A method for permeability improvement for a downhole coal seam by directional fracturing with pulsed detonation waves, which is applicable to gas control in coal seam areas with high gas concentration and low air permeability. The permeability improvement method is as follows: first, drilling a pulsed detonation borehole and pulsed detonation guide boreholes from a coal roadway to a coal seam respectively; then, pushing a positive electrode connected to a positive output side of an explosion-proof high-voltage electrical pulse generator to the bottom of the pulsed detonation borehole and pushing a negative electrode connected to a negative output side of the explosion-proof high-voltage electrical pulse generator to the bottom of the pulsed detonation guide borehole; connecting the pulsed detonation borehole and the pulsed detonation guide boreholes to an extraction pipeline for gas extraction, after electrical pulsed detonation fracturing for the coal seam is carried out. The method disclosed in the present invention utilizes the high instantaneous energy provided by electrical pulsed detonation waves to fracture a coal mass, so as to form a fissure network in the coal mass between the pulsed detonation borehole and the pulsed detonation guide boreholes; thus, the air permeability coefficient of the coal mass can be increased by 200-400 times, the effective influence scope of gas extraction of a single borehole for gas extraction can be enlarged by 3-4 times, the extracted gas volume from the borehole can be increased by 3-8 times, and the coal seam gas pre-extraction time can be shortened effectively.

A method for thermal-displacement-type strengthened extraction in a drill hole, suitable for efficient gas extraction in a coal mine, the method comprising the following steps: arranging an extraction drill hole and a thermal displacement drill hole at intervals in a coal seam; continuously heating coal in the drill hole to form a stable temperature field by using a heat pipe; and significantly reducing gas adsorption potential by utilizing a heat effect, prompting gas desorption, and strengthening gas extraction. The method enlarges a range of effective pressure relief influence of a single hole, increases an extraction efficiency of gas in a coal seam by more than 40%, is safe, reliable and low-cost, and is easy to operate, saving both time and labor.

The present disclosure relates to the technical field of mine ventilation, and in particular, to a three-dimensional ventilation method and system for mining by 110 construction method in coal and gas outburst mines. The three-dimensional ventilation method comprises: constructing a first process roadway and/or a second process roadway before stopping the working face; forming a first roof-cutting and roadway retaining section by a part of the working face track gate located in the goaf, and/or forming a second roof-cutting and roadway retaining section by a part of the working face transport gate located in the goaf during the stopping process of the working face, so that the air inlet of the first roof-cutting and roadway retaining section enters the gas drainage air return roadway through the first process roadway to form return air, and/or the inlet air of the second roof-cutting and roadway retaining section enters the gas drainage air inlet roadway through the second process roadway to form return air, the three-dimensional ventilation system is constructed by using the gas drainage air inlet roadway and the gas drainage air return roadway, during the conversion from the 121 construction method to the 110 construction method, a complete ventilation system can be formed in the roadway retaining section, real-time monitoring of the roadway retaining section can be carried while eliminating harmful gas accumulation in the retaining section.

The present disclosure relates to the technical field of mine ventilation, and in particular, to a three-dimensional ventilation method and system for mining by 110 construction method in coal and gas outburst mines. The three-dimensional ventilation method comprises: constructing a first process roadway and/or a second process roadway before stopping the working face; forming a first roof-cutting and roadway retaining section by a part of the working face track gate located in the goaf, and/or forming a second roof-cutting and roadway retaining section by a part of the working face transport gate located in the goaf during the stopping process of the working face, so that the air inlet of the first roof-cutting and roadway retaining section enters the gas drainage air return roadway through the first process roadway to form return air, and/or the inlet air of the second roof-cutting and roadway retaining section enters the gas drainage air inlet roadway through the second process roadway to form return air, the three-dimensional ventilation system is constructed by using the gas drainage air inlet roadway and the gas drainage air return roadway, during the conversion from the 121 construction method to the 110 construction method, a complete ventilation system can be formed in the roadway retaining section, real-time monitoring of the roadway retaining section can be carried while eliminating harmful gas accumulation in the retaining section.

A portable monitor used to measure landfill gas and landfill well parameters. The portable monitor includes a control unit and a measuring unit that can communicate wirelessly with one another. The control unit and/or measuring unit can include a heating arrangement to increase the temperature of one or more components in the control unit and/or measuring unit in cold environments.

A liquid nitrogen cyclic freeze-thaw permeability-improvement gas drainage method based on horizontal directional boreholes comprises: first constructing a main borehole at an intake roadway or a return roadway, a low-level roadway and a high-level roadway, after a drill bit reaches a pre-set target position of a coal bed, uniformly and directionally constructing a plurality of branch boreholes along a horizontal direction of the coal bed, injecting water to the coal bed, opening a valve, filling the main boreholes with liquid nitrogen, rapidly freezing the water injected into the branch boreholes and the periphery of the coal bed, and stopping injecting the nitrogen when an average temperature of a pre-permeability-improvement area monitored by a temperature measuring hole is lowered to 2 C. or lower.

Utilization of mine methane produced by mining a non-combustible ore, such as trona, as an energy source for heat, steam, and/or power generation. Such utilization is beneficial for a surface appliance which is close to surface outlet(s) of mine methane recovery system(s). A method for reducing greenhouse gas emissions generated during mining of a non-combustible ore uses the combustion of co-produced mine methane. The mine methane is recovered in a mine ventilation air exhaust with very low methane content, and may be additionally recovered in a drainage gas, such as gob gas, with much higher methane content. The surface appliance may be selected from the group consisting of calciner, dryer, boiler, kiln, furnace, engine, turbine, power generation unit, co-generation unit, and any combinations thereof. Benefits may include reduction in energy purchases, reduction in greenhouse emissions, and/or gain through sale of carbon credits to the carbon market by registering carbon reductions.

Utilization of mine methane produced by mining a non-combustible ore, such as trona, as an energy source for heat, steam, and/or power generation. Such utilization is beneficial for a surface appliance which is close to surface outlet(s) of mine methane recovery system(s). A method for reducing greenhouse gas emissions generated during mining of a non-combustible ore uses the combustion of co-produced mine methane. The mine methane is recovered in a mine ventilation air exhaust with very low methane content, and may be additionally recovered in a drainage gas, such as gob gas, with much higher methane content. The surface appliance may be selected from the group consisting of calciner, dryer, boiler, kiln, furnace, engine, turbine, power generation unit, co-generation unit, and any combinations thereof. Benefits may include reduction in energy purchases, reduction in greenhouse emissions, and/or gain through sale of carbon credits to the carbon market by registering carbon reductions.

A method for thermal-displacement-type strengthened extraction in a drill hole, suitable for efficient gas extraction in a coal mine, the method comprising the following steps: arranging an extraction drill hole and a thermal displacement drill hole at intervals in a coal seam; continuously heating, by using a heat pipe (5), coal in the drill hole to form a stable temperature field; and significantly reducing gas adsorption potential by utilizing a heat effect, prompting gas desorption, and strengthening gas extraction. The method enlarges a range of effective pressure relief influence of a single hole, increases an extraction efficiency of gas in a coal seam by more than 40%, is safe, reliable and low-cost, and is easy to operate, and saves both time and labour.

A ventilation method for a high gas working face based on alternating intake and air return in a mine gallery is provided. In this method, an isolated island working face is divided into several sections along a strike direction. A coal pillar is alternately set as a conventional section and a gas-drainage section. Opposite coal pillars in the two mine galleries within the same section are respectively used as the conventional section and the gas-drainage section. Two mine galleries on both sides of the isolated island working face are alternately used as an intake gallery and a return gallery. The coal pillar at the side of the mine gallery as the return gallery is the gas-drainage section. A gas-drainage hole communicating a goaf is provided in the gas-drainage section, so that gas in the goafs at two sides of the isolated island working face can be extracted alternately.