The Influence of the Sample Preparation on the Result of Coal Propensity to Spontaneous Combustion in the High-temperature Adiabatic Method

The liability of coal to spontaneous combustion is the principal cause of mine fires. Spontaneouscombustion is one of the main threats in Polish and Vietnamese coal mines. The article presents an analysisof the spontaneous combustion of coal in mines of both countries. It is related to the natural prone of coalto spontaneous heating and consequently to its self-ignition. Despite the relevant recognition of themethods of preventing this threat, in mines, spontaneous combustion occurs during the exploitation ofcoal seams with low and very high self-ignition tendency. Apart from the technical factors related to thedesign of coal seam mining, the properties of coal have a significant impact on the occurrence ofspontaneous combustion. Their correct recognition is essential to the precautions against spontaneouscombustion for minimalizing the risk of a mine fire. Therefore, it is necessary to study the factorsinfluencing the propensity of coal to spontaneous heating. A review of the methods used to determine thepropensity of coal to spontaneous combustion is presented in the article. Based on the high-temperaturemethod of determining the propensity of coals to spontaneous combustion, the influence of selectedfactors related to samples' preparation for testing on the determination result was investigated. Theinfluence of the fractional decomposition and the moisture content in the prepared samples on thedetermination result was demonstrated. The presented research results may improve research proceduresfor determining the propensity of coal to spontaneous combustion.

Influence Mechanism of Nitrogen Injection Into Closed Fire Zone On the Re-Ignition For Residual Coal in Goaf

Coal is the foundation of Chinese energy and economic structure, and the unsealing of coal mine fires would cause a great risk of coal re-ignition. The uniaxial compression equipped with a temperature-programmed (UCTP) device was built to explore the influence of pressure-bearing state on the re-ignition characteristics of residual coal. The Scanning Electron Microscope (SEM), Synchronous Thermal Analyzer (STA) and Fourier Transform Infrared Absorption Spectrometer (FTIR) was applied to investigate the microscopic structure and thermal effect of the coal samples. Moreover, the microscopic effect of uniaxial stress on coal re-ignition was revealed, and the re-ignition mechanism was also obtained. As the uniaxial stress increases, the number, depth and length of the fractures in the pretreated coal increase, and the filling material increases. The application of uniaxial stress causes the thermal conductivity to change periodically, which enhances the heat transfer inhibition effect of nitrogen and prolongs the oxidation exothermic stage. The content of oxygen-containing functional groups has a high correlation with apparent activation energy, and coal samples at 6 MPa are more likely to re-ignition when the fire zone is unsealed. Uniaxial stress controls the re-ignition mechanism by changing the structure of fractures and pores. The side chains and functional groups in the coal structure are easier to break under thermal-stress coupling. The higher the ·OH content, the more difficult it is to re-ignition. The research results have laid a solid theoretical foundation for the safe unsealing of coal field fire areas, tightened the common bond between the actual industry and the experimental theory in the closed fire area, and provided theoretical guidance for preventing coal re-ignition.

Coal Mine Safety Monitoring and Alert System

The accidents in coal mines are increased day by day. There are numerous life losses of many skilled workers and laborers. There is no advent precaution measure to detect the alarming cause of the coal mine accidents and provide an alert system. Occupational accidents and occupational diseases are common in the mining. The most common causes of accidents in coal mining are firedamp and dust explosions, landslips, mine fires, and technical failures related to transport and mechanization. An analysis of occupational accidents in the consideration of social and economic factors reports that the real causes behind these accidents, which are said to happen inevitably due to technical deficiencies or failures. Thus an automated alarming coal mine accident detect ion system is employed to rescue and protect the workers from the hazards. This system incorporates the combined action of the temperature, pressure and gas sensor and IOT module to detect the temperature, pressure and atmosphere in the coal mine and log every data onto the cloud using data logging. Then these data are accepted by a admin controlled sever page through data acquisition. The data processing takes place at a server page and the alert is send to the device to glow the alarm and to the concerned officials and rescue stations for taking the prevention measures.

PENNSYLVANIA’S ABANDONED MINE LAND (AML) EMERGENCY PROGRAM

The Pennsylvania Department of Environmental Protection’s Bureau of Abandoned Mine Reclamation (BAMR) implements an Abandoned Mine Land (AML) Emergency Program to address high-priority, abandoned mine land (AML) problems that suddenly occur throughout Pennsylvania’s coal fields. BAMR maintains two field offices: one in eastern Pennsylvania (Anthracite Region) in Wilkes-Barre and one in western Pennsylvania (Bituminous Region) in Ebensburg. Both field offices maintain in-house construction crews with significant equipment available to respond to and address many small AML Emergencies (hazards) such as pothole (or cavehole), subsidences, and mine drainage breakouts. For larger AML Emergencies such as subsidence events causing structural damage to homes, businesses, and roads; mine fires; coal refuse fires; landslides; or other large-scale or complex AML problems, projects are completed by outside contractors. Project designs are completed by BAMR engineering staff. The contractors are then hired through solicitation of bids or proposals with very short timeframes between bid issue and bid opening. Since October of 2010, BAMR has addressed nearly 800 AML Emergencies which equates to approximately 80 AML Emergency projects each calendar year. The average construction cost to address those emergencies was just over $3.25 million per year. Due to the increased precipitation over the Commonwealth the last several years, that number has increased to an average of 86 AML Emergency projects over the last five (5) years (2015–2019) with a record number of 127 addressed in calendar year 2018. The average cost to address those AML Emergency projects over that five-year period was $4.66 million per year. This paper will provide some background on Pennsylvania’s AML Emergency Program, some summary statistics including the annual number and types of projects completed including costs, and also highlight through both photos and video links some typical projects recently completed by the program.