Dec 1, 2024 · In this work, a novel approach of partially reverse drawing technique (PRDT) was proposed to improve the top coal recovery at the roof side in SLTCC. The definition and procedures of PRDT were introduced, and theoretical mechanism of PRDT in reducing top coal loss was analyzed based on four-element top coal drawing theory.

Sep 1, 2022 · Based on the data collected during drilling, a 3D model of top coal caving surface space was established to determine the relationship between the location of the stope roof and the caving surface, enabling the mathematical computation of the top caving angle (φ).

Oct 1, 2014 · The top-coal caving longwall mining is one of the major mining methods for extracting thick coal seams in China. The top-coal caving mining was estimated to have produced about 0.6 billion metric tons every year, accounts for 18% of underground coal mining in China [3].

Jan 7, 2025 · By summarizing the motion characteristics of top coal and gangue in upward mining or downward mining, the dynamic caving interval technology for the upward–downward transition is proposed in this paper, and the variation of top coal boundary, caving body and top coal recovery at different caving stages in this technology is analyzed by ...

Jul 21, 2021 · Longwall top coal caving (LTCC) is a special type of mining method commonly used to extract coal seams thicker than 4.5 m (Wang et al. 2018a). This method originated in France and Eastern Europe in the 1950s for extracting coal pillars from marginal areas of coalfields (Wang et al. 2014).

Dec 26, 2024 · Longwall top coal caving (LTCC) mining technique is widely used in thick and extra-thick coal seams in China, India and Türkiye. Considering that the depth of coal seam varies widely (from 188 to 988 m in China), the different overburden pressure has great influence on the failure and drawing process of top coal in LTCC.

Oct 18, 2024 · At low backfilling ratios, premature gangue exposure causes the loss of high-position top coal. Conversely, higher backfilling ratios facilitate the creation of a reconstructed floor, thereby enhancing top coal recovery. This work was supported by the National Natural Science Foundation of China [grant number 52130402]

The integrated FDM–DFN model enabled the influence of the preexisting fracture, stress redistribution, stress rotation, caving material compaction, and periodic rupture of roof strata to be superimposed on the failure process of top coal. It was revealed the LTCC influenced both magnitude and orientation of the principal stress within top coal.

The top coal caving (that is, the difficulty of top coal mining under the action of in situ stress and gravity ) is one of the critical factors determining the success of longwall top coal caving mining, and it is also an essential reference for designing longwall top coal caving mining technology and improving the recovery rate of top coal .

Jun 24, 2021 · To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30...