Effects of CaO, Al2O3 and MgO on Kinetics of Lead-Rich Slag Reduction

Abstract

Lead-rich slag as a green feedstock can be used in a blast furnace or smelting reduction furnace to produce lead metal. It is desirable to understand the reduction mechanisms of lead-rich slag to optimize the reduction operations. The volume of CO/CO2 gases was continuously measured in the experiments to determine the reduction degree of lead-rich slag by carbon. The effects of CaO, Al2O3 and MgO on reaction kinetics of lead-rich slag with carbon were investigated in the temperature range 1073 to 1473 K. The activation energies of the reduction were determined experimentally in the chemically controlled and diffusion-controlled stages, and the reduction mechanism is analyzed using experimental results and thermodynamic calculations. It was found that the activation energies at the chemically controlled and diffusion-controlled stages decrease with increasing optical basicity. CaO and MgO have a similar behavior to accelerate the reduction of the lead-rich slag by carbon. In contrast, Al2O3 can increase the activation energies at both chemically controlled and diffusion-controlled stages resulting in a slow reaction.

Phase Equilibrium Studies of Nonferrous Smelting Slags: A Review

“…The minimum liquidus temperature in the olivine primary phase field was found to be 1117 • C. This means that a fully liquid slag can be obtained at temperatures above 1117 • C with optimum flux additions. Mukhopadhyay et al [21] studied the phase relations in CaFeSiO 4 -Fe 2 SiO 4 and found a miscibility gap below approximately 1041 • C. the sinter plant-blast furnace process due to its high thermal efficiency, less feed preparation, and efficient SO2 utilization [16]. Although oxygen pressure leaching has been developed for producing zinc in recent years, pyrometallurgy is still utilized to extract zinc from lead and zinc mixed concentrate [17].…”

“…Similar to the smelting technology used in copper production, flash smelting [14] and bath smelting [15] technologies are the main oxidation methods employed for lead concentrates. Bath technology has replaced the sinter plant-blast furnace process due to its high thermal efficiency, less feed preparation, and efficient SO 2 utilization [16]. Although oxygen pressure leaching has been developed for producing zinc in recent years, pyrometallurgy is still utilized to extract zinc from lead and zinc mixed concentrate [17].…”