scholarly journals Technical Aspects of Mining Rate Improvement in Steeply Inclined Coal Seams: A Case Study

Resources ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 138
Author(s):  
Zbigniew Rak ◽  
Jerzy Stasica ◽  
Zbigniew Burtan ◽  
Dariusz Chlebowski
Keyword(s):  
Similar Rate ◽  
Single Pair ◽  
Coal Seams ◽  
Mining System ◽  
Roof Caving ◽  
Sublevel Caving ◽  
Rate Improvement ◽  
Loss Estimations ◽  
Production Output

This paper presents our experience obtained when mining the thick and steeply-inclined Seam 510 in the Polish Kazimierz-Juliusz coal mine with the use of a unique mechanical face mining system. Seam 510, which is 15–20 m thick and inclined at angles of 40°–45°, was initially treated as uneconomical because effective mining systems were not available. However, to extract high-quality coal resources, a completely mechanized variant of the sublevel caving system was designed based on standard machines and equipment applied in coal mining. Extraction was conducted top-down at the levels of the particular mining sub-level drifts with roof caving. The faces in the extracted coal release areas were protected by a single pair of specially designed mechanized mining system sections. One of the basic problems revealed during extraction of subsequent mining panels, was the observed changeability of the resource mining rates. The extraction losses changed in the available resources from less than 10% to about 50%. This paper presents two typical courses of changes in the extractable resource mining rates. Similar rate changes occurred in both cases with continued mining of a single seam section. Our analysis enabled deposit loss estimations and production output planning under the sublevel caving systems applied in the extraction of seam deposits of similar structure.

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Optimization of roadway layout in ultra-close coal seams: A case study

PLoS ONE ◽  
2018 ◽  
Vol 13 (11) ◽  
pp. e0207447 ◽  
Author(s):  
Gang Wu ◽  
Xinqiu Fang ◽  
Hualin Bai ◽  
Minfu Liang ◽  
Xiukun Hu
Keyword(s):  
Coal Seams ◽  
Close Coal Seams

scholarly journals MODERNIZATION OF THE MINING SYSTEM OF SMALL DEPOSITS OF RICH COPPER PYRITE ORES

2020 ◽  
Vol 12 (3) ◽  
pp. 444-453
Author(s):  
Igor SOKOLOV ◽  
◽  
Yury ANTIPIN ◽  
Artem ROZHKOV ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Rock Mass ◽  
Average Length ◽  
Thickness Variation ◽  
Chamber System ◽  
Mining Operations ◽  
Mining System ◽  
Ore Body ◽  
Experimental Block ◽  
Sublevel Caving

The purpose work. Substantiation and selection of a safe and effective option of mining technology of the experimental block in the pilot industrial mining of the Skalistoe deposit. Method of research. Analysis and synthesis of project solutions, experience in mining inclined low-thickness ore bodies, economic and mathematical modeling and optimization of the parameters of options mining systems in the conditions of the experimental block. Results of research. As a result of research it was established: - the sublevel caving mining system with the parameters adopted in the project does not guarantee the completeness of the extraction of reserves and the effectiveness of mining operations. Project indicators of extraction by sublevel caving technology with frontal ore drawing are overestimated and difficult to achieve in these geological and technical conditions (combination of low thickness and angle of ore body); project scheme for the delivery and transportation of rock mass seems impractical due to the significant volume of heading workings and increased transportation costs; - eight technically rational options of various mining systems were constructed, most relevant to the geological and technical conditions of the deposit. Five variants of the sublevel chamber system and pillar caving, a project variant of sublevel caving technology with frontal ore drawing and two options flat-back cut-and-fill system were considered; - for mining the Skalistoe deposit, according to the results of economic and mathematical modeling, optimal by the criterion of profit per 1 ton of balance reserves of ore is a option of the technology of chamber extraction with dual chambers, frontal drawing of ore by remote-controlled load-haul-dump machine and subsequent pillars caving, as having the greatest profit; - the calculations justified stable spans of dual chambers (25.3 m) and the width of panel pillars (3 m). With an allowable span of 25.3 m, the roof of the dual chambers will be stable with a safety factor of 1.41, and a panel pillar with a width of 3 m has a sufficient margin of safety (more than 1.6) in the whole range of ore body thickness variation; - the proposed scheme of delivery and transportation of rock mass, which allows to reduce the volume of tunnel works by 26% and the average length of transportation by 10-15% compared with the project. Findings. Developed in the process of modernization the technology sublevel chamber system with double-chamber, compared with the project technology, it is possible to significantly increase the efficiency of mining of the low thickness deposit of rich ores Skalistoe by reducing the specific volume of preparatory-rifled work by 34%, the cost of mined ore by 12%, losses and ore dilution – by 2 and 2.9 times, respectively.

