US Coal Sector Realizes the New Norm Exports will help offset further declines in 2 Editorial 4 Leading Developments News 6 U.S. News 8 Worldwide News 10 People 12 Commentary 14 Calendar 40 Operating Ideas 42 Suppliers News 44 Product News 46 Classifieds 48 Legally Speaking In addition to the Annual Forecast, this month, Coal Age offers extended coverage of the longwall mines with its U.S. Longwall Census. On the cover, a longwall shearer cuts coal with water sprays suppressing dust.
The reasons for the lag of the indicators of the leading Russian coal mines engaged in the longwall mining of the flat-lying coal seams from similar foreign mines are considered. The analysis of the efficiency of the longwall face move operations at the JSC SUEK-Kuzbass mines was carried out. A significant excess of the planned deadlines for the longwall face move during the thick flat-lying seams mining, the reasons for the low efficiency of disassembling operations and the main directions for improving the technology of disassembling operations are revealed. The directions of ensuring the operational condition of the recovery room formed by the longwall face are considered. The recommended scheme of converged coal seams mining and a three-dimensional model of a rock mass to justify its parameters are presented. Numerical studies using the finite element method are performed. The results of modeling the stress-strain state of a rock mass in the vicinity of a recovery room formed under conditions of increased stresses from the boundary part of a previously mined overlying seam are shown. The main factors determining the possibility of ensuring the operational condition of the recovery rooms are established. It is shown that it is necessary to take into account the influence of the increased stresses zone when choosing timbering standards and organizing disassembling operations at a interbed thickness of 60 m or less. A sufficient distance from the gob of above- or undermined seams was determined to ensure the operational condition of the recovery room of 50 m, for the set-up room – 30 m. Recommendations are given for improving technology and organization of the longwall face move operations at the mines applied longwall mining of flat-lying coal seams with the formation of a recovery room by the longwall face.
The authors point at the criticality of timely reproduction of longwall panels in coal mines toward sustainable and high-rate coal mining based on the utilization potential of modern longwall equipment. A case-study of SUEK-Kuzbass mines shows that there is a need to change approaches to improvement of economic efficiency and competitiveness of coal mining and to shift from the common practice of production cost reduction to productivity enhancement through implementation of high-performance equipment capabilities. Efficiency of road heading in mines of SUEK-Kuzbass is analyzed, and the main causes of long downtime in operation of modern high-performance continuous miners (CM) or continuous bolter miners (CBM) are identified. Recommendations have been developed for improved planning of preparatory works in mines and for introduction of significant action time margin to eliminate downtime when actual drivage performance lags behind the planning data. The action time structure of modern CBM is presented, and recommendations are given on CBM efficiency evaluation as actual action time in cutting road face rocks. The application areas of various modern CBM types are justified. Recommendations are proposed for changing the parameters of longwall panels and to change to multi-entry longwall panels in order to increase efficiency of preparatory works and actual coal production. The authors describe expediency of widespread use of shuttle cars to improve efficiency of haulage of rocks and materials. The organizational and technological principles of the efficiency increase in preparatory works in coal mines are substantiated.
The problem of formation of extended zones with high rock pressure (HRP) from safety pillars at the boundaries of extraction pillars formed due to the mine layout of complex geometry is considered at the example of JSC Vorkutaugol mines. A detailed analysis of the remaining reserves of the near-bottom part of the deposit was carried out to estimate losses and the impact of HRP zones from the Chetvertyi protective seam to mining operations on the Troinoi upper seam along with the possibilities for the reduction of sizes of HRP zones at the account of expanding the underworked space. Due to research on the near-bottom part of the Vorkuta deposit, within the framework of the accepted layout, a zone at the Komsomolskaya mine and two zones at the Zapolyarnaya-2 mine were singled out, at which losses at the boundaries of the extraction pillars amount up to 13-22 % of the total resources of the mine field. The high volume of losses in these pillars indicates the relevance of research on the priority extraction impact of protective seams on the efficiency and safety of mining operations in the working area of underworked and HRP zones. Based on the analysis of foreign and Russian experience in the pillar cleaning-up at the boundaries of working areas and the methodical guidelines and instructions, a technological scheme was developed that allows increasing the coal mining recovery factor in the near-bottom part of the Vorkuta deposit from 0.75 to 0.9 without fundamental changing of the ventilation and transport networks and also without purchasing any additional mining equipment. The conducted economic calculations confirmed the effectiveness of implementing the new technological scheme for cleaning-up reserves at the boundaries of extraction districts. The economic effect is from 0.079 to1.381 billion rubles of additional profit from coaxial extraction pillars, depending on the mining and geological conditions and the size of the pillars.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.