A methodology for assessing underground coal mines for high safety-related risk

In 2008 the authors developed a methodology for assessing underground coal mines for high risk for major-hazard events. It focused on major hazard-related violations of safety standards associated with high-risk conditions. Later using the same stratified pilot sample of 31 mines, injury measures and MSHA citation data were combined into a Safe Performance Index (SPI). Using 2009 data, the database was expanded to 107 mines, which is a 30% sampling of all underground coal mines. The SPI was used to assess the relative safety-related risk of mines, including by mine-size category. The methodology can be used to assist companies, the Mine Safety and Health Administration, or state agencies in targeting mines with high risk for serious injuries and elevated citations for remediation of their violation and/or injury experience.     

新形势下煤矿安全教育研究

通过分析我国煤矿安全教育的现状以及存在的问题,提出了目前完善我国煤矿安全教育体制应采取的新举措,对提高我国煤矿安全教育水平,改善煤矿安全生产状况具有重要的意义.     

Collecting representative dust samples: A comparison of various sampling methods in underground coal mines

Former methods used in the U.S. to assess hazardous and explosible coal dust date back to the 1950s. As mining technologies advanced, so too have the hazards. Given the results of the recent coal dust particle size survey and full-scale experimental mine explosion tests, the National Institute for Occupational Safety and Health (NIOSH) recommended a new minimum standard, in the absence of background methane, of 80% total incombustible content (TIC) be required in the intake airways of bituminous coal mines, replacing the previous 65% TIC requirement. Most important to monitoring and maintaining the 80% TIC is the ability to effectively collect and analyze representative dust samples that would likely disperse and participate in dust explosion propagation. Research has shown that dust suspended on elevated surfaces is usually finer, more reactive, and more readily dispersible while floor deposits of dust are generally coarser and more difficult to disperse given the same blast of air. The roof, rib, and floor portions of the dust samples were collected and analyzed for incombustible content separately and the results were compared to a band sample of the roof, rib, and floor components. Results indicate that the roof and rib dust samples should be kept separate from floor dust samples and considered individually for analyses. The various experimental collection methods are detailed along with preferred sampling approaches that improve the detectability of potentially hazardous accumulations of explosible dust.     

Analysis and assessment of a critical event during an underground coal gasification experiment

The main goal of the study presented in this paper was to analyse the mechanisms affecting an Underground Coal Gasification (UCG) process and to identify possible deviations of the system from normal work to limit, or even avoid, losses. The UCG process is one of the most innovative technologies connected with the exploitation of coal deposits that are currently being tested and developed all around the world. It allows the conversion of a coal seam into gas under in situ conditions of high temperature with the use of gasifying agents such as air, oxygen, steam or with a mixture of them.The paper presents the results of the analysis and assessment of a critical event during the process: a dangerous gas accumulation that occurred during an underground coal gasification experiment in the Experimental Mine “Barbara” of the Central Mining Institute (Poland). The UCG experiment using the shaft method is described, together with its monitoring system and the problems that appeared during the process. The application of the Fault Tree Methodology allowed the establishment of the main factors that may lead to the explosion and to present possible scenarios of its occurrence.Moreover, calculations were carried out to evaluate the risk level of explosion for the gas mixture and the minimum level of oxygen in the mixture that is necessary to initiate an explosion. These calculations were based on a modification of the formula proposed by Le Chatelier. During the course of the underground experiment, original information of the process behaviour has been acquired that can be used in the preparation of other UCG experiments in operational mines to guarantee the safety and the stability of the process.     

Development of algorithms for predicting ignition probabilities and explosion frequencies

A project was performed for the Explosion Research Cooperative to develop algorithms for predicting the frequencies of explosions based on a variety of design, operating and environmental conditions. Algorithms were developed for estimating unit-based explosion frequencies, such as those reported in API Recommended Practice 752, but in more detail and covering a much broader range of chemical process types. The project also developed methods for predicting scenario-based explosion frequencies, using frequencies of initiating events and conditional probabilities of immediate ignition and delayed ignition resulting in explosion. The algorithms were based on a combination of published data and expert opinion.     

