"Detailed Rules for Fire Prevention and Control in Coal Mines"

Article 82: When using three-phase foam for fire protection, the following regulations shall be observed:

(1) The slurry-to-soil (or soil-to-ash) ratio for preparing three-phase foam should be 4:1 to 6:1.

(2) The gas source can be either nitrogen or air. The pressure of the gas entering the foamer inlet must exceed the foam flow resistance between that point and the filling point, and should not be lower than 0.2 MPa.

(3) The foaming agent must not be flammable, combustible, toxic, radioactive, or irritating.

(4) The longwall mining face can be grouted from higher-level roadways, while the inclined strip mining face can be simultaneously grouted in both the intake and return air roadways. In areas of roadway roof overhangs, borehole grouting is recommended.

Product Overview

The three-phase foam generation device for coal mines consists of a foaming system and a foaming agent injection pump. It leverages the mine’s existing grouting system—whether on the surface or underground—to inject the foaming agent, thereby reducing the surface tension of water and altering the physicochemical properties of fly ash and yellow mud surfaces. This process effectively achieves rapid fire prevention and extinguishing. The device ensures complete coverage of floating coal, both at low and high elevations, seamlessly overcoming the common issue of uneven grout coverage that often leads to "grout leakage" and "channeling." By isolating oxygen from coming into contact with the coal, it halts the oxidation process and stops the exothermic reactions that sustain fires.

Product Features

1. The foam formed after foaming significantly increases in volume, spreading extensively throughout the mined-out area and even accumulating at higher elevations.

2. Effectively and swiftly addresses hidden fire sources of coal spontaneous combustion in areas such as goaf zones and high-roofed roadway sections.

3. Simple structure, high foaming multiple, and no need for any external power devices—instead, it relies solely on the energy of the slurry itself. This approach not only saves energy and protects the environment but also ensures thorough mixing of gas, liquid, and solid phases, resulting in foam that is uniform, fine, and stable.

4. Wrap the coal body to isolate it from oxygen, and seal off leakage air pathways and cracks within the coal.

New Construction Techniques

Strip-type three-phase foam grouting construction technique for preventing spontaneous combustion in goaf areas. Foam and nitrogen gas pipelines are laid along the upper and lower roadways, extending to the mining line position. After the working face advances by xx meters, foam injection begins. The amount of foam required is carefully calculated to ensure that a continuous foam wall—sufficiently thick to seal off the mining line—is formed, at which point foam injection is halted. Next, -30°C nitrogen gas is injected into the goaf area, with pipelines being gradually withdrawn as mining progresses. Once the working face has advanced to xxx meters, foam injection resumes at the predetermined location, once again creating a robust foam barrier. This process effectively establishes a low-temperature zone between the two foam walls, while simultaneously using nitrogen gas to inert the surrounding space. As mining continues, the pipelines are steadily removed. Finally, cold nitrogen gas is injected to further freeze the foam walls into an ice-like structure. By repeating this procedure multiple times, several small, cryogenically inerted low-temperature zones are created within the goaf area, significantly delaying the oxidation and subsequent temperature rise of the coal. This innovative approach effectively prevents spontaneous combustion in the goaf region.

Main Technical Parameters