Verfahren zur Herstellung gekoernter Duengemittel

摘要

A melt of ammonium phosphate ammonium nitrate and 0-2% of water is granulated by spraying at a temperature of 140-200 DEG C. on to tumbled particulate solid, including recycled product, at a temperature of 45-140 DEG C. in a granulation zone maintained at a temperature of 100-150 DEG C. The ammonium phosphate has an N:P ratio of 0.9-2 to 1. The N:P2O5 ratio of the ammonium phosphate plus nitrate is 0.5-3 to 1. The melt may also contain 5-20% of ammonium sulphate. The particulate solid contains 50-100% of undersize and crushed oversize granulated product. It may also contain potassium chloride, sulphate or nitrate; ammonium phosphate or sulphate; or urea. The ratio of recycled material to other material in the granulation zone may be 0.5-2 to 1. Granulation is effected in a horizontal rotating drum. The temperature of the particulate solid may be adjusted before granulation by means of heating or cooling gases.