Phase equilibrium and minor element distribution between FeO x -SiO2-MgO-based slag and Cu2S-FeS matte at 1573 K under high partial pressures of SO2

Abstract

As part of a fundamental study of copper smelting processes using oxygen or oxygen-enriched air as a blowing gas, phase equilibrium and distribution of minor elements between copper matte and SiO 2 -saturated FeO X -SiO 2 -MgO-based slag containing 5 to 10 wt pct MgO have been investigated at 1573 K under the SO 2 partial pressures of 10.1, 50.7, and 101.3 kPa. The copper and sulfur solubilities in the slag were found to be independent of p SO 2 when the matte grade was specified, and this behavior was ascribed to the constancy of ( p O 2 /p S 2 ) against p SO 2 at a given matte grade. When the distribution ratio of a minor element (X) between the slag and matte phases was defined as L s/m x ϭ (wt pct X in slag)/{wt pct X in matter}, L s/m x for arsenic, antimony, and bismuth at a given matte grade increased with increasing p SO 2 . On the other hand, the distribution ratio of silver at a given matte grade was almost constant against p SO 2 .

Arsenate capacities of copper smelting slags

“…. ), and, by a previous thermodynamic calculation, the was found to be the most stable species of arsenic in the copper smelting slags at higher temperature 1573 K. [16] The equilibrium constant, K M , for Reaction [1] is given by [2] The arsenate capacity, , in terms of measurable quantities is defined as [17] [3]…”

“…The knowledge of its behavior as fractional distribution between the gas and the condensed phases of copper matte and fayalite or ferrite-base slags is needed for the smelting and converting stage of copper and controlling the process parameters. [1][2][3][4][5][6][7][8] The new proposed "ferrous calcium silicate" slags in the olivine region for continuous smelting and converting copper is very promising. [9,10] However, very limited data are available on the behavior of arsenic in the olivine-type slags.…”

“…[9,10] However, very limited data are available on the behavior of arsenic in the olivine-type slags. [2][3][4][5][6][7][8] Hence, due to the difficulty in performing experiments, the arsenic model becomes an essential tool to derive the necessary data and to predict its behavior.…”

Phase equilibria studies of zinc-containing copper smelting slags

“…[62,66] ..... 24 Figure 2.16 Liquidus in the pseudo-ternary system ZnO-''FeO''-(Al2O3+CaO+SiO2) with varied CaO/SiO2 and (CaO+SiO2)/Al2O3 ratios as under metallic iron saturation [70,71,[73][74][75] varied MgO concentration (2, 4 and 6 wt pct) for Zn-containing multi-component system [76] ......... 31 Figure 2.21 Proportion of activity as function of matte grade (pct Cu), reproduced from Yazawa [80] . [88] ... 37 29 Relationship between distribution coefficient of arsenic between slag and matte, and the mass ratio of slag to matte [91] . reproduced from Itagaki [96] .…”

“…However, the enhanced effect is not sufficient from the viewpoint of industrial removal As by slagging. [86] Roghani et al [87,88] investigated the distribution behaviour of As between magnesia ferrite silicate slag and copper matte under controlled PSO2 and Ps2 at 1300 °C. By applied the developed experimental techniques, the effect of PSO2 and matte grade on the partitioning effect of As can be evaluated, as shown in [88] Reddy and Font [89,90] thermodynamically evaluated the arsenate (the most stable arsenic-bearing species in the copper slag) in ferrite slags and silicate slags at 1300 °C.…”