AND MgO ON LIQUIDUS TEMPERATURES OF COPPER SMELTING AND CONVERTING SLAGS UNDER CONTROLLED OXYGEN PARTIAL PRESSURES

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1 J. Min. Metall. Sect. B-Metall. 49 (2) B (2013) Jurnal f Mining and Metallurgy, Sectin B: Metallurgy EFFECTS OF CaO, AND MgO ON LIQUIDUS TEMPERATURES OF COPPER SMELTING AND CONVERTING SLAGS UNDER CONTROLLED OXYGEN PARTIAL PRESSURES B. Zha a,*, P. Hayes a, E. Jak a a The University f Queensland, Schl f Chemical Engineering, Brisbane, Australia Abstract (Received 12 August 2012; accepted 01 March 2013) Phase equilibria f silicate slags relevant t the cpper smelting/cnverting peratins have been experimentally studied ver a wide range f slag cmpsitins, temperatures and atmspheric cnditins. Selected systems are f industrial interest and fill the gaps in fundamental infrmatin required t systematically characterise and describe cpper slag chemistry. The experimental prcedures include equilibratin f synthetic slag at high temperatures, rapid quenching f resulting phases, and accurate measurement f phase cmpsitins using electrn prbe X-ray micranalysis (EPMA). The effects f CaO, and MgO n the phase equilibria f this slag system have been experimentally investigated in the temperature range 1200 t 1300 C and xygen partial pressures between 10-5 and 10-9 atm. It was fund that spinel and silica are majr primary phases in the cmpsitin range related t cpper smelting/cnverting slags. In additin, livine, dipside and pyrxene als appear at certain cnditins. The presence f CaO, MgO and in the slag increases the spinel liquidus and decreases the silica liquidus. Liquidus temperatures in silica primary phase field are nt sensitive t P 2 ; Liquidus temperatures in spinel primary phase field increase with increasing P 2. At 1300 C and lw P 2, the spinel (Fe 2+,Mg 2+ )O.(Al 3+,Fe 3+ ) primary phase field can be replaced by wustite (Fe 2+,Mg 2+ )O. Key wrds: Cpper smelting; Cpper cnverting; Liquidus temperature; Slag. 1. Intrductin Cpper sulphide res are the majr surce f the wrld s primary cpper; the cpper is present in a number f minerals, cmmn examples being CuS, Cu 2 S, CuFeS 2, Cu 5 FeS 4, Cu 12 As 4 S 13. Assciated with these minerals are typically, FeS, FeS 2, silicate-based and minr minerals frm the hst rck. The cpper must be chemically separated frm sulphur, irn and a wide range f impurity elements in rder t meet specificatins fr sale n wrld markets. The pyrmetallurgical prcessing f these res invlves a series f high temperature xidatin reactins under cntrlled cnditins. The verall scientific basis fr the pyrmetallurgical prductin f cpper is nw well understd, and wrk in this field is exemplified by a series f experimental studies carried ut by Prf Akira Yazawa, and subsequent c-wrkers at Thuku University, Japan [1-6]. These studies essentially demnstrated that the Cu-Fe-O-S liquids generated during partial xidatin f cpper cncentrates are cmpletely miscible, but that phase separatin t sulphur-rich Cu 2 S-FeS melts (mattes) and * Crrespnding authr: bajun@uq.edu.au DOI: /JMMB Z xygen rich FeO-SiO 2 phase (slag) can be prduced thrugh the additin f silica t the system. It is nw well established that the partitining f the varius elements between metal, matte, slag and gas phases are principally functins f bulk cmpsitin, xygen and sulphur partial pressures and temperature. The liquidus temperatures (cnditins when the system is cmpletely liquid) have been determined fr the system FeO-Fe 2 -SiO 2 fr a range f xygen pressures, FeO -CaO-SiO 2 at irn metal saturatin and FeO-Fe 2 -CaO-SiO 2 in air [7]. The liquidus temperatures in the system Fe-Ca-O have als been determined at temperatures between 1200 and 1300 C [6]. One f the imprtant bjectives f cpper smelting/cnverting prcess is t remve impurities frm matte r metal thrugh the frmatin f the slag phase. The majr cmpnents f the cpper smelting and cnverting slags are irn xide and silica. Other cmpnents can als present in the slags, such as CaO, and MgO. Knwledge f the phase equilibria infrmatin f this slag system is required t determine the ptimum perating temperature. An ptimum perating temperature shuld enable 1) the MOLTEN12 - Cnference Special Issue Ninth Internatinal Cnference n Mlten Slags, Fluxes and Salts

