Study On The Causes Of Coal Mine Gas Explosion Accidents

The analysis on the causation of accidents is the basis of accident prevention.For the past few years,the proportion of the serious and major coal mine gas explosion accidents in the whole serious and major coal mine accidents is increasing greatly,which keeps the number of accidents and death tolls stubbornly high.Many previous papers and scholars have analyzed the causes of gas explosion accidents occurred inside the coal mine,but they mainly focus on the direct cause of unsafe acts and unsafe conditions,and seldom involved in the hidden cause which behind the direct cause,like the individual habitual behavior and the weakness of safety management system.To provide entry or emphasis points,train of thought for the present and future accident prevention and for the employee training,the cause of people,condition,individuals and organizations in gas explosion accident should be analyzed in all possible ways.This paper selects 24 Model as the theoretical basis to analyze the gas explosion,and studies 105 major gas explosion accidents occurred between 2005-2014 in details.The paper firstly analyzes the accidents' causation factor of the serious gas explosion accidents in nearly ten years,such as the accident location,the time of the accident occurred,the death toll,the gas ranks and the ownership of the coal mine,then the internal reasons,such as unsafe acts,unsafe conditions,habitual behavior and the weakness of safety management system in two aspects: ignition source and gas accumulation.At last,the paper also gives some advices about the application of the cause analysis in gas explosion accident prevention.The main conclusions are as follows:(1)Based on the 24 Model,this paper proposes an accident analysis method which roots in the employee behavior.The method can be described as 7 steps:(?)dividing the organization occurring accident and finding the targets needed to be analyzed;(?)describing the scene of the accident;(?)identifying unsafe acts of employees within the accident organization;(?)examining the courses of unsafe condition;(?)investigating the habitual acts;(?)pointing out the safety management system and exploring the reasons;(?)concluding the causes of the coal mine gas explosion accidents and how the causes affects an accident.(2)The paper finds the reasons leading to serious and major gas explosion accidents.Based on the statistical analysis of the causes of the 105 serious and major coal mine gas explosion accidents occurring between 2005 and 2014,conclusions can be obtained as follows.The main problems,which were seldom in state-owned coal mine but still existed in township coal mines,were blasting flame,spark and disorder ventilator management.In state-owned coal mine,the causes of the gas accumulation accident were friction collision spark and spontaneous combustion of coal in confined space,which were more difficult to prevent.(3)The cause maps(Appendix C)of ignition source and gas accumulation in the accident is obtained.By analyzing the various causes of sample accidents,the cause maps of gas explosion accidents are obtained according to the frequency of causes.(4)Factors triggering the ignition source in gas explosion accidents are obtained.As for the causes of blasting frame,sealing technology and explosive and blasting equipment management were the main unsafe acts leading to blasting flame.In addition,in 36 accidents,blasters were working without specialized training or without license;in 37 accidents,there were such acts like illegal command,neglecting or tolerating illegal blasting;in 38 accidents,there was no blasting guidance or not enforcing relative guidance.These factors in all played important roles in forming blasting workers' habitual regulation violation.As for the electric sparking,the operations of electrical equipment which did not meet explosion-proof requirements(17)and the maintenance of electrical equipment without cutting off power(9)were the two main unsafe conditions that lead to accident directly.16 of the total 17 classes of unsafe conditions belonged to the failure to meet explosion-proof requirements.Among these 16 classes,the cable joint mine coal drill(11)took the largest part.36 of the 41 coal mines occurring accidents were not equipped with the facility of power blocking or the power control equipment which can cut off power in advance,all these reveal the shortage of knowledge about the function of power blocking.In addition,such laws like how to operate the electrical equipment,how to maintain the cable,and the life circle of an explosive-proof equipment,the function of the electrical equipment maintenance account are absent of coal mines accidents,and such crew are lack of knowledge of electrical equipment maintenance and management,which leading to the unsafe acts and unsafe conditions in combination.As for open fire and heat radiation,the paper finds that most of the accident were caused by such unsafe acts,like the lack of periodic inspection on enclosure's integrity,seal condition and anti-air-leakage measures(7),and the absent of fire prevention measures for the spontaneous combustion existing for a long time and the presence of fire(6),which were caused by unsafe conditions.In addition,3 of 13 coal mines occurring accidents were not equipped with temperature detection in mined out area or warning system,fire extinguishing system.It is means that,in accident coal mine,instead of the lack of technology,the management system was not practice totally.As for the causes of spark caused by friction,the collision of metal equipment during operation,installation location direction and maintenance management of electrical equipment,integrity of spare mechanical and electrical equipment and roof management should be stressed to prevent spark caused by friction.And,it was clear that the knowledge of spark caused by friction should emphasized in safety training(8).