Technology for extracting zinc from waste from the metallurgical industry.

The waste from processing scrap steel in smelting furnaces is dust (Welz-sublimation) in (~30 kg per 1 ton of steel). Dust composition up to 40% Zn (ZnO) and ferrite, as well as oxides of Fe, Pb and other metals. The world stock of waste is > 5 billion tons.

Zinc extraction steps

• 1) leaching of sublimate in NaOH or NH₄Cl solution;
• 2) cleaning the solution from Pb(II) ions by contact displacement with zinc;
• 3) electrodeposition of Zn on steel (graphite anodes, alkaline or ammonium chloride electrolyte with a developed package of additives for high deposition rates and obtaining a compact deposit).

Technical characteristics of the zinc electrodeposition process:

• -Current density 5−6 A/dm²;
• -Electrolyte temperature 65−70 °C;
• -Electrolytes are stable and easy to adjust;
• -Deposition rate 85−100 µm/h;
• -Zn content in the cathode deposit ≥ 98 wt. %;
• -Specific electricity consumption 3000 kW∙h/t;
• -Zinc current output 92−97%;
• -Closed cycle;
• -The coating is compact, easily separated from the steel;
• -There is no or minimized chlorine release.

Leaflet in CHINESE (传单)