Improvements in the manufacture of fertilizer of low hygroscopicity notably for use in tropical soils and climates

摘要

A diralium phosphate-containing fertiliser is prepared by decomposing phosphates at temperatures not exceeding 35 DEG C. with nitric acid together with ammonium sulphate or ammonia and sulphuric acid, neutralizing the paste obtained at below 40 DEG C. with ammonia and passing the product to a granulator together with dried recycled powdered product, to produce spherical granules with a diameter above 1/8 inch. Potassium salts may be added and the ammonification may occur in stages, for example first with gaseous, then with 25 per cent. aqueous ammonia. Specifications 440,214 and 615,476 are referred to.ALSO:A dicalcium phosphate-containing fertilizer is prepared by decomposing phosphates at temperatures not exceeding 35 DEG C. with nitric acid together with ammonium sulphate or ammonia and sulphuric acid, neutralizing the paste obtained at below 40 DEG C. with ammonia and passing the product to a granulator together with dried recycled powdered product, to produce spherical granules with a diameter above 1/8 inch. Potassium salts may be added and the ammonification may occur in stages, for example, first with gaseous, then with 25 per cent aqueous ammonia. Specifications 440,214 and 615,476, [both in Group III], are referred to.