To study the fracture law of different overlying strata during mining lower protective seam under a close distance coal at depth 1000 m, roof bed-separation and fissure imaging monitoring were carried out in inlet roadway ahead working face JI15-31040 Pingdingshan XII mine. The results show that with being affected by mining, displacement 0–4 m was relatively large, development very significant...

Bumps and other types of dynamic failure have been a persistent, worldwide problem in the underground coal mining industry, spanning decades. For example, in just five states in the U.S. from 1983 to 2014, there were 388 reportable bumps. Despite significant advances in mine design tools and mining practices, these events continue to occur. Many conditions have been associated with bump potenti...

Previous studies have established that the selection of gas extraction borehole parameters is crucial for effectiveness extraction. To more accurately determine reasonable radius boreholes in coal seam, this study was based on actual occurrence conditions body. A coal-seam gas-seepage model, considering dynamic changes permeability under gas–solid coupling conditions, constructed. It combined w...

Phosphorus contents of coal from around the world vary although there is a tendency for Permian coals from India and Australia, and Cretaceous coals from Western Canada to have more phosphorus than Carbcmiferous coals from Europ+ and USA (Table 1). This may be because of the evolution of vegetation type over geological time or because of the conditions in the coal swamps. Data presented here su...

Employees of coal-fired power stations and people living nearby as well as those involved in the shipment and processing of coal fly ash can be exposed to coal fly ash (pulverised fuel ash or “PFA”). An extensive research program was carried out in order to map such exposure and its effects. Particle size distribution, chemical composition, quartz, radioactivity, emission factors and fugitive d...

Recent research into very large, regularly shaped, geological structures has shown that in the 100 kHz to 10MHz frequency range electromagnetic waveguide behaviour is observed when the material forming the structure is not too lossy (conductivity σ < 0.0001). While mode formation and modal behaviour in electromagnetic waveguides is very well understood, much of the literature describes high fre...