METHOD FOR COMPLEX TREATMENT OF QUARRY AND DUMP WASTEWATER Russian patent published in 2024 - IPC C02F1/58 C02F1/44 C02F9/00 

FIELD: water treatment.

SUBSTANCE: invention relates to multi-stage methods for treating quarry and wastewater generated during mining of ore containing precious metals. The method involves step-by-step removal of impurities, including filtration, purification by reverse osmosis, and chemical purification. Initially, mechanical impurities are removed from the source water by pre-coat filtration using filtering powder. The resulting clarified filtrate is subjected to multi-stage purification by reverse osmosis. Before purification by reverse osmosis, an anti-scaling is added to the clarified filtrate. At reverse osmosis desalting section, the liquid is divided into two streams. One stream in the form of a concentrate containing most of the pollutants in increased concentrations is sent for chemical treatment. In this case, the stream is also divided into two unequal parts. The smaller part - the blow-off - is sent for partial purification from nitrate and nitrite by interaction of these pollutants with a suspension of zinc powder, a solution of sulphuric acid, and a nitrogen-containing substance: sulphamic acid, urea, glycine. After partial removal of nitrate and nitrite in the form of nitrogen gas, a solution of magnesium or calcium dihydrogen orthophosphate is introduced into this stream. The blow-off is mixed with the concentrate - most of the flow - and sent for treatment with carbonate and calcium hydroxide to precipitate heavy metal hydroxides, calcium sulphate, and magnesium ammonium phosphate. After separating the solid phase in the clarifier, the circulation stream is fed for mixing with the source water and then for filtration. The other permeate stream is sent to chemical treatment, in which sodium hydroxide solution is initially fed into it until a pH of 11 is reached. Then a solution of sodium hypochlorite is fed into it, the amount of which is determined based on the concentrations of ammonium and nitrite in the permeate and the content of active chlorine in sodium hypochlorite. After introducing the entire dose of hypochlorite, water is stirred for 20–40 minutes and, after a negative analysis for ammonium and nitrite ions, the excess alkali is neutralized with concentrated sulphuric acid to a pH of 7–8.5. Water is pumped through activated carbon. The exiting solution is monitored for presence of active chlorine and, if it is detected, water is directed onto a layer of fresh activated carbon. Then purified water is accumulated or discharged.

EFFECT: high degree of comprehensive purification of quarry and dump wastewater from pollutants containing heavy metal, sulphate, nitrate, nitrite and ammonium ions.

1 cl, 6 dwg