2 154 B. Zha et al. / JMM 49 (2) B (2013) slag t be tapped smthly; 2) freeze lining is frmed between the slag and refractry t increase the life f the furnace; 3) matte r metal can be separated frm the slag. Phase equilibria f ferrus silicate slags in the systems -CaO- [8] and FeO - SiO 2 -CaO-MgO [9] at irn saturatin have been investigated in the cmpsitin ranges related t cpper smelting slags. Hwever, cpper smelting/cnverting prcesses perates at intermediate xygen partial pressures between 10-5 and 10-9 atm. Infrmatin f the chemistries and phase equilibria f ferrus silicate slags in air r at irn saturatin is nt sufficient t accurately describe the cmmercial cpper smelting/cnverting prcesses. It is imprtant t btain the infrmatin f phase equilibria and liquidus temperatures at the intermediate xygen partial pressures relevant t cpper smelting and cnverting fr the imprvement f existing and develpment f new technlgies. Phase equilibria and liquidus temperatures in the system FeO-Fe 2 -CaO-SiO 2 at the intermediate xygen partial pressures between 10-5 and 10-9 atm have been reprted recently [10-11]. Hwever, limited infrmatin is available n the effects f MgO and n phase equilibria and liquidus temperatures at the intermediate xygen partial pressures relevant t cpper smelting and cnverting slags. The aim f the present study is t demnstrate the methdlgy that is nw being used t prvide infrmatin n the slag chemistries f MgO- and -cntaining silicate slags, and t shw that the gaps in fundamental infrmatin, encmpassing the cnditins f industrial interest, in particular cpper prductin peratins, can be filled thrugh careful systematic labratry-based studies. Examples f new phase equilibrium infrmatin are prvided in this study n imprtant ferrus calcium silicate slag systems. 2. Experimental Experimental prcedure, including sample preparatin, equilibratin and examinatin, applied in this paper is in accrdance with already presented details in Ref.[10]. 2.1 Sample preparatin High purity xide and metal pwders were used as starting materials, i.e. CaO pwder (calcined at 1000 C frm 99.0 wt. % pure CaC pwder), SiO 2 (99.99 wt. % pure 1-3 mm fused lump that had been grund with an agate mrtar and pestle), Fe 2 pwder (99.99 wt. % pure), MgO pwder (99.95 wt. % pure), (99.99 wt. % pure) and Fe pwder (99.9 wt. % pure). Mixtures f varius cmpsitins were prepared by accurately weighing the xide/metal pwders and mixing them thrughly using an agate mrtar and pestle. The initial cmpsitins f the mixtures were selected such that at equilibrium there wuld be liquid phase in equilibrium with ne r mre slid phases. Each mixture was then pressed with pressure f 40 MPa t prduce a pellet weighing less than 0.2 grams [10]. T avid cntaminatin f the slag by the crucibles, apprpriate types f cntainment materials must be selected. Fr the slag system investigated in this study, platinum envelpes were used. The size f the platinum envelpe was 10 mm x 12 mm, made frm mm-thick platinum fil. The use f platinum envelpe ensures that n unexpected cmpnents are intrduced int the slag. It was fund that under the experimental cnditins a small amunt f irn was disslved in the platinum. Althugh