Processing of the zinc-lead-bearing flotation middlings by sulfidizing roasting with pyrrhotites production by predicted properties

Abstract

The accumulated amount of lead-zinc ore flotation tailings in the dumps of concentrating plants today can be considered as independent man-made deposits. In addition to their resource value as sources of lead and zinc, as well as associated gold, silver, cadmium, selenium and other metals, tailings are an environmentally hazardous source of heavy metal pollution of ground and surface waters. The environmental hazard of stale tailings is exacerbated by the fact that they occupy large areas that cannot be used for agricultural or other purposes of the national economy. Wastes of flotation enrichment of lead-zinc ores significantly differ from the source material not only in the content of minerals, but also in the degree of oxidation of their surface, fractional composition, and the presence of a significant amount of mineral intergrowths. In view of this, the use of existing flotation technologies is ineffective for obtaining standard lead and zinc concentrates from enrichment tailings. This paper describes the technology that has been developed for processing of zinc and lead-bearing enrichment wastes by sulfidizing roasting followed by magnetic and flotation concentration of cinders. It was found that, as a result of the sulfidizing- pyrrhotizing roasting process, the flotation ability increases for lead compounds and decreases for iron compounds, while the magnetic susceptibility of lower iron sulfides formed during roasting increases. It has been established that sulfidizing takes place with sufficient completeness, and during subsequent flotation, it is possible to extract up to 95% of zinc and up to 80% of lead into sulfide concentrate. These results have a technological advantage in contrast to the other methods that have been used. It was found that at roasting temperatures of 700–800 °C, pyrrhotites have a maximum magnetic susceptibility of 3.75, 5.43 and 2.18 SI units for Fe0.855S, Fe0.888S and Fe0.909S, respectively. Technological recommendations are acceptable for similar raw materials. The research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan Grant №AP08052829.