Abstract: The present invention relates to the technical field of mine fire prevention and extinguishing, in particular to a liquid nitrogen direct injection and low-temperature foaming intelligent filling system based on mine fire area characteristics and an application method, comprising a liquid nitrogen storage tank, a liquid nitrogen direct injection system and a low-temperature foaming system, wherein the liquid nitrogen storage tank communicates with a liquid nitrogen pressurizing device through a main pipeline; a temperature control unit is arranged on the main pipeline; and the liquid nitrogen pressurizing device is connected with the liquid nitrogen direct injection system and the low-temperature foaming system, respectively, liquid nitrogen is directly injected into a foam liquid, to prepare a low-temperature foam type fire preventing and extinguishing material by means of forced convection, membrane boiling, explosion boiling and nucleate boiling between the liquid nitrogen and water.

Abstract: 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.

Abstract: 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.

Abstract: A plastic gel material for preventing spontaneous combustion of coal, including water, a crosslinking agent, a toughener, a coagulant, an aggregate and a water glass. The crosslinking agent (AlCit) is prepared by mixing a polyaluminum chloride solution and a citric acid solution then neutralizing the mixture with a sodium hydroxide solution. The coagulant is one or more of potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, sodium carbonate or glucono-?-lactone (GDL). The toughener is one or more of pregelatinized starch, sodium alginate, carboxymethyl cellulose or polyacrylamide. The aggregate is coal ash or bentonite. The plastic gel has good water retention, toughness and inhibition performance, and helps avoid easy cracking and pulverization in inorganic silica gel consolidating bodies after losing water. The plastic gel can cover the surface of burning coal mass, reduce the temperature of the ignition source, heat radiation and production amount of CO, and have a fire extinguishing effect.

Abstract: A microcapsule of sustainable self-healing coal mine ventilation sealing material crack. The microcapsule includes a microcapsule core material and a microcapsule wall material. The microcapsule core material is prepared using a bacterial lyophilized powder and a substrate. By using urease-producing bacteria, there is provided a method of protecting bacteria to survive a long time in the cement-based material, supplying sufficient nutrient substances and reducing the impact of the doping of bacteria on the mechanical property of the cement-based material. The bacterial lyophilized powder and substrate are prepared into microcapsules which are added into the cement-based material when the cement-based material is mixed. In this case, once concrete cracks, the microcapsules breaks and the spores in the material are activated to perform normal metabolism so as to induce precipitation of calcium carbonate continuously, thereby continuously realizing self-healing of coal mine ventilation sealing material cracks.