GB349998A - Process for the production of ammonium-nitrate-ammonium-sulphate mixed fertilisers - Google Patents

Abstract

Ammonium nitrate-ammonium sulphate mixed fertilizers are obtained by directly neutralizing with ammonia a mixture of sulphuric acid and nitric acid which has been obtained by the oxidation of ammonia and sulphur dioxide, the sulphur dioxide either being added to the ammonia before oxidation and oxidized with it or being subsequently added and oxidized. The addition of sulphur dioxide to the ammonia before the oxidation allows the oxidation to be carried out by means of oxygen or air enriched with oxygen without overheating the catalyst. According to one example ammonia is oxidized by a large excess of air at a platinum surface into nitrous gases and sulphur dioxide in the liquid, dissolved or gaseous form is sprayed together with steam into the slightly cooled combustion gases. The mixture thus obtained is fed, together with gaseous ammonia, into a solution saturated with ammonium nitrate and ammonium sulphate, the mixed salts separating on cooling. In another example ammonia and sulphur dioxide together with excess of air and steam are passed over platinum, the resulting vapours being condensed in lead chambers and diluted with water. Liquid ammonia is added to the resulting mixture of nitric and sulphuric acids intermittently while stirring. Water not removed by the heat of the reaction is removed by evaporation. In a further example a mixture of ammonia and sulphur dioxide is oxidized by air enriched with oxygen, the resulting mixed acids are neutralized with ammonia the heat of the reaction removing most of the water; the proportion of sulphur dioxide and ammonia for oxidation is chosen so that the double salt (NH4)2SO42NH4NO3 is obtained.ALSO:Ammonium nitrate-ammonium sulphate mixed fertilizers are obtained by directly neutralizing with ammonia a mixture of sulphuric acid and nitric acid which has been obtained by the oxidation of ammonia and sulphur dioxide, the sulphur dioxide either being added to the ammonia before oxidation and oxidized with it or being subsequently added and oxidized. The addition of sulphur dioxide to the ammonia before the oxidation allows the oxidation to be carried out by means of oxygen or air enriched with oxygen without overheating the catalyst. According to one example ammonia is oxidized by a large excess of air at a platinum surface into nitrous gases, and sulphur dioxide in the liquid, dissolved or gaseous form is sprayed together with steam into the slightly cooled combustion gases. The mixture thus obtained is fed, together with gaseous ammonia, into a solution saturated with ammonium nitrate and ammonium sulphate, the mixed salts separating on cooling. In another example ammonia and sulphur dioxide together with excess of air and steam are passed over platinum, the resulting vapours being condensed in lead chambers and diluted with water. Liquid ammonia is added to the resulting mixture of nitric and sulphuric acids intermittently while stirring. The water not removed by the heat of the reaction is removed by evaporation. In a further example a mixture of ammonia and sulphur dioxide is oxidized by air enriched with oxygen, the resulting mixed acids are neutralized with ammonia the heat of the reaction removing most of the water; the proportion of sulphur dioxide and ammonia for oxidation is chosen so that the double salt (NH4)2SO4-2NH4NO3 is obtained.