METHOD OF PROCESSING COPPER-FREE SLUDGE FROM ELECTROLYTIC REFINING OF SECONDARY COPPER Russian patent published in 2024 - IPC C22B7/00 C22B11/00 C22B15/00 C22B3/12 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy of non-ferrous and noble metals, in particular to processing of copper-free sludge from electrolytic refining of secondary copper. Method involves reduction of silver chloride. Reduction treatment of sludge is carried out in NaOH solution while maintaining pH of not less than 12, temperature of not less than 50 °C, consumption of D-glucose, as a reducing agent, not less than 0.6 mol/mol AgCl and duration of not less than 0.5 h.

EFFECT: method provides resource saving, increases environmental safety due to use of low-temperature hydrometallurgical reduction of silver chloride, providing a degree of reduction to metallic silver of not less than 99%, using a safe reducing agent in solid form, which reduces the volume of waste water, eliminates contamination of the solid product and enables, during its subsequent processing, to exclude redistribution of melting of de-copper sludge to Dore alloy and to extract silver into the solution by low-temperature nitric acid leaching by not less than 99%.

1 cl, 1 tbl, 10 ex