Application of the latest foam fire-fighting mater

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Application of new foam fire-fighting materials in Xinji Coal Mine

Huainan Xinji coal mine has an annual production capacity of 4million tons. At present, the mining level is -450m, and the main coal seams are mined. The average thickness of the coal seams is 8m, the dip angle is 5 ° ~ 25 °, and the natural ignition period is 3 ~ 6 months, with a minimum of 36d. In terms of mining method, fully mechanized caving coal mining technology is adopted; In the layout of the roadway, all the coal is used to go up (down) the mountain; In the mining area, the small-stage continuous mining technology without coal pillars is adopted; This mining layout achieves the goal of high yield and efficiency, but it also produces a series of safety problems, especially the mine spontaneous combustion fire is becoming more and more serious. Since the mine was put into operation, there have been 17 spontaneous combustion fires, including 11 high-rise spontaneous combustion, 4 stoping line spontaneous combustion and 1 working face spontaneous combustion. In order to ensure safety in production, in recent years, a variety of fire prevention technologies have been adopted in the mine, especially the Rockwell foam fire prevention technology, which has greatly improved the mine fire prevention situation

1 application range characteristics and technical parameters of rockhew foam

1.1 application range

rockhew foam is a hollow filling product with good mechanical compressibility (about 0.2 MPa) of Hua MAOZe, chairman of liangchengdu Jiahao group. It can be used for sealing walls in coal mines, filling high caving, plugging coal seam cracks, building firewalls, etc

1.2 characteristics

the product has high expansion rate, the expansion volume is 25 ~ 30 times of the original volume, and the filling dosage is small; The foam reacts quickly. When the temperature is 30 ℃, it can react in 30s. When the temperature is 10 ~ 15 ℃, it can react in 8min and harden within 20min. No leak proof support is required; It has good compressive capacity (about 0.2MPa) and can withstand the operation of rock stratum; It does not spread flames and is suitable for underground fire extinguishing

1.3 technical parameters

see Table 1 for the technical parameters of Roxburgh foam

Table 1 technical parameters of Rockwell foam

see table

2 construction process

2.1 process flow

use a special pneumatic pump to send the resin and catalyst into the pressure gun at a ratio of 4:1 and then spray it out. After mixing the two raw materials, they will foam and harden rapidly. The process flow is shown in Figure 1

Figure 1 process flow chart

calculation of material consumption: q = v × (1+i)/(n × 25)

where Q - material consumption, barrel

v - void volume, m3

i - construction error coefficient, taken as 10%

n -- foaming multiple, n = 25 ~ 30

25 - capacity of each barrel, L

in case of multi hole transposition injection, when the pressure is found to rise to 10MPa, it means that the injection cannot go in, and the hole should be changed. The steps of hole changing and pressure injection are as follows:

(1) turn off the gas shut-off pump with very optimistic development prospects, open the unloading valve of catalyst pipeline for backflow unloading, and close the stop valve of pressure injection gun

(2) turn on the pump, flush the pipeline and gun with resin, and then turn off the pump

(3) change the hole, close the unloading valve, open the stop valve, and start the pump to continue pressure injection

(4) cycle (1) - (3)

(5) after the pressure injection of all holes, shut down the pump, change the cleaning agent, remove the interface between the gun and the pressure injection pipe, and start the pump to clean the pipeline and gun

2.2 precautions

(1) generally, the length of the outlet hose of the pressure injection gun should not exceed 6m, otherwise it is easy to be blocked; The outlet pipe diameter should be dn10~dn13 hose, not large diameter

(2) shake the resin evenly with static force before pressure injection

(3) prepare enough raw materials during pressure injection to avoid damaging the piston or blocking the pipeline by suction

(4) the catalyst is corrosive, so protective glasses and rubber gloves should be worn during construction

(5) when the temperature exceeds 30 ℃, the pressure injection pipe should not be used and the gun should be used directly. When the temperature is low, the pressure injection speed should be accelerated accordingly

