Technology for extracting zinc from metallurgical waste (冶金废料锌提取技术)

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)