Role and Significance of the Sulfur Allotropes in Autoclave Hydrometallurgical Processes

—Data on the physicochemical properties of the sulfur allotropes in the temperature range used in autoclave processes are presented. Elemental sulfur is shown to have an enhanced sensitivity to a temperature change. The chemical activity of sulfur can change by several orders of magnitude in a range of 30°C, and the viscosity changes by several thousands of times. The oxidation leaching of sulfides, sulfur hydrolysis, sulfidizing, and precipitation of nonferrous metals are considered. The laws according to which the leaching processes occur depending on the allotropic composition of sulfur are revealed. The activators capable of decreasing the temperature range of the transformation of cyclic sulfur molecules into chain molecules are considered. The yield of elemental sulfur is explained using the polysulfide mechanism of oxidation of sulfides and the physicochemical properties of sulfur allotropes.