METHOD OF PRODUCING AMMONIUM SULPHATE Russian patent published in 2014 - IPC C01C1/24 

FIELD: chemistry.

SUBSTANCE: to obtain ammonium sulphate from waste dump or quarry water from abandoned deposits of iron-copper-zinc sulphide ores, containing 1-40 g/l iron (III) sulphate, 2-10 g/l sulphuric acid and sulphates of trace elements, said water is neutralised with ammonia to achieve pH of the reaction mixture of 8.0-9.0. The reaction mixture is then treated with ammonium carbonate with weight ratio of said water to ammonium carbonate of (200-350):1. The obtained precipitate is then separated from the ammonium sulphate solution by settling and filtering. The ammonium sulphate solution is evaporated, followed by crystallisation and drying the crystals to obtain the end product.

EFFECT: invention reduces content of heavy metals, particularly cadmium, in the end product.

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