Ural Mining and Metallurgical Company, Verkhnyaya Pyshma, Sverdlovsk Oblast, Russia

A. M. Panshin, Technical Officer

Engineering Center of “Chelyabinsk Zinc Plant” JSC, Chelyabinsk, Russia
P. A. Kozlov, Head, e-mail: pak@zink.ru
D. A. Ivakin, Head of Technological Bureau
V. N. Vyatkin, Leading Processing Engineer

Waelz oxides contain a large amount of halogenides during the primary Waelz process of metallurgical production wastes. It is necessary to remove these impurities before the extraction of zinc into the solution and its electric extraction. Calcination is an efficient method of chlorine and fluorine removement from Waelz oxides. This method makes it possible to concentrate the considered components in a relatively small volume of secondary distillation, for the purpose of which, there is offered the separate technology of metals recovery and recycling. There is researched the kinetics of distillation of chlorine and fluorine compounds during the oxidizing roasting (calcination) of Waelz oxides in pipe furnace. There is substantiated that the distillation of halogenides is carried out in kinetic and allied diffusive-kinetic area, in terms of the nature of Waelz oxide (type of wastes, recycled by Waelz process) and original content of halogenides in this oxide. Activation energy of chlorine distillation varies from 1 to 60 kJ/mole. At the same time, activation energy of fluorine distillation varies from 3–110 kJ/mole. Increasing of calcination temperature and containing time of Waelz oxide in pipe furnace makes it possible to increase the chlorine distillation ratio and fluorine distillation ratio to 92–99% and 91–98% respectively. At the same time, the residual content of chlorine in calcined material is not more than 0.05%, and the residual content of fluorine is not more than 0.01%. This makes it possible to use the hydrometallurgical extraction of zinc into the sulphate solution for calcined Waelz oxides of the products, obtained from wastes.

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