Sulfidation behaviors and phase transformation mechanism of zinc silicate

To achieve the sulfidation of zinc silicate to zinc sulphide, the sulfidation behaviors and phase transformation mechanism of zinc silicate were investigated under different conditions. The thermodynamic basis forzinc silicate sulfidation was studied by using HSC and Factsage calculation. The sulfidation behaviors of willemites were then investigated via TG-DSC analysis and roasting experiments. Meanwhile, the phase transformations and microtopography changes during the roasting process were studied by XRD and SEM-EDS, respectively. The results show that the sulfidation of zinc silicate is mainly through the reactions of zinc silicate with the gas sulfur produced from the decomposition of pyrite. Temperature, pyrite dosage, and carbon dosage are the main factors affecting the sulfurization behavior of zinc silicate. Properly increasing the temperature pyrite dosage, and increasing carbon dosage and pyrite dosage can improve the sulfidation of zinc silicate, and the addition of sodium salt is conducive to the sulfidation of zinc silicate. Under the optimum conditions, the sulfidation rate of zinc reaches 92%. During the sulfide roasting process of zinc silicate, the roasted products are mainly composed of wurtzite, sphalerite, magnetite and cristobalite, implying that the selective sulfide of zinc has been achieved. However, the synthetic zinc sulfides have fine grains and poor crystallization, and the addition of sodium salts can effectively promote crystallization process and grain growth of ZnS fines. © 2022, China Science Publishing & Media Ltd. All right reserved.