3 field application

3.1 high fake filling

the main mining 13# coal seam in Xinji Mine is soft, and it is easy to form roof fall in the process of tunneling and roadway repair. Because the high caving has spontaneous combustion conditions, spontaneous combustion fire is very easy to happen. Since the mine was put into operation, there have been 11 high spontaneous combustion, accounting for 64.7% of the total. In order to fundamentally eliminate the hidden danger of spontaneous combustion of high caving, Xinji Mine uses Rockwell foam to fill the high caving. 53 high risk points at 1305c, 241303 lower roadway, 241303 outer section joint roadway and other places have been treated successively, and a total of 1560m3 Rockwell foam has been filled. In order to investigate the effect of rochugh foam on the treatment of high spontaneous combustion hazards, representative hidden danger points were selected in the outer section of 1305c and 241303, and temperature thermocouples and observation holes were pre buried for long-term observation. The CO concentration was reduced from 300 before treatment ×~ seven hundred × When the temperature drops to 0, the temperature drops from 50 ~ 60 ℃ before treatment to below 30 ℃ and remains stable for a long time

3.2 sealing air leakage with pressure injection airtight wall

due to the continuous extraction of fully mechanized top coal caving without coal pillars, the adjacent goafs are connected with each other, and the air leakage in the goaf of the upper stage during the mining period in the next stage; However, due to the poor recovery of supports and the supporting effect of coal pillars, the roof rocks of the stoping line and abandoned upper and lower roadways in the previous stage did not fall sufficiently, forming a good air leakage channel. And because the mining area adopts all the coal up (down) mountain, the upper and lower roadways of the working face are arranged in the coal seam, the sealing wall is not closed tightly, and there is air leakage for a long time, which leads to the spontaneous combustion of the stoping line. Since it was put into operation, there have been 4 spontaneous combustion fires on Stoping lines, accounting for 23.5% of the total number of spontaneous combustion fires, and the spontaneous combustion goaf accounts for 33.3% of the total number of mining areas

in order to eliminate the hidden danger of spontaneous combustion fire in the stoping line, Xinji Mine changed the traditional double tiled stone single wall into double tiled stone double wall, and left a 200 mm spacing between the walls. Measure holes were left at the upper, middle and lower positions of the outer wall, and Rockwell foam was injected into the middle of the two walls by using measure holes for filling; Drill around the wall to the side and top, and inject foam by drilling, which can not only connect the closed wall with the side and top as a whole, prevent air leakage, but also increase the pressure bearing capacity of the wall. In 2002, a total of 11 closed walls in 5 goafs were treated, and no signs of spontaneous combustion occurred in the treated areas

3.3 fast closing fire area

the 241301 fully mechanized top coal caving face in Xinji Mine was mined near the f085 fault (h=10~8m). The water in the working face was stopped on March 4, 2002, and then paved. The paving was completed on March 9, and the fully mechanized mining support was removed on April 18. By may, the electrical device of the tensile testing machine was in the dynamometer. On the 9th, 241301 stoppage line had a spontaneous combustion fire, and the CO concentration in the upwind Lane reached 1000 ×, And smoke. At the time of the fire, the lower lane was just closed, and the return column of the upper lane was less than one third

in order to prevent the expansion of the fire, it is decided to set up three temporary regulating dampers on the return air side, and use two local fans to supply air to the upwind lane for pressure equalization, so as to control the massive emission of toxic gases. Then, two boards are set at the pillar return point of the upper roadway, with a spacing of 500mm between them. Rockwell foam is used for filling. It takes only 4 hours to close, which not only controls the spread of the fire, but also wins time for fire treatment. After drilling and grouting, high water filling and other measures were taken to completely extinguish the fire

4 conclusion

the successful application of Rockwell foam in mine fire prevention and extinguishing completely changed the fire prevention situation of Xinji No. 1 mine with high-strength bolts, nuts and gaskets for 42 steel structures, and achieved good economic and social benefits

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