Provided is a multi-functional plugging agent for a coal mine and a preparation method thereof. The preparation method comprises: by taking Ecklonia Kurome Okam as a raw material, mixing an Ecklonia Kurome Okam suspension with phosphorus pentoxide for reaction, then performing biodegradation to obtain an Ecklonia Kurome Okam biological extract, adding urea for neutralization, mixing a neutralization product with an inorganic catalyst and melamine for reaction to obtain a bio-based plugging synergist solution, finally cooling the bio-based plugging synergist solution, and mixing the cooled bio-based plugging synergist solution with a certain amount of pentaerythritol and ammonium polyphosphate to obtain the multi-functional plugging agent for the coal mine based on the Ecklonia Kurome Okam biological extract. According to the invention, not only a coal crack can be effectively plugged for a long time, but also an efficient flame-retardant effect can be achieved in a complete period of coal spontaneous combustion.

Provided is a multi-functional plugging agent for a coal mine and a preparation method thereof. The preparation method comprises: by taking Ecklonia Kurome Okam as a raw material, mixing an Ecklonia Kurome Okam suspension with phosphorus pentoxide for reaction, then performing biodegradation to obtain an Ecklonia Kurome Okam biological extract, adding urea for neutralization, mixing a neutralization product with an inorganic catalyst and melamine for reaction to obtain a bio-based plugging synergist solution, finally cooling the bio-based plugging synergist solution, and mixing the cooled bio-based plugging synergist solution with a certain amount of pentaerythritol and ammonium polyphosphate to obtain the multi-functional plugging agent for the coal mine based on the Ecklonia Kurome Okam biological extract. According to the invention, not only a coal crack can be effectively plugged for a long time, but also an efficient flame-retardant effect can be achieved in a complete period of coal spontaneous combustion.

A method for ecological filling with mixed coal gangue and fly ash includes the following steps: S1: construction of a double-impermeable base layer: leveling a pit or gully, laying a fly ash-based cementitious material, compacting and curing; spraying a layer of polymer waterproof coating on a surface of the fly ash-based cementitious material, and fully curing to obtain a double-impermeable protective structure; S2: three-dimensional layered filling: dumping coal gangue and fly ash in sequence on the double-impermeable protective structure formed in S1, where the coal gangue and the fly ash are three-dimensionally layered and well graded; the coal gangue is coal gangue after coal washing, which is used as an aggregate; the fly ash is used as a filler and cementitious material to achieve a compact filling structure; and S3: rolling: rolling by a roller after the three-dimensional layered filling.

The present invention discloses a multi-energy complementary system for a co-associated abandoned mine and a use method. The multi-energy complementary system for a co-associated abandoned mine includes a mining mechanism, a grouting mechanism and an energy mechanism. In the present invention, the mining of coal and uranium resources is realized through the mining mechanism, the subsidence and seepage reduction of the stratum is realized through the grouting mechanism, and the effective utilization of waste resources is realized through the energy mechanism. Finally, with the efficient cooperation of the three mechanisms, safe and efficient development and utilization of co-associated resources in the full life cycle are realized, and the purposes of green and efficient mining of coal and uranium resources and secondary development of a coal seam goaf are achieved, thereby facilitating the realization of dual-carbon goals and the development of low-carbon green energy.

A method for disposing of biomass waste. The method includes locating an abandoned mine having a first well drilled into or through the abandoned mine. Water is removed from a mine cavity through a second well drilled into or through the abandoned mine. The water from the mine is combined with a biomass waste that is at least 70 wt. % carbon to provide biomass waste entrained in the water. The biomass waste entrained in the water is pumped through the first well into the mine cavity to fill the mine cavity. As the biomass waste settles in the mine cavity, the water used to entrain the biomass waste is recirculated to combine with additional biomass waste.

A method for efficiently treating spontaneous ignition of the remaining coal in a large area goaf of a shallow-buried coal bed, which method integrates leaking stoppage, airflow control and fast inerting and cooling so as to efficiently prevent and treat the spontaneous ignition of the remaining coal in the large area goaf of the shallow-buried coal bed.

Provided is a method for recovering room-type coal pillars by cemented filling of reserved roadways, which is especially suitable for safe and efficient recovery of left coal pillars in room-type mining faces in mining areas where the ecological system is fragile, such as in western China. In the method, by constructing reserved roadways in two adjacent rows of room-type goafs, excavating coal pillar roadways in room-type coal pillars, and finally interconnecting the reserved roadways with the coal pillar roadways to form a U-shaped working face, room-type left coal pillars are recovered. Thus, not only the workload of roadway excavation is reduced, but also the recovery ratio of the coal resources is maximized. The method provides a novel technical model for the recovery of room-type left coal pillars in mining areas, such as in western China.

Treatment technology directed to using mine waste as a raw material to manufacture a mine filling product for use as a suitable precursor product or mine filling product to be used as a backfill material to close a mine. The precursor product or mine filling product retains its metals and is not be able to generate acidity. According to the disclosure, the precursor product or mine filling product, when placed in a mine, may also remove metals from mine fluids in the mine it contacts, and still retain the metals it hosted when it was a mine waste prior to it being used as a raw material to manufacture the precursor stowing backfill product.

An internally injected replacement support room-type coal pillar recovery method is provided. During the recovery, the room-type coal pillars with an aspect ratio greater than 0.6 are divided into two parts: reserved coal pillars and pre-mined coal pillars. After the mining of the pre-mined coal pillars, a cemented filling material is injected into a goaf surrounded by the reserved coal pillars, and is stabilized to replace the coal pillars for support, and the reserved coal pillars are recovered. A mechanical model of the reserved coal pillars in a support overburden stage is established based on the Winkler beam theory, to obtain displacement and stress conditions of a roof of the reserved coal pillar in a support stage. A theoretical reserve-width of the reserved coal pillars is obtained according to a first strength theory of the roof and a criterion of ultimate strength of the reserved coal pillars.

A process for controlled in-situ coal gasification is disclosed. The process includes surveying one or more selected coal bearing sites for designing a plurality of panels; designing a plurality of sub-panels of a plurality of corresponding panels with a plurality of bi-directional boreholes and a plurality of vertical service boreholes; channelizing the plurality of bi-directional boreholes and vertical service boreholes to one or more layers of coal seams; constructing one or more coal slice areas of predefined dimensions within the one or more layers of the coal seams; combusting coal inside the one or more coal slice areas; extracting combusted coal from the one or more coal slice areas through the plurality of vertical service boreholes; monitoring physical condition of at least one cavity created by extraction of the combusted coal; controlling remote filling of a filling material simultaneously at the at least one cavity using the filling device.