(5)Factors leading to gas accumulation in gas explosion are obtained.As for the causes for insufficient air supply in coal mine,many unsafe acts were conducted by management staff or even the managers of the mine.Accidents caused by the reasons,such as unauthorized power block-out for entire mine(8),no mechanical ventilation(7),cross-mining(6),over-mining(3),all of which may lead to insufficient ventilation,revealing that the management staffs were lack of relevant knowledge.As for the causes for management disorder in the local ventilator,the statics finds that no local ventilator was used in the working face(9),the error of installation position on local ventilator led to the wind circulation(8)causing inadequate effective air in the working face.The three main unsafe conditions of matters involved in 43 accidents were,local ventilator which was related in 30 accidents,hair dryer which was related in 15 accidents and ventilation structure which was related in 5 accidents.Moreover,most staffs in such accident mine were lack of knowledge about the caused and the harm of local ventilator's wind circulation(15)and harm of switching local ventilator randomly(8).Ventilation team generally failed to fulfill their responsibility,and such regulations on the installation,operation,management of local ventilator(16)and inspection,maintenance management of hairdryer(15)were also lacked.As for the reasons for the unreasonable ventilation system,the error of ventilation structure setting in the mining area caused the place no wind,leading to 5 accidents,and it also showed that workers did not understand the role of ventilation structures.What's more,there was no ventilation system or an unreasonable ventilation system in 7 accidents,or there were no safety technical measures in holing process(2),causing a disorder of the ventilation system.As for the causes of roadway clogging,there was no regulation or no implementation of such regulations on maintenance management of roadway in such 4 accident mines,and in 1 accident,there were no safety technical measures formulated before drainage,which shows the workers were lack of awareness of the risks of the roadway blockage.As for the causes of improper gas emissions,the study finds that simply blow away(6)and randomly switch of local ventilator(4)were the main unsafe conditions causing gas accumulation.Accordingly,the management did not develop or require the implementation the rule of gas emission or local fan ventilator in the compliant way.As for the reasons for the abnormal emission of gas,it can be finds that although the gas emission was a sudden occurrence,there would be obvious signs before the accident.In the actual accident,however,the staff ignored.For example,in daily operations,workers took little measures to prevent shock bump or gas emission anomalies,or they dogged in high-gas mines(or high-gas areas)without gas emission in ahead.As for the reasons for gas accumulation in confined space,it is necessary to focus on two aspects in confined space:(?)monitoring the gas concentration,(?)taking effective and safe technical measures to prevent gas emission when working near the confined space.12 of the 22 accidents,there was no monitoring system in the confined space.and 10 accidents were lacking effective and safe technical measures,when occurred near the confined space,indicating the unsafe acts.As for the reasons for gas concentration during blasting,the paper finds that 5 accidents were occurred because of the specifications for blasting operation,which were not formulated before blasting.In 3 accidents,the workers went back to working face without any ventilation,or examining the gas concentration.All can indicate Obviously that the blasters and the manager on duty did not realize the importance of formulating specifications for blasting operation and that of the check after blasting.As for the reasons of gas concentration examine,it shows that gas concentration examine cannot be tracked in operation process in 74% accidents.78 accidents were occurred because the inspector on duty did not checked the concentration of gas before operation,while 63 accidents were because the gas concentration was not checked before operation.For the unsafe condition,there were no gas sensors near the workplaces in 43 accidents,no portable gas detectors carried by miners in 32 accidents,and no normal gas monitoring systems in 29 mines,which blocked the operation of gas detection.Basically,the miners in accident mines did not catch the significance of gas detection by rule,reflecting the weakness of safety management system.And there were 54 accident mines where the number of gas checkers was not enough and 47 mines where the requirement of check for miners on their wearing of portable gas detectors was not specified in the security censorship.(6)The advices on application of results from the reason analysis of gas explosion accidents are presented.The analysis results of the reasons for the single accident can be adopted in the exhibition and case teaching.Since the reasons of gas explosion in a given period are obtained by analysis and statistics in this paper,the statistics of accident causes can be used to inspect whether these problems are avoided in productive mines through check of all sorts of reasons,in which the usual ones and those have not been noted can be known,and advices for prevention of accidents can be made based on these laws obtained.