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Panel development
Published in Syd S. Peng, Longwall Mining, 2019
Panel development is an integral part of longwall planning. As the longwall becomes more productive, the possibility that development cannot catch up with longwall mining is very real. In fact, there are many cases where the next panel was not ready, and impromptu measures had to be adopted, such as cutting the next panel short or employing innovative ventilation methods to make the next panel ready, reducing the number of entry development, slowing down the longwall mining rate in the current panel, adding one more development unit on the opposite end, or simply parking or idling the longwall. With a quoted revenue loss of US$ 500 to US$ 2000 per minute of longwall idle time, inadequate panel development simply cannot be tolerated.
How Coal is Mined
Published in H. Townshend-Rose, The British Coal Industry, 2017
Advantages of longwall mining are the high percentage of coal extraction which it makes possible, the small amount of development work necessary prior to productive operations, and the control of subsidence which is possible. Disadvantages are the amount of labour and material required for support of roadways and at the working face, and the fact that, because factory methods of supervision cannot be applied to mining, lower standards of work and discipline are sometimes associated with the larger concentrations of men that the system requires. The rigid cycle of operations necessary for longwall working is easily disorganized by absenteeism and slow working.
Coal
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
The type and size of coal deposits, including their hardness, will determine the types of equipment to use. The seam and working height, mining dilution limits, production rates, and property extent, ventilation, size constraints, regulations, and floor pressures may impact the choice of equipment. For example, a large flat-lying coal seam may allow the use of longwall mining equipment. Floor condition plays a big part in the equipment type. Equipment productivity is also a factor that might prove essential in the final decision.
Characterizing strata deformation over coal pillar system in longwall panels by using subsurface subsidence prediction model
Published in European Journal of Environmental and Civil Engineering, 2020
Jianwei Cheng, Gang Zhao, Guorui Feng, Siyuan Li
Meanwhile, the subsidence of overlying strata could be regarded as the superposition of several subsidence-related factors which results in final subsidence both for surface and subsurface strata over coal pillars becomes more and more complex. Generally speaking, the final total subsidence of overlying strata over coal pillar including two parts: (1) normal subsidence induced by longwall extracted panels; (2) additional subsidence which is consist of pillar punch into mine roof, pillar convergence and pillar punch into mine floor. The subsidence caused by longwall mining contributes a lot to the subsidence over coal pillars which could result in massive damages to ground buildings, surface water system and land, etc. Thus, a model that could completely predict the subsurface strata movements, especially for indexes like vertical subsidence and horizontal displacements, could be very helpful to deal with the overlying strata deformation and damages over gobs and coal pillar and make any mitigate plans in advance.
Research on the Control Process of Mining and Combustion Disturbance Zone Based on the Three-Dimensional Dynamic Distribution Model of Void Fraction
Published in Combustion Science and Technology, 2022
Longwall mining is a widely used method for mechanized and large-scale mining of underground seams. As the long coal seam is mined piece by piece, a rectangular mining area is formed, and the length of the goaf gradually increases with the advancement of the longwall mining face. As mining progresses, the overlying strata destabilize and sink, and move toward the gob. Discontinuous subsidence of the overburden creates voids. For the horizontal rectangular goaf formed by longwall mining, according to the key layer theory, the settlement of the i-th key layer can be expressed as (Li, Qian, and Shi 2000):
Development of predictive methods for strain at the surface due to longwall coal mining
Published in Mining Technology, 2018
James Barbato, Bruce Hebblewhite, Rudrajit Mitra, Ken Mills, Arthur Waddington
Longwall mining is a widely used method for the underground extraction of coal. This mining method results in subsidence at the surface that comprises both vertical and horizontal components. Mine subsidence can result in impacts on natural and built features that are located directly above the longwalls. These impacts generally result from the relative (i.e. differential) horizontal movements, rather than from the absolute horizontal movements or the vertical component (Peng 1986; Bai et al. 1989; Tandanand and Powell 1991; Li et al. 2011).