Selective recovery by precipitation of selenium and mercury from acid leaching solutions

  • D. D’Hondt
  • N. Gérain
  • A. Van Lierde
Chapter

Synopsis

This paper concerns the hydrometallurgical treatment of lead, selenium and mercury muds coming from the gas cleaning stage of zinc sulfide concentrates roasting. In a first step, the muds are leached at a pulp dilution of 250 g/l and a temperature of 90°C with a 150–200 g/1 HCl and 100–150 g/1 HNO3 solution. Such conditions give outstanding results both in recovery (96.7% for Se and 99.1% for Hg) and selectivity towards lead: after cooling the solution to about 25°C, 97.5% of this metal remains in a 40% Pb residue.

Preliminary tests have shown that high purity chemical precipitates of selenium and mercury can be obtained by using a SO2 solution. When sulfur dioxide is added to selenium in a ratio of 3.3/1 (E = 670 mV SHE), Se and Hg are coprecipitated as Hg3Se2Cl2 with recoveries higher than 98%.

A careful study of the crystals’ stability shows that they can be decomposed to metallic selenium and soluble mercury chloride with a very high efficiency by keeping them under moderate oxidative conditions (900–910 mV SHE). 90% of the selenium remains in a 88% Se precipitate assaying less than 5% Hg. The mercury can thereafter be recovered by precipitation as Hg2Cl2 using iron powder as the reducing agent: with a consumption of 850 g Fe/kg Hg, the mercury yield reaches 97% and the precipitate assays 83% Hg2Cl2.

Keywords

Iron Powder Leach Liquor Mercury Removal Lead Recovery Hydrometallurgical Treatment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Institution of Mining and Metallurgy 1991

Authors and Affiliations

  • D. D’Hondt
    • 1
  • N. Gérain
    • 1
  • A. Van Lierde
    • 1
  1. 1.Unité des ProcédésUniversité Catholique de LouvainLouvain-La-NeuveBelgium

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