Equipment selection for high selective excavation surface coal mining

Transcription

1 Syopsis Equipmet selectio fo high selective excvtio sufce col miig by H. Aykul*, E. Ylcı, I.G. Ediz*, D.W. Dixo-Hdy, d H. Akckoc* The choice of which miig method to use t my lge sufce col mies is ofte dicted by wht mchiey is vilble o wht expeiece the mie mgemet c offe. Oe of the most sigifict sufce col mies i Tukey is owed d opeted by the Tukish Ntiol Col Bod, locted to the west of the city of Küthy. The Seyitöme Ligite Etepise (SLE) extcts low qulity col, the mjoity of which is supplied to djcet powe sttio. The col seems t SLE coti bds of sh which ude oml miig coditios e extcted with the col. This iceses the sh cotet of the u of mie col d esults i lowe efficiecy t the powe sttio d ficil pelties fo SLE. I this ppe, theefoe, selectio of the best possible equipmet d poductio method ws idetified to chieve high selective miig t SLE. The esech foud tht two diffeet high selective miig methods wee suitble fo selective excvtio of the B3 sem, which wee hydulic excvto d tuck d sufce mie d tuck combitios. It ws lso foud tht high selective excvtio could povide the desied col qulity t 52% lowe costs whe the whole pocess (excvtio, tspottio, pocessig, etc.) ws cosideed. Keywods: col miig, sufce miig, selective miig. Itoductio Oe of the pmetes tht povide miimum cost fo the tgeted poductio i mie is suely the suitbility of the mchies/ equipmet selected. Moeove, equipmet selectio diectly ffects the pit desig d poductio plig. I ope pit miig, equipmet selectio is mde ccodig to my fctos elted to the oe d miig coditios. These fctos c be qulittive d qutittive i tue. The mi pupose of equipmet selectio is to choose the optimum d cost-effective equipmet by istllig decisio-suppot system, which c lyse vious d complex fctos. The tem optimum hee eflects tht the equipmet selected must comply with the miig coditios/limittios d meet the bsic equiemets d pefeeces of the mie1,2. Vious types of equipmet selectio models hve bee poposed to icopote ito decisio-suppot system fo pplictio to the selectio of miig equipmet. These models e life cycle cost lysis3, et peset vlue lysis4, lie bekeve model5, lie pogmmig6 d decisio mkig tools such s elibility lysis, kowledge bsed expet systems d lyticl hiechy pocesses7 9. The most impott fctos fo the selectio of opecst miig equipmet my be idetified s site o deposit pmetes, ogiztiol cultue, dptbility to chge, techicl fetues, poductio pefomce, opeto cpbility, mie/mchiey life, pefomce moitoig fcilities, dmiisttio, ficil cosidetio, mufctue s eputtio, delivey led time d wty, elibility of mchiey, employee pticiptio i the decisio-mkig pocess (mitece d opetio), dive system (hydulic/ electic/mechicl), mitibility, powe souce equied (diesel/electic), vilble tiig fcilities, uxiliy mchies equied, geel supevisio equied, logistics suppot o mgemet, degee of utomtio, opetig coditio, level of sfety, wokig eviomet d the ese of cofigutio2. The bsic piciple i equipmet selectio is to defie the degee of pioity o goveig fctos mog the oes give bove d the detemiig the mtchig equipmet d the ltetives to these pmetes comptively. I most istces, howeve, it is difficult to detemie the equipmet meetig ll the equiemets stted. * Dumlupi Uivesity, Deptmet of Miig Egieeig, Küthy, Tukey. Eylül Uivesity, Deptmet of Miig Egieeig, Izmi, Tukey. Uivesity of Leeds, School of Pocess, Eviometl d Mteil Egieeig, UK. The Southe Afic Istitute of Miig d Metllugy, SA ISSN X/ Ppe eceived Feb. 2007; evised ppe eceived M T s c t i o P p e The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

2 Equipmet selectio fo high selective excvtio sufce col miig Seyitöme Ligite Etepise of the Tukish Ntiol Col Bod (SLE) is oe of the lgest col poduces i Tukey d poduces 7.5 millio toes of ligite col pe ye fom opecst mie close to the city of Küthy (Figue 1).The most sigifict poblem tht the etepise cuetly fces is the low qulity u of mie col (ROM), which is mily sold to the eby powe sttio. The excvtio of the ptigs i the sem togethe with col iceses the sh cotet of the col poduced, which i tu deceses the efficiecy of the col buig pocess t the powe sttio d esults i high pelty costs fo the mie. Sice the mi poblems t SLE wee cused by the cuet col qulity ot meetig the stdds equied by the powe plt d the mket, d the eed fo blced pit developmet, ttempt ws mde t qulity plig to meet the vious equiemets. Fctos elted to qulity impovemet fo cuet d poposed poductio sttegies wee detemied, ccodig to the customes qulity demds d the sleble col qulity eseves. Aftewds, the ecessity d the degee of selectivity fo ech sttegy d detemiig of optimum excvtio cofigutio ws defied. The esult ws high selective miig t the B 3 sem to icese the powe plt col qulity up to 1761 kcl/kg usig poductio sttegy bsed o mximum col supply to the mket10. Oce decisio ws mde fo qulity impovemet upo high selective excvtio t the etepise, it ws the impott to select suitble mchiey/equipmet d poductio methods tht will esult i the equied col qulity impovemet. I ode to mke the selective excvtio pplicble, the mchiey to be selected must hve highly selective d poductive cpbilities t esoble costs. I fct, thee e my exmples of selective excvtio pplictios i opecst mies to emove the ptigs fom col to be sold fo powe sttios. The mi esos fo these mies to employ selective excvtio e the difficulties i solvig the poblems duig the pocessig stge d tht the selective excvtio poduces moe ecoomicl solutio Loctio d geology The SLE ligite bsi is locted to the oth-west of the city of Küthy (Figue 1) d it cosists of thee mi egios: Seyitöme, Asllı d Ayvlı s show i (Figue 2). The Seyitöme egio is divided ito thee sub-egios (disticts), which e Seyitöme-Est, Seyitöme-West d the Dglie Distict. The Asllı egio cosists of two septe disticts clled Asllı-1 d Asllı-2. I the Seyitöme bsi, thee e two 0 70 dipped hoizotl ligite sems, which e simply efeed to s sem-a d sem-b d the veticl distce betwee the sems vies fom 10 to 50 m. Both sems coti itebudes with thickesses vyig fom 0.1 m to 2 m. The thickess of sem-a vies betwee 5 to 25 m but the vege thickess is ccepted s 10 m. This sem cotis vey itesive itebudes d hs vege cloific vlue of 1820 kcl/kg14. BLACK SEA KUTAHYA Figue 1 Loctio of the Seyitöme col field ISLANLI COAL FIELD SEYITÖMER WEST FIELD SEYITÖMER EAST FIELD SEYITÖMER DRAGLINE FIELD Figue 2 Reseve Boudies d Poductio Fields of the Seyitöme-Asllı Regio 196 MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

