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

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.