Fire and explosion risk assessment for large-scale oil export terminal

Now in Russian Federation and other countries large-scale oil terminals (volume of one tank exceeds 100 000 m³, total volume of tanks exceeds 300 000 m³) are designed and constructed. Therefore fire safety of such objects becomes a very important task, solution of which is hardly possible without detail fire risk assessment. This study is aimed to a solution of this problem. Potential, individual and social risks were calculated. The potential risk was defined as a frequency of occurrence of hazardous factors of fires and explosions in a given point of space (the so-called risk contours). The individual risk was defined as a frequency of injuring a given person by hazardous factors of fires and explosions. Time of presence of this person in hazardous zones (near the hazardous installation) is taken into account during calculations of the individual risk. Social risk was defined as a dependence of frequency of injuring a given number of people by hazardous factors of fires and explosions on this number. In practice the social risk is usually determined on injuring not less than 10 people.

The oil terminal under consideration includes the following main parts: crude oil storage consisting of three tanks of volume 100 000 m³ each, input crude oil pipeline of diameter 0.6 m, crude oil pumps, output crude oil pipeline of diameter 0.8 m, auxiliary buildings and facilities. The following main scenarios of tank fires have been considered: rim seal fire, pool fire on a surface of a floating roof, pool fire on a total cross-section surface of the tank, pool fire in a dyke, explosions in closed or semiclosed volumes. Fires and explosions in other parts of the terminal are also taken into account. Effects of escalation of accidents are considered.

Risk contours have been calculated both for the territory of the terminal and for the neighbouring space. The potential risk for the storage zone is near 10⁻⁴–10⁻⁵ year⁻¹, and at a distance 500 m from the terminal the potential risk values do not exceed 10⁻⁶ year⁻¹. The values of the individual risk for various categories of workers are in the range of 10⁻⁵–10⁻⁶ year⁻¹. Because of low number of the workers on the terminal and large distances to towns and villages the social risk value is negligible. These risk values are consistent with practice of the best oil companies, and fire hazard level of the terminal can be accepted as tolerable.     

Dynamic risk assessment for underground gas storage facilities based on Bayesian network

Loss of the underground gas storage process can have significant effects, and risk analysis is critical for maintaining the integrity of the underground gas storage process and reducing potential accidents. This paper focuses on the dynamic risk assessment method for the underground gas storage process. First, the underground gas storage process data is combined to create a database, and the fault tree of the underground gas storage facility is built by identifying the risk factors of the underground gas storage facility and mapping them into a Bayesian network. To eliminate the subjectivity in the process of determining the failure probability level of basic events, fuzzy numbers are introduced to determine the prior probability of the Bayesian network. Then, causal and diagnostic reasoning is performed on the Bayesian network to determine the failure level of the underground gas storage facilities. Based on the rate of change of prior and posterior probabilities, sensitivity and impact analysis are combined to determine the significant risk factors and possible failure paths. In addition, the time factor is introduced to build a dynamic Bayesian network to perform dynamic assessment and analysis of underground gas storage facilities. Finally, the dynamic risk assessment method is applied to underground gas storage facilities in depleted oil and gas reservoirs. A dynamic risk evaluation model for underground gas storage facilities is built to simulate and validate the dynamic risk evaluation method based on the Bayesian network. The results show that the proposed method has practical value for improving underground gas storage process safety.     

PTA生产火灾爆炸危险性分析与评价

采用道化学公司的火灾、爆炸危险指数法对PTA生产工艺进行了分析与评价。首先分析了PTA具体的生产工艺流程,其次对其生产原料、生产流程中的高温氧化反应、加氢反应阶段的火灾危险性以及PTA装置的包装工段的火灾危险性进行了具体的分析。接着运用道化学公司的火灾、爆炸危险指数法,系统地对PTA生产装置的火灾爆炸危险性进行了评估。文章选取该装置中火灾爆炸危险性较大的高温氧化单元以及加氢精制单元为评价单元。并依照火灾爆炸指数法的评价程序进行评价,确定物质系数、单元危险系数、火灾爆炸指数、安全措施补偿系数、危害系数等一系列参数。最后就评价结果及各单元补偿前后危险程度进行详细的分析并提出了防止PTA生产装置燃烧爆炸的安全对策措施,文章为后期系统深入地研究PTA安全生产提供了一定的参考。     