3 Equipmet selectio fo high selective excvtio sufce col miig Sem-B is locted beeth sem-a d its thickess vies betwee 2 d 30 m with vege thickess of 20 m. Sem-B cosists of thee diffeet sub-levels fom top to bottom which e clled B 1, B 2 d B 3 d the cloific vlues of these sub-levels decese fom top to bottom due to the itesified itebude sequecig. I pticul the B 3 sem thoughout the bsi icludes ptigs thie th 0.5 m i thickess14,15. The col poduced fom the Seyitöme ligite bsi hs high moistue cotet vyig fom 33% to 39% d they e clssified s soft d mte ligite14. The cols of B 1 d B 2 sem levels hve highe cloific vlues d e ofte sold s domestic col i the mket. Howeve, the col of sem B 3 hs lowe cloific vlue d fie pticle size (-200 mm) d theefoe, it c be sold oly to the eby powe plt. Appoximtely 12% of the totl poductio i the col field ( toes) is sold i the mket fo domestic use d the emiig 88% of the poductio ( toes) is cosumed t the powe plt. Howeve, the icome obtied pe toe of col sold to the mket is lmost twice s much s the icome fom sle to the powe sttio. Optimum equipmet d method selectio fo high selective excvtio t SLE Idetifictio of mi fctos elted to equipmet selectio Fistly, thee pioity degees of effective pmetes wee detemied ccodig to the miig d geologicl coditios i ode to select optimum mchiey d miig methods. These pmetes wee detemied ccodig to the pupose of the esech, obsevtio mde t the mie d the discussios with the expets. Afte ovell ssessmet, thee pioity degee pmetes wee detemied s follows: Fist pioity degee pmetes ese of ock excvtio, high selective bility of the mchiey Secod pioity degee pmetes te of poductio, cpcity d poductivity of mchiey, cpitl d opetig cost of mchiey Thid pioity degee pmetes geologicl/miig fetues (fultig, bech width, sem dip, wste ock fetues, floo coditio, mteil size fte fgmettio), flexibility, mitibility (lbou s skill d techicl kowledge equied, mitece suppot, spe pts vilbility, bck-up sevice). High selective bility of the mchiey is fist pioity sice chievig high selective excvtio is diectly depedet o the miimum septio thickess d septio ccucy of the mchie o equipmet used. The poductio method to be pplied will lso be detemied ccodig to the selected mchiey hvig the cpbility of high selective excvtio. This ssumptio ctully mkes the selectio moe stightfowd d less complex. Evlutio d selectio of mchies Afte defiig the goveig pmetes give bove, it is the ecessy to evlute the ltetive mchiey fo thei suitbility to the pmetes i comptive ppoch. I this evlutio, fist pioity pmetes wee egded s o-flexible pmetes d the equipmet meetig these pmetes will the be evluted fo the secod d tetiy degee pmetes. Filly, the equipmet will ll be eevluted cosideig thei suitbility fo ll the whole pmetes befoe the selectio is mde. Fo the fil selectio, lmost ll clssicl miig (ippig, shovel diggig) mchiey d cotiuous sufce mies (CSM) excvtig with low opetio height wee cosideed. Fist pioity degee pmetes Ese of ock excvtio The detemitio of ese of ock excvtio is oe of the citicl stges i sufce miig pojects. O my pojects the ese of ock excvtio is mily bsed o the piciple of whethe the ock c be ecoomiclly excvted by mechicl excvtos o is dillig d blstig ecessy16. I this esech, the diggbility idex tig method d its clssifictio cht wee used to detemie the ese of excvtio t the B 3 sem. I this method, the idex fo the ese of excvtio ws detemied ccodig to the ock mss pmetes such s wetheig, uixil compessive stegth (UCS), joit spcig d beddig spcig. The idex ws the used to defie the ock clssifictio d the elted excvtio method s well s the mchiey to be used. I this method, the ese of ock excvtio is clssified ito 7 goups s vey esy, esy, modetely difficult, difficult, vey difficult, extemely difficult d mgil without blstig 16,17. The esults of ivestigtio d expeimets cied out o the col d cly of the B 3 sem usig the ese of excvtio ppoch explied e give i Tble I. The compessive stegths of the col lyes i the B 3 sem wee obtied s betwee 7.7 MP d 17.9 MP. The itebudes e mily compised of cly with white gy d blck colous, d thei stegth vlues e lible to chge ccodig to the type of the miel compositio d vy betwee 0.81 MP d 24.5 MP. Also the SiO 2 cotet of these cly fomtios, which is detemiig fcto i poductio pefomce d excvtio cost, vies betwee 55 d 61%18. As it is see fom Tble I, the ese of excvtio fo col lyes d clyey itebudes wee foud to be esy d modetely difficult, espectively. Whe whole lyes wee cosideed, it ws see tht exceptig ippe-scpe d lode excvtio methods, both ippig d shovel diggig methods wee pplicble. Theefoe, excludig scpe d lode wokig s the mi excvtig uit, thee is o limittio o the use of clssicl excvtio mchies d the sufce mies wokig with ippig piciples s f s diggbility is coceed. I fct, it hs bee well kow fo 20 yes tht it is possible to employ CSMs diectly o without usig explosives fo the oes o ocks hvig uixil compessive stegth up to 118 MP. CSMs e geelly selected fo the excvtio of oes such s col, buxite, d gypsum19,20. Ability of high selective excvtio The possibility of extctig lyes septely by suitble mchie/equipmet duig the excvtio stge is the mi T s c t i o P p e The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

