Equilibrium Relations between Liquid Copper and Calcium Ferrite Slag

Abstract

Experiments were carried out on equilibrium between calcium ferrite slag and metallic copper under a controlled partial pressure of oxygen by using a mixture of CO2 and CO. Lime, magnesia or iron crucibles were used in the temperature range from 1423 to 1623K. The results were summarized as follows:(1) The solubility of copper in the stags is affected by the oxygen potential and temperature, and the solubility amounts to 70% of that in the case of iron silicate slags.(2) The value of (Fe+++/Fe++) in slags fits the equation previously obtained in the plain FeO-FeO1.5-CaO ternary system, and this ratio in the basic calcium ferrite slags is ten times as large as that in acidic iron silicate slags.(3) The iron contents in metallic copper are related to the oxygen potential, temperature and iron content in the slag.

Distribution Equilibria between Cu-Fe-As Ternary Speiss and Slag Phases.

“…<n t > and {n t } are obtained from the experimental results in the present study, and { } as well as ≅ { } can be also calculated from the data of arsenic and copper activities shown in Figs.1 and 2. Furthermore, it is possible to estimate the oxygen partial pressure for the calcium-ferrite slag / speiss equilibration by combining the data of the iron activity in the speiss determined in the present study with the relationship between the partial pressure of oxygen and the activity of iron in the calcium-ferrite slag, which was investigated by Yazawa and Takeda 4) . It was evaluated that the oxygen partial pressure is decreased from 2.5 × 10 -11 to 4.6 × 10 -13 atm when the activity of iron in the speiss increased from 0.15 to 1.…”

Copper Solubility and Redox Equilibria in Magnesia Saturated CaO-CuOx-FeOx Slags

“…The dissolved copper has a linear dependence on the oxygen partial pressure in logarithm, especially at low oxygen partial pressures of about 0.22. [11] At higher oxygen partial pressures, the linear dependence has been observed to break down, and the copper content of slag has been shown to increase with a higher dependency. There is some uncertainty where the change in dependence on oxygen partial pressure occurs.…”

“…There is some uncertainty where the change in dependence on oxygen partial pressure occurs. In the work of Eerola et al, [14] the change occurred at an oxygen partial pressure of about 10 À7 atm, while for Yazawa and Takeda [11] and Takeda et al, [15] the change occurred at about 10 À5 atm. Eerola et al [14] attributed this increased dependence to a decrease in the activity coefficient of CuO 0.5 (cCuO 0.5 ).…”

“…[14,15] Most of the thermodynamic investigations into calcium ferrite slags have concentrated on liquidus boundaries at copper-making temperatures, [10,[16][17][18][19][20] iron redox equilibria, [16][17][18][21][22][23][24] and the solubility of copper in slag. [11,15,19,25,26] Nikolic et al [27] and Hidayat et al [28] investigated the thermodynamics of complex slag systems relevant to modern copper smelting and converting processes as part of a thermodynamic modeling study. Jak et al [5] also investigated calcium ferrite-based slag systems in a study on the control of slag freeze linings which are used in new copper converting processes.…”

“…Commercial processes such as the Mitsubishi process, [1][2][3][4] the Kennecott flash converting process, [5][6][7] as well as other proposed continuous and single-stage converting processes [8][9][10] advocate the use of calcium ferrite slags. The advantages of calcium ferrite slags over the more conventional iron silicate slags include A lower dissolved copper content at a given activity of copper in slag, [11,12] A higher capacity to dissolve ferric iron and, hence, magnetite, and [13] A higher capacity for some acidic minor elements such as arsenic and antimony. [14,15] Most of the thermodynamic investigations into calcium ferrite slags have concentrated on liquidus boundaries at copper-making temperatures, [10,[16][17][18][19][20] iron redox equilibria, [16][17][18][21][22][23][24] and the solubility of copper in slag.…”