this wuld slightly change the bulk cmpsitin f the mixture, the cmpsitins f the phases in equilibrium at temperature will be unchanged. At 1300 C and P 2 = 10-9 atm the SiO 2 cncentratin in liquid in wustite primary phase field is relatively lw, which results in high fluidity f the slag. On cling the crystallisatin rates are very high. The liquid phase in this system is therefre difficult t be quenched. New experimental prcedures have been develped t vercme this difficulty [12-13]. The new technique, the primary phase substrate suspensin technique used in the present study, invlves the preparatin f substrate materials that are knwn, frm preliminary experiments, t crystallise first during slidificatin f the melt. The irn xide substrate used in this prject was prepared frm irn fil (99.5 wt. % Fe, 0.1 mm thickness) supplied by Gdfellw Ltd. The substrate was first made t the shape required in the final experiment and then treated at required temperature and P 2 t frm wustite. The slag mixture was placed n the utside f the substrate and raised t the temperature in a P 2 cntrlled by CO 2 /CO gas mixtures. As the slag melts the mixture was held n the surface f the substrate by surface tensin frces, frming a thin film apprximately 100 µm thickness. Fllwing equilibratin the substrate and sample are released and quenched directly int water. The direct cntact f the liquid slag with the quenching medium and the thin slag film leads t rapid cling rates, much greater than can be achieved with the use f larger samples cntained in metal fil r in crucibles. 2.2 Equilibratin T mnitr the actual temperature surrunding the sample, a calibrated wrking thermcuple was placed immediately adjacent t the sample in a recrystallised alumina thermcuple sheath. The temperature f the experiment was cntinuusly

3 B. Zha et al. / JMM 49 (2) B (2013) cntrlled within 1 C f the target temperature. It is estimated that the verall abslute temperature accuracy f the experiment is within 3 C [10]. The xygen partial pressure inside the reactin tube was cntrlled by intrducing gas with a specific CO/CO 2 rati. The experiments were carried ut at xygen partial pressures between 10-5 and 10-8 atm. These xygen partial pressures required very lw CO/CO 2 ratis, thus premixed CO and Ar gases were used t achieve the target CO/CO 2 ratis. 5% and 20% CO diluted in high purity Argn (Beta standards, 0.02 % uncertainty) mixtures were supplied by BOC and high purity CO 2 ( % pure) was supplied by Cregas. The prprtin f each gas was cntrlled using pressure differential type flw-meter. The ttal flw-rate f the gas inside the furnace was ml/min and the fluctuatin f the gas flw-rate was fund less than 1 % f the ttal flw-rate [10]. A DS-type xygen prbe supplied by Australian Oxygen Fabricatrs (AOF, Melburne, Australia) was used t cnfirm the xygen partial pressures during the experiments. This was dne by directing the utput gas frm the equilibratin furnace int a separate vertical tube furnace held at the same temperature equipped with the DS-type xygen prbe. By this arrangement, the xygen partial pressure during the equilibratin was directly measured. The results f the measurements in the present study are within the accuracy f the DS-type xygen prbe, i.e. ± 0.1 lg (P 2 ) units. Equilibratin experiments were carried ut in a vertical tube furnace [10]. The specimen with suitable cntainer material was intrduced frm the bttm f a vertical tube furnace and suspended n a sample hlder made f platinum wire. Befre the specimen was raised int the ht zne f the furnace, the reactin tube was precnditined fr 30 minutes t the required temperature and xygen partial pressure/gas cmpsitins. The specimen was then raised int the ht zne f the furnace