Filling of voids in coal longwall mining with caving – technical, environmental and safety aspects

Palarski, Jan; Plewa, F.; Strozik, Grzegorz

doi:10.36487/acg_rep/1404_39_strozik

Cited by 6 publications

(7 citation statements)

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“…The proportions of water and solids (W/S ratio = 0.38) were selected so that the resulting mixtures had mainly a liquid consistency, as well as that of pastes. Liquid consistency results from the fact that the transport of mixtures from the surface to an underground working, in line with the conditions of Polish mining, takes place in a gravitational way (Palarski et al, 2014). The fluidity of the mixture determines, among others, their transport and penetration capabilities (Palarski et al, 2005).…”

Section: Methodsmentioning

confidence: 99%

“…The primary purpose of filling cavings in mines is to improve ventilation and protect against spontaneous ignition of coal residues in the gob areas. As a material for filling voids, fly ash from the combustion of hard coal mixed with water is used, mainly due to these mixtures' ability to solidify and convenient rheological properties that allow their easy hydraulic trans port in pipelines and placement into the cavings (Palarski et. al.…”

Section: Use Of Fine-grained Fill Mixtures In Longwall Mining With Ca...mentioning

confidence: 99%

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Minefill 2020-2021

Hassani¹,

Palarski²,

Sokoła-Szewioła³

et al. 2021

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The series of International Symposium on Mining with Backfill (Minefill) explores both the theor etical and practical aspects of the application of mine fill, with many case studies from both under ground and open-pit mines. Minefill attendees include mining practitioners, engineering students, operating and regulatory professionals, consultants, academics, researchers, and interested indi viduals and groups from within the wider community. There are presentations from people from around the world working in very diverse environments, with a range of local expertise showing their unique problems but common solutions.Since the first Symposium held in Mount Isa in 1973, the series has had 12 editions. Since 1998 it has a form of a triennial symposium being held most frequently in Australia, Canada, South Africa, and the United States.The Symposium topics evolve with the development of trends in mine fill technologies, overall mining problems, hazards, environmental standards, etc.In the current edition of the Symposium Minefill 2020-2021, the following range of detailed themes has been proposed: ➢ Legal, safety, environmental and financial drivers for backfill ➢ Mine fill geomechanics, numerical modeling, the interaction between backfill and rock mass ➢ Bulkhead capacity and fill strategies ➢ Binders, admixtures, and other chemicals to improve fill performance ➢ Backfill reticulation: pumping, piping, hydraulic analyses ➢ Field fill mass blast and stress monitoring before and after exposure and data analysis ➢ Laboratory testing on static and dynamic behaviors of backfill ➢ Hazard and risk control practices in backfill application ➢ Application of new technology and new equipment in mining with backfill ➢ Influence of mining with backfill on the mitigation of subsidence related hazards ➢ Case studies. This year, the Symposium is organized in the Silesia Coal Region in Poland, where hydraulic fill has been used for the first time in the world. Originally, the Symposium was planned for 2020, but due to the extraordinary epidemic situation related to COVID-19 (SARS-Cov-2 virus), the conference was moved to 2021, with the name of the Symposium being Minefill 2020-2021. The organization of the Symposium was adopted in a remote form on a specially dedicated platform.Polish underground mines of salt, base metals, and coal have used sand, gravel, underground waste rock, tailing, smelter slag, and coal combustion by-products since the end of the 19th century to fill underground voids. Fills used in coal mines have evolved from early loosely dumped rock, ash, and slag through hydraulically placed sand fill (in the early 1880s), pneu matic (the year 1920), and throwing (the year 1947) stowing up to today's hydraulically trans ported, densified fills with fly ash, tailing and flue-gas desulphurisation by-products. The use of fly ash, slimes, and water mixture as compaction grout of roof fall materials in gob area

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Section: Methodsmentioning

confidence: 99%

Section: Use Of Fine-grained Fill Mixtures In Longwall Mining With Ca...mentioning

confidence: 99%

Minefill 2020-2021

Hassani¹,

Palarski²,

Sokoła-Szewioła³

et al. 2021

Self Cite

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“…Another method requires location of the pipeline in the longwall, mounted on the face conveyor or hanging under the shields, with pipe outlets directed into the gob between the shields. Grout injections are especially effective in inclined coal seams, where elevation differences increase range of flow of slurries in voids (Palarski et. al., 2011).…”

