UMMC Technical University, Verkhnyaya Pyshma, Russia:

P. A. Kozlov, Deputy Director Responsible for Research, Doctor of Technical Scienses, e-mail: p.kozlov@tu-ugmk.com

UMMC (OJSC), Verkhnyaya Pyshma, Russia:
S. A. Yakornov, Deputy Technical Director Responsible for Metallurgical Production, Candidate of Technical Scienses
A. M. Panshin, Technical Director, Doctor of Technical Scienses

UMMC Technical University, Verkhnyaya Pyshma, Russia¹ ; Chelyabinsk Zinc Plant (PJSC), Chelyabinsk, Russia²:
D. A. Ivakin, Head of the Metallurgy Laboratory¹, Head of the Process Department at the Engineering Centre², Candidate of Technical Scienses, e-mail: dai@zinc.ru

Ural Mining and Metallurgical Company developed and adopted a pyrohydrometallurgical process to recycle zinc dusts generated by iron and steel industry. The process involves Waelz processing of electric arc furnace dusts in two stages. Stage 1 produces Waelz-fumes and iron-bearing clinker, while Stage 2 produces zinc clinker (containing 60–68% of zinc), as well as chlorine-, fluorine- and lead-containing secondary fumes. The zinc clinker then goes for alkaline leaching and electrolysis and finely dispersed zinc powder is produced as a result. After halogenides have been removed from the secondary fumes through alkaline cleaning, zinc (by means of sulphuric acid leaching) and lead (by means of carbonization and lead cake melting) are recovered from the latter. Zinc powder is used in gold cementation processes, as well as for purification of zinc solutions. Electrolytic powder has an advantage in that its particles have an effective surface and a small size, and this helps reduce its specific consumption in the process. Addition of up to 1% of lead to the powder at alkaline solution preparation stage produces a positive effect. Iron-bearing clinker is used as a ferrous additive in cement production or as a component of the filling mix in mining. The adoption of new advance technology made it possible to:
– obtain zinc powder from waste rather than from commercial zinc metal, thus lowering the cost of the product;
– effectively use zinc powder for purification of zinc solutions, as well as in gold cementation process;
– achieve a 17%-reduction in the consumed electrolysis power;
– reduce the cost of pyrometallurgical treatment by 10 % (due to extended kiln campaigns following the adoption of new advanced solutions);
– use clinker in the production of filling mixes for mining (thus reducing the consumption of cement by 1.8 times) and as iron-calcium additives in the production of high-grade cement.

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