GB588358A - Improvements in and relating to granular fertilizers - Google Patents

Abstract

A process for producing a granular ammonium chloride fertilizer comprises mixing 85-50 per cent. of ammonium chloride with 15-50 per cent. by weight of clay (on a moisture-free basis) in the presence of a minor proportion of water. Granulation may be effected by imparting a circular, rotatory or swirling-motion, e.g., stirring or tumbling, to the mass during or after addition of water. The clay may be dried and ground before 'mixing with dry ground ammonium chloride, the mixture granulated by adding water thereto in a granulator, e.g., a liner mixer, Eirich mixer, drum granulator or a paddle granulator, the product dried in a drier, e.g., of rotary type, and the granulate screened. The oversize granulate may be crushed and returned to the drier and the undersized returned to the granulator or the crushed material may be screened free from fines before returning to the drier and the fines introduced into the granulator. In the preferred process unground ammonium chloride and wet clay are mixed in a pug-, pan-, or edgerunner mill and granulated in a paddle granulator by addition of 5-10 per cent. by weight of water from evenly-distributed overhead jets. In a modification, ammonium chloride and wet clay are mixed in a pug mill, roughly mixed or sprinkled with water, introduced into a rotary drier and granulated and dried therein. If desired, part of the ammonium chloride may be dissolved in the water used for granulating. Specifications 389,473 and 403,781 are referred to. The Provisional Specification describes also the use of plaster of Paris, finely ground anhydrite and chalk, one or more of which may be employed with or without clay.