A new practical approach to risk management for underground mining project in Quebec

The mining industry worldwide is currently experiencing an economic boom that is contributing to economic recovery and social progress in many countries. For this to continue, the mining industry must meet several challenges associated with the start-up of new projects. In a highly complex and uncertain environment, rigorous management of risks remains indispensable in order to repel threats to the success of mining.In this article, a new practical approach to risk management in mining projects is presented. This approach is based on a novel concept called “hazard concentration” and on the multi-criteria analysis method known as the Analytic Hierarchy Process (AHP). The aim of the study is to extend the use of this approach to goldmines throughout Quebec. The work is part of a larger research project of which the aim is to propose a method suitable for managing practically all risks inherent in mining projects.This study shows the importance of taking occupational health and safety (OHS) into account in all operational activities of the mine. All project risks identified by the team can be evaluated. An adaptable database cataloguing about 250 potential hazards in an underground goldmine was constructed. In spite of limitations, the results obtained in this study are potentially applicable throughout the Quebec mining sector.     

The effect of ventilation on spontaneous heating of coal

Ventilation plays an important role in the spontaneous heating of coal in an underground coal mine. If the ventilation rate is too high, heat is carried away by convection. If the ventilation rate is too low, the reaction rate becomes oxygen-limited. The effect of ventilation on the spontaneous heating of coal was investigated in an isothermal oven in this study. Experiments were conducted on three U.S. coal samples with ventilation rates ranging from 100 to 500 cm³/min. Experiments under ventilation were conducted to determine the critical ambient temperature, which is the minimum oven temperature required for a coal sample to achieve thermal runaway. Spontaneous heating tests were then conducted at various ventilation rates at the critical ambient temperature and the results were compared with spontaneous heating tests without ventilation. It was found that there is an optimum ventilation flow to produce the maximum rate of temperature rise at the critical ambient temperature. When the coal sample particle size was increased, a higher critical ambient temperature was required. The results in this study have application in the prevention of spontaneous combustion in underground coal mines.     

Risk assessment method of polyethylene dust explosion based on explosion parameters

The explosion characteristic parameters of polyethylene dust were systematically investigated. The variations in the maximum explosion pressure (P_max), explosion index (K_st), minimum ignition energy (MIE), minimum ignition temperature (MIT), and minimum explosion concentration (MEC) of dust samples with different particle sizes were obtained. Using experimental data, a two-dimensional matrix analysis method was applied to classify the dust explosion severity based on P_max and K_st. Then, a three-dimensional matrix was used to categorize the dust explosion sensitivity based on three factors: MIE, MIT, and MEC. Finally, a two-dimensional matrix model of dust explosion risk assessment was established considering the severity and sensitivity. The model was used to evaluate the explosion risk of polyethylene dust samples with different particle sizes. It was found that the risk level of dust explosion increased with decreasing particle size, which was consistent with the actual results. The risk assessment method can provide a scientific basis for dust explosion prevention in the production of polyethylene.     

我国地方煤矿职业危害现状调查报告

目的：通过对华东、东北、华北、西南4个地区4个省市的1个地方国有集团公司、16个地方国有煤矿的调查,了解我国地方国有煤矿的职业危害现状。方法：通过现场调查的方法,抽取4个省市的1个地方国有集团公司16个地方国有煤矿,对其职业危害防治管理、职业危害监测、职业危害防护及健康监护等方面进行调查。结果：被调查的地方国有煤矿47．06％有职业危害防治领导机构;采煤工作面总尘浓度平均超标10．7倍,呼尘浓度平均超标4．6倍;职业健康监护岗前体检100％,离岗体检为0,专家抽检尘肺病检出率5．12％。结论：我国地方国有煤矿职业危害防治管理水平参差不齐,作业场所粉尘浓度超标,尘肺病危害比较严重。     

