2009 Ladislav Duslo WO2009008845 Method of preparation of granulated industrial nitrogen-calcium fertilizer
Method of preparation of granulated industrial nitrogen-calcium fertilizer from the reaction mixture resulting from decomposition of mineral salts of calcium cations with nitric acid, by the action of a basic agent at pH of 6 to 10 and at a temperature of 50 to 120 °C. Undesirable cations are precipitated, they are separated, in the obtained solution the ratio Ca : NH 4 is adjusted to 4.5 to 9.4 by adding aqueous solution of nitric acid and gaseous and/or liquidammonia and/or ammonia nitrate. The obtained solution is thickened, overheated solution having a temperature of 100 to 170 °C is injected into a granulator, powder phase is added, it is granulated at a temperature of 40 to 135 °C, and adjusted to a temperature of the resulting granulate not exceeding 110 °C. The granulated material is screened, the appropriate fraction of the granulated fertilizeris separated, oversized fraction is grind and together with the undersized fraction is cooled and returned into the granulator.