Precipitating heavy metals from e.g. waste water

摘要

Precipitation of dissolved heavy metals from a fluid is effected using iron sulfide, this preferably being followed by removal by sedimentation or filtration. Independent claims are included for: (i) the preparation of a granulate for use in the precipitation by mixing iron sulfide powder with a porous material such as a clay slip and then burning the mixture; and (ii) an apparatus for the precipitation comprising a reactor (7) for the iron sulfide; a conduit (1) feeding the fluid to the reactor (7); and a vessel (15) containing acid (16) and a liquor (17), the vessel having (a) an acid conduit opening into the conduit (1) before the reactor (7) and (b) a liquor conduit (21) connected to the conduit (1) after reactor (7).