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Application of process mineralogy as a tool in sustainable processing C.L. Evans a,⇑ , E.M. Wightman a , E.V. Manlapig a , B.L. Coulter b a The University of Queensland, Sustainable Minerals Institute, Julius Kruttschnitt Mineral Research Centre, Indooroopilly, QLD 4068, Australia b Xstrata Technology, Level 4, 307 Queen St., Brisbane, QLD 4000, Australia a r t i c l e i n f o Article history: Available online 9 April 2011 Keywords: Ore mineralogy Comminution Froth flotation Liberation a b s t r a c t The obse rved beh avio urs of min era l part icle s in min eral proc essin g ope ratio ns have been exp loite d in the past to mod el commin utio n and conc entr atio n proc esse s. In this work this co nce pt has b een take n a step further, exploiting the mineralogical characteristics of particles to link comminution, concentration and smelt ing . This appro achis de mo nst rat ed usi ng a lab oratory- bas ed ca se stu dy of a Ni –Cu sul phideore. The case study focused on the effect of shifting energy between the comminution and smelting stages on the overall energy consumption for the metal production process. To model this effect the mineral composi- tion of the particles was linked to the behaviour of the ore particles in the primary grinding, regrinding and flotation stages. This application of process mineralogy provides a methodology to minimise energy use across mineral concentration and smelting processes, an important aspect of sustainable processing. 2011 Elsevier Ltd. All rights reserved. 1. Introduction The increasing availability of automated mineralog y systems provides an opportuni ty for metallurgists to mode l miner al pro- ces sin g op era tio ns in terms of pa rt icl es an d th eir mi ne ra l co mp osi - tion. Th e models pu bli shed in the lit er ature fal l into two cat eg or ies – those based on fundamental properties of the mineral particles and tho se base d on heu rist ics dev elop ed by obse rvi ng the pro cess- ing beh av iours of ore pa rticles. Th e fund amental modelli ng of mi n- era l lib era tio n in com mi nu tio n is a resear ch ar ea wh ich ha s exercised the minds of many researchers, starting with Gaudin in 1939 and continuing to the present day ( Wiegel , 1976; Barbery and Leroux, 1988; King, 1979; Gay, 1994). Similarly the prediction of flotation behaviour from fundamentals is a continuing area of research with many branches of science including surface chemis- try and electrochemistry contributing to the understanding of this comple x process. Wh ile the fun dam ent al rese arch con tinu es, the nee d for mo dels which can be appl ied to sim ulate the eff ect of cha ng es to liberation and the subs equ ent impact on flot atio n pro cesses has led oth er researchers to develop models of these processes based on heuris- tics. Such models have been used in the past to optimise the pro- cess chain in te rms of a va riety of pa ram ete rs for ex ampl e mineral recovery (Bazin et al., 1994) and economic value (McIvor and Finch, 1991). With the recent focus on sustainability in mining and the drive for reso urce s compan ies to minimise the energy use in ene rgy - intensive processes such as comminution and smelting, there is a ne ed fo r to ol s wh ich all ow com pa nies to op timise thei r pr ocess en- ergy use. This research focuses on using quantitative mineralogy and heuristic models to identify where in the comminution–flota- tion–smelting process chain energy is most efficiently applied; in particular, this work can assist engineers in developing strategies to reduce overall ene rgy con sum ptio n across the concen tra tor and smelt er pr ocess cha in by ad din g more reg rin di ng ener gy to re- move from the final concentra te minerals which are deleter ious to the smelting process. Metallurgists recognise that there is scope to tune the operation of a concentrator to change the product quality and also scope to tune the smelter operation to smelt a different gra de of con cen trat e. How ever, there is no integrated tool cur - rently available which allows companies to model the combined effect of these changes on overall energy consumption in the mill and smelter. The methodology developed in this research, termed ‘‘Mill to Melt’’ provides such an integrated approach in which the linkage between the various processes is information on particle mineralogical composition. 2. Modelling liberation and flotation The met hod olo gy dev elop ed in this rese arch exp loit s some heu- rist ics wh ich are base d on the obs erv ed beh aviours of ores in com- minution and flotation. A range of authors, starting with Bérubé and Ma rch an d in 1984, ha ve ob serve d that the amou nt of lib erate d mineral in a given size fraction is the same, regardless of where in the comminution circuit the sample is taken. The heuristics have been reported to be applicable to a range of ores including iron ore (Bérubé and Marchand, 1984), Mt Isa lead–zinc ore ( Manlapig et al., 1985), a range of Australian copper ores and a lead–zinc ore 0892-6875/$ - see front matter 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2011.03.017 ⇑ Corresponding author. Address: JKMRC, 40 Isles Road, Indooroopilly, QLD 4068, Australia. Tel.: +61 7 3365 5888; fax: +61 7 3365 5999. E-mail address: [email protected] .edu.au (C.L. Evans). Minerals Engineering 24 (2011) 1242–1248 Contents lists available at ScienceDirect Minerals Engineering journal homepage: www.elsevier.com/locate/mineng
