Patent ID: 8157935

Claim:
A method for producing explosive grade ammonium nitrate granules, suitable in an Ammonium Nitrate and Fuel Oil (ANFO) explosive composition, wherein the granules have microvoids which have a diameter of 10 to 100 microns and an oil absorption of 6 to 15% of fuel oil, the method including: a) providing an ammonium nitrate melt containing 93% to 95% by weight concentrate ammonium nitrate and 300 to 600 ppm of a salt of an alkyl naphthalene sulfonate crystal habit modifier on an active basis; and b) spraying the ammonium nitrate melt, through at least one nozzle, into a first fluidised bed which is supplied with air that has been conditioned to a relative humidity of less than 30% at 40° C. and heated to a temperature of 95° C. to 105° C. to form ammonium nitrate granules.