Thermal imaging study to determine the operational condition of a conveyor belt drive system structure

The paper discusses the results of a study carried out to determine the thermal condition of a conveyor power unit using a thermal imaging camera. The tests covered conveyors in the main haulage system carrying coal from a longwall. The measurements were taken with a thermal imaging diagnostic method which measures infrared radiation emitted by an object. This technology provides a means of assessing the imminence and severity of a possible failure or damage. The method is a non-contact measuring technique and offers great advantages in an underground mine. The thermograms were analysed by comparing the temperature distribution. An analysis of the operating time of the conveyors was also carried out and the causes of the thermal condition were determined. The main purpose of the research was to detect changes in thermal state during the operation of a belt conveyor that could indicate failure and permit early maintenance and eliminate the chance of a fire. The article also discusses the construction and principle of operation of a thermal imaging camera. The findings obtained from the research analysis on determining the thermal condition of the conveyor drive unit are a valuable source of information for the mine's maintenance service.Web of Science1411art. no. 325

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

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

State Policy of Environmental Convergence in Economy Transition to Sustainable Development

Structural shifts caused by the expansion of "green" convergent technologies significantly enhance the ecological convergence of the economies in the countries in which they determine the exit to the trajectory of sustainable development. At the same time, in an economy where the commercialization and diffusion of green technologies is constrained by structural problems, the prerequisites for environmental divergence are formed, which can finally consolidate technological lag and a long-term trend of environmental degradation. The transition from environmental divergence to convergence should be carried out in a system of convergentoriented structural policy. It presents a three-level complex: targeted changes in the reproductive structure, the proportion of production factors (the first level); impact on the sectoral, technological, market-competitive, social structures of the economy (the second level), development of research, production and financial infrastructure for the commercialization and transfer of "green" technologies (the third level)

Inter gases as one of the ways to reduce the risk of endogenous fires in hard coal mines

Endogenous fires are currently one of the most common threats in hard coal mines. They are very dangerous for the staff and can cause very large economical loses. Therefore, the scope of activities aimed at limiting the possibility of these fires and reduction of their consequences constantly broadens. The paper presents the results of research aimed at determining the efficiency of the ventilation system applied to reduce the risk of endogenous fires in the areas where inert gases are used. The calculations included carbon dioxide and nitrogen. Inertisation is one of the ways of combating endogenous fires. This method is included in the developed comprehensive method to reduce the possibility of these fires. The results obtained and the method developed and later applied, should have a significant impact on improving the safety of operations in the scope of occurrence and consequences of endogenous fires

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

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 operatio

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

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 Impact of the Ventilation System on the Methane Release Hazard and Spontaneous Combustion of Coal in the Area of Exploitation—A Case Study

Various types of natural hazards are inextricably linked to the process of underground hard coal mining. Ventilation hazards—methane and spontaneous combustion of coal—are the most dangerous; they pose a major threat to the safety of the workers and decrease the effectiveness of the whole coal production process. One of the methods designed to limit the consequences of such hazards is based on the selection of a ventilation system that will be suitable for the given mining area. The article presents a case study of an active longwall area, where—due to increasing ventilation hazard (methane and spontaneous combusting of coal)—the whole system was rebuilt. The U-type ventilation system was used in the initial stage of the extraction process, however, it often generated methane in amounts that exceeded the allowable values. Consequently, such conditions forced the change of the ventilation system from a U–type to Y–type system. The new system was installed during the ongoing mining process, unlike the usual practice. The article presents the results of tests on mine gas concentrations and descriptive statistics for both types of ventilation system. The results clearly demonstrate that the U-type longwall ventilation system, in the case of high methane release hazard, prevents safe and effective operation. At the same time, the use of this system limits the carbon oxidation reactions in the goaf, leading to spontaneous heating and combustion, which is confirmed by the low concentrations of gases—by-products of these reactions. In turn, the use of the Y-type longwall ventilation system ensures safe and effective operation in areas with high methane release hazard, but at the same time deteriorates the safety associated with the spontaneous combusting of coal. The presented case—both from a scientific and practical perspective—is quite interesting and greatly broadens the knowledge in the scope of an efficient ventilation system for underground workings

Integration of Environmental Information in a Mining Region Using a Geoportal

At present, the complex nature of the impact on the ecosystem in regions with intensive mining creates a multidimensional information “plume” consisting of data on mineral reserves, the state of mining operations, accumulated, current and future environmental pollution. The transition to the lean use of the subsoil and the reasonable disposal of mining waste requires fundamentally new forms of environmental information accumulation and processing during designing new enterprises and regulating the activities of existing ones. The most promising form of information support for the greening of mining is a geoportal. It is a complex of software and technological support for working with spatial data. Its key task is to provide the users with tools and services for storing and cataloging, publishing and loading spatial and environmental data, searching and filtering by metadata, interactive web visualization, direct access to geodata based on map web services

Geometrical Tests of Powered Roof Support Positioning in a Longwall Complex

A powered roof support protects people and equipment in the longwall from potential danger posed by the surrounding rock mass. The study to determine the position of the powered roof support was conducted in an active longwall. The research team made measurements of the geometric height of the powered roof support structure located in the longwall complex. The main objective of this study was to determine the position of the powered roof support in actual underground conditions. The analysis of the results provided data on whether the assumed height of the longwall was maintained during operation of the complex