Evolution characteristics of spontaneous combustion in three zones of the goaf when using the cutting roof and release pressure technique

Abstract

The changes associated with the cutting roof and release pressure mining method in the three zones that are susceptible to spontaneous combustion in the goaf with “Y” type ventilation system were studied. For the investigated underground coal mine working face, its three zones of spontaneous combustion have a “U” type ventilation system for the traditional mining method and a “Y” type ventilation system for the cutting roof and release pressure mining method. These systems were monitored using a beam tube method, and the evolution characteristics of spontaneous combustion of the three zones was analysed. The monitoring data showed that when using a traditional mining method with a “U” type ventilation system, the scattered tropical zone converts into the oxidation heating zone after 68.5 m in the goaf, and the suffocative zone presents after 85.5 m. For the cutting roof and release pressure mining method together with a “Y” type ventilation system, the scattered tropical zone converts into the oxidation heating zone after 84 m in the goaf, and the suffocative zone appears after 198.8 m. Compared to traditional mining, the width of the oxidation heating zone increases when using the cutting roof and release pressure method. To prevent spontaneous combustion of the goaf, the comprehensive techniques of the pressure balance for fire control, ground fissure sealing, working face sealing, retained roadways guniting and inert gas fire extinguishing have been used in the studied coal mine. The CO concentration of the goaf is less than 300 ppm during the mining process. Safe mining of the tested working face shows that the cutting roof and release pressure technique can be applied to control the coal seam spontaneous combustion.

Targeted inertization with flue gas injection in fully mechanized caving gob for residual coal spontaneous combustion prevention with CFD modeling

“…The void characteristics of fractured coal rocks are the key parameters affecting the volume and path of air leakage. 10,[47][48][49][50] Therefore, there is a relationship between the void fraction and the bulking factor of fractured coal rocks in a gob:…”

“…Air leakage in a gob supplies oxygen to the residual coal while taking away the heat generated by oxidation. The void characteristics of fractured coal rocks are the key parameters affecting the volume and path of air leakage 10,47‐50 . Therefore, there is a relationship between the void fraction and the bulking factor of fractured coal rocks in a gob: where K p is the bulking factor of the fractured coal rocks.…”

Deformation Mechanism and Stability Control of Roadway Surrounding Rock with Compound Roof: Research and Applications

“…Wu et al [24][25][26][27] put forward the criteria and basis for judging separation stability, through five levels and six orthogonal factors including original rock stress, roadway width, compound roof lithology, compound roof thickness, structural cohesion, and structural internal friction angle that affect the separation of the compound roof. He et al [28][29][30][31] analyzed the characteristics of a jointed compound roof, pointed out its deformation mechanics mechanism with dual attributes of expansion type and structural deformation type, studied the transformation process from composite to a single mechanical mechanism, and put forward the form and sequence of combined support with bolt, mesh, and cable. However, the various layers of the compound roof were prone to plastic shear movement along the sliding surface, and then flexed and deformed to leave the layer.…”

Evolution and application of airflow permeability characteristics of gob in roof cutting and pressure releasing mining method

“…Since the industrial revolution, development of the economy, society, and energy industry has relied on fossil fuels such as coal, oil, and natural gas . Coal is the world's most widely distributed fossil fuel and currently accounts for more than 40% of global power generation . As a developing country, coal is the main energy source in China .…”