scholarly journals Integrated Method of Reducing the Threat of Endogenous Fires in Hard Coal Mines

2019 ◽  
Vol 105 ◽  
pp. 01013 ◽  
Author(s):  
Dawid Szurgacz ◽  
Leszek Sobik ◽  
Jarosław Brodny
Keyword(s):  
Fire Hazard ◽  
Mining Operation ◽  
Climatic Conditions ◽  
Hard Coal ◽  
Effective Prevention ◽  
Integrated Method ◽  
Preventative Measures ◽  
Endogenous Fire ◽  
Prevention Methods ◽  
Fire Threat

Underground exploitation of hard coal based on a longwall system is increasingly exposed to various types of threats. In particular, this applies to endogenous fire threat. It results from coal left in the goaf, which due to favourable climatic conditions may lead to self-heating and self-ignition. In practice, due to the maintenance of the roof or the passage through the fault zones, coal is often left in the caving zone, which significantly increases the possibility of endogenous fires in this zone. Therefore, it is necessary to develop an effective prevention solution. The method presented in this paper combines all previously used methods aimed at reducing fire hazard. The levels of fire hazard indicators significantly dropped in the areas where the method had been applied. This, in turn, enabled safe mining operation in the tested longwalls, their decommission and the isolation of longwall workings. The results confirm the validity of the adopted assumptions. The method is based on practical and effective use of preventative measures designed to reduce endogenous fire threat. It can be successfully applied not only in mines without extensive fire prevention system but also in mines where other prevention methods are successfully used. It may support and supplement them. The article discusses basic assumptions of the method and presents a model of application.

scholarly journals Preliminary results of tests on nitrogen cushion for combating fire hazard in longwalls rich in methane

2020 ◽  
Vol 174 ◽  
pp. 01066
Author(s):  
Dawid Szurgacz ◽  
Leszek Sobik ◽  
Jarosław Brodny ◽  
Maxim Grigashkin
Keyword(s):  
Fire Hazard ◽  
Main Idea ◽  
Extraction Process ◽  
Coal Extraction ◽  
Hard Coal ◽  
High Tendency ◽  
Preventive Actions ◽  
Wide Range ◽  
Endogenous Fire ◽  
Roof Support

Ventilation hazard is the most dangerous phenomena occurring in the hard coal extraction process. This particularly applies to endogenous fire hazard. In order to reduce it, it is necessary to improve the effectiveness of preventive measures. Hence this paper presents new solutions that substantially improve fire prevention effectiveness. The main idea is to develop and create an additional nitrogen cushion in the zone behind the powered roof support operating in a longwall face. The solution is based on installations for inerting of goafs and sections of the powered roof support. The nitrogen cushion restricts the access of air and oxygen to the area of goafs and limits the possibility of fire. Practical application of the developed solution allowed for effective reduction of fire hazard in conditions of a very high tendency of coal to self-ignite at short incubation period. This, in turn, enables safe exploitation and decommissioning of the longwall. Undoubtedly, the solution presented and the results obtained constitute a new approach to preventive actions in mines. It is the result of the work of theoretical and practical researchers. The solution is a combination of the potential of these two environments. The developed solution should find wide range of applications in the areas where endogenous fire and methane hazards occur.

The current state of the problem of predicting spontaneous combustion and explosiveness of sulfide ores and host rocks at a depth of more than 1500 m.

2021 ◽  
pp. 77-80
Author(s):  
Z.G. Ufatova
Keyword(s):  
Moisture Content ◽  
Air Temperature ◽  
Initial Phase ◽  
Spontaneous Combustion ◽  
Fire Hazard ◽  
Free Access ◽  
Sulfide Ores ◽  
Working Face ◽  
Time In Treatment ◽  
Endogenous Fire

The mining factors of ore fire hazard during mining of the lower horizons of the Oktyabrskiy and Talnakhskiy northern deposits are considered. It is noted that the probability of self-heating of sulfide ores and the sulfide dust’s tendency to spontaneous combustion and explosiveness in certain sections of rich sulfide copper-nickel ores are quite high. The oxidation of sulfide ores occurs continuously due to the absorption of oxygen from the mine atmosphere and is accompanied by the release of heat. The oxidation can be accompanied by intense heating of the ore in mining conditions, with the accumulation of large volumes of broken rock mass for a long time in treatment and preparation workings and with free access of air to the bulk of the ore mass. The processes of ore and rock oxidation are especially intense when their moisture content is 1–4%. When the ore is heated above 35 °C, sulfurous gas (SO2) may be released. The main signs of the above-mentioned oxidative processes’ development and signs of the initial phase of a possible underground endogenous fire are indicated along with a constant increase in the temperature of the air coming from the bottom of the face. It is noted that in case of detecting at least one of the signs of a possible underground endogenous fire’s initial phase, urgent measures are taken to improve the ventilation of this working face, to ensure maximum intensity of shipped ore from the fresh stream and the content of sulfurous gas and hydrogen sulfide and mine air temperature are determined every 4 hours. If after two days on the outgoing stream there is no decrease in the content of sulfur dioxide and air temperature, then it should be considered that an endogenous fire has occurred. Measures for the prevention, localization and elimination of foci of spontaneous combustion are given. As an additional safety measure, it is recommended to moisten the dust, since sulfide dust becomes non-explosive at a moisture content of 9–9,5%, and at a humidity of 10% the dust does not transmit an explosive impulse.