4 Equipmet selectio fo high selective excvtio sufce col miig Tble I Detemitio of ese of diggig d excvtio method ccodig to the diggbility idex tig method fo B3 sem level t SLE Pmete d selectio Col Rock fomtios i B 3 level Cly Pmete Wetheig Slightly Slightly Rtig Stegth UCS (N/m2) Rtig 0 10 Joit spcig (m) Rtig Beddig spcig (m) Rtig Selectio Idex (totl tig) Ese of diggig Esy Modetely difficult Excvtio method Rippig, shovel diggig Rippig without scpe, shovel diggig gol of col qulity impovemet. Extctio of the lyes septely is elted to the selective wokig bility of the excvtio mchies the th the poductio method21. So, i the Seyitöme sttified col deposit, to select suitble mchie povidig col poductio with the qulity demded, the most impott citei to be cosideed is the bility of the high selective opetio of the mchie to be used. At this poit, the fist cosidetio hs to be give to the miimum septio thickess d the septio ccucy of the mchies/equipmet beig selected. Mchies with high cuttig depth opete s ule with low septio ccucy d vice ves. Also, iccucy of septio iceses with icesig miiml sepble thickess22,23. The selective wokig bility of diffeet types of excvtio d lodig mchies used i ope pits shows get vitios. The bility of the high selective opetio of these mchies ude 0.5 m septio thickess should be ivestigted fo the selectio of the Seyitöme cse. The use of explosives should be voided i the selective excvtio sice high mteil dmixtue is ot voidble i sttified deposits whe explosives e used23. Rippes e used successfully i stt iclied up to 300 whe the fomtios povide stisfctoy tctio sufce. Rippes tht e used togethe with dozes d lodes i poductio could be successfully used i high selective opetio becuse of thei suitble cuttig depth. The popotio of dilutio by usig ippe is lowe th excvtio by explosives d by most of the othe excvtio methods23. Rope shovels e geelly usuitble fo ll degees of selective excvtio. The bucket motio, icludig its fowd d upwd cicul c, cuses uvoidble mixtue of oe d wste i iteclted beds23. Fot d bckhoe shovels e successfully used i high selective excvtio. Bsic fetues of these mchies e fee motio of the bucket fom the bucket boom, which mkes the hoizotl motio cpbility (pllel cowdig) of the bucket highe24. Howeve, oly the shovels whose cpcities e lowe th 15 m3 c be used fo selective d high selective opetio. I othe wods, highe cpcity shovels cot be used fo high degee of selective excvtio22. Thee e some cosideble supeioities d dvtges of bckhoes ove fot shovels i tems of excvtig selectivity i deepe sems d upbech opetio22. Wheel o tck type lodes c be oly used i selective excvtio if the fomtio is vey soft o well fgmeted23. Theefoe, lodes loe cot be egded s mi excvtig uit whe the ese of diggig is cosideed t the B 3 sem level. Howeve, combitio of ippe-doze-lode could be suitble excvtio method fo high selective opetio t the B 3 sem level. Bucket wheel excvtos c be used oly ude semiselective coditios with lye thickess betwee 1 d 3 m22. Amog the CSMs oly the cetlly positioed shee dums c wok i high selective opetio. So f, mchies of this type mufctued by Witge (Witge Sufce Mie) d Huo (Esy Mie) Mufctuig Compy hve bee employed i sufce miig opetios. Othe types of CSMs e less suitble fo high selective excvtio22. Afte the lysis of fist pioity degee pmetes, it ws cocluded tht the mchiey ltetives to be used fo high selective excvtio t the B 3 sem wee ippe-dozelode combitios, shovels (fot d bckhoe type) d CSMs with cetlly positioed shee dums. Vey high selectivity coditios ecessitte vey low septio thickesses (0.1 m 0.3 m) to chieve the equied qulity, d the Witge sufce mie ws see s moe suitble i compiso to the othe mchies becuse it could opete with less miig loses d dilutio. Secod pioity degee pmetes Rte of poductio, cpcity d poductivity of the mchiey I ode to ccomplish mximum col supply to the mket d povide blced pit developmet, it ws clculted tht bout 4.5 millio toes of col d 3 millio toes of wste mteil hd to be excvted septely ully fom the B 3 sem level10. I othe wods, the selective mchiey to be used hs to posses poductio cpcity of 820 m3/h (1350 toe/h) t the B 3 sem level d it must be opeted efficietly. 198 MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

5 Equipmet selectio fo high selective excvtio sufce col miig Opetig efficiecy of ll miig mchies used i selective miig opetio decese pidly s the degee of selectivity iceses. Poductio losses d opetio costs icese i coectio with cosideble decese i efficiecy22,23. Howeve the oly miig mchies tht c be used i high selective opetio with the highest cpcity d efficiecy e CSMs with cetlly positioed shee dums d smll shovels. The Witge d Esy Mie chieve the highest septio ccucy togethe with the highest cpcity of ll the othe excvtig mchies. Howeve, these dvtges c be oly obtied whe they wok i hoizotl d ely hoizotl sems up to 12. Depedig o mchie size, cuttig thickess d othe wokig coditios, effective output of 225 m3/h to m3/h is chievble22. The eso fo this high efficiecy is explied by its cotiuous cuttig system, especilly i log legth of cut. The othe fcto icesig the poductivity whe wokig with these CSMs is tht the opetio steps, such s looseig, cushig d lodig, e ll combied i oe mchie19. Hydulic excvtos lso hve high opetiol cpcity i high selective excvtio, but the output chieved is less th those of CSM mchies used i high selective opetio. Hydulic shovels with shovel cpcity of up to 15 m3 e suitble fo selective d high selective opetio s well. The houly output of these mchies vies fom 110 to m3/h depedig o mchie size d diggig height. Thi cuttig slices led to icesed legth of sigle cut, moe complicted shovel movemet cotol d decese of the fillig fcto. Howeve, the shot cycle time of shovels mke these mchies efficiet i compiso to othe tditiol excvtio mchies, especilly whee the high selective excvtio is equied22,23. Houly poductio cpcity t the Seyitöme ope cst mie ws clculted s toe/h fo the Witge sufce mie 4200 SM model; 442 toe/h d 620 toe/h fo 4.59 m3 d 7.65 m3 cpcity hydulic excvtos, espectively. The ippe-doze-lode combitio dpts esily to high selective diggig i tems of thei wokig pttes. Howeve, the use of this combitio will esult i upoductive excvtio opetio esultig fom the theestge excvtio pocedue (ippig, dozig d lodig). Accodig to SLE opetiol dt, the vege cpcity of the ippe-doze-lode (7.65 m3) combitio used fo selective excvtio t the B 3 sem level dow to 0.5 m ws 250 m3/h (410 toe/h). This vlue would be educed to 326 toe/h fo high selective excvtio coditio. Theefoe, fo the Seyitöme cse, eve though the use of dozes d lodes met the qulity equiemets, it would esult i cosideble upoductive output i tems of meetig the cpcity comped to Witge sufce mies (WSM) d shovels. Cpitl d opetig cost of mchies Whe the poductio demd is cosideed, it is see tht the mie equies 4 mchies of 4.59 m3 o 3 mchies of 7.65 m3 i shovel opetio, 2 WSMs (4200 SM) i sufce mie opetio d 5 ippes-dozes