Phase Evolution During the Oxidation Process of Low Grade Lead-Zinc Oxide Ore

摘要

The phase evolution during the oxidation process of low grade lead-zinc oxide ore was investigated at 1173-1473 K under air atmosphere. A thermogravi-metric and differential thermal analysis was carried out to investigate the oxidation mechanism. The products obtained at different temperatures were analyzed by X-ray diffraction. It was found that the sulfides in the ore were oxidized and the carbonates in the ore decomposed when the temperature was higher than 1173 K. During the oxidation process from 1173 to 1273 K, the main phases in the products were CaSO_4, Fe_3O_4, MgFe_2O_4, ZnFe_2O_4, Zn_2SiO_4, ZnO, and PbFe_4O_7. Along with the increase of the reaction temperature, a new phase of Ca2Fe20s appeared in the products after the decomposition reaction of Zn_2SiO_4 and CaSO_4. Based on the formation of the low melting point phase, the sintering phenomenon of the ore occurred obviously at 1473 K. With the increase of the reaction temperature, the content of Pb in the products decreased gradually.