN ccoding to EN 10088, EN nd S31803 ccoding to ASTM A240), ws theefoe, investigted. SAF 2205 is highly lloyed duplex stinless steel of Swedish oigin, with typicl chemicl composition s shown in Tble I. SAF 2205 displys excellent coosion esistnce in wide nge of envionments, esists loclised coosion (such s pitting nd cevice coosion), is highly esistnt to integnul coosion nd is not susceptible to chloide stess coosion ccking. It hs typicl hdness of 293 HB (hdness on the Binell hdness scle) o 31 HRC (hdness on the Rockwell C scle)5. This is equivlent to hdness of 8 on the MOH scle ( pcticl method of comping the hdness o sctch esistnce of minels). SAF 2205 stinless steel is high stength lloy, with typiclly yield stength of 520 MP nd n ultimte tensile stength of 760 MP. Fo compison puposes, the bick lining used, until ecently, t the BMR hs typicl hdness of MOH 9, but without ny tensile mechnicl stength. SAF 2205 mteil is edily vilble, nd hs dul-phse feitic-ustenitic stuctue which ensues the good mechnicl popeties nd excellent coosion esistnce equied in this ppliction. Tble II summizes selected popeties of SAF 2205 duplex stinless steel. Smples of SAF 2205 nd lowe lloyed AISI 316L stinless steel wee plced into n oiginl 2nd stge lech utoclve in egion of the ptition wll whee the gitting effect ws t mximum. The AISI 316L stinless steel smples displyed pid deteiotion in this envionment, which is in geement with vilble litetue6 8. The SAF 2205 smples, howeve, did not show ny signs of we o chemicl ttck, nd no evidence of pitting coosion ws obseved. This suggested tht SAF 2205 is comptible with the envionment inside the 2nd stge lech utoclve. Novel edesign of the 2nd stge lech utoclve On completion of the successful in situ tils, the 2nd stge lech utoclve ws completely edesigned using SAF 2205 duplex stinless steel s mteil of constuction. This design tkes into considetion the ecent impovements in technology in duplex stinless steel poducts. The newly designed utoclve does not equie ny led o bick lining, nd the fist instlled vessel hs ledy been in continuous opetion fo the lst 24 months. Its pefomnce hs exceeded the highest expecttions. The min dvntges of the newly designed utoclve e: 1. Downtime is minimized, llowing fo educed mintennce sevicing. 2. Woking volume is incesed substntilly, which minimizes btch-time pocessing nd theefoe ensues n incese in the output of the plnt. 3. The intenl components cn be esily djusted ccoding to pocess equiements. The poduct hs been ptented, in ddition to egisttion deed fo the utiliztion of duplex mteils without the need fo dditionl bick lyes (which would hve been necessy s coosion bie in the conven- Tble I The typicl chemicl composition of SAF 2205 (weight%, blnce Fe) 5 C Ni C Mn Si N Mo 21 23% % 0.03 mx. 2.0 mx. 1.0 mx Tble II Selected popeties of SAF 2205 duplex stinless steel 5 Hdness Density Theml Het Theml expnsion esistnce conductivity 293 HB 7850 kg/m3 13.5x10-6 No embittlement 17 W/mK up to 300 C J o u n l P p e The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 109 NON-REFEREED PAPER NOVEMBER

7 Novel edesign of pessue lech utoclve tionl utoclve design) (Ptent 2004/8085 fo the use of stip-lining of SAF 2205 duplex stinless steel on cbon skin s mteil of constuction fo high pessue lech utoclves; nd Ptent 2005/08637 fo the use of solid SAF 2205 duplex stinless steel s mteil of constuction fo high pessue lech utoclves.) Tble III compes the opeting pmetes nd dimensions of the newly designed SAF 2205 utoclve with those of the oginl bick nd led lined vessels. The vessel shell ws mnufctued fom SAF 2205 duplex stinless steel pltes which