Does your facility have a dust problem: Methods for evaluating dust explosion hazards

The hazards of dust explosions prevailing in plants are dependent on a large variety of factors that include process parameters, such as pressure, temperature and flow characteristics, as well as equipment properties, such as geometry layout, the presence of moving elements, dust explosion characteristics and mitigating measures. A good dust explosion risk assessment is a thorough method involving the identification of all hazards, their probability of occurrence and the severity of potential consequences. The consequences of dust explosions are described as consequences for personnel and equipment, taking into account consequences of both primary and secondary events.While certain standards cover all the basic elements of explosion prevention and protection, systematic risk assessments and area classifications are obligatory in Europe, as required by EU ATEX and Seveso II directives. In the United States, NFPA 654 requires that the design of the fire and explosion safety provisions shall be based on a process hazard analysis of the facility, process, and the associated fire or explosion hazards. In this paper, we will demonstrate how applying such techniques as SCRAM (short-cut risk analysis method) can help identify potentially hazardous conditions and provide valuable assistance in reducing high-risk areas. The likelihood of a dust explosion is based on the ignition probability and the probability of flammable dust clouds arising. While all possible ignition sources are reviewed, the most important ones include open flames, mechanical sparks, hot surfaces, electric equipment, smoldering combustion (self-ignition) and electrostatic sparks and discharges. The probability of dust clouds arising is closely related to both process and dust dispersion properties.Factors determining the consequences of dust explosions include how frequently personnel are present, the equipment strength, implemented consequence-reducing measures and housekeeping, as risk assessment techniques demonstrate the importance of good housekeeping especially due to the enormous consequences of secondary dust explosions (despite their relatively low probability). The ignitibility and explosibility of the potential dust clouds also play a crucial role in determining the overall risk.Classes describe both the likelihood of dust explosions and their consequences, ranging from low probabilities and limited local damage, to high probability of occurrence and catastrophic damage. Acceptance criteria are determined based on the likelihood and consequence of the events. The risk assessment techniques also allow for choosing adequate risk reducing measures: both preventive and protective. Techniques for mitigating identified explosions risks include the following: bursting disks and quenching tubes, explosion suppression systems, explosion isolating systems, inerting techniques and temperature control. Advanced CFD tools (DESC) can be used to not only assess dust explosion hazards, but also provide valuable insight into protective measures, including suppression and venting.     

煤矿瓦斯爆炸主要原因的试验研究

利用长径比为7,横截面积为1m~2,一端开口的7m~3的爆炸试验装置,停放成下斜、水平和上倾状态,模拟一段煤巷道的走向。用和瓦斯气具有相同比重的天然气作为试验的可燃气体,在上述试验装置内进行了一系列爆炸试验。试验结果证明了:煤矿向下倾斜的巷道对瓦斯气的自洁作用可保证不集存大量瓦斯气,是安全的;水平走向的巷道在有合适的通风情况下也是安全的;向上倾斜的巷道有集存瓦斯气的自恶化作用,会造成较强的爆炸。     

基于灰色-物元模型的煤矿瓦斯爆炸风险评估

为了明确风险因素间的作用路径并提出科学可行的瓦斯爆炸灾害风险评估方法,首先基于3类危险源理论梳理分析以往典型瓦斯爆炸案例,识别并提取14个影响因素;然后通过集成灰色系统理论和物元可拓模型,构建灰色-物元评估模型;最后以山西省某煤矿的实际调研数据为例,计算各影响因素的权重和关联函数,梳理风险因素致灾的逻辑关系,得出该矿井...     

