GB426380A - Improvements in fertilisers - Google Patents

Abstract

Fertilizers are obtained by subjecting porous materials in the form of small rigid pieces, said pieces being other than pieces of coke of 1/20 inch size to 1/4 inch size, or mixtures of small rigid pieces of porous materials other than coke and small pieces of coke, to treatment to remove air by means of steam or a gas capable of condensation and/or solution in a liquid containing one or more fertilizing substances and then causing the thus treated porous materials to take up the said liquid. If necessary, the pieces of porous material may be reduced to 1/2 inch size to 1/4 inch size after the above treatment. The pieces may be impregnated in the above manner with p the same or different fertilizing substances. The fertilizing substances referred to are ammonium nitrate, sulphate or phosphate, sodium nitrate, potassium chloride, calcium nitrate, and urea. Examples of suitable porous materials are pumice, sandstone, calcareous sinter, kieselguhr, tufta, volcanic tuff, or mixtures thereof with or without the addition of coke. Examples of gases which may be used to remove air are ammonia and carbon dioxide. The pieces of porous material may be preheated before the current of gas or vapour is introduced. When ammonium nitrate is the fertilizing material and particularly when pieces of coke are admixed with the pieces of other porous material, ignition is avoided by introducing the ammonium nitrate in the form of an aqueous solution at a temperature of below 100 DEG C. The pieces of porous material containing fertilizers may be provided with protective coatings of substances of low solubility and which act as a mechanical protective such as fine dry clay or coke dust or dust of manurial value. Specification 422,126 is disclaimed.