Section: Technology Of Underground Voids Fillingmentioning

confidence: 99%

Filling of Underground Voids with Fy Ash – Water Slurries as a Contribution Into the Reduction of Saline Waters Discharge from Coal Mines Into the Odra River

Strozik,

Popczyk

2023

The 20th International Conference on Transport and Sedimentation of Solid Particles. 50th Anniversary

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Drainage and discharge of mine waters belong to main environmental issues that must be appropriately addressed by underground coal mining industry. Saline mine waters from both active and already closed mines contribute the environmental risks for rivers and their catchments. Increasing average depth of mining works and necessity of drainage of numerous closed mines results in increasing amounts of chlorides and sulphates being introduced into water environments, even then coal production of Polish mining industry is decreasing. Majority of mines waters are discharging directly to watercourses and the only significant environmental protection measure is control of the concentration of salt in main rivers. Balance of mine waters and Cl- + SO4 - ions demonstrates the weight of this issue and gives a background, on which technology of filling of underground voids has been discussed as a method, which, under several conditions, may reduce the discharge of brines and highly salinized mine waters (mineralisation above 42 g/dm3 ) by about 30%. Although technology of filling of voids with mixtures of water and finely grained solids (mostly fly ash) is well known and adopted by most of the coal mines, its potential in reduction of saline waters discharge is being wasting due to inconsequence in its use and underestimating its value in terms of saline waters management. Influence of waterʼs salinity on the physical properties of the fill, as well as benefits gained by the coal mines as result of filling of voids, show that these operations should be conducted in the possibly largest extent, limited only by availability of fly ash and volume of voids, being created as result of coal extraction.

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“…Then how to treat the loss of coal resource and repair the generated seam floor failure becomes the next question. Accordingly, during or after coal mining, there are some primary remedial engineering measures used to prevent water inrush from confined aquifers underlying coal seams (Cai et al 2019;Junthong et al 2019;Meng et al 2018;Niedbalski et al 2018;Palarski et al 2011Palarski et al , 2014Strozik 2017). One measure is draining the aquifer to lower the pressure on the aquiclude, but the aquifer is usually so thick that the aquifer is usually overdrained over long period without knowing how much water should be drained, which leads to many environmental problems (Meng et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Development of a combined mining technique to protect the underground workspace above confined aquifer from water inrush disaster

Zhu

et al. 2020

Bull Eng Geol Environ

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One task facing by the geotechnical engineers is to protect the workspace in an underground construction/excavation site from various forms of geological disasters, such as the water inrush, rock burst, and collapse of the surrounding rock/soil. In this paper, a combined controlling measure was proposed based on underground mining and water environment: the method of strip mining has been initially proposed as an effective measure against underground workspace floor failure when mining above confined aquifer in the Bucun coal mine, China, and however, its ability to avoid floor water inrush has yet to be demonstrated; in the next step, field trials using caving zone backfill technology to prevent underground workspace floor failure and excavate retained strip coal pillars were implemented based on the theoretical calculation and numerical simulation results. Engineering practice showed that the failure depth of the underlying strata of the workspace had no growth without the possibility of water inrush, and the safety of the underground space was achieved. Thus, this study represents a successful attempt to develop the combined strip mining and caving zone backfilling technique to ensure the safety of the underground workspace and control surface subsidence when excavating the retained strip coal pillars above confined aquifer. The proposed combined technique can also be used in other underground excavation activities with similar problems.

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Filling of voids in coal longwall mining with caving – technical, environmental and safety aspects

Cited by 6 publications

References 0 publications

Minefill 2020-2021

Minefill 2020-2021

Filling of Underground Voids with Fy Ash – Water Slurries as a Contribution Into the Reduction of Saline Waters Discharge from Coal Mines Into the Odra River

Development of a combined mining technique to protect the underground workspace above confined aquifer from water inrush disaster

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