Addressing the envelope

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Addessing the envelope by P. Hnd* nd D. Wisemn J o u n l Synopsis Most col plnts must un unde conditions of vying feed conditions o e sked to poduce qulities diffeent fom tht used in the design.

1 Addessing the envelope by P. Hnd* nd D. Wisemn J o u n l Synopsis Most col plnts must un unde conditions of vying feed conditions o e sked to poduce qulities diffeent fom tht used in the design. This cn cuse oveloded conditions s the bottlenecks within the plnt, depending on plnt opetion o s the feed chnges. Duing plnt design, geologicl infomtion cn be used to detemine wshbility envelopes nd blends tht my be expected. Histoicl dt cn lso be used to develop size distibution envelope s well s to ssign esonble models fo ech of the unit pocesses. In opetion, plnt cn be smpled to detemine chnges nd to efine pocess models. The infomtion obtined cn then be used in n ccute simultion to define how the plnt cn del with the chnging envionment. This ppe uses Limn:The Flowsheet Pocesso to simulte the col plnt in detil nd will poduce n ccute model, in tems of equipment sizing s well s wte, medium, nd solids blnce, fo ech chnge in feed condition. It will show exmples of unning the simultion though complete density nd size nges nd will detemine the equipment equied to ddess ech pt of the pefomnce envelope. Intoduction Simultions of col wshing plnts e used fo mny esons, fom investigtion of difficult to wsh cols, to the effect of using diffeent seption equipment on yield nd qulity of poduct (Clkson, Edwd, nd Lhey 1998). In ddition, since simultion pckges such s Limn:The Flowsheet Pocesso (Leoux nd Hdie. 2003, Wills nd Npie-Munn, 2006) cy stem popety infomtion such s mss flow, volume nd density of sluies s pt of the simultion, this infomtion cn be used to detemine on the fly the equipment equied to wsh the feed col. This ppe shows n exmple simultion of col fom thee souces, ech with diffeent wshbility, nd with two types of pticle size distibution (PSD). Use is mde of scenio solve to exmine the equipment equied to pocess the wshbility nd PSD envelopes tht my be sent to the plnt. The use of efficiencies fo ech piece of equipment enbles tue estimte of wshing pefomnce nd the development of pcticl wshbility. This will depend on equipment used nd fines nd slimes tetment, unlike the theoeticl wshbility geneted fom geologicl models, to which fudge fctos o plnt fctos e nomlly pplied. The plnt flowsheet Fo the puposes of simplifiction of options fo this ppe, fines nd slimes tetment consists of clssifying into fines nd slimes fctions. The fines e dewteed on high fequency sceen then discded while the slimes e thickened nd the undeflow discded. In moe complex studies, tetment of both fctions cn be (nd often e) simulted. In ddition, lso fo simplifiction, the dense medium cyclones e fixed t 810 mm dimete. Once gin, in pctice the effect of lge o smlle cyclones cn be simulted with chnges to the model E pm bsed on cyclone dimete nd pticle size. This is citicl e, pticully when wshing difficult cols such s those fom South Afic nd Indi. Figue 1 shows the model of E pm nd ctul cutpoint vesus pticle size fo 810 mm dense medium cyclone. The plnt flowsheet used fo the simultions in this ppe is shown in Figue 2. The plnt model is blnced in cicuit in col nd eject solids s well s mgnetite nd wte (Hnd nd Wisemn 2008). This is chieved by clcultions within the equipment models s well s by using constint * Isndl Col Consulting, Johnnesbug, South Afic. Dvid Wisemn Pty Ltd, Adelide, Austli. The Southen Aficn Institute of Mining nd Metllugy, SA ISSN X/ This ppe ws fist pesented t the 16th Intentionl Col Peption Congess in Lexington fom Apil 2010 nd is epinted with pemission of the Society fo Mining, Metllugy, nd Explotion. P p e The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 110 JULY

Addessing the envelope Figue 1 Size vition of Epm nd cutpoint RD (Rho50) pmetes used in 810 mm dense medium cyclone model Deslime wte Wte ing min Plnt wte Feed CM hede box CM feed Dilute Med splitte

2 Addessing the envelope Figue 1 Size vition of Epm nd cutpoint RD (Rho50) pmetes used in 810 mm dense medium cyclone model Deslime wte Wte ing min Plnt wte Feed CM hede box CM feed Dilute Med splitte box Totl poduct Totl poduct Deslime undeflow CM delivey Mke up medium Deslime Mg sep feed Discd Mke up wte Fine poduct CM wte mke up Clssifying cyclone feed Thickene u flow Wte stoge tnk Figue 2 The plnt flowsheet used fo the simultion studies descibed in this ppe contolles on the wte ing min to chieve blnce fo wte, s shown in Figue 3. The equipment models used cn be eithe igoous o ule of thumb, depending on necessity nd the vilble dt (Osbone 1988). An exmple of dense medium cyclone dt pge is shown in Figue 4 nd n exmple of the Excel VBA code used in the clcultions is shown in Figue 5. Vying feed conditions It hs been sid tht constnt chnge is the only tue constnt nd this is pticully tue of col wshing plnt feeds. Pope blending fcilities e needed befoe wsh plnt ttempt to emove lge vitions in feed in tems of both wshbility nd pticle size distibution. Howeve, vitions will still occu nd judgements must be mde bout the size of envelope tht cn be llowed to ensue miniml eduction in plnt thoughput while minimizing plnt cpitl expenditue. Rel wold wshing plnt simultions Hving set up the flowsheet nd the feed chcteistics, the simultion cn be used to obtin infomtion on the equipment equied to wsh the envelope. Pcticl wshbility Figues 6 nd 7 show the esults of seies of simultions, esulting in the pcticl wshbility ove blend of the thee col types. A wsh is cied out in medium of RD 1.2 to Fom this the cutpoint is clculted t ech RD nd 366 JULY 2010 VOLUME 110 The Jounl of The Southen Aficn Institute of Mining nd Metllugy

