Technology of high-temperature sulfidizing roasting of oxidized lead-zinc ore in a fluidized bed furnace

Abstract

Zinc and lead are one of the most used metals in the world. The average annual growth rate of the zinc market is about 3.5%. Half of the zinc consumed in the world is used as electroplating, more than 30% is spent on the production of zinc alloys, including for the production of brass and bronze. At present, polymetallic ores are the main raw material for the production of lead and zinc. The production technology includes flotation enrichment of the initial ore raw material with subsequent pyrometallurgical or hydrometallurgical processing of the resulting concentrates. Unfortunately, the reserves of well-enriched sulfide ores are declining, which leads to the need to involve mixed and oxidized ores in the production. Obtaining zinc is also a relatively expensive process, one of the stages of which is the roasting of zinc sulfide concentrates in a fluidized bed furnace using oxygen-enriched air blast. In this regard, technologies aimed at processing hard-to-cut oxidized lead-zinc ores, as well as improving the process of roasting in a fluidized bed, are topical and in demand today. The article presents the technology and method for processing oxidized lead-zinc ore, including high-temperature sulfidizing roasting of oxidized compounds of lead and zinc, the results of roasting carried out in the presence of a high-sulfur sulfidizing agent in the form of pyrite (sulfur content is 45.15%), at molar ratios of metal oxide to pyrite NZnO/NFeS 2 and NPbO/NFeS 2 equal to 0.1-0.14 for sulfidizing in an air-blown fluidized bed furnace at a flow rate of 10 to 20 l/min, at a temperature of 750-800 °C, with a roasting time of 30-45 minutes. As a result of sulfidizing roasting, the degree of sulfidization reaches 88%, and the subsequent extraction of zinc from the non-magnetic fraction into a froth product in an open flotation cycle is 90% with a content of 23.4% zinc.