Distribution of Various Elements Between Copper, Matte and Slag

The distribution behaviour of various elements between liquid copper, matte and slag was discussed thermodynamically combining with the experimental results obtained recently. The behaviour of impurities differs greatly depending on the compositions of equilibrating liquid phases and oxygen potential, and the various copper smelting systems were classified in 6 cases for discussion. In accordance with thermodynamic predictions, increasing oxygen potential results in increasing distribution fractions in slag phase for various elements, but any appreciable influence did not be observed in the distribution ratios between copper metal and matte. Under the coexistence of liquid copper phase, substantial fractions of detrimental impurities are distributed in copper phase. Distribution ratios between matte and slag are also influenced by the coexistence of liquid copper or γ-iron phase, especially for arsenic distribution. Because of the differences in thermodynamic characters, the distribution relations for calcium ferrite slag system seem to be different considerably

Thermodynamics of Calcium Ferrite Slags at 1200 and 1300℃

Oxygen isobars and liquidus isotherms of the system CaO-FeO-Fe_2O_3 at 1200 and 1300℃ were determined by quenching samples equilibrated with CO_2-CO mixtures. The iron liquidus and the melt coexisting with two solids were carefully examined in terms of their composition as well as the equilibrium oxygen partial pressures, po_2. At 1200℃, po_2 was 10^ atm when the slag coexisted with magnetite and dicalcium ferrite. At 1300℃, the melt region extends to the CaO-Fe_2O_3 join, where po_2 was 10^ atm (air) or higher. Within the range of po_2 from one order above that at iron saturation to 10^ atm, the slag composition, po_2, and the temperature T are related by the equation : log(Fe^/Fe^) ≈ 0.170logpo_2 + 0.018(wt % CaO) + 5500/T - 2.52. Activities of CaO(s), FeO(l), and Fe_3O_4(s) in the slag were calculated from the po_2 data by combining the available thermal data and/or by Gibbs-Duhem equation