The autoignition preventing experiment was carried out for a novel flame retardant covering agent in coal heap

and the fire resistance performance of the novel flame retardant covering agent was analyzed.The results show that

after covered evenly by the flame retardant agent with low porosity and permeability

the rough coal surface became smooth

the porous structure disappeared and a dense sealing cover formed on the pulverized coal surface

which can prevent the oxygen going into the pile inside

thus to prevent the spontaneous combustion.Preventing the air flowing into the pile inside can control the temperature rise rate of coals

and the coal temperature can be kept at about 100℃

thus the spontaneous combustion tendency of coals can be reduced.When the temperature increased to above 110 ℃

the temperature rise rate of the coals covered by the flame retardant cover agent was dramatically lower than that of the reference sample

at the time of 2.2×104s

the detected coal temperature was 150℃

indicating the spontaneous combustion of the coals was effectively inhibited.For the improved covering agents

the coals' temperature rise rate was lower than that of the original one

at time of 2.4×104s

the temperature difference between the coals covered by the two agents was still about 12 ℃

implying the improved flame retardant covering agent has more excellent flame retardant effect.