Method of coal gangue separation and coordinated in-situ backfill mining

Coal mining is accompanied by the discharge of solid waste such as coal gangue and the control of mining pressure and surface subsidence. Promoting the green development of coal mines will be an important mean of protec- ting the ecological environment of the mining area from the source. The overall consideration of the relationship among coal mining, raw coal processing, and solid waste discharge is particularly important for the construction of green mines,and the collaboration of mining-dressing-backfilling will be a technical approach to fundamentally solve the above problems. Based on a full consideration of coal mining,coal-waste separation and backfill,and taking under- ground separation as the core,a mode of coal waste separation and coordinated in-situ backfill and mining has been constructed,the space-time synergy of the “mining,dressing,backfilling” system in the coal mine has been described, and the scientific connotation of “close sorting+in-situ backfilling” has been revealed. The coordination of backfilling capacity and sorting capacity,the arrangement of mining and backfilling system and sorting system,the organization of mining and backfilling process and sorting process,and the transportation and control of gangue have been realized. A coal mine gangue underground sorting collaborative in-situ backfilling and mining system to achieve different target levels has been proposed,which mainly includes three different levels of underground coal gangue separation technolo- gy,i. e. full particle separation,coal gangue separation and raw coal gangue discharge,and two aspects of underground in-situ backfilling technology to achieve different objectives of mine pressure and surface subsidence control,gangue treatment and resource recovery. The applicability of five underground coal gangue sorting methods,including new jig sorting,cyclone sorting,heavy medium shallow slot sorting,moving sieve jig sorting and γ-ray sorting,has been ana- lyzed and evaluated,and the selection process of coal mine gangue underground sorting methods has been given. The coal mine gangue underground sorting system and roadway layout requirements have been determined and the develop- ment direction of full-grain sorting in underground coal mines has been proposed,and four typical models in backfill of gob,including complete mining and complete backfill of gob ( CMCB),complete mining and partial backfill of gob (CMPB),partial mining and partial backfill of gob (PMPB),and partial mining and complete backfill of gob ( PM- CB) have been proposed,the definition,system layout and technical advantages of the four typical models in backfill of gob are defined,and the selection process of the backfill mining methods has been formed. Also,the surface subsidence and mining pressure control effects of the four typical models have been further compared and analyzed. The research results provide a technical reference for the realization of coal mining,underground separation and gangue treatment in- tensification,and further enrich the technical system of green coal mining in China.