and pre-melting f the sample was carried ut at temperature 20 C abve the target temperature. After 30 minutes f pre-melting, the sample was equilibrated fr 24 hurs at the target temperature and xygen partial pressure/gas cnditin. After the equilibratin the bttm end f the furnace was released and the base f the furnace was immersed in water. The specimen was rapidly quenched int the water by pulling the sample hlder upward. The quenched sample was dried n a ht plate, sectined int smaller pieces and munted in epxy resin. The munted sample was then plished fr metallgraphic and EPMA examinatins. 2.3 Examinatin The plished samples were initially examined using an ptical micrscpe t identify the phases present. Then the sample was cated with carbn film using a JEOL (Japan Electrn Optics Ltd) Carbn Cater fr electrn micrscpic examinatin. A JXA 8200 Electrn Prbe Micranalyser (EPMA) was used fr further analysis. Quantitative analysis was perfrmed at an accelerating vltage f 15 kv and a prbe current f 15 na. The Duncumb-Philibert ZAF crrectin prcedure supplied with the EPMA was applied. The standards used fr analysis were frm Charles M. Taylr C. (Stanfrd, Califrnia): fr Al, CaSi fr Ca and Si, Fe 2 fr Fe and MgO fr Mg. The average accuracy f the EPMA measurements was estimated t be within ± 1 weight percent f the element cncentratin. Irn is present in the slag in bth Fe 2+ and Fe 3+ frms. EPMA cannt measure Fe 2+ and Fe 3+ separately. All irn is calculated as FeO in this article fr presentatin purpse. 3. Results Irn xide (spinel r wustite) and tridymite (SiO 2 ) are majr primary phases in the cmpsitin ranges investigated. Typical micrstructures f the quenched samples are presented in Figures 1 and 2, shwing Figure 1. Typical micrstructures f quenched slags frm a) spinel and b) tridymite primary phase fields, 1300 C, P 2 = 10-7 atm

4 156 B. Zha et al. / JMM 49 (2) B (2013) well-quenched liquid slag in equilibrium with the primary phases. Figure 1a shws a typical micrstructure f quenched sample frm the spinel primary phase field; Figure 1b shws a typical micrstructure f quenched sample frm the tridymite primary phase field. Figure 2 shws a typical micrstructure f quenched sample frm the wustite primary phase field. The liquid phase present in this sample has a lw SiO 2 cncentratin and is difficult t quench t hmgenus glass using cnventinal appraches. An irn xide substrate rather than a Pt envelpe was used in this experiment; it can be seen that hmgenus glass was btained as a result f this rapid quenching technique. Figure 2. A typical micrstructure f quenched slag frm the wustite primary phase field, 1300 C, P 2 = 10-9 atm Phase diagrams in the multi-cmpnent systems -CaO-MgO-, fr cnvenience f use, are ften presented in a frm f pseud-ternary sectins -CaO at fixed r MgO cncentratins. Fr these multi-cmpnent systems it is difficult t experimentally btain the exact target cncentratins f all cmpnents in the liquid phase (fr example, MgO = 4.0 wt. %) due t the precipitatin f slid phases frm the melt and interactin f the liquid with the cntainer/substrate. An ptimisatin prcedure has therefre been intrduced t analyse and interplate all experimental data having a range f cncentratins f the minr cmpnents r MgO in the liquid at a given primary phase field, temperature and xygen partial pressure. The basis f the ptimisatin is that at a given CaO cncentratin in liquid the FeO /SiO 2 rati in liquid is functin f and MgO cncentratins. The experimental measurements can then be described by the fllwing empirical equatins: X(F/S) = F 0 + F Ca1 *(X Ca ) 2 + F Ca2 *X Ca + + F Al *X Al + F Mg *X Mg...(1) X Si =(100-X Ca - X Al X Mg )/(1+X(F/S))...(2) X Fe = 100-X Ca - X Al X Mg -X Si...