d 5 lodes (7.65 m3) i ipe-doze-lode opetio. Shovel ltetives with 4.59 vesus 7.65 m3 cpcity mchies hve lmost simil ivestmet costs (US$4 millio) d this coespods to 10% of the ul pofit. WSM ivestmet cost is much highe th shovel ivestmet d is lmost US$7 millio coespodig to 18% of the ul pofit. Although the mie ledy hs ippes, dozes d lodes i dequte umbes, the opetiol cosistecy o elibility my be vey low owig to thei ge. If the mchies e eewed the the cost will be oud US$4 millio fo 10 mchies of this ltetive. Cosideig the ul pofit d the eseve vilble (250 millio toes) t the mie, ivestmet costs fo y excvtio ltetives e see to be fesible. Ivestigtio hs show tht the opetio costs of sufce mies d hydulic shovels e i the ge of $0.2 /toe d $0.6/toe. Although these mchies ccomplish the selectivity i the fce, the excvtio cost iceses mssively with decesig septio thickess d low efficiecy. I pticul, the use of high cpcity hydulic shovels i too thi slices leds to extemely high costs, which my eve exceed $1.2/toe22. Thee-stge excvtio pocess t ippe-doze-lode combitio leds to educed poductio cpcity which, i tu, iceses the poductio cost comped to othe ltetives23. At SLE coditios, excvtio costs of high selective opetio (icludig depecitio d iteest) fo the hydulic excvto d WSM vesus ippe-doze+lode combitio wee clculted s $0.13/toe, $0.27/toe d $0.625/toe, espectively. Ivestmet costs fo ech ltetive ffects the excvtio costs evely, which e i the ge of 15% to 25%. I othe wods, if ivestmet costs e excluded fom the opetiol costs, the ctul opetiol o excvtio costs fo hydulic excvto d WSM vesus ippe-doze-lode combitio e $0.10/toe, $0.20/toe d $0.52/toe, espectively. I shot, the hydulic excvto ltetive ws foud to be the most dvtgeous ltetive cosideig both ivestmet d totl opetiol costs. Whe the ltetives wee comped ccodig to the secod pioity degee pmetes, shovels (fot d bckhoe) d CSMs with cetlly positioed shee dums (WSM) wee foud to be moe dvtgeous th the ippedoze-lode combitio. Amog these ltetives, WSMs hve highe poductio cpcity i hoizotl deposits foud t SLE th hydulic shovel; howeve, hydulic excvtos e much moe ecoomicl cosideig thei ivestmet d opetio costs. Tetiy pioity degee pmetes These pmetes wee detemied s the mie fetues (fultig, bech width, sem dip, wste ock fetues d floo coditio, mteil size fte fgmettio), flexibility, mitibility (lbou s skill d kowledge, mitece suppot, spe pts vilbility, bck up sevice). Theefoe, WSM, shovel d ippe-doze-lode combitio ltetives hd to be comped ccodig to the pmetes detemied i this ctegoy. Mie fetues Thee e my oblique fults i the distict which e mily i the south-oth diectio dividig the col-sem ito blocks14. This is limitig fcto fo ech ltetive i tems T s c t i o P p e The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

6 Equipmet selectio fo high selective excvtio sufce col miig of poductio cpcity. I this espect, hydulic excvtos e see to be moe dvtgeous sice they c opete t ow excvtio fce. Howeve, fo such coditios, it is dvisble fo the WSM to cotiue cuttig with the selected cuttig depth d chge the tuck whe the mteil chges i the fult. The disdvtge of the WSM is tht it equies m bech width, whees m bech width is sufficiet fo hydulic excvto. Icesed wokig iclitio ffects opetiol coditios of WSM moe egtively. Nevetheless, thee e pplictios of WSMs i dipped d steep sems. Up to ceti gle i coss diectio (8%) d legth diectio (12 ) the WSM c follow the dippig sems if wished13. Regdig the bsi coditios t Seyitöme, the low fomtio dip (5 7 ) will ot cuse poblem o big i y limits i tems of WSM opetio. Wste ock o bse fomtio popeties such s plsticity, sticky tue d silt cotet especilly ffect mchie pefomce. As esult of the pticle size lysis of wste ocks i the B 3 level, it ws detemied tht the ocks cotied 16 33% cly; 49 74% silt; d 9 26% sd. As it is clely see fom the lysis, the fomtios pimily coti silt. Cly lysis ws chieved usig the X-y diffctio (XRD) method; illite d chloite wee foud to be the mjo miels18. Moeove, it ws detemied tht gee cly, which is the floo fomtio, hd high plsticity d cotis the motmoilloite type of swellig cly25. I the othe levels, swellig type clys e e d, theefoe, swellig is ot impott poblem except fo floo fomtio. I swellig fomtio, the pefomce of the WSM d ippe-doze-lode is educed; howeve, this poblem c be ovecome by usig bckhoe type of shovel. Hydulic bckhoes hve dvtge if thee is ibility to wok o sticky o swellig footwll mteils, becuse it opetes o the hgigwll of the sem23. Fo the wste ocks t the B 3 sem level, stickiess is uvoidble o iy dys. Thee will be ceti mout of decese i the pefomce of the thee ltetives whe opetig o these sticky cly fomtios. Pefomce eductio will be much highe with ippe-doze-lode d WSM ltetives sice they cotiuously opete o this sticky fomtio. Fo the WSM, cuttig of plstic, sticky mteil c lso be difficult. I this cse the cuttig dum stts to clog d poductio will decese. I some istces, this poblem could be ovecome by icesig the cuttig dum s pm, spyig wte ito the cuttig dum housig d cuttig osticky mteil togethe with sticky mteil13. Moeove, usig tck type of WSM is much moe dvtgeous th ippe-doze-lode i sticky fomtio. As esult of the chemicl lysis doe by the X-y fluoesece (XRF) method, it ws mily foud tht Al, Si, K, d C wee the pimy elemets. Fom the chemicl lysis, o the othe hd, it ws foud tht the SiO 2 cotet of the wste ock fomtios vies fom 55% to 61%18. This obviously cuses egtive effect o the pefomce of the mchiey to be used i these fomtios d iceses the bit cost comped to the col fomtios. This fct ws cosideed i the cost lysis fo ech opetio. Whe mteil size fte fgmettio is cosideed, the WSM ws foud to be much moe dvtgeous th hydulic excvtos d the ippe-doze-lode. Smlle sized mteils icese the cpcity of tucks fo mteil tspottio d, theefoe, educe tspottio cost13. Flexibility Hydulic shovels e much moe flexible d moe esily dptble comped to CSMs with espect to thei coectio to the hulig system d diffeet miig d deposit coditios. Although diect coectio of hydulic shovel to coveyo system is ot possible, the mteil tsfe poblems c be solved esily vi mobile cushe d itemedite coveyo becuse of the low dvcig speed comped to CSMs22,26. The bility to esily espod to chgig