scholarly journals Changes in the Distribution of Temperature in a Coal Deposit and the Composition of Gases Emitted during Its Heating and Cooling

2018 ◽  
Vol 10 (10) ◽  
pp. 3587 ◽  
Author(s):  
Marek Więckowski ◽  
Natalia Howaniec ◽  
Eugene Postnikov ◽  
Mirosław Chorążewski ◽  
Adam Smoliński
Keyword(s):  
Fire Hazard ◽  
Hot Spot ◽  
Measuring System ◽  
Hard Coal ◽  
Coal Deposit ◽  
Hazard Indices ◽  
Heating And Cooling ◽  
Cooling Phase ◽  
Percentage Share ◽  
The Given

This article presents the results of tests conducted on a measuring system for monitoring changes in the distribution of temperature in a coal deposit during the heating and cooling phases, and their correlation with the analysis of the concentration of gases. The tests were conducted on five samples of hard coal collected in deposits mined in Poland. Measurements of the changes in temperature and changes in gas concentration were conducted from the temperature of 35 to 300 °C, for the heating phase, and from 300 to 35 °C, for the cooling phase. The percentage share of coal of given temperatures was calculated. When comparing the percentage share for the same temperature in the hot spot, for the heating and cooling phase, significant differences in the distribution of the given percentages were observed. Changes in gas concentrations during heating and cooling were analyzed and the dynamics of changes in gas concentrations were determined for the coals tested. Changes in the values of fire hazard indices were analyzed. There were significant differences in the concentration of gases and the values of fire hazard indices between the heating and the cooling phase. The application of different criteria to assess coal during heating and cooling was proposed.

scholarly journals Reversal Ventilation as a Method of Fire Hazard Mitigation in the Mines

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1755 ◽  
Author(s):  
Grzegorz Pach ◽  
Zenon Różański ◽  
Paweł Wrona ◽  
Adam Niewiadomski ◽  
Pavel Zapletal ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Fire Hazard ◽  
Full Range ◽  
Acceptable Level ◽  
New Method ◽  
Underground Mines ◽  
Operating Parameters ◽  
Smoke Control ◽  
Prevention Methods ◽  
Air Control

Reversal ventilation is one of prevention methods against fire hazard in underground mines, but it is not recommended for the mines where methane is present. The authors introduce the new method of reversal and by conducting numerical simulations they prove that it allows to keep methane at the acceptable level during miners escape. However, it requires connection between the subnetworks of the main ventilation fans. It was also shown, that by using the method some escape routes will be shortened. It is possible to apply this method in the mines where the fans and stoppings are fully controlled across the full range of their operating parameters. The findings are important for underground mines, as well as for surface facilities where air control or smoke control is managed by two or more fans.

scholarly journals Analysis of methane hazard in longwall working equipped with a powered longwall complex

2020 ◽  
Vol 174 ◽  
pp. 01011
Author(s):  
Leszek Sobik ◽  
Jarosław Brodny ◽  
Gennady Buyаlich ◽  
Pavel Strelnikov
Keyword(s):  
High Performance ◽  
Underground Mining ◽  
Practical Knowledge ◽  
Mining Operation ◽  
Mining Area ◽  
Hard Coal ◽  
Coal Seams ◽  
Methane Drainage ◽  
High Degree ◽  
Advanced Model

Most of currently exploited hard coal seams has a very high degree of methane saturation. Consequently, the mining process of such deposits generates substantial amounts of methane. This in turn increases the risk of fire and/or explosion of this gas. Methane hazard is currently one of the most dangerous threats occurring in the process of underground mining exploitation. In particular, this applies to longwall excavations where the rock mass mining process generates the highest level of this gas. Commonly used high-performance longwall complexes cause an increase in the amount of coal output, which also causes an increase in the amount of methane released. In order to prevent hazardous concentrations, appropriate ventilation systems and atmosphere monitoring in mining excavations are used. The paper discusses currently used methods designed to limit risks caused by methane such as methane drainage. The paper presents an example of the use of an innovative method of analysing methane risk status and measures aimed at minimizing it. The developed method is based on air parameters in the actual mining area which were then used to create a method of ventilation for such excavations. The method combines advanced model analysis and experience of mine employees and integrates academic and practical knowledge. The main objective of the activities presented in the article was to improve the safety of mining operation

scholarly journals “Off-Label” Usage of Testicular Self-Examination (TSE): Benefits Beyond Cancer Detection