(3) where X(F/S) is the weight rati f FeO /SiO 2, F 0, F Ca1, F Ca2, F Al and F Mg are the interplatin cefficients btained fr a given temperature and P 2 by minimising the sum f squared differences f experimental and calculated cncentratins, and X Si, X Fe, X Ca, X Al and X Mg are the cncentratins f SiO 2, FeO, CaO, and MgO respectively in weight percent in the liquid. The examples f the interplatin results fr relatinship between FeO (r SiO 2 ) cncentratin and in liquid are shwn in Figures 3 and 4 fr 1300 C and P 2 = 10-7 atm. In these figures slid symbls represent experimental pints, straight lines represent the interplatin at a given CaO cncentratin and pen symbls represent calculated pints at the same cncentratins. It can be seen that nt nly the cncentratin but als CaO cncentratin has significant effect n the liquidus cmpsitin. This interplatin prcedure intrduces a number f advantages. It enables the cnsistency f experimental results t be checked during the curse and after the investigatin. Experiments are planned s that the whle range f cncentratins f interest is described with ne set f interplatin cefficients rather than fcusing n exact fixed cmpsitins. All experiments at a given temperature and xygen partial pressure are used simultaneusly fr a given fixed cncentratin f FeO, CaO, SiO 2, and MgO. Istherms at any required fixed cncentratin within the investigated cmpsitin range can then be cnstructed using this set f interplatin cefficients. Figure 3. Crrelatins between FeO and cncentratins in the liquid in equilibrium with spinel at 1300 C and P 2 = 10-7 atm in the -CaO- slags, the number abve each f the symbl is the actual CaO cncentratin in liquid; Slid symbls: experimental results; Open symbls: interplated pints; Straight line: best fitted line fr the given CaO cncentratin

5 B. Zha et al. / JMM 49 (2) B (2013) Figure 4. Crrelatins between SiO 2 and cncentratins in the liquid in equilibrium with spinel at 1300 C and P 2 = 10-7 atm in the -CaO- slags, the number abve each f the symbl is the actual CaO cncentratin in liquid; Slid symbls: experimental results; Open symbls: interplated pints; Straight line: best fitted line fr the given CaO cncentratin It can be seen frm Figure 3 that bth and CaO have significant effects n the FeO cncentratin in the liquid. At a given CaO cncentratin, the FeO cncentratins in the liquid decrease with increasing cncentratin. The slpes f the three lines at 0, 8 and 17 wt% CaO in Figure 3 are apprximately -1.4 regardless CaO cncentratins. At a given cncentratin, the FeO cncentratins in the liquid decrease with increasing CaO cncentratin. Similarly, Figure 4 shws that at a given CaO cncentratin the SiO 2 cncentratins in the liquid increase with increasing cncentratin. At a given cncentratin, the SiO 2 cncentratins in the liquid increase with increasing CaO cncentratin. It is well knwn that liquidus temperatures in spinel primary phase field increase with increasing FeO /SiO 2 rati. Increased CaO and cncentratins in the slag require extra SiO 2 flux t remain the same liquidus temperature and t avid the frmatin f spinel slid. Using the abve relatinships the liquidus istherms fr 1300 C at P 2 = 10-7 atm are presented in Figures 5 and 6 fr additins f and MgO respectively. These are the prjectin f the 1300 C istherms with 0, 2, 4 and 6 wt% r MgO in liquid nt the plane -CaO. It can be seen that the istherms in bth spinel and tridymite primary phase fields mve twards SiO 2 directin with increasing r MgO cncentratin in liquid. This indicates that the liquidus temperatures in the spinel primary phase field increase with increasing r MgO cncentratin in liquid. In cntrast, the liquidus temperatures in the tridymite primary phase field decrease with increasing