GB559482A - Improvements relating to the manufacture of granular superphosphatic fertilisers - Google Patents

Abstract

559,482. Mixing-appliances. STURTEVANT ENGINEERING CO., Ltd., RICHARDSON & CO. (YORK)., Ltd., H. PROCTOR, J. T., and OGILVIE. A. June 9, 1942, Nos. 7869/42 and 1017/43. [Class 86] [Also in Group III] Granular calcium superphosphate is produced by a continuous process in which ground phosphate rock and sulphuric acid are intimately mixed and retained in a mixer until a superphosphate slurry is produced, the slurry then being continuously delivered into a rotating granulator, open to atmosphere, in which granules are formed and from which they are continuously delivered to a rotary dryer wherein they are retained until hardened and from which they are passed continuously to a grading separator. The process is conducted in an apparatus comprising a mixer in which the reaction occurs and into which is delivered ground phosphate from a hopper 2 and acid from a metering device. The reacted mixture passes to a granulator 10, open to the atmosphere, which may be of the type described in Specification 544,274, [Group III]. The granules pass down a shoot 13 into a dryer 14 and thence to a screen 18 of say 1 inch mesh. The large granules pass to a mill, while those which pass the mesh are carried up by a conveyer 20 to a grading screen 23. the coarser granules pass down a shoot 27 to the grinding mill, the desired grade to a conveyer 25 for bagging, and the fines to a conveyer 28a to be returned to the granulator. The mixing reactor may be as shown in Fig. 5. comprising shaft stripper arms 4 and paddles 5 of opposite inclinations but arranged to cause a slow advance of the material. Specification 491,841, [Group III], also is referred to.