GB783507A - Improvements in or relating to the manufacture of phospho-nitrogenous fertilizers - Google Patents

Abstract

783,507. Fertilizers. SOC. ANON. DES MANUFACTURES DES GLACES ET PRODUITS CHIMIQUES DE ST.-GOBAIN, CHAUMY & CIREY. July 23, 1952 [July 23, 1951], No. 18629/52. Class 111. In the production of a phospho-nitrogenous fertilizer wherein an acid sludge resulting from the attack of nitric acid alone or with other acids on natural phosphate, is directly neutralized by gaseous ammonia to form dicalcium phosphate, the ammoniation is effected by introducing air with the ammonia into the sludge in amounts such as to maintain the sludge at a temperature of 10‹ to 20‹C. below its boiling point. Suitably the quantity of air is 1 to 1À5 times that of the ammonia. A suitable apparatus is shown in the Figure where a vat 1 is provided with an inverted frustoconical funnel 4 open at both ends, in the centre of which is placed an impeller 5. A sludge resulting from the acid attack on phosphate is fed through an opening 2 and ammonia is passed in below the impeller through pipe 6 whilst air is fed through pipe 8 and a perforated jet pipe 9. According to an example, an acid sludge prepared by the nitric acid attack on natural phosphate followed by the elimination of calcium nitrate or the addition of phosphoric acid to bring the molecular ratio of P 2 O 5 to soluble CaO to about 2, is ammoniated with gaseous ammonia together with 1À3 to 1À5 times the quantity of air whereby the temperature of the sludge is maintained at 10‹ to 20‹ below its boiling point from beginning to end of the treatment. Practically all of the phosphate is assimilable.