poductio equiemets is lso fetue of hydulic shovels s movig them fom oe egio to othe s esult of chges i shot-tem plig is moe pid26. This is lso the cse fo SLE d oly the ippe-doze-lode ltetive hs simil dvtgeous of hydulic excvtos i this sese. Mitibility Oe of the most impott fctos tht will ffect the poductive opetio of poductio system bsed o the WSM t SLE is the tiig of the techicl stff. It will ot be esy to dpt the techicl stff who fo yes hve bee used to oly poductio system bsed o mchies such s shovel, ippe, doze d lode. Theefoe, the dpttio of the WSM to SLE coditios idelly will lso deped o the cofomig of the techicl stff to this poductio system. I this espect, it will be ecessy to hve itesive tiig couse fo the techicl stff, whe the utility of this mchiey will be decided. The use of the poductio system upo these mchies i my of the metl d col etepises hs cused the gowth of mitece suppot, spe pt supplyig d sevices of the mufctue of these mchies. Cotiuous excvtio systems i ope mies e techology tht hs bee developig oly ecetly i the wold. Fo this eso, spe pt supply d vilble sevicig of WSMs hve ot bee developed s much s the mchies themselves. This difficulty is lso the cse fo SLE. This subject is impott i tems of poductive opetio of the etepise lthough it is citeio cosideed oly i the lst stge. Geel ssessmet of the thee excvtio ltetives ccodig to the thee pioity degee pmetes is lso give i Tble II. I this tble, diffeet pecetges epesetig the pioity degee, which e ttched to ech pmete, e multiplied byh ceti poits (fom 0 to 5) epesetig the ppopiteess of the mchie, to fid out the mchie s degee of suitbility. The sum of this pocedue yields the ovell tig of the mchie d the clssifictio fo optimum equipmet selectio. As see fom Tble II, the WSM d hydulic excvtos pefom vey good while the ippe-doze-lode combitio oly pefoms good. The pecetges ttched to ech pmete wee detemied ccodig to expet opiio, pst expeiece, elted litetue d ifomtio gtheed fom the poduce compies, etc. It ws decided tht the hydulic excvto 200 MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

7 Equipmet selectio fo high selective excvtio sufce col miig Tble II Geel evlutio of mchie ltetives d the ovell esults Pmetes Pioity of pmetes (PP) (%) Pioity of mchie ltetives (PMA)* Rippe doze lode Hydulic shovel WSM Ability of high selective miig Poductio pefomce i high selective opetios t hoizotl deposits Advtge of cpitl d opetiol costs Opetiol dvtges whe wokig i fulty zoes Adptbility to chgig floo coditios Advtge of mteil size fte fgmettio Flexibility Adptbility of stff Mitibility Ovell tig ( PP PM*) Geel suitbility** Good Vey good Vey good *Pioity of mchie ltetives (PMA): 0=Isufficiet, 1=Vey bd, 2=Bd, 3=Modete, 4=Good, 5=Vey good **Geel suitbility: (0 1)=Vey bd, (1 2)=Bd, (2 3)=Modete, (3 4)=Good, (4 5)=Vey good d the WSM wee the optimum ltetives fo high selective excvtio t SLE. Rippe-dozes d tck o wheel type lodes vilble i the mie (beig used i the B 3 level) c lso be used s uxiliy mchies whicheve method is chose sice they esily dpt to selective miig coditios. I dditio, thei good mobility d usefuless fo bech mitece mke them impott i excvtio. Method selectio d poductio plig Fo complete poductio plig, tspottio of the excvted oe lso hs to be cosideed. I pevious study o tspot plig, it ws decided to use tucks, lthough te of poductio d lge col eseves fcilitte the use of coveyo d ilwy tspottio system too. The eso fo choosig tuck tspottio ws explied s give below27,28: Iegulities d discotiuities i the col-sem due to mjo fults cuse poblems fo cotiuous tspot systems The eed fo flexible poductio method ccodig to mket d powe plt demds ecessittes poductio fom diffeet pts of the mie d this equies moe mobile tspot system The iclitio of the tspot ods is ot suitble fo ilwy systems Rilwy d coveyo systems e ot flexible eough fo SLE coditios Possible iteuptios i the tspottio due to bekdows i the ilwy o coveyo systems e possible The highe ivestmet costs d loge time eeded fo the costuctio of ilwy d coveyo systems e disdvtgeous. Fom these esos, oly tucks hve bee employed fo the wste ock d oe tspottio t SLE. Tuck tspottio still seems to be dvtgeous eve if WSM o hydulic excvtos e used fo high selective excvtio t B 3 sem level fo the followig dditiol esos: I selective miig, col lyes d the itebude lyes hve to be excvted d tspoted septely. I ode to ccomplish this, the most flexible d esily dptble system is tuck tspottio29. Diect coectio of hydulic shovel to coveyo system is ot possible; the mteil tsfe poblems c be solved oly vi mobile cushe d itemedite coveyo22. Cosequetly, it ws foud tht thee e two ltetive high selective poductio methods pplicble to the B 3 level, mely: hydulic excvto tuck o WSM tuck combitios. As explied befoe, col qulity distibutios i the field mke it ecessy to pply high selective miig i the B 3 sem level10. Howeve, the use of the ope shovel excvtos vilble seems to be possible i the B 1 d B 2 levels sice the col hs mssive stuctue d the qulity of col poduced is suitble to meet mket demd. Fo the cuet poductio, 3 ope shovel excvtos with 7.65 m3 shovel cpcity wee clculted s dequte i the B 1 d B 2 levels. Theefoe, geel poductio plig ws mde ccodig to the ssumptio tht the covetiol method with ope shovel excvtos could emi opetiol i the B 1 d B 2 levels, d high selective miig method be employed i the B 3 level with ew mchies. I this esech, poductio plig fo both WSM d hydulic excvtos wee mde to cy out high selective excvtio of the B 3 sem level. The poductio sttegy fo SLE ws bsed o mximum col supply to the mket by sellig +0.1 m fctio of B 1 d B 2 sem levels oly to the mket10. Accodig to this sttegy, ully, 6.5 millio toes of col with vege cloific vlue of kcl/kg d pticle size of (-0.2 m) e sold to the Seyitöme powe plt. About 2 millio toes of this mout comes fom the col peptio plt s fie col (-0.1 m) d its cloific vlue vies betwee d kcl/kg, depedig o the te of poductio fom the B 1 d B 2 levels. The est of the col, which is bout 4.5 millio toes, is poduced fom the B 3 level. The equied miimum cloific vlue of the col poduced fom the B 3 level chges betwee d kcl/kg, depedig o the vege cloific vlue of the fie col fom the peptio plt. I othe wods, the cloific vlue of the col to be poduced fom the B 3 level should be ised fom kcl/kg to kcl/kg, which ecessittes idel selective excvtio i ode to obti blced mie T s c t i o P p e The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