A methodology for evaluation and monitoring of recurring hazards in underground coal mining

This study provides a methodology for evaluation and monitoring of recurring hazards in underground coal mining. An important measure in this regard may be the ‘time between occurrences’ (TBO) of hazards that can be modeled in the similar fashion of ‘time between failures’ (TBF) data modeling which is practiced in reliability study. Typically, time between accidents is modeled in safety study. This study is therefore new in two counts: (i) statistically modeling hazard occurrences based on inspection reports and (ii) monitoring of safety status based on control charting of hazard occurrences. The methodology includes Weibull-distribution based hazard rate functions, Poisson-distribution based cumulative risk functions, and Weibull-distribution based control charts. The new methodology is applied to an underground coal mining worksystem and the results are discussed. The case study results show that hazards related to machinery, ground-fall, housekeeping, roadways, and materials are more frequently occurring. It is recommended that in addition to planned inspections for identification of hazards, a control chart based hazard mitigation scheme should be employed at the mine sections for better monitoring and control of hazards.     

A semi-quantitative methodology for risk assessment of university chemical laboratory

University chemical laboratory is a high-risk place for teaching and scientific research due to the presence of various physical and chemical hazards. In recent years, university chemical laboratory accidents occur frequently. This urges the need to enhance university chemical lab safety. A semi-quantitative methodology comprising Matter-Element Extension Theory (MEET) implemented with Combination Ordered Weighted Averaging (C-OWA) operator is proposed to assess the risk of a university chemical laboratory. First, an index-based risk assessment system of university chemical laboratory is built by identifying various risk factors from a system perspective. Then, C-OWA operator is used to calculate the weight of assessment indices, whereas MEET is employed to determine the correlation degree of assessment indices. Finally, the comprehensive risk of university chemical laboratories is assessed, and some safety measures are proposed to reduce the risk of university chemical laboratories. The applicability of the proposed methodology is tested using a practical case. It is observed that the methodology can be a useful tool for risk assessment and management of university chemical laboratories.     

大型露天煤矿绿色开采评价体系研究

为解决露天煤矿开采给环境带来的诸多不利影响,以露天煤矿绿色开采为理念,从固体环境、水体环境、气体环境和生态环境4个方面构建了露天煤矿绿色开采评价体系。通过数学方法和数学模型对影响露天煤矿的基本指标进行量化处理和权重分配,得出露天煤矿开采"绿色度"指标值。建立了露天煤矿绿色开采评价标准,并利用所建立的评价指标体系和评价模型对黑岱沟露天煤矿进行了应用研究。     

构建煤炭企业负责人培训考核长效机制研究

针对我国煤矿普遍存在的规模差异较大、生产条件复杂、煤炭企业负责人文化素质和专业素质都相对较差的实际情况,对我国现在实施的培训和发证的相关政策和措施进行了分析和研究;指出现行的培训考核机制对煤炭企业负责人能力和水平的差异缺乏针对性,对煤炭企业可持续发展对管理人才的知识结构需求缺乏系统性,对煤矿企业主要负责人的综合素质的提高缺乏强制性;提出了现行开展的对煤炭企业负责人的培训考核机制应该结合煤矿矿长安全培训、矿长资格培训和煤炭职业经理人培训所提出的综合素质要求,结合地区和企业的煤炭行业的实际和发展需要,实行统筹规划、分段培训、分级考核和发证,以构建符合我国实际的培训考核长效机制;并按照这一设想进行了长期的探索和实践,取得了一些可以借鉴的经验和成果。     

Effect of ignition delay on explosion parameters of corn dust/air in confined chamber

This paper presents the explosion parameters of corn dust/air mixtures in confined chamber. The measurements were conducted in a setup which comprises a 5 L explosion chamber, a dust dispersion sub-system, and a transient pressure measurement sub-system. The influences of the ignition delay on the pressure and the rate of pressure rise for the dust/air explosion have been discussed based on the experimental data. It is found that at the lower concentrations, the explosion pressure and the rate of pressure rise of corn dust/air mixtures decrease as the ignition delay increases from 60 ms; But at the higher concentrations, the explosion pressure and the rate of pressure rise increase slightly as the ignition delay increases from 60 ms to 80 ms, and decrease beyond 80 ms. The maximum explosion pressure of corn dust/air mixtures reaches its highest value equal to 0.79 MPa at the concentration of 1000 gm⁻³.