中国有色冶金

Zinc sulfide concentrate is usually associated with a certain amount of thallium, and in some zinc-lead deposits, the content of Tl can be particularly high. In a conventional hydrometallurgical zinc refining process, the Tl contained in the raw material can affect the operation and product quality. The symptoms include problematic assaying, difficulty in zinc dust precipitation, and cobalt removal. As the stream and distribution of Tl across a hydrometallurgical zinc refining process is closely related to its content in the ore, the selection of auxiliary materials and operating conditions, by manipulating these factors the adverse effect of Tl can be controlled. There are three paths of bleeding Tl from a conventional hydrometallurgical zinc refining process: oxidizing precipitation during leaching, zinc dust precipitation during purification, and concentrating Tl into high F-Cl offgas dust by volatilizing thallium chloride in the rotary kiln. When the Tl grade in the feed is low and when Mg powder or oxygen is used as the oxidant for leaching, Tl can be removed mainly through sponge cadmium or cobalt residue (dependent on the lead content in the zinc dust); when the feed Tl is high and when hydrogen peroxide, or potassium permanganate or ozone is used as oxidant, Tl can be removed through high F-Cl offgas dust.