8 Equipmet selectio fo high selective excvtio sufce col miig plig. To chieve this gol, bout 4.5 millio toes of col d 3 millio toes of wste mteil hve to be excvted septely pe ye fom the B 3 sem level10. Hydulic excvto-tuck method The excvtio t the B 3 level c be ccomplished by usig hydulic excvto-tuck combitio d ippe-dozelode c be opeted fo uxiliy woks togethe with hydulic excvtos. The septed wste is tspoted to the dumpig e d the col is set eithe to the peptio plt o diectly to the powe plt by tucks of 85 shot toe cpcity. The selectivity of hydulic excvto is elted to the shovel cpcity selected. Geelly, smll shovel cpcities icese the selectivity, but t the sme time educe both poductivity d efficiecy of the mie22. The shot cycle time of shovels mkes these mchies efficiet i compiso to othe tditiol excvtio mchies, especilly whee high selective excvtio is equied22,23. Howeve, the poductio plig bsed o the use of hydulic excvto ws mde ccodig to shovel cpcities with 4.59 m3 d 7.65 m3. I fct, lge shovel cpcities (>20 yd3) e ot suitble fo high selective excvtio22. Moeove, the stted cpcity shovel c opete moe pecisely d ccommodte chgig sem height dow to 5 6 m t the B 3 sem level. The pmetes used i the lysis d the umbe of mchies equied i this method e summized i Tble III. The dt except bucket peiod i this tble e deived fom the mie, d the bucket peiod deived fom mufctue s dt. Sice thee is possibility of hvig swellig floo, oe o two of the hydulic excvtos to be bought should be bck hoe type d the othe should be of the fot shovel type. Witge sufce mie-tuck method The excvtio t the B 3 level c be ccomplished by usig WSM 4200-tuck combitio d ippe-doze-lode c be opeted fo uxiliy woks togethe with the WSM system. The septed wste is tspoted to the dumpig e d the col is set diectly to the powe plt by tucks of 85 shot to cpcity. The sufce mie hs cotiuous excvtio system d the excvtio is ccomplished with the movemet logside the hoizotl xis of the lye. This hoizotl movemet of the sufce mie o the lye iceses the selectivity d i this espect, they e cosideed to be the best excvtio mchies of ll. WSM look like lge pvemet stippes d opete bsiclly o the sme piciple. They c cut lyes eve if they e too thi (dow to m) d these mchies hve the best selective excvtio cpbility mog CSMs. While the mchie moves o the fomtio, the fomtio is cumbled by excvtig with cotiuously ottig cuttig dum. The mteil tht is ude specific size is tsfeed to pimy coveyo d the oto dischge coveyo i the mchie. The mteil filly is dumped to tucks, coveyig system o wokig field (Figue 3). I othe wods, i this opetio system, cuttig, pimy cushig d lodig e pefomed Figue 3 Opetiol system of Witge sufce mie 13 Tble III Opetiol pmetes d the equipmet list fo selective excvtio with hydulic excvto Pmetes Hydulic excvto with 4.59 m 3 Hydulic excvto with 7.65 m 3 Dily wokig peiod (hou) Aul wokig peiod fo 300 dys (hou) Bucket peiod (s) Bucket efficiecy (%) Bucket cpcity (m3) Tuck cpcity (st) Wokig efficiecy fo col (%) Wokig efficiecy fo itebude (%) Rte of wokig ode Wokig time pe hou (mi/h) Col desity (t/m3) Itebude desity (t/m3) Swellig fcto fo col Swellig fcto fo itebude (cly) Col poductio (toe/ye) Itebude toge septed (toe/ye) Totl umbe of mchies equied MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

9 Equipmet selectio fo high selective excvtio sufce col miig 1. Col extctio close to ptigs 2. Cuttig of ptigs 3. Col extctio T s c t i o Figue 4 High septio ccucy of Witge sufce mie 13 Tble IV Opetiol pmetes of WSM 4200 Pmetes Vlue P p e Miig Relted Pmetes Dily wokig Peiod (hou) 18 Aul wokig dy 300 Aul wokig peiod (hou) 5400 Mteil elted pmetes Col Cly Desity, δ, (toe/m3) Absiveess Noe Low Compessive stegth (N/m2) Tesile stegth (MP) Legth of cut, L, (m) Width fo opetio (m) Tuck cpcity, T, (sto) Tuck fillig fcto, F, (%) Mchie pmetes Width of cut, W, (m) 4 4 Depth of cut, D, (m) Fowd speed, S, (m/mi) Poductio elted pmetes Theoeticl cuttig pefomce (m3/h) Tuck lods (N) pe cut Tuck exchge time, e, (sec) Totl exchge time pe cut (E), (mi) Meuve time, M, (mi) Opeto efficiecy, O, (%) Effective poductio (m3/h) Effective toge (toe/h) pidly by oe mchie26,13. Whe WSM is used i sttified sufce col mie, it hs impott fetues d dvtges; s the WSM chieves smll ggegte size (<0.3 m), pimy cushig is ot ecessy. With the WSM, s the wste mteil i the ROM poduct deceses, thee will be o eed to tspot this wste mteil. Besides, sice sems o ptigs s thi s m e mied selectively with 0.01 m exceptiol septio ccucy s see Figue 4, both cle d high qulity u of mie oe poductio is chieved d utiliztio of miel sems d ecoveble of eseve e impoved13. The opetiol pmetes of the WSM 4200 model t the B 3 level of Seyitöme field e give i Tble IV. The dt i Tble IV wee obtied both fom the mie (mteil elted pmetes) d fom the mufctue s (mchie elted pmetes) ctlogue13. Poductio pmetes wee detemied by usig the followig equtios: Theoeticl cuttig pefomce = W D S 60 Tucklods (N) pe cut = (W D L ) /(T F) Totl exchge time pe cut (E) = (e/60) (N 1) Effective toge = W D L 60 O /(L/S + M + E) The vibles such s depth of cut (D), fowd speed (S) d legth of cut (L) s see i Tble IV e vied ccodig to the poductio desig, ese of excvtio, lye thickess, te of poductio d eed fo selectivity. The two impott fctos tht ffect the poductivity of sufce mie duig the excvtio e the cuttig legth d the cuttig depth, which e depedet o poductio The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