wee fomed in cicul sections ssembled in n butting end-to-end composition nd welded togethe to fom n elongted impemeble cylindicl body. The pltes wee stepped nd welded in stggeed y to incese igidity nd to void continuous cicumfeentil sem. Stict qulity contol ws mintined duing ll stges of fbiction. The dished ends wee hot foged nd welded to the cylindicl body to fom the vessel. Sevel mnhole nd nozzle openings wee included fo ccess to the inteio of the vessel nd fo connections to the pocess piping, whee equied. The nozzles wee hot foged nd welded to the vessel body using ptil penettion fillet welds. Figue 1 shows dwing of the top view of the utoclve, Figue 2 n elevtion dwing, nd Figue 3 side view. A numbe of intenl bffles wee fixed t suitble loctions inside the body of the vessel in ode to cete comptments fo the diffeent stges of the pocess. Isometic views of the two types of ptition wlls used in the utoclve e shown in Figues 4 nd 5. Agittos wee positioned inside of the utoclve to ensue pope mixing of Tble III Compison of bick lined nd SAF2205 utoclves Popety Bick utoclve SAF 2205 utoclve Mteil of constuction BS A SAF 2205 Design tempetue 165 C 185 C Design pessue 1034 kp 1070 kp Befoe bicking Inside dimete 2845 mm 2955 mm Tn to tn mm mm Shell thickness 40 mm uppe 22 mm thoughout 25 mm lowe Dish hed thickness 25 mm 16 mm Bick lining Yes N/A Led Yes N/A Agitto nozzle A1 A4 777 mm 1073 mm Sevice nozzle N1 N mm 437 mm Nozzle ngles Afte bicking Inside dimete 2555 mm 2955 mm Tn to tn mm mm Agitto nozzle A1 A4 670 mm 1073 mm Sevice nozzle N1 N mm 437 mm Pss ptition width 345 mm bick 30 mm SAF 2205 Vessel weight (Empty) kg kg Vessel volume 53.7 m m3 Figue 1 Top view dwing of the edesigned 2nd stge lech utoclve Figue 2 Elevtion dwing of the edesigned 2nd stge lech utoclve 680 NOVEMBER 2009 VOLUME 109 NON-REFEREED PAPER The Jounl of The Southen Aficn Institute of Mining nd Metllugy

8 Novel edesign of pessue lech utoclve the cidic substnces used in the leching pocess. These gittos hve to be well suppoted nd secued to mnholes to educe vibtions s f s possible, theeby educing stesses nd voiding ftigue filue of the vessel components. Finite element method (FEM) nlysis ws cied out fo ll the components subjected to cyclic stesses to demonstte the integity of the elements nd to pove tht the opeting stesses in the shell nd othe elements do not exceed the mximum pemissible stesses llowble fo the mteil of constuction. The clculted stess pofile in one of the two types of ptitioning wll used in the second stge lech utoclve is shown in Figue 6. An isometic side view of the gitto opening nd the clculted stess distibution e shown in Figues 7 nd 8, espectively. The Codes of Design nd Constuction pplicble to the utoclve hd to be stictly followed nd igoous clcultions wee equied to veify tht the cceptnce citei wee met. J o u n l P p e Figue 3 Side view dwing of the edesigned 2nd stge lech utoclve Figue 4 Thee-dimensionl isometic views of type I ptition wll in the 2nd stge lech utoclve Figue 5 A thee-dimensionl isometic view of type II ptition wll in the 2nd stge lech utoclve Figue 6 Clculted stess distibution in type I ptition wll The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 109 NON-REFEREED PAPER NOVEMBER

