Desulfurization mechanism of calcium salts in direct reduction roasting of pyrite cinder

This paper reports the influence of different combinations of reductants and calcium salt desulfurizers on desulfurization of pyrite cinder in direct reduction roasting process. The roasted ore obtained at different conditions was analyzed by X-ray diffraction and scanning electron microscopy. It is found that pyrite and forsterite in pyrite cinder react with different kinds of calcium salt desulfurizers in the high-temperature and reducing atmosphere to form metallic iron and different sulfur-bearing minerals, calcium sulfide or jasmundite. The sulfur-bearing minerals can be removed from the roasted ore through grinding and magnetic separation, thereby reducing the sulfur content. Different intergrowths between sulfur minerals and metallic iron in the roasted ore formed by different combinations of reductants and calcium salt desulfurizers make the contents of iron and sulfur in direct reduction iron have different change laws. With different combinations of reductants and desulfurizers, the sulfur minerals and their intergrowth with metallic iron in the roasted ore are also different.