In underground mining of horizontal and gently dipping coal beds with longwall method in the direction along the strike using power-driven machines (makes 90% of total coal mining in Russia), the strata control involves roof caving behind the support units as they advance. The application of this mining system results in displacement of large volumes of rocks in the Earth's interior. It has been found that rock caving in a closed space has a small time gap: roof is stable for a short duration, then weak rocks of the weakest bottom layer of the roof fall and, later on, large blocks of the upper roof collapse. This temporary hanging and slow caving of roof rocks offers a possibility to convert kinetic energy of caved rocks in electric energy. Electric energy generation method consists in cyclic effect of gravity force of caved roof rocks on mobile units of powered support. Design of the powered support units includes a spring-loaded moving board attached to the guard on the caving side and connected to an electric generator rotor by a rack bar. As the unit advances after the coal cutter-loader by the value of thickness of coal cut, the board goes up and the follow-up fall of roof rocks affects the board and makes it to go down and transfer rotary moment to the rotor of the electric generator. The generated electric energy goes to an accumulator to be used further. Along with the unit-by-unit generation of electric energy, grouped generation is expected: when extended spans in longwalls are caved, a few support units will simultaneously generate electric energy. Electric energy generated and accumulated by all (150-250) units of powered support can be used for internal mine supply instead of non-conventional energy. The proposed method offers a possibility to utilize a huge energy potential of the process of production-induced transformation of lithosphere.
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology