METHOD FOR PROCESSING SLURCHEN OF ACID MINE WATER Russian patent published in 2019 - IPC C22B3/08 C22B3/20 C22B7/00 

FIELD: technological processes; metallurgy.

SUBSTANCE: invention relates to the field of hydrometallurgy of heavy non-ferrous metals and can be used in the complex processing of sludge neutralizing acidic mine waters and processing sewage sludge from electroplating and similar industries. Sludge sour mine water simultaneously crushed to a particle size of 12–18 microns in a bead mill and leached with 40 % sulfuric acid to a pH of 3–3.5 at a temperature of 70–80 °C for 2.5–3 hours. Suspension is cooled to a temperature of 40–50 °C, gypsum is separated. Resulting filtrate is mixed with the spent etching solution of aluminum alloys to achieve the required pH in three stages. At each stage, precipitates in the form of hydroxides – copper, zinc, and iron – are isolated from the mixture obtained. At the 1^st stage, the neutralization is carried out to a pH of 5.0–6.0, at the 2^nd – to pH 6.2–7.2, on the 3^rd – to a pH of 7.2–8.0. At each stage after settling the mixture is cooled to a temperature of 40–50 °C, the precipitated precipitates are simultaneously dried and crushed to a particle size of 15–20 mcm in combined “fluidized bed” dryers to produce pigments. Filtrates of the 1^st and 2^nd stages are transferred to the next stage, and after the 3^rd stage, dust is mixed with lime to a pH of 8.0–9.7, the precipitate is separated in the form of gypsum, which is used in construction, and the remaining filtrate is returned to process.

EFFECT: method allows waste-free processing of sludge with the production of marketable products.

1 cl, 1 dwg, 2 tbl, 2 ex