Wet Leaching Process Of Low-grade Polymetallic Bismuth And Its Basic Theory

The current situation of leaching of bismuth from the low-grade mineral was summed up. The low grade complex multi-metal bismuth ore used in this experiment contains 7.25 percent of bismuth and 25.53 percent of sulfur. The purpose of this experiment was to probe a new hydrometallurgical approach to extract bismuth from the low grade and complex multi-metal sulfide ores at high recoveries but low costs, low pollution by MnO₂Based on the analysis of thermodynamics and mechanism of the leaching process, laboratorial-scale experiments about new technology had been invested systematically in this paper under normal pressure and room temperature. The optimum conditions we obtained as follows: concentration of hydrochloric acid=4.0 mol/L, stirring speed=800 rpm, particle size=0.105-0.074 mm, concentration of sodium chloride=1.5 mol/L, solid/liquid ratio=1:5, leaching time=180 min. Under the optimum conditions, the comprehensive leaching rate is more than 96%.The kinetics of leaching bismuth from low grade and complex multi-metal sulfide ores was also investigated. Results showed that the leaching process canbe simulated with a shrinking core model 1- (1-η)^1/3 = kt. The activation energy calculated according to the Arrhenius equation was 56.868 kJ/mol. There was a linear relation between the apparent rate constant and the reciprocal of the mean particle diameter. The results of kinetic analysis of the leaching data under various experimental contions indicated a reaction controlled by the solution transport of protons through the product layer; the following rate equation was established:The cementation of bismuth on iron powder from solutions had been studied. Iron powder used in this experiment was recycled from steel slag by magnetic separation method. The influence of several parameters on the course of the...