3 Addessing the envelope J o u n l Figue 3 Constint contolle setup fo detemining wte mke up equiement P p e Figue 4 Dense medium cyclone model input Figue 5 Exmple VBA Code The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 110 JULY

Addessing the envelope Figue 6 Pcticl wshbility Figue 7 Pcticl wshbility nd equied equipment Figue 8 Scenio solve showing diffeent feed wshbilities (blended befoe the plnt) nd two PSDs the esultnt

The selected equipment then defines the envelope within which the plnt cn opete.

A combintion of col types nd feed size nges cn be fed to the simultion using the scenio solve. An exmple is given in Figue 8.

4 Addessing the envelope Figue 6 Pcticl wshbility Figue 7 Pcticl wshbility nd equied equipment Figue 8 Scenio solve showing diffeent feed wshbilities (blended befoe the plnt) nd two PSDs the esultnt col qulities detemined. Figue 6 is the pcticl wshbility showing yield nd NCVAR, nd Figue 7 shows the numbe nd size of the equipment equied to wsh t ny density. The selected equipment then defines the envelope within which the plnt cn opete. Fo this feed consist nd poduct size distibution, the point t which equipment is dequte to wsh the col cn simply be ed off the gph. A combintion of col types nd feed size nges cn be fed to the simultion using the scenio solve. An exmple is given in Figue 8. The gph in Figue 9 shows the yields nd CV obtined by wshing fo consistent 15% sh, contolled within the simultion using constint contolle. Figue 10 shows the totl widths equied (in metes) fo the desliming, flot, nd sink sceens s well s the totl width of the 0.9 m dimete mgnetic septos equied. 368 JULY 2010 VOLUME 110 Figue 11 then shows the numbe of 810 mm dense medium cyclones needed nd the thickene dimete bsed on volumetic nd solids loding possible obtined fom settling tests. The infomtion glened cn then be used to detemine the numbe of modules equied o the simultions cn be epeted using diffeent cyclone dimetes, bnn sceen fctos, etc. to mtch chnging design o opeting specifictions. Plnt blnce The plnt consumption of consumbles cn lso be estimted using expected mgnetite nd wte losses fom mgnetic septos, poducts, nd discds. An exmple is shown in Figue 12. The Jounl of The Southen Aficn Institute of Mining nd Metllugy

5 Addessing the envelope J o u n l P p e Figue 9 Yields nd CV fo consistent sh but vying feeds Figue 10 Sceen nd mgnetic septo dimensions equied to wsh the envelope Figue 11 Numbe of cyclones nd thickene dimete The Jounl of The Southen Aficn Institute of Mining nd Metllugy VOLUME 110 JULY Figue 12 Mgnetite nd wte consumption clcultions

Addessing the envelope Conclusions Refeences The ppe hs given n illusttion of the use of simultion pckge to detemine the equipment equied in wsh plnt needed to ccommodte vying feeds, in tems of

6 Addessing the envelope Conclusions Refeences The ppe hs given n illusttion of the use of simultion pckge to detemine the equipment equied in wsh plnt needed to ccommodte vying feeds, in tems of wshbility nd PSD, plnt lyout, nd indeed ny vible tht my be encounteed. The plnt simultion cn be set up to be fully blnced in tems of mteil, wte, nd mgnetite. The pcticl wshbility cn lso be used, even t n ely stge in the mine plnning pocess, to give tue estimte of yield t given qulity, pticully with difficult to tet cols. All plnts hve bottlenecks; the key is in moving them to whee they e less impotnt. The use of simultion pckge cn fcilitte the design of wsh plnts to ddess the envelope while minimizing ovedesign. CLARKSON, C.J., EDWARD, D.J., nd LAHEY, A.E. Use of Simultions in Col Peption Plnt Pctice. XIII Intentionl Col Pocessing Congess, ACPS, Bisbne Austli JULY 2010 VOLUME 110 HAND, P.E. nd WISEMAN D.M. Combined Col And Medium Cicuit Simultion Fo Design And Optimistion 12th ACPC (Austlin Col Peption Society Confeence). Sydney LEROUX, D. nd HARDIE, C. Simultion of Closed Cicuit Minel Pocessing Opetions using Limn Flowsheet Pocessing Softwe. CMP 2003 Cndin Minel Pocesso s 35th Annul Opeto's Confeence, Quebec, Cnd OSBORNE, D.G. Col Peption Technology, Ghm & Totmn Limited, London, UK WILLS, B.A. nd NAPIER-MUNN, T.J. Will s Minel Pocessing Technology, Buttewoth-Heinemnn, London, The Jounl of The Southen Aficn Institute of Mining nd Metllugy

The influence of the quality of ferrosilicon on the rheology of dense medium and the ability to reach higher densities

The influence of the quality of ferrosilicon on the rheology of dense medium and the ability to reach higher densities The influence of the qulity of feosilicon on the heology of dense medium nd the bility to ech highe densities by H.A. Mybugh* J o u n l Synopsis The dense medium beneficition of hevy metl oxide oes such