10 Equipmet selectio fo high selective excvtio sufce col miig (pel) desig, lye thickess, te of poductio d eed fo selectivity. The poductivity d the cpcity of the mchie c be icesed s the cuttig legth iceses. Cuttig depth is the key citeio fo the selectio efficiecy t col-cly sequecig. I plces whee the selectivity equiemet is high, the oly wy to icese the poductivity is to icese the legth of the cut. Aothe poductio pmete, fowd speed (S), is depedet o fomtio thickess to be excvted d the physicl d mechicl popeties of fomtio; the vlues wee obtied fom the mufctue s ctlogue. Poductio pmetes give i Tble IV wee clculted usig the ssumptio tht legth of cut is 50 m, depth of cut fo col is 0.7 d 0.2 m, d depth of cut fo cly is 0.5 m to 0.2 m (the umbes show the highest d the lowest selectivity). Tble V explis the effective cpcities d ul wokig hous clculted fo vious legths of cut depedig o highest selectivity coditios (0.2 m fo col d 0.2 m fo cly) d lowest selectivity coditios (0.7 m fo col d 0.5 m fo cly) fo poductio of toes of col d toes of cly fom the B 3 level i the mie. As c be see fom Tble V, the equied excvtio time deceses s the legth of cut iceses. Whe cosideig SLE coditios, the mximum legth of cut ws ssumed to be 300 m. Aftewds, the poductio cpcities fo col d the cly wee clculted s toe/h d toe/h, espectively, ssumig the mximum legth of cut ws 300 m d the vege depth of cut ws 0.3 m. As give i Tble IV, the ul opetiol time ws ssumed to be hous with 300 wokig dys ye d 18 wokig hous dy with 3 shifts. Usig this ul opetiol time, two sufce mies wee foud to be sufficiet to fulfil the ul demd. Schedulig Thee must be dequte poductio schedulig fo the excvtio to be doe by eithe of the mchies t the B 3 sem level. I the mie, i ode to poduce B 3 sem level col which is sold to the powe plt, the uppe levels of the B 1 d B 2 cols which e sold to the mket must be fistly poduced (Figue 5). I egios whee the tio of the B 3 sem thickess to totl sem thickess is lowe th 58%, the poductio t the B 3 sem level will educe owig to the lte dvce i the uppe levels. Fo this eso, i the fist yes the poductio should ot be mde s dul fce, d B 1 d B 2 sem poductio d B 3 sem poductio should be ccomplished t diffeet pels. The idel schedulig could be to poduce B 1 d B 2 sem cols whee the B 3 sem thickess is lowe (whee the lowest block cloific vlue exists, see Figue 5), d to poduce B 3 cols whee B 1 d Tble V Effective poductio cpcity of WSM 4200 d the equied excvtio time fo diffeet cuttig legths Legth of cut (m) Lowest selectivity Highest selectivity (septio thickess=0.7 m fo col d 0.5 m fo cly) (septio thickess=0.2 m fo col d 0.2 m fo cly) Poductio cpcity (toe/h) Requied excvtio time, (h) Poductio cpcity (toe/h) Requied excvtio time, (h) Col Cly Col Cly B1,B2 Steil Field B1,B2.B B2.B B Hetig Cotet (Kcl/Kg) Figue 5 Distibutio of the Levels ccodig to the egios 204 MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

11 Equipmet selectio fo high selective excvtio sufce col miig B 2 sem thickess e vey low o B 1 d B 2 levels wee ledy emoved (egios whee block cloific vlues e less th kcl/kg, see Figue 5). This type of schedulig lso povides eough wokig spce fo WSM pplictio which equies bech width of 60 m. Figue 6 shows the WSM-tuck pplictio t the B 3 level whose uppe level cols wee extcted befoe i the Asllı distict. I this poductio toes of col d toes of cly will be poduced i ye by two WSMs d with 0.3 m depth of cut d 300 m legth of cut t the B 3 level. Effects of selective excvtio o the ovell pocess compiso of the methods Fist of ll, high selective excvtio will ffect the qulity d the qutity of the col poduced t the B 3 sem level. The effects of selective excvtio o col qulity wee exmied by lysig d compig 3 diffeet coditios, mely; o-selectivity, cuet selectivity equiig 0.5 m septio thickess d vege col qulity of kcl/kg, d idel selectivity (high) equiig vege 0.3 m septio thickess d vege col qulity of kcl/kg i the B 3 level of the mie10. I this compiso, ul poductio ws ssumed to be 7.5 millio toes t the B 3 sem level, the mout of itebude d ecoveble col, col qulity d selectivity wee clculted cosideig the dilutios d miig losses. While the esults of these compisos e peseted i Tble VI, detiled fetues of the tble d the clcultio of pmetes e peseted i Appedix 1. As it is see fom Tble VI, ROM col qulity iceses due to the icese i selectivity. Fo idel selectivity coditios which lso equie blced mie plig, the composite cloific vlue of the B 3 level col give to the powe plt should hve vege cloific vlue of kcl/kg to comply with the equied cloific vlue of kcl/kg i the ROM col s see fom Appedix 1. I this idel selective miig coditio, lmost 7.5 millio toes of col d itebude will be excvted d 3 millio toes (~1.2 millio m3) of this poductio will be septed s wste i the B 3 level. The emiig 4.46 millio toes will be set to the powe plt s ROM col. I the cuet selectivity coditios, o the othe hd, 7.5 millio toes of col d itebude e excvted d 2.11 millio toes of this poductio is septed s wste i the B 3 level. The emiig 5.38 millio toes e set to the powe plt s ROM col. High selective miig will ot oly ffect the poductio cost but lso ffect the tspottio d col pocessig costs. I this esech, the totl costs of the cuet selective miig (excvtio dow to 0.5 m septio thickess) d high selective miig usig hydulic excvto-tuck d WSM-tucks dow to 0.3 m septio thickess wee comped d lysed. I the totl cost clcultios, excvtio, tspottio d pocessig costs wee ll cosideed fo the miig opetios usig the cuet selectivity d the high selectivity t the B 3 sem level. The excvtio costs of col d the wste i the B 1 d B 2 levels wee foud to be $0.124/toe d $0.067/toe, espectively, ssumig poductio of 3.22 millio toes of col d 1.7 millio toes of itebude mteils. The uit stippig cost fo ovebude ws tke s $0.156/m3. Howeve, these vlues wee ot used i the compisos of high selective miig ltetives sice the poposed high selective excvtio will be oly pplied t the B 3 sem level. I ode to detemie the excvtio costs t the B 3 sem level, fistly houly poductio cpcity of the selected excvtio mchies to be used t the peset d t idel (high) selectivity coditios ws detemied, d the esults e summized i Tble VII. Fo the houly poductio cpcity of hydulic excvto t col d cly excvtio, shovel cpcity of 4.59 m3 ws cosideed d the clcultios wee mde usig the pmetes i Tble III. The pmetes give i Tble III epeset the idel selectivity coditios d the poductio cpcities wee foud to be 347 toe/h d 543 toe/h fo col d cly, espectively. Fo the cuet selective excvtio, the poductio cpcities wee foud to be 442 toe/h d 693 toe/h fo col d fo cly, espectively, ssumig tht bucket efficiecy will ise but bucket peiod will educe. I these clcultios, bucket efficiecy d the bucket peiod wee tke s 0.90 d 23 secods fo both col d the cly; wokig ode pmetes, o the othe hd, wee tke s 0.85 d 0.80, espectively. The othe pmetes e give i Tble III. T s c t i o P p e Asli I A Asli III A 1 A Asli IV Figue 6 Applictio of WSM-tuck method t Asllı egio The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH

