process and installation for the removal of arsenic and sulphate in pressure with other metals in waste water from plants imdustriali.

摘要

Removal of As and other metals from waste water currents, opt. in presence of H2SO4, in soln. in varying ratios, involves (a) treating the water with H2S under pressure in countercurrent, in 1 or more stages, giving a soln. with pptd. sulphides, and a soln. contg. gas, comprising, among others, unreacted H2S, (b) filtering to remove the ppte. and give a clear soln., and (c) de-gassing the clear soln. with air, giving a soln. free from As and metals, suitable for further treatment, and a gas-contg. soln. loaded with H2S. The soln. contg. H2S is washed with alkali before release, free from H2S, into the atmos., giving a small amt. of a soln. of alkali sulphide, which can be used as additional source of sulphide. USE/ADVANTAGE - Long residence times, mechanical stirring, and high acidity are avoided, and an easily filterable ppte. is obtd. without use of filtration aids. The waste water esp. originates from treatment of sulphide ores with H2SO4. Treatment of waste water from H2SO4 processes, contg. up to 20 g/l of As, is claimed.