Model of Fire-fighting and Spontaneous Combustion Control for High-Sulfur Coal Waste Pile in Yangquan

摘要

Coal mining and processing activities in China result in the generation of huge quantities ofcnal waste and cause severe impacts to environment and human health. The most serious safety issues associated with surface disposal of high sulfur coal waste due to spontaneous combustion as a result of the oxidation of sulphide and carbon which likely leads to geo-disasters and environmental pollution. The potential of fire-fighting and spontaneous combustion control were compared through field tests in Yangquan of Shanxi province, for three models as surface slurry-praying, deep slurry-infusing and clay overcastting-rolling, and study the most effective model. Chemical analysis indicated that the coal waste in Yangquan contained high sulfur as 6.23%, being typically high-sulfur coal waste and showing high risks of spontaneous combusting under natural conditions due to the high calorific capacity (12000J/g) and carbon amount (above 20%). Field tests indicated that the 3 models could control the spontaneous combustion under experimental conditions. Comparatively, the model of surface slurry-praying is simple and easy to handle, but exhibit risks of re-combustion in the short term due to the thin slurry layer (0.2m). The model of deep slurry-infusing showed much longer duration for combustion control, through the interaction between slurry and deeply imbedded coal waste with high temperature. Unfortunately, it was relatively to handle, especially on sites as slope. The model of clay overcastting-rolling employed local clay for combustion control could be easily mechanically-handled with higher efficiency and shorted time. Furthermore, this method provided soils necessary for ecological restoration, which would fundamentally control the spontaneous combustion on coal waste pile. The effective model implemented in No.3 spot of Danaoliang in Yangquan Coal Industry Group is clay overcastting-rolling (thickness 0.7 m, compacting factor >85%) primarily, assisted with partial deep slurry-infusing (depth 5m, platoon interval 3.0-3.5m), finally vegetation planting, and the soil cover parameter has been optimized. Results of continuous monitoring demonstrated the excellent effects of controlling combustion for method of clay overeastting-rolling assisting with deep slurry-infusing. As being indicated, the average value of SO2, NO2, CO concentration was 11.2 mg/m3, 0.438 mg/m3 and 27.33 mg/m3, respectively. Comparatively, the average concentration for these gases sequentially decreased to 0.13 mg/m3, 0.035 mg/m3 and 4.36mg/m3, accordingly. The test demonstrated that the surface temperature of the coal waste pile has fallen to 50 °C below fundamentally.