9 Novel edesign of pessue lech utoclve Figue 7 Isometic side view of the gitto opening in the 2nd stge lech utoclve Figue 8 Clculted stess pofile in the shell suounding the gitto opening Accoding to code equiements, mteils of constuction must be listed in the code fo mteil popeties. SAF 2205 is listed in the ASME Section VIII Division 1 code unde the designtion ASME SA 240-S31803, with the following design popeties: Allowble stess t mbient tempetue MP Ultimte tensile stength t mbient 620 MP tempetue Yield stess t mbient tempetue 448 MP Young s modulus t mbient 1.95x105 MP tempetue Benefits of the new utoclve design Afte ppoximtely 24 months in sevice in the sme envionment nd unde the sme opeting conditions s those used fo the oiginl bick nd led lined utoclves, the solid duplex stinless steel 2nd stge lech utoclve showed no signs of coosion nd the leching pocess poceeded s noml. The thoughput ws, howeve, significntly incesed due to the lge open volume in the utoclve. The elimintion of the bick lining lso emoved the isk of collpse nd fll of bick pts s esult of the gittion ction. The mintennce equiements of the newly designed vessels wee substntilly educed. Sustinbility In the olde vesion of the utoclve, the use of led substnces mde fo hzdous nd dngeous woking envionment. Eliminting the use of led in the edesigned utoclve, theefoe, povides fo sfe woking envionment fo those hndling the diffeent mteils used duing the mnufctue of the vessel, s well s fo plnt opetos, nd lso duing the disposl of the vessel t the end of its opeting life. An ttempt ws, theefoe, mde to ddess the issue of occuptionl helth egultions by optimising woking conditions in the pocessing plnt. Futhemoe, fom n envionmentl point of view, the use of toxic nd hmful led substnces hd been eliminted nd eplced with moe envionmentlly sustinble duplex stinless steel. The new mteils will ensue longe nd moe duble lifespn. This is owing to the fct tht the duplex stinless steel mteil is esistnt to coosion in the cidic solution used in the lech pocess, theeby lengthening the lifespn nd incesing the sustinbility of the vessel. 682 NOVEMBER 2009 VOLUME 109 NON-REFEREED PAPER The Jounl of The Southen Aficn Institute of Mining nd Metllugy

10 Novel edesign of pessue lech utoclve J o u n l P p e Figue 9 Delivey of the completed second stge lech utoclve t the BMR in June 2007 Figue 10 Instlltion of the completed second stge lech utoclve t the BMR in June 2007 Two photogphs of the completed vessel duing delivey nd instlltion t the Impl Pltinum Bse Metl Refiney e shown in Figues 9 nd 10. Acknowledgements The uthos wish to expess thei gtitude to the entie poject tem including Impl Pltinum Refineies (Spings), Engineeing Systems, the Univesity of Petoi, nd the mnufctue, Metso ND Engineeing. Refeences 1. LAMB, S. nd THAYER, M.J. Mteils fo the hydometllugicl industy. Poceedings of Coosion 2001 (NACE Intentionl). Houston, Texs Mch GOBELL, M. Titnium cld nd bick/led lines utoclve constuction. Poceedings of ALTA 2000 Nickel/Coblt-6. Peth, Austli My FRANCIS, R., BYRNE, G., nd WARBURTON, G.R. The use of supe duplex stinless steel fo high pessue cid lech cicuits. Poceedings of ALTA 2000 Nickel/Coblt-6. Peth, Austli My FRANCIS, R. nd BYRNE, G. The pefomnce of Z100 (UNS S32760) supeduplex stinless steel in sulphuic cid. Poceedings of Coosion 2006 (NACE Intentionl). Sn Diego, Clifoni Mch Outokumpu Stinless Steel. Duplex Stinless Steels. Outokumpu Stinless Steel Poduct Bochue, vilble t 6. KISH, J.R., IVES, M.B., nd RODDA, J.R. Coosion mechnisms of nickelcontining stinless steels in concentted queous solutions of sulfuic cid. Coosion, vol. 60, no. 6, June pp RODDA, J.R. nd IVES, M.B. Detemintion of coosion tes in hot, concentted sulfuic cid. Coosion, vol. 59, no. 4, Apil pp Li, Y., Ives, M.B., Coley, K.S., nd Rodd, J.R. Coosion of nickelcontining stinless steel in concentted sulphuic cid. Coosion Science, vol. 46, no. 8, August pp The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 109 NON-REFEREED PAPER NOVEMBER