METHOD FOR PURIFICATION OF MINE WASTEWATER FROM SULFATES Russian patent published in 2022 - IPC C02F9/04 C02F9/10 C02F103/10 

FIELD: wastewater purification.

SUBSTANCE: method for purification of mine wastewater from sulfates is described, in which hydrochloric acid and barium chloride are introduced into incoming wastewater after preliminary averaging to pH of 4-4.5, and then, the mixture enters a reaction chamber to form slightly soluble barium sulfate salt, after which it is sent to sedimentation tanks and for further purification, and a settled precipitate is dewatered on filter-presses with the return of a filtrate obtained during dewatering of the precipitate in front of the reaction chamber. The process of purification from sulfates is carried out in two stages: at the I stage, incoming wastewater is partially frozen beforehand to concentrate sulfates, formed ice is stored at sites, and then, in the warm season, melt water is sent to a reservoir, and the remaining part of unfrozen water is averaged, mixed with lime to bring pH to 10.5-11 to form CaSO₄, and then, mixed with a fine-dispersed opacifier, and wastewater is directed in sedimentation tanks of the I stage of purification, after which, before wastewater is fed to the II stage of purification, the flow is divided into two unequal parts, wherein one part of it is mixed sequentially with alkali to pH of 10.5-11.0, barium hydroxide, and flocculant, and the second part is mixed with hydrochloric acid to pH of 4.0-4.5, barium chloride, and flocculant, and then, both flows are combined and clarified in sedimentation tanks of the II stage, and the precipitate from sedimentation tanks is sent for dehydration, after which wastewater purified from sulfates is sent to a carbonizer to reduce pH to 8-8.5, where flue gases are fed, and then, wastewater is fed into a vortex reactor or to a filter, where gypsum crystals, a suspension of sulfates and barium carbonates are separated from wastewater, and purified wastewater enters the reservoir or is sent for reuse.

EFFECT: reduction in the cost of purification; possibility of use of the proposed purification method at any concentration of sulfates in source wastewater, increase in the environmental safety of the proposed purification method.

2 cl, 1 dwg, 3 tbl