r MgO cncentratin in liquid. Figure 5. Effect f n liquidus istherms at1300 C and P 2 = 10-7 atm in the -CaO- slags, prjected nt the -CaO plane Figure 6. Effect f MgO n liquidus istherms at 1300 C and P 2 = 10-7 atm in the -CaO-MgO slags, prjected nt the -CaO plane Figures 7 and 8 shw experimentally determined istherms f 1300 C at P 2 = atm fr additins f 4 wt% r 4 wt% MgO respectively. It can be seen that the istherms in tridymite primary phase field are nt sensitive t xygen partial pressure. The istherms in spinel primary phase field mve twards SiO 2 directin with increasing xygen partial pressure. This indicates that the liquidus temperatures in the spinel primary phase field increase with increasing xygen partial pressure. It can be seen frm the Figure 7 that with 4 wt% present in the slag, the primary phase at high-irn regin is changed frm spinel t wustite at xygen partial pressure between 10-8 and 10-9 atm. The slid thick line indicates the bundary between the spinel and wustite primary phase field. It can be seen frm Figure 8 that with 4 wt% MgO present in the slag, the primary phase at high-irn regin is changed frm spinel t wustite at xygen partial pressure between 10-7 and 10-8 atm. The liquidus temperatures in the

6 158 B. Zha et al. / JMM 49 (2) B (2013) wustite primary phase field seem nt t be sensitive t changes in xygen partial pressure between 10-8 and 10-9 atm. same liquidus temperature, Fe/SiO2 rati in the liquid needs t be decreased t balance the increment in Al2O3/CaO/MgO cncentratin. Fr example, at 1300 C and P2 = 10-7 atm, the Fe/SiO2 rati is 2.33 fr a slag withut Al2O3, CaO and MgO. If the CaO cncentratin in this slag is increased t 10 wt%, the Fe/SiO2 rati has t be decreased t 1.71 t maintain the same liquidus temperature. This means that mre silica flux has t be added. Mre detailed crrelatins between Fe/SiO2 rati and Al2O3/CaO/MgO cncentratins at 1300 C and P2 = 10-7 atm are shwn in Figure 10. It can be seen clearly frm Figure 10 that Al2O3, CaO and MgO shw slightly different effect n Fe/SiO2 rati. CaO seems t have mre significant effect. Figure 7. Effect f P2 n istherms at 1300 C and 4 wt% Al2O3 in the FeO -SiO2-CaO-Al2O3 slags, prjected n the FeO -SiO2-CaO plane Figure 9. Effect f Al2O3/CaO/MgO n istherms f 1300 C and P2 = 10-7 atm in the spinel primary phase field, prjected n the FeO -SiO2-CaO plane Figure 8. Effect f P2 n istherms f 1300 C and 4 wt% MgO in the FeO -SiO2-CaO-MgO slags, prjected n the FeO -SiO2-CaO plane Al2O3, CaO and MgO are usually present in cpper smelting slag as minr elements. They are intrduced thrugh cncentrate, flux, cal and refractries. Analysis f experimental data shws that they have similar effect n the liquidus temperature in spinel primary phase field. Figure 9 shws the mvement f the spinel liquidus at 1300 C and P2 = 10-7 atm with increasing Al2O3/CaO/MgO cncentratin. The starting FeO -SiO2 slag has Fe/SiO2 rati f It can be seen that the spinel liquidus mves twards lw Fe/SiO2 rati with increasing Al2O3/CaO/MgO cncentratin in the liquid. In the ther wrd, the liquidus temperatures in the spinel primary phase field are increased with increasing Al2O3/CaO/MgO cncentratin in the liquid. The rder f the effect n the liquidus temperature is CaO > MgO > Al2O3. T maintain the Figure 10. Crrelatins between Fe/SiO2 weight rati and Al2O3/CaO/MgO cncentratins at 1300 C and P2 = 10-7 atm Figure 11 shws liquidus temperature as a functin f Fe/SiO2 weight rati at P2 = 10-8 atm. The lines are calculated results by FactSage 6.2 [14] and

