Abstract:

In order to prevent high-level fire hazards such as spontaneous combustion of top coal and upper layer residual coal, a self-produced gas expansion slurry was prepared by taking industrial solid waste phosphogypsum as the base material, adding components such as sodium bicarbonate and polyacrylamide. Firstly, a thermogravimetry(TG) analyzer was used to study the thermal stability of the slurry at different heating rates. Then, a self-built insulation performance testing system was used to test the thermal insulation performance of the slurry. Finally, the fire extinguishing and cooling performance of the slurry was studied through fire extinguishing experiments. The results show that when the temperature of phosphogypsum based self-produced gas expansion slurry is below 160 ℃, there is a mass loss of 35% to 46% in the slurry. When the temperature is above 160 ℃, the mass fraction of the slurry no longer changes. The thickness of the slurry accumulation reaches 30 mm, and the effective insulation time exceeds 139 min, which can achieve good coverage of coal spontaneous combustion hazardous areas. The slurry expands and diffuses in the cracks of the coal pile, completely enveloping the broken coal from bottom to top, isolating oxygen, and having good cooling and fire extinguishing performance. After 36 min of grouting, the temperature at all points has been decreased to below 50 ℃, and no reignition phenomenon has occurred.

Key words: phosphogypsum based self-produced gas expansion slurry, coal spontaneous combustion, thermal stability, thermal insulation performance, fire extinguishing and cooling, effective insulation time