The use of thermochemical technologies for mining abandoned coal reserves
Authors:   Institute of Comprehensive Exploitation of Mineral Resources Russian Academy of Sciences, ZAKORSHMENNYI Iosif , GRABSKY Alexander ,   Sergo Ordzhonikidze Russian State University for Geological Prospecting, BLOKHIN Dmitry ,   Institute of Comprehensive Exploitation of Mineral Resources Russian Academy of Sciences, KOBYLKIN Alexander ,   Institute of Comprehensive Exploitation of Mineral Resources Russian Academy of Sciences
Published: March 2024

Introduction. Currently, despite the intensive development of high-performance mining equipment, significant coal reserves remain in the subsurface, which are impractical to extract using existing technologies and methods of mining them. At the same time, underground and especially open-pit mining operations are significantly inferior to the technologies of thermochemical mining of reserves in their place of occurrence due to the combined influence of negative factors (dust and gas emissions, seismic effects, etc.) at all stages of extraction, transportation and processing. The purpose of the research. Assessment of the possibilities of using thermochemical technologies to involve coal reserves left in the subsurface for mining geological and mining engineering factors in the field of industrial production. Methodology. To substantiate the choice of promising areas for the development of technical solutions for the integrated use and energy-efficient development of unprofitable coal reserves using traditional technologies, an analysis of factors that reduce their effectiveness and negatively affect the environmental situation in coal-mining regions was carried out. Within the framework of this analysis, the possibilities of mining reserves using alternative technologies are considered. For these purposes, an assessment of the effectiveness of thermochemical technologies (underground gasification of coal seams (UCG) and underground combustion (UCC)), tested in a wide range of mining and geological conditions and acceptable for processing thermal coal, was carried out. Results and discussions. An analysis of research in the field of UCG technologies has shown that, depending on the quality and composition of the blast, the heat of combustion of gasification products can vary widely, providing the required parameters. At the same time, the quality of coals significantly affects the efficiency of the technology, so during the gasification of hard and brown coals, the heat of combustion of gas differs by an average of 20%. Along with the significant positive factors of the UCG technology, it should be noted the high requirements for the tightness of the underground gas generator and the entire aerodynamic network and the loss of coal in the safety pillars and in the area of the gas generator. The elimination of these shortcomings is ensured by the consistent application of the UCC technology - the proposed combined technology of phased mining of prepared reserves, effective at depths up to 300 m. One of the most promising areas of implementation of such technology is distributed (small) energy. Conclusion. Traditional technologies of open-pit and underground mining of coal deposits require human participation in the implementation of basic technological processes. The development of the field’s reserves is accompanied by a number of concomitant negative environmental factors, one of the most significant is gas and dust emission during drilling and blasting operations. An alternative way of mining coal deposits is the use of thermochemical methods for mining coal reserves at the place of its occurrence, but their implementation in conditions of large-scale energy consumption is limited by the presence of large enterprises of a similar profile in the immediate vicinity. There is a steady positive trend in the development of small (distributed) energy in Russia. The proposed combined technology, which reduces environmental harm, can be used for mining deposits with limited reserves and in difficult mining and geological conditions and used for these purposes. Resume. 1. The article presents the results of research on the possibilities of using thermochemical technologies to increase the efficiency of extracting coal reserves. 2. It has been established that coal mining in modern conditions is accompanied by significant losses of reserves in the subsurface due to the requirements for the manufacturability of reserves when using high-performance equipment. The advantages of shaft-free thermochemical methods of mining coal seams are determined and the relevance of developing technical solutions for their practical implementation is substantiated. It is shown that the use of these technologies leads not only to an increase in the efficiency and completeness of coal reserves extraction, but also to a reduction in the environmental burden on the environment by eliminating blasting operations, as well as technological procedures related to the transportation and preparation of coal for use. A basic technological scheme for mining coal reserves based on the joint use of underground gasification and underground combustion technologies is presented. 3. The results of the research may be useful for assessing the possibilities of creating distributed energy facilities involving, among other things, coal reserves left behind as a result of mining with traditional technologies, especially in remote decentralized areas.