GB643762A - Improvements in and relating to the granulation of superphosphatic fertilisers - Google Patents

Abstract

<PICT:0643762/III/1> A granular phosphatic fertilizer is made by forming a slurry of matured or partially matured superphosphate by adding moisture thereto prior to introduction into a conditioner and controlling the moisture content by introducing a moisture absorbing material into the slurry in the conditioner. In one embodiment, superphosphate is conveyed (12) to a mixer 14 and sufficient water and/or ammoniacal liquor is added to form a slurry which is fed continuously to a conditioner 16 and mixed with fines (from the screening apparatus) or other moisture absorbent, e.g. powdered "den" superphosphate, sulphate of ammonia or potash or dried sewage matter, and if desired with other fertilizing salts. Granules from 16 are passed to a dryer-hardener 20 and thence to a screening apparatus. The process is applicable to the granulation of "den," double and triple superphosphates and to mixed fertilizers containing superphosphate, and may also be used where the process starts with rock phosphate and acid as given in another embodiment (Fig. 1, not shown) in which acid and rock phosphate are delivered to a mixer and the slurry therefrom is fed into a first conditioner, the granules from which are then reslurried in another mixer and the resulting slurry passed into a conditioner &c. as in the first embodiment. Specifications 559,482 and 625,863 are referred to.