GB342524A - Improved process for the production of ammonium sulphate - Google Patents

Abstract

<PICT:0342524/III/1> Ammonium sulphate is obtained by the reaction of ammonia and sulphur dioxide in the gaseous phase, with or without diluents, in the presence of such a limited amount of water vapour that the reaction product is substantially a dry powder, and during and/or after the reaction exposing the reactants or the product to an atmosphere containing free oxygen and nitric oxide or other higher oxide of nitrogen. The amount of nitrogen oxides may be small, say up to 2 per cent of the ammonia present and the reaction may be effected using small partial pressures of ammonia and sulphur dioxide, e.g. up to 5-10 milliatmospheres. The temperature should preferably be maintained between 20 and 50 DEG C., if necessary by the provision of cooling tubes in the reaction chamber. In the illustrated modification, ammonia and sulphurous gases are admitted at entrances C, D of a reaction chamber A which may be constructed of austenitic nickel chrome steel, and their mixing may be promoted by propellers near the inlets. Water vapour may be introduced as atomized water or steam but preferably by saturating one of the incoming gases. Nitrogen oxide and oxygen containing gas enters at E and passes in counter current to the solid reaction product which is caused to descend a series of trays in a collecting vessel F by the rotatory movement of a scraper. The residual gases pass out through an electrical precipitation B and their content of oxides of nitrogen may be recovered by washing with alkalies or ferrous sulphate. The oxidized product may be freed from traces of acid by treatment with gaseous ammonia.