Measures to prevent mine fires

The basic principle of treating mine fires is to prevent and focus on prevention.

1. General measures for mine fire prevention

(1) Supporting wellbore with non-combustible materials

Downhole yards, main roadways and diverticularies, in the event of a fire, pose a great threat to the entire mine. Thus, the wellbore when the adit, and cut along the shaft bottom coal layer, must Arching; when cut in the rock formation, nonflammable application support. The location where the wellbore is connected to the yard or the main road shall be built or supported by incombustible materials. The underground permanent central substation and other electromechanical chambers in the bottom hole yard must be built, and the power in the mining area is supported by non-combustible materials, from the chamber, the underground gunpowder warehouse and the roadway on both sides (need to be less than 5m) Must be built or supported by non-combustible materials.

(2) Set up fire protection materials library

Each mine must also store fire-fighting materials and tools, and establish a batch of fire-fighting warehouses, while meeting the following requirements:

1) ground fire material library to be set up in the vicinity of the wellhead housing (but shall not be located at the wellhead room), and iron is accessible wellhead;

2) The underground fire protection material warehouse shall be located in the transportation lane of each production level;

3) The variety and quantity of materials and tools stored in the fire materials warehouse are determined by the mine manager and are regularly inspected and replaced. These materials can only be used to deal with accidents and should not be used. The materials consumed for handling accidents should be replenished in time. Source: Examination Pass

(3) Set fire doors

In order to prevent the ground fire from being introduced into the underground, the inlet wellhead and the inlet air level should be equipped with fireproof iron gates. The iron gates should cover the wellhead tightly and be easy to close. The entrance to the wind tunnel and the horizontal bottom hole yards are equipped with two iron doors that are easy to close or fire doors that are covered with iron on the boards.

Mining coal seams with spontaneous combustion and igniting, in the mining and returning wind tunnels, must first build a firewall with a threshold, and place a door leaf near the threshold to reserve enough material to block the firewall threshold so that it can be closed at any time.

(4) Setting up fire fighting pools and underground fire fighting piping systems

Each mine must have a fire pool and a downhole fire piping system on the ground. Pumps shall be installed near the fire pool, and the head and displacement shall be specified when designing the mine fire equipment. In the deep horizontal mine, in addition to the ground fire pool, the upper horizontal or production level water tank can be used as the fire pool.

2. Prevention of external fires

Prevention of external causes of fire should start with the elimination of open flames and electric sparks. The main measures are:

(1) Gas mines should use safe explosives, and firearms must comply with safety regulations.

(2) Correctly select, install and maintain electrical equipment to ensure that the line is intact and to prevent short circuit and overload from generating sparks.

(3) It is strictly forbidden to use bulbs for heating and using electric furnaces. Underground and wellhead rooms shall not be engaged in electric welding, gas welding or torch welding. If it is necessary to carry out the above work, special safety measures must be established and reported to the mine manager for approval. And the designated person of the mine designated to be present for inspection and supervision.

3. Prevention of internal fires

(1) Correct selection of mining and mining methods

The requirements for preventing spontaneous combustion are: minimum exposed coal seam surface, maximum coal mining volume, fastest recovery speed and easy isolation of mining area.

1) Use concentrated rock roadway or reduce the cutting amount of mining area. It is necessary to adopt Shimen, rocky alleys or concentrated roadways (uphill and downhill); as far as possible, open auxiliary roadways in the mining area, increase the distance between roadways as much as possible, and arrange the main roadways in hard rock, which must be mainly drilled in the coal seams. When selecting roadway, it is necessary to select coal seams that are not self-igniting or have less risk of spontaneous combustion. The relative position between coal roadways in the mining area should avoid the influence of supporting pressure, and the size of coal pillars and roadway support should be reasonable.

2) Choose a reasonable coal mining method. The mining method of the old coal mining method such as the high-rise type and the room-column type is very low. The large amount of concentrated coal is left in the goaf, and there are many roadways for tunneling, and the air leakage is large and difficult to isolate. It is very dangerous to mine coal seams that are prone to spontaneous combustion.

The wall mining method has a high recovery rate, and the roadway layout is relatively simple, which facilitates the use of mechanized equipment, thereby speeding up the recovery speed. This method has better fire safety. Experience has shown that thin coal seams use this coal mining method and rarely ignite spontaneously.

The mining of thick coal seams and medium-thick coal seams adopts inclined stratification and horizontal stratified artificial false roof mining method, supplemented by preventive grouting. As long as the quality of grouting is ensured, thick and medium thick coal seams can be mined safely, reliably and economically. .

The roof management method can affect the coal recovery rate, coal pillar, coal retention integrity and air leakage. It is prudent to select the roof management method for coal seams with spontaneous combustion hazard. All the collapse methods manage the roof, which is generally prone to spontaneous combustion in the goaf, and filling all the goafs with inert materials in a timely and dense manner can greatly reduce the occurrence of spontaneous combustion fires.

3) Improve the recovery rate and speed up the recovery. Using advanced labor organizations, use high-efficiency coal mining equipment and comprehensive mechanized equipment as much as possible to speed up the recovery. In addition, it is necessary to determine the area of ​​the spontaneous combustion according to the spontaneous combustion tendency of the coal seam and the mining and geological factors, and to divide the area of ​​the mining area reasonably with the recovery speed. The mining area is closed before the spontaneous combustion.

(2) Ventilation measures

1) Select a reasonable mining area ventilation system. Combine the development plan and the mining sequence, and choose a reasonable ventilation mode in the mining area. It can reduce the amount of air leakage in the goaf.

2) Implement partition ventilation. Partition ventilation is a reasonable ventilation method, which can reduce the total resistance of the mine, expand the ventilation capacity of the mine, and easily adjust the air volume to reduce air leakage. At the same time, it is also convenient to stabilize the wind flow and isolate the fire area during the fire.

(3) Preventive grouting

1) Use mud as a grouting material. Preventive grouting is to send mud (water, loess, sand, etc. according to a certain proportion) to the area prone to spontaneous combustion by means of slurry equipment, and play a role in fire prevention. The use of mud as a grouting material is a more effective measure to prevent spontaneous combustion, and has been widely used in production mines where conditions are used for grouting.

2) Use tailings as a grouting material. Tailings pulping is much simpler than the yellow mud pulping process. It only needs to use the ash pump or sand pump to pump the flotation slurry to the ground circular mixing tank, and then filter through two sieves without any other processing. As a fire-fighting grouting material.

The process is: flotation machine → (tail) concentrator → tailings (slurry slurry) → sand pump conveying → round mixing tank → through the pipeline into the underground grouting place.

3) Inhibitor fire extinguishing is to use a solution or emulsion of one or several substances to inject into the gob area, coal pillar gap and other places that are prone to spontaneous combustion, reduce the oxidation capacity of coal, and prevent the oxidation process of coal. The anti-fire extinguishing agent is easy to operate and economical and reliable. This method is for lack of soil. Fire prevention and control in water-deficient mining areas has important practical significance.

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