Fire accident and prevention of drilling hole in t

In recent years, there have been many coal mine drilling fire accidents in Henan Province, which have caused certain losses to national property and people's life and health, and have an adverse impact on coal mine safety production. In order to prevent the recurrence of coal mine construction borehole fire accidents and further ensure coal mine safety production, this paper preliminarily analyzes the coal mine construction borehole fire accidents and their causes in Henan Province in recent years, and puts forward countermeasures and suggestions to prevent coal mine construction borehole fire accidents for your reference

I. overall situation of coal mine construction drilling fire accidents in Henan Province in recent years

according to incomplete statistics, 16 coal mine construction drilling fire accidents have occurred in Henan Province since 1987. In terms of the purpose of the construction boreholes in which the accident occurred, there are 11 gas drainage boreholes, one for water exploration, one for coal exploration, one for fault exploration, one for roof grouting, and one for coal sampling; In terms of accident distribution area, there were 5 accidents in Jiaozuo mining area, 4 in Dengfeng mining area, 1 in Xinmi mining area, 4 in Pingdingshan mining area, and 1 in Anyang and Yongcheng mining areas respectively; According to the types of gas in the mine, 14 accidents occurred in outburst mines and 2 accidents occurred in low gas mines; In terms of the way of discharging powder from the construction boreholes of coal mines where accidents occur, 15 adopt the way of air discharging powder, and 1 adopts the way of self discharging powder with threaded drill pipes (dry discharging powder, so the cleaning after each application is 10 points key type); In terms of the year of accident, there were one accident in 1987, 1991, 1993, 1997, 1999, 2000, 2003, 2004 and 2005, three in 2009 and four in 2010; In terms of whether the accident caused death, there were 4 fatal accidents in the 16 accidents, causing a total of 12 deaths; In terms of the nature of the mines where fatal accidents occurred, one occurred in the main mines of provincial backbone coal enterprises, and three occurred in township coal mines or resource integration mines of provincial backbone coal enterprises; In terms of the year of the fatal accident, there was one fatal accident in 2004, one fatal accident with seven people in 2009, and two fatal accidents with two people each in 2010

to sum up, no matter what purpose the drilling hole in coal mine construction is used for, as long as the drilling tool contacts the coal seam during drilling construction, fire accidents may occur, which will occur not only in outburst mines, but also in high gas or low gas mines; It will occur not only in the main mines of provincial backbone coal enterprises, but also in township coal mines or resource integration mines of provincial backbone coal enterprises. At the same time, the coal mine construction drilling process using the air discharge method is easier to occur than other coal mine construction drilling processes, and the film blown out by high-pressure PE is suitable for all kinds of fresh-keeping bags to cause fire accidents. In addition, since 1987, the occurrence of drilling fire accidents in coal mine construction has evolved from one in several years to one every year, and then to several in one year, and the fatal accidents basically occurred in the past two years. Therefore, the situation of drilling safety in coal mine construction in our province shows an increasingly severe trend. It is very necessary and urgent to pay close attention to the prevention and control of drilling fire accidents in coal mine construction

II. Preliminary analysis of the causes of fire accidents in coal mine construction boreholes

at present, there are three basic types of powder discharge methods in coal mine construction boreholes: air powder discharge, water powder discharge and self powder discharge (including dry powder discharge and wet powder discharge with appropriate amount of water in the borehole). Among them, the coal mine construction drilling technology with the method of air discharge of pulverized coal is prone to fire accidents; Drilling fire accidents may occur in the drilling process of coal mines with dry powder discharge type; The wet powder discharge type in the water powder discharge mode and self powder discharge mode generally does not cause drilling fire accidents in coal mine construction. Therefore, this paper makes a preliminary analysis of the direct causes of the coal mine construction drilling fire accidents of the dry powder discharge type in the air powder discharge mode and the self powder discharge mode

there are several direct reasons for the drilling fire accident in the construction of air pulverized coal extraction method:

first, the drill bit or drill pipe continues to drill after falling off, and the high temperature is caused by the friction between the drill bit and drill pipe, drill pipe and drill pipe. At the same time, due to the air supply to the drill hole, there are oxygen conditions, causing the determination of the water vapor permeability of pulverized coal or hard foam qb/t2411 ⑼ 8 gas combustion

second, continue to forcibly drill after sticking and jacking, and the friction between the drill bit and the coal seam increases, resulting in high temperature. At the same time, due to the supply of air to the drill hole, oxygen conditions are available, causing the combustion of pulverized coal or gas

third, new and old drill pipes or different types of drill pipes are mixed, and the gap between drill pipes is mismatched or even slips, resulting in high temperature caused by mutual friction between drill pipes. At the same time, due to the air supply to the drill hole, oxygen conditions are available, causing pulverized coal or gas combustion

fourth, the air pressure in the drill hole decreases, resulting in unclean discharge of powder or excessive amount of powder in the drill hole. At the same time, due to the supply of air to the drill hole, oxygen conditions are available, and in case of high temperature, pulverized coal or gas combustion is caused

the direct cause of the coal mine construction drilling fire accident of the dry powder discharge type in the self discharge mode is: the high temperature caused by the sticking of the drill or the forced drilling after the jacking, the mutual friction after the bit or drill pipe falls off, etc., which causes the high-temperature pulverized coal, gas or the mixture of the two in the drill to burn when encountering oxygen after being discharged from the drill hole, or ignite the combustible substances such as gas or pulverized coal in the coal mine construction drilling operation site, Thus a fire accident occurs

in addition, due to the following reasons, the development of drilling fire accidents in some coal mines has expanded, causing greater economic losses and even casualties

(I) the dust on the drilling site of some coal mines is too large, and the sensors such as carbon monoxide and gas are missing or suspended in the wrong position, which leads to the failure of on-site operators to detect the accident omen as soon as possible, delaying the opportunity of accident disposal. For example, in 2009, a coal mine in Dengfeng mining area, because the carbon monoxide digital portable instrument hung at the construction drilling site was too close to the coal wall to truly detect the concentration of carbon monoxide in the return air flow at the operation site, the on-site operators failed to find the fire in the construction drilling in time. Until the accident developed and expanded, the fire was extinguished with the participation of the mine rescue team, causing great economic losses

(II) many operators at the drilling site of coal mine construction have insufficient experience and ability in emergency disposal, and they have not taken early disposal measures and reports in time after the accident, leaving the accident to develop. For example, in a construction borehole fire accident in a coal mine in Jiaozuo mining area in 1987, the on-site operators felt dizzy and nauseated and immediately evacuated without taking any measures. Due to the continuous supply of air to the borehole and the availability of oxygen conditions, the borehole caught fire. The fire was not extinguished until the mine rescue team arrived underground and took measures to supply water to the borehole

(III) some coal mines do not place and use fire-fighting equipment and facilities in the construction drilling operation site in accordance with the regulations, or use pig iron in the coal mine construction drilling operation site, which has a general market performance and places combustible materials. For example, after a fire accident occurred in the construction borehole of a coal mine in Xinmi mining area in 2009, the on-site personnel did not use fire extinguishers or take water injection to extinguish the fire, but used coal to bury and press the flames, which affected the fire extinguishing process, and combustible plastic braids were used around the borehole opening for protection. As a result, the plastic braids were ignited by about 0.5 square meters, which had an adverse impact on the rescue and disaster relief work