RU2472938C1 - Method for preventing coal self-ignition in mines - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method involves supply of frozen fluid obtained by mixing with liquid gas to the worked-out space. In addition, distribution of coal dust supplied to the worked-out space is determined as to particle fractions. Distribution of the obtained frozen fluid particles as to fractions is equal to distribution of coal dust as to particle fractions.

EFFECT: improving the prevention efficiency of coal self-ignition in mines.

Description

The invention relates to the mining industry and can be used to prevent fires arising from spontaneous combustion of coal in the worked out space of mines.

A known method of preventing spontaneous combustion of coal in mines, including the isolation of the mined space of mines by constructing jumpers in the mine workings (Skochinsky A.A., Ogievsky V.M. Mining fires. - M.: Ugletekhizdat, 1954. - 387 p.).

The disadvantage of this method is the low efficiency due to air leaks through the jumpers and the impossibility of their construction in existing lavas.

There is also a method of preventing spontaneous combustion of coal, which includes supplying an inert gas to the worked out space (see AS 158837, class E21F 5/00).

The disadvantage of this method is the resumption of the process of spontaneous combustion of coal in the event of a cessation of inert gas supply.

The closest technical solution is a method for preventing spontaneous combustion of coal in mines, which includes supplying to the worked out space a frozen liquid obtained by mixing with liquid gas (AS 1718981 class A62C 5/00; AS 1714159, class E21F 5 / 00).

The disadvantage of this method is its low efficiency due to the uncontrollability of the processing process deposited in the worked-out space of coal dust supplied composition.

The technical result of the invention is to increase the efficiency of the method for preventing spontaneous combustion of coal in mines.

The specified technical result is achieved by the fact that in the method for preventing spontaneous combustion of coal in mines, which includes supplying to the worked-out space a frozen liquid obtained by mixing with liquid gas, the distribution of particles of coal dust carried into the worked-out space is further determined according to the invention, the distribution of the resulting particles the frozen liquid in fractions is equal to the distribution of coal dust particles in fractions.

The introduction of an increasingly powerful coal mining technology in mines leads to an increase in the amount of coal dust generated during coal mining. Moreover, a significant amount of this coal dust is carried away into the worked out space, settling in voids and cracks. Due to the large specific surface area, coal dust has a high chemical activity and is able to quickly ignite on contact with air if its mass reaches a critical value.

When moving along the developed space, the process of settling of coal dust particles depends on the size of the particles and the flow rate of the carrier gas. The gas velocity in the worked-out space is determined by the cross-sectional area of the channels along which the mixture of gas and coal dust moves. Since the cross-sectional area of the channels in the worked-out space changes, the amount of deposited coal dust in different zones of the worked-out space will be different.

In the known method with an unregulated particle size of the frozen liquid, the settling of the coal dust particles and the frozen liquid may not coincide, therefore, some accumulations of coal dust will have an amount of settled frozen liquid in an amount insufficient to prevent spontaneous combustion of coal.

Adjusting the particle size of the frozen liquid will allow you to distribute these particles in the channels of the worked out space in proportion to the settling amount of coal dust. To achieve this effect, it is necessary to determine the distribution of coal dust particles by fractions.

The same fractional distribution is created for the formed particles of the frozen liquid. Therefore, the moving particles of the frozen liquid settle in the worked out space in proportion to the deposited coal dust, uniformly treating the coal particles when the frozen liquid melts and reduces its chemical activity and temperature.

An example of a specific application of the method

Coal mining was accompanied by the formation of a large amount of dust carried away by the air flow into the exhausted space. The high chemical activity of coal dust led to the development of spontaneous combustion of dust deposited in the worked out space, which ended with the isolation of the site with the loss of coal mining equipment.

To prevent spontaneous combustion of coal dust into the air stream entering the exhausted space, it was decided to supply particles of frozen liquid obtained by the joint spraying of liquid gas (liquid nitrogen) and liquid. In this case, liquid antipyrogen (aqueous urea solution) was used. To evenly distribute the flame retardant into the settled coal dust, measurements were first made of the concentration of coal dust in the air and the distribution of dust particles in fractions. Measurements showed that the concentration of coal dust in the air entering the exhausted space is 0.8 g / m ³ . Dispersion analysis showed that the dust distribution by fractions is as follows:

- less than 5 microns - 10%;

- from 5 to 20 microns - 25%;

- from 20 to 40 microns - 30%;

- from 40 to 60 microns - 25%;

- from 60 to 100 microns - 5%;

- more than 100 microns - 5%.

In order to uniformly fill the deposited coal dust with particles of frozen liquid, the liquid is sprayed before freezing to particles whose fractional distribution corresponds to the content of coal dust fractions. For this purpose, nozzles are selected in which liquid particles are formed, as well as the ratio of the liquid flow through the corresponding nozzles, which allows one to obtain the desired distribution of frozen liquid particles into fractions. So, 6 nozzles were selected. In the first, particles up to 5 microns in size are formed, the second from 5 to 20 microns, the third from 20 to 40 microns, the fourth from 40 to 60 microns, the fifth from 60 to 100 microns, in the sixth more than 100 microns. Then, the liquid flow rates through the nozzles were determined, which made it possible to obtain the percentage distribution of particles of the freezing liquid over the fractions corresponding to the distribution of dust particles. For example, with a total flow rate of liquid flame retardant of 6 l / min, 0.6 l / min of liquid was supplied to the first nozzle, 1.5 l / min to the second, -1.8 l / min to the third, and 1.5 l / min to the fourth , fifth and sixth - at 0.3 l / min. Thanks to preventive work, spontaneous combustion in the worked out space was avoided.

The application of the proposed method will reduce the economic damage caused by endogenous fires to mines by preventing the spontaneous combustion process and increase the safety of mining operations.

Claims (1)

A method for preventing spontaneous combustion of coal in mines, comprising supplying a frozen liquid obtained by mixing with liquid gas to a mined space, characterized in that it further determines the fractional distribution of coal dust particles carried into the mined space, wherein the distribution of the obtained frozen liquid particles by fractions is equal to the distribution by fractions of coal dust particles.