METHOD OF PRODUCTION OF A COMPLEX CALCIUM-CONTAINING FERTILIZER WITH A CONTROLLED RATIO OF Ca:PO Russian patent published in 2005 - IPC

FIELD: chemical technology; production of complex mineral fertilizers.

SUBSTANCE: the invention is pertaining to chemical technology and may be used in production of the complex mineral fertilizers by a method of nitric acid treatment of natural phosphates. The method provides, that a part of calcium is removed from the nitric acid extract using a crystallization of calcium nitrate under cooling conditions with the subsequent separation of crystals from a mother liquor. The rate of calcium separation is preferably kept within the limits of 68÷76 %. At that the mother liquor is divided in two parts. One part, the share of which makes preferably 30÷70% is ammonated up to pH 3÷7. From the ammonated suspension separate a sediment of calcium phosphates and mix it with the second part of the mother liquor. The mixture is processed into the target product with the help of an ammonation, evaporation, drying and granulation. Produce complex calcium-containing NP- or NPK-fertilizers with the ratio of Ca:P₂O₅ within the limits of 0.3÷0.5 5 and simultaneously balanced by nitrogen and phosphorus, that is NP 1:1 or NPK 1:1:1. The mother liquor after separation of a sediment of calcium phosphates is reprocessed into the complex water-soluble fertilizers with the ratio of Ca:P₂O₅ less than 0.02 with application of an ammonation, evaporation, drying and granulation. So the invention allows to produce the complex mineral fertilizers with the controlled ratio of nutritive substances.

EFFECT: the invention allows to produce the complex mineral fertilizers with the controlled ratio of nutritive substances.

4 cl, 2 ex, 1 tbl