Experimental Study of the Combined Effects of Al2O3, CaO and MgO on Gas/Slag/Matte/Spinel Equilibria in the Cu–Fe–O–S–Si–Al–Ca–Mg System at 1473 K (1200ºC) and p(SO2) = 0.25 atm

Abstract

The combined effects of Al2O3, CaO and MgO slagging components on phase equilibria and thermodynamics in the basic Cu–Fe–O–S–Si system have been evaluated at 1473 K (1200 ºC) and p(SO2) = 0.25 atm for a range of oxygen partial pressures and matte compositions. The experimental technique included high-temperature equilibration of the samples on a spinel substrate under controlled gas atmosphere (CO/CO2/SO2/Ar), followed by rapid quenching and subsequent measurement of the equilibrium phase compositions using Electron Probe X-ray Microanalysis (EPMA). The experimental data have been compared with the results of thermodynamic calculations undertaken using FactSage software and an internal thermodynamic database. Both the experimental results and the calculations results revealed that the presence of Al2O3, CaO and MgO reduced both the sulphur and copper concentrations in the slag phase for a given set of process conditions. The data have been used for further optimisation of the parameters of the thermodynamic database describing multicomponent metallurgical systems. The resulting thermodynamic database is capable of predicting, with high accuracy, the phase equilibria and the distribution of all elements between the phases in the Cu–Fe–O–S–Si–(Al, Ca, Mg) system. Graphical Abstract

Multiphase Equilibrium Relationships between Copper Matte and CaO-Al2O3-Bearing Iron Silicate Slags in Combined Smelting of WEEE and Copper Concentrates

“…In the literature, the Fe and S concentrations showed similar downward trends against the matte grade and were not affected by adding CaO, Al 2 O 3 , and MgO in slags. The oxygen dissolution in matte displayed the opposite trend with the increasing matte grade (Figure 3d), as iron had a stronger chemical affinity for oxygen than copper [23]. The presence of CaO had no apparent impact on oxygen concentration in matte, showing good agreement with the previous data [15,17].…”

“…Chen et al [15] and Sukhomlinov et al [17] reported similar trends of FeO in slags with different concentra-tions of CaO and Al 2 O 3 . This tendency can be explained by the decrease in FeO activity in slags resulting from increasing amounts of the slag modifiers CaO and Al 2 O 3 [23].…”

Phase Equilibrium Studies of Nonferrous Smelting Slags: A Review

“…The effect of Al 2 O 3 showed the same trends as that of MgO and CaO [53]. The combined effects of CaO, MgO, and Al 2 O 3 on gas/slag/matte/solid equilibria were studied in the Cu-Fe-O-S-Si-Al-Ca-Mg system at a fixed Pso 2 of 0.25 atm and 1200 • C [54] and 1300 • C [55]. Figure 14a shows the predictions by FactSage 7.3 together with the experimental results.…”

“…The effect of Al2O3 showed the same trends as that of MgO and CaO [5 combined effects of CaO, MgO, and Al2O3 on gas/slag/matte/solid equilibria were in the Cu-Fe-O-S-Si-Al-Ca-Mg system at a fixed Pso2 of 0.25 atm and 1200 °C [ Both MgO and Al2O3 are present in the spinel phase to form extensive solid soluti which are important for development of the thermodynamic database. Figure 15 sh the distributions of Al2O3 and MgO between liquid slag and spinel as a function of m grade, at 1200 °C and Pso2 = 0.25 atm [54]. It can be seen from Figure 15a that experimental results did not give a clear trend.…”

“…(a) Comparison of the liquidus temperatures with a fixed amount of 2 wt% MgO; (b) comparison of the liquidus temperatures at a fixed Pso 2 of 0.3 atm, solid and dashed lines are experimental results and FactSage predictions respectively, square, circle and triangle are experimental measurements.Both MgO and Al 2 O 3 are present in the spinel phase to form extensive solid solutions, which are important for development of the thermodynamic database. Figure15shows the distributions of Al 2 O 3 and MgO between liquid slag and spinel as a function of matte grade, at 1200 • C and Pso 2 = 0.25 atm[54]. It can be seen from Figure15athat the experimental results did not give a clear trend.…”