X-ray Advances in Support of Advanced Packaging – Today and Tomorrow

2018 ◽  
Vol 2018 (1) ◽  
pp. 000409-000414
Author(s):  
David Bernard
Keyword(s):  
Heat Dissipation ◽  
X Ray ◽  
Destructive Test ◽  
Heat Transfer Efficiency ◽  
Advanced Packaging ◽  
History Of ◽  
Production Output ◽  
2D And 3D ◽  
Non Destructive

Abstract As advanced packaging continues to develop to support novel and emerging technologies, the need for, ideally non-destructive, test and inspection continues to be vital to ensure the quality and assurance of functionality, wherever the package may go. This is made ever more difficult as the package complexity increases, whilst the feature sizes within continue to decrease. X-ray technology has long been an important part of the non-destructive inspection protocol over the history of advanced packaging and will continue to need to play a more important part in the future. This paper will review the advances made in both 2D and 3D X-ray inspection over recent years and the new opportunities that are now starting to be available, especially in 3D, or CT, inspection, that will enable this 120-year-old technology to remain relevant to and supportive of the needs of advanced packaging. To highlight the above, a case study will be presented on the faults that 2D and CT X-ray analysis can find in LEDs during their manufacture. LEDs are a good example of the remarkable developments in packaging and technology over the last 20 years, where the use of higher powers, smaller sized features and increased reliability requirements intensify the need for higher quality, more consistent production output. Flaws cannot be accepted, especially as higher usage powers mean higher operating temperatures which, in turn, then requires very good thermal conductivity in the package to move heat away from key areas. Without good heat dissipation then heat stresses at the interfaces can cause delamination or die fractures, so reducing LED lifetimes. The presence of voids, particularly at the die to package interface, creates air gaps that reduces heat transfer efficiency. As many LEDs are potted, or encapsulated, the only non-destructive test option to check for voiding and other faults is by using 2D and CT X-ray analysis.

scholarly journals Dynamic simulation of an opencast coal mine: a case study

2019 ◽  
Vol 7 (1) ◽  
pp. 164-181 ◽  
Author(s):  
Kesavan Muniappen ◽  
Bekir Genc
Keyword(s):  
Dynamic Simulation ◽  
Coal Mine ◽  
Value Chain ◽  
Dynamic Simulations ◽  
Mining System ◽  
Materials Handling ◽  
Review Team ◽  
Project Construction ◽  
Unique Approach

AbstractDynamic simulations are powerful tools, but only if they are developed using the correct methodology, and with information that has been verified. Mining houses rely on simulation to confirm that complex, integrated systems can achieve design capacity before investment decisions are made. Work conducted in the realm of validation can make an invaluable contribution to the success of future projects undertaken around the world. Coal mine a life of mine extension project was approved for implementation when export coal prices were on the low end of the price cycle. The dynamic simulation of the full materials handling value chain conducted during the project feasibility study in 2016 was of utmost importance and provided assurance to the project review team that annual production targets can be achieved. The simulation development methodology was based on a unique approach that reduced time spent on the simulation. Upon completion of project construction and commissioning in 2018, it was essential to validate the simulation, which could lead to the adoption of this approach on future projects. This paper explains the steps taken to validate the dynamic simulation. This case study confirmed that dynamic simulation can add value and predict mining system performance, such that informed decisions can be made.

scholarly journals Roof Movement and Failure Behavior When Mining Extra-Thick Coal Seams Using Upward Slicing Longwall-Roadway Cemented Backfill Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xuejie Deng ◽  
Zongxuan Yuan ◽  
Lixin Lan ◽  
Benjamin de Wit ◽  
Junwen Zhang
Keyword(s):  
Mechanical Analysis ◽  
Movement Behavior ◽  
Failure Behavior ◽  
Mining Method ◽  
Coal Seams ◽  
Flat Bottom ◽  
Final State ◽  
Performance Requirements ◽  
Cemented Backfill

A novel and environmental-friendly backfill mining method known as upward slicing longwall-roadway cemented backfill (USLCB) technology has recently been proposed and successfully applied in mines extracting extra-thick coal seams located under sensitive areas. This paper studies the effects USLCB had on roof movement and failure behavior using the mechanical analysis approach. The application of USLCB in the Gonggeyingzi Mine is taken as a case study with roof movement behavior being monitored over a single mining cycle, as well as over multiple mining cycles of different coal slices. In addition, backfill performance requirements to prevent roof failures where USLCB is implemented are studied. The results show that the deflection curves of the roof at the end of each mining cycle during mining the first and the six slices are symmetrical, but they change from asymmetrical to symmetrical during the mining progresses of the second slice to the fifth slice. The final state of roof movement after the first slice, and through to the fifth slice, displays an obvious “flat bottom” pattern in the middle of the deflection curve. The roof movement during the removal of the top slice is noticeably different from other slices. The results also show that the requirements of the elastic modulus, as well as the strength of the backfill, increase as the number of mined slices increases from 1 to 5, but the requirements drop sharply for mining the top slice.

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