2015 ◽  
Vol 12 (3) ◽  
pp. 505-513 ◽  
Author(s):  
Michael J. Rovito ◽  
James E. Leone ◽  
Chase T. Cavayero
Keyword(s):  
Treatment Options ◽  
Future Research ◽  
Self Awareness ◽  
Net Benefit ◽  
Health Concerns ◽  
Off Label ◽  
Preventative Measures ◽  
Prevention Methods ◽  
Male Specific ◽  
Self Examination

Testicular cancer (TCa) is the most common cancer among 15- to 34-year-old males. Treatments are highly effective, which help foster approximately 98% 5-year survival rate. There are very few known causal factors of the disease (e.g., cryptorchidism and family history), thus possibly limiting primary prevention methods. Secondary preventative measures, on the other hand, most notably testicular self-examination (TSE), are well-known and are promoted to help prevent late-stage diagnosis of TCa. However, debate ensues as to whether or not TSE provides any benefit. In light of a recent systematic review conducted by these authors assessing the effectiveness of TSE promotion interventions, we propose that the behavior can serve as a tool not just for detection of TCa, but other male-specific urogenital health concerns, including varicoceles, hydroceles, among others. Furthermore, we suggest that TSE can also help foster informed decision-making skills among males with regard to health concerns and treatment options. However, our advocacy is in direct conflict with U.S. Preventive Services Task Force’s influential “D” rating of TSE and others who recommend against performing TSE. This article offers an overview of the dispute over TSE’s purpose and net benefit. We conclude that TSE is a behavior that is beneficial beyond detecting cancer. These proposed “off-label” uses of the procedure make for an effectual means to promote testicular health, self-awareness, and wellness among males. Recommendations for future research and advocacy are presented to the academy.

Bridge Disaster Prevention and Disposal Methods in Mining Area

2012 ◽  
Vol 204-208 ◽  
pp. 3494-3498
Author(s):  
Qing Jie Wen ◽  
Hui Lu
Keyword(s):  
Large Deformation ◽  
Mining Operation ◽  
Mining Area ◽  
Structure Type ◽  
Design Code ◽  
Subsidence Area ◽  
Working Face ◽  
Standard Value ◽  
Prevention Methods ◽  
Reliable Basis

Surface subsidence caused by mining operation can amount to several meters, which is far above the standard value in design code. Once mining collapse occurs, bridges’ large deformation can result in bridge disasters. In order to prevent bridge disasters in mining area, bridge disaster characteristics in different districts in working face of mining are analyzed on the base of large deformation regularity of ground. A method of avoiding location of piers at inferior fovea and superior fovea in the migrated basins is presented to reduce the deformation of bridges on condition that subsidence area can’t be bypassed. And smooth joints between road and bridge are also advised to be designed to reduce staggering of joint and cracking. Moreover, applicability of several prevention methods for bridge disasters is demonstrated based on different bridge design and foundation treatments in mining area. The results show that geological disasters of bridges can be prevented by choosing reasonable foundation and structure type, which provides reliable basis for bridge construction in mining area.

scholarly journals Proposal of Economic Assessment of Hard Coal Mines Operation Conducted in Polish Conditions with the Use of Cost Benefit Analysis

2016 ◽  
Vol 61 (4) ◽  
pp. 875-892
Author(s):  
Piotr Krawczyk ◽  
Marzena Majer ◽  
Joanna Krzemień
Keyword(s):  
Economic Evaluation ◽  
Cost Benefit Analysis ◽  
Coal Mines ◽  
Cost Benefit ◽  
Mining Operation ◽  
Economic Assessment ◽  
Point Of View ◽  
Hard Coal ◽  
Benefit Analysis ◽  
Social Costs And Benefits

Abstract The paper presents possibilities of an economic evaluation of hard coal mines, using Cost Benefit Analysis (CBA). Suggested methodology for CBA applied to the economic evaluation of a mine allows to conduct a complex evaluation of mine’s functionality in connection to Polish conditions. Additionally to financial aspects, significant from the point of view of the mine’s owner, the paper includes social and environmental effects as a result of mining activities. Proposed methodology has undergone tests which used averaged data obtained from two selected hard coal mines located in the Upper Silesian Coal Basin. Presented results confirm the validity of social costs and benefits, and environmental losses resulting from mining operation, which were included in analysis comprehensively evaluating the efficiency of hard coal mines.

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