GB818668A - Improvements in and relating to phosphates and other fertilizers - Google Patents

Abstract

818,668. Treating fertilizers with acid. DUNGEMITTEL-TECHNIK A.G. Feb. 12, 1958 [Feb. 16, 1957], No. 4639/58. Class 111. A method of treating fertilisers, phosphates and calcium cyanamide with mineral acids comprises introducing the finely ground fertilizer in continuous flow into a treatment chamber, blowing air into the chamber by means of nozzles arranged at the bottom of the chamber to create a vortex whereby the finely ground particles are held in suspension and simultaneously spraying on to the fertilizer sulphuric acid and/or phosphoric acid and/or nitric acid. Ammonia may be sprayed on to the phosphate simultaneously with the acid. Granulation of the fertilizer particles may be produced by means of an agitator device rotating in the whirling mass. The fertilizers used may be natural phosphates, phosphates produced by chemical methods, Thomas slag, calcined phosphates, aluminium phosphate and may contain powdered organic substances such as ground peat, decantation sludges, saw-dust, ground lignin. In Fig. 1, nozzles 3 in the bottom of reaction chamber 1 blow vertical jets of air from lower chamber 4 supplied with air under pressure. Fertilizer fed in at 6 is momentarily held in suspension to receive jets from nozzle 11 on pipe 10. Reaction takes place and the treated product collects in layer 18 which is evacuated through orifices 14 and 15. Blown air carrying with it water vapour and gases generated by reaction passes out at 12 to dust extractor 13. Rotary agitator 19 produces an agglomeration of the treated products in the form of granules.