The room and pillar method (RPM) of coal extraction is used by Russian mines in areas unsuitable for longwalling while foreign mines apply it as the dominant technology at high cost-performance ratio. Evaluation of potential expansion of application domain for RPM in Russia needs in-depth study of foreign high-efficiency coal mining technologies. This article reviews process flow charts of coal extraction from pillars in the room and pillar mining technology in the USA, Australia, South Africa, etc. The technological advance is based mobile roof support applied since 1970 for ground control and to ensure safety of people and equipment. The structure and implementation variants of the support are discussed. There are two groups of the pillar recovery technologies with mobile roof support. The groups differ by conditions, parameters and sequence of mining operations. The first group includes variants of coal extraction from extended pillars between long rooms. The flow charts of one-side and two-side pillar recovery with different sets of MRS are discussed. The sequence of cutting entries in pillars, advancing the support and leaving support segments in the pillars are described. The second group of the process flow charts concerns square rib pillars. Such pillars left with initial parameters in mines resulted in high coal loss, and variants of partial coal extraction have been found therefore. Square pillars are recovered with mobile roof supports subsequently from four sides. The roof support is ensured by three MRS. The entries in the pillars are cut by the Christmas tree method, which shortens ferry time of cutter-loaders and improves coal production output. In hazardous conditions, pillars are cut by entries made along two sides. Diagonal entries can be used as well. Design and application of the advanced equipment for RPM has offered diverse technologies possibilities to miners in different countries to carry out safe extraction of coal from pillars and to increase the rate of of coal pillar recovery to 90 % and higher.
ASJC Scopus subject areas
- Business and International Management
- Geotechnical Engineering and Engineering Geology
- Economic Geology
- Industrial and Manufacturing Engineering
- Management of Technology and Innovation