7 B. Zha et al. / JMM 49 (2) B (2013) the symbls are experimental results interplated frm present experimental data. It can be seen frm FactSage calculatins that spinel and tridymite are the primary phases present in this cmpsitin range fr, -CaO and -CaO- slags. Olivine is als a primary phase in FeO - SiO 2 -CaO-MgO slag. Liquidus temperatures always decrease in tridymite primary phase field and increase in spinel and livine primary phase fields with increasing the Fe/SiO 2 rati. Fur experimentally determined liquidus pints at 1200 C and ne at 1300 C are shwn in the figure fr cmparisn. The pints at 1200 C are frm the spinel primary phase field and the pint at 1300 C is frm the wustite primary phase field. It can be seen frm the cmparisn that in system, experimentally determined liquidus in the spinel primary phase field is at a Fe/SiO 2 weight rati f 1.4 rather than 1.7 predicted by FactSage. The actual liquidus temperatures in spinel primary phase field are higher than the predictins. FactSage indicates the slags with Fe/SiO 2 weight rati less than 1.6 are saturated with silica. in -CaO and -CaO- systems, experimentally determined liquidus temperatures in spinel primary phase field are apprximately 15 and 20 C respectively higher than the predictins. in -CaO-MgO system, experimentally determined liquidus temperatures in wustite primary phase field (Fe/SiO 2 = 2.5) is apprximately 10 C higher than the predictins. Hwever, at Fe/SiO 2 = 1.2, livine is predicted t be the primary phase and experimentally it has been shwn that this is the spinel primary phase. The measured spinel liquidus is apprximately 40 C lwer than the predicted livine liquidus. Figure 11. Liquidus temperature as a functin f Fe/SiO 2 weight rati, P 2 = 10-8 atm, lines are calculated by FactSage 6.2, symbls are experimental results in spinel (1200 C) and wustite (1300 C) primary phase fields 4. Cnclusins The liquidus temperatures f cpper smelting/cnverting slags have been determined by equilibratin/quenching/epma technique. It has been demnstrated that phase equilibria can be determined ver a wide range f cmpsitins, temperatures and xygen partial pressures t prvide the essential infrmatin required t describe cpper slag chemistries. The effects f xygen partial pressure and additinal minr cmpnents, CaO and MgO n the phase equilibria and liquidus temperatures f silicate slags have been discussed. The infrmatin will be used t imprve the industrial peratins and fr the ptimisatin f thermdynamic databases. Acknwledgement The authr wuld like t thank Ms Jie Yu fr general labratry assistance and careful sample preparatin. The Australian Research Cuncil Linkage prgram, Ri Tint Kennectt Utah Cpper, Crp., Xstrata Technlgy, Xstrata Cpper, BHP Billitn Olympic Dam Operatin and Outtec Finland Oy fr their financial supprt. References [1] A. Yazawa, M. Kameda, Tech Repts Thku Univ., (1953) 50-58; (1954) 1-22; (1955) , ; (1956) [2] E. Mtnri, A. Yazawa, Trans. J. Inst. Metals, 18 (1977) [3] K. Masaru, E. Mtnri, A. Yazawa, Trans. J. Inst. Metals, 19 (1978) [4] C. Acuna, A. Yazawa, Trans. J. Inst. Metals, 28 (1987) [5] A. Yazawa, Can. Met. Quart., 13 (1974) [6] Y. Takeda, S. Nakazawa, A. Yazawa, Can. Met. Quart., 19 (1980) [7] VDEh, Slag Atlas, 2nd ed, Verlag Stahleisen, [8] B. Zha, E. Jak, P.C. Hayes, Metall. Mater. Trans. B, 30B (1999) [9] B. Zha, E. Jak, P.C. Hayes, Metall. Mater. Trans. B, 30B (1999) [10] T. Hidayat, P.C. Hayes, E. Jak, Metall. Mater. Trans. B, 43B (2012) [11] T. Hidayat, P.C. Hayes, E. Jak, Metall. Mater. Trans. B, 43B (2012) [12] B. Zha, C. Nexhip, D. P. Gerge-Kennedy, P.C. Hayes, E. Jak, Cpper 2010, Hamburg, Germany, 2010, Vl. 3, p [13] E. Jak, B. Zha, C. Nexhip, D. P. Gerge-Kennedy, P.C. Hayes, Cpper 2010, Hamburg, Germany, 2010, Vl. 2, p [14] C.W. Bale, P. Chartrand, S.A. Decterv, G. Erikssn, K. Hack, R.B. Mahfud, J. Melançn, A.D. Peltn, S. Petersen, FactSage, Ecle Plytechnique, Mntréal.