By using the vibratory milling method and adding abrasive

superfine powder of ammonium phosphate was produced from the ammonium phosphate dry powder.The superfine ammonium phosphate dry chemical fire extinguishing agent

of which the average diameter was 4.12 μm and the average specific surface area was 880.43 m2/kg

was produced through the special surface modification by using the hydric cymene silicon oil in the mixing equipment.The fire extinguishing agent featured better hydrophobicity.It was anti-caking

and its moisture adsorption rate was 1.7%.The anti-agglomeration was 30.5 mm(by penetration degree).The experiments showed that the ejection rate was 98.7%

the ejection time was 10 s

the fire extinguishing time was 3 s

and the average fire extinguishing quantity was 60 g/m3.