METHOD OF CLEANING ARSENIC-POLLUTED SOLVENTS Russian patent published in 2007 - IPC C02F1/62 C01G28/00 C02F103/16 

FIELD: waste water treatment.

SUBSTANCE: invention relates to treatment of waste waters and solvents containing significant amounts of hydrochloric or sulfuric acid and arsenic and can be used in metallurgy, especially in manufacture of nonferrous metals, as well as in chemical industry. Method consists in that arsenic is precipitated by sulfide-containing reagent, e.g. sodium hydrosulfide, said sulfide-containing reagent being added to solution to be treated from below while simultaneously stirring the solution. Specific weight consumption of the reagent is not higher than 1.5 kg*S^-2*h^-1. Hydrodynamic regime of stirring is maintained within the Reynolds number range 600 to 6000. Precipitation of arsenic is effected until its residual concentration in solution not below 0.03 g/dm³. Addition of sulfide-containing reagent is stopped when redox potential value is achieved in the curve break point on diagram depicting consumption of the reagent as function of arsenic concentration in solution.

EFFECT: achieved simplicity and safety of arsenic precipitation excluding emission of toxic gases.

1 dwg, 3 tbl