12 Equipmet selectio fo high selective excvtio sufce col miig Tble VI Compiso of o-selective, cuet selective d idel selective coditios Pmetes Selectivity No Cuet (>0.5 m septio thickess) Idel ( m septio thickess) Avege cloific vlue of sem (kcl/kg) Avege col sem thickess (m) I situ col thickess (m) I situ ptig thickess, (m) Cloific vlue of i situ col, (kcl/kg) I situ col volume (m3/ye) I situ ptigs volume (m3/ye) Totl excvted toge (toe/ye), M Totl excvted volume (m3/ye), V=M/yt Compositig Amout of dilutio i composite oe (toe/ye) Amout of miig losses i composite oe (toe/ye) Composite col toge (toe/ye) Composite ptigs toge (toe/ye) Cloific vlue of composite col (kcl/kg) Selective miig No Yes Yes Amout of dilutio i ROM col (toe/ye) Amout of miig losses i ROM col (toe/ye) Septed itebude toge (toe/ye) ROM col poductio (toe/ye) Cloific vlue of ROM col (kcl/kg) Selectivity, S Tble VII Cpcity of the mchies fo diffeet selective coditios Altetives Selective coditios Cpcity (toe/h) Col Cly WSM 4200 (ecommeded) Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) Hydulic excvto (4.59 m3) (ecommeded) Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) Rippe-doze-lode (7.65 m3) (i use) Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) The cpcity of the WSM fo idel d the cuet selectivity ws detemied by usig the pmetes i Tble III. Fo the idel selectivity, the cpcities wee foud to be toe/h d toe/hou fo the col d the cly, espectively, ssumig the vege legth of cut s 300 m d the vege depth of cut s 0.3 m. Fo the cuet selectivity, the cpcities wee detemied s toe/h d toe/h fo col d the cly, espectively, ssumig the vege legth of cut s 200 m d vege depth of cut s 0.5 m. Sice compessive stegth fo cly fomtios is highe th col, the speed d m3 pefomce of the WSM i this fomtio will be lowe th i col. Optimum opetiol speed of the WSM iceses s the thickess of the lye excvted deceses, s obtied fom the mufctue s ctlogue. The cpcity clcultios of ippe-doze-lode (7.65 m3) combitio wee mde by usig the pmetes i Tble III d 410 toe/h d 328 toe/h cpcities wee detemied fo the cuet d idel selectivity, espectively. Although the bucket cpcity of the lode ws selected s 7.65 m3, the houly cpcity ws foud to be lowe th the WSM d hydulic excvto. The eso fo tht ws the high time losses fo looseig, gtheig d lodig opetios i this combitio. Amog the thee ltetives, the WSM povides the highest cpcity due to the cotiuous system of opetio. Howeve, s the selectivity iceses, poductio cpcity fo ech system deceses. Afte houly cpcities of ech ltetive wee detemied, houly costs of the mchies wee foud fo the cuet d high selectivity i ode to clculte cost pe toe of col d cly excvtio. The esults e give i Tble VIII. I the clcultio the pmetes such s cpitl cost, fuel cost, lubictio cost, epi d mitece cost, spe pt cost d opeto cost wee couted. Most of the pmetes i Tble VIII wee obtied fom both the mie d the mchie mufctues. As see fom Tble VIII, the clssifictio of the systems ccodig to the houly cost dvtges is s follows: hydulic excvto, ippe-dozelode combitio d WSM. Cost costituets fo the WSM e much highe th the othes except fo opeto cost. Additiolly, withi spe pt cost, the excvtig bit cost fo the WSM becomes highe i cly fomtios due to silt cotet d the highe compessive stegth vlues of cly. 206 MARCH 2007 VOLUME 107 REFEREED PAPER The Joul of The Southe Afic Istitute of Miig d Metllugy

13 Equipmet selectio fo high selective excvtio sufce col miig Tble VIII Houly ivestmet d opetio cost of mchies Costs Ivestmet d opetiol costs ($/h) WSM 4200 Hydulic excvto (4.59 m 3 ) Rippe-doze-lode (7.65 m 3 ) Col Cly Col Cly Col Cly Cpitl cost (depecitio+iteest) Fuel cost Lubictio cost Repi d mitece cost Spe pt cost Opeto cost Totl cost T s c t i o Tble IX Uit excvtio d ul opetiol costs of selective excvtio ltetives Altetives Selective coditios Excvtio cost ($/toe) Aul opetio cost ($/ye) Col Cly WSM Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) Hydulic excvto (4.59 m3) Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) Rippe-doze-lode (7.65 m3) Cuet (1 462 kcl/kg) Idel (1 761 kcl/kg) P p e Tble X Geel poductio cost evlutio fo diffeet selective coditios Cost beig pocesses Costs fo cuet selective Costs fo idel selective coditio ($/ye) coditio ($/ye) Hydulic excvto WSM 4200-tuck Rippe-doze-lode (4.59 m 3 )-tuck method -tuck method method Excvtio Col d itebude tspottio Tspottio to the plt I situ dumpig Totl tspottio Pocessig Totl The eso why the ivestmet d opetiol costs e highe fo the ippe-doze-lode combitio th the hydulic excvto is tht it equies two mchies d moe opetios fo the excvtio/tspottio of the sme mout of mteil. Fo ech ltetive, the excvtio cost i cly ws foud to be highe th i col owig to excvtio difficulties. Cost pe toe ws detemied by dividig the clculted houly cost to houly cpcities fo col d cly i both the cuet d the idel (high) selectivity coditios. Aftewds, ul excvtio costs wee clculted by multiplyig the costs pe toe by ul col o cly poductios; the esults e summized i Tble IX. As see fom Tble IX, the clssifictio of excvtio ltetives ccodig to the cost dvtges pe toe o fo ul excvtio is s follows: hydulic excvto ($0.133/toe) WSM ($0.27/toe) ippe+doze+lode combitio ($0.625/toe). As c be see fom Tble VIII d Tble IX, the cpcity of the mchies deceses d the cost of opetio iceses s the te of selectivity iceses. The ovell cost evlutio of the peset d high selective miig ws mde by cosideig the cost of excvtio, tspottio d pocessig fo the cols fom the B 3 level d these evlutios d compisos e summized i Tble X. As see fom Tble X, if the col excvtio is cosideed loe, the ul poductio cost t the B 3 level with the WSM-tuck method is highe th the cost of the hydulic excvto-tuck method t idel selectivity coditios d th the lode-doze-tuck method The Joul of The Southe Afic Istitute of Miig d Metllugy VOLUME 107 REFEREED PAPER MARCH