Preparation method for ammonium phosphate dry-powder fire extinguishing agent

The ammonium phosphate dry powder fire extinguishing agent is prepared with wet process ammonium phosphate 700-900 (in weight portions, the same below), calcium carbonate 50-250, active white clay 40-60, silicified silica white 20-25 and silicon oil 12-15. The said materials are mixed, constant temperature dewatered at 85-90 deg.c with hot air flow to water content below 0.1 %, and crushed to required size. The ammonium phosphate dry powder fire extinguishing agent of the present invention has low production cost, low hygroscopic rate, low product storing period and other advantages.