Fully Mechanized Mining Technology and Practice of Water Conservation with Large Gravity Filling of Aeolian Sand‐Like Paste

Abstract

Aiming at the serious problem of Salawusu formation aquifer damage caused by caving mining in Yuyang coal mine, the technique of mechanized backfill mining with Aeolian sand-like paste was invented. Aeolian sand was used as aggregate and alkali-activated fly ash as cementing agent in the backfill material. Slurry ratio was studied where the water-sand ratio was 1 : 1.3 and the mass concentration was 72%, while slurry initial fluidity could reach 210 m. The author proposed the local resistance loss calculation method of slurry pipeline transportation, and the field gravity transport test results showed that resistance loss of unit length elbow was 4.26 times as big as loss of resistance along path; thus the pipeline diameter with 14.9 gravity of self-flowing was determined, and the pipeline flow design precision was improved by more than 10%. The backfill capacity could reach 360 m3/h and the running energy consumption was lower because of adopting backfill station model with double pulping system and underground equipment pool. The author also put forward whole backfill space sealing in which cloth consumption was only 40% of bag backfill. Industrial test showed that the backfill mining technique met requirements of water resources protection, primarily because the filling rate was 98.5% in goaf, strata behavior appeared slightly, roof water leaching was less than 2 m3/d, and surface subsidence value was only 38 mm. There were great breakthroughs in cost and production efficiency in this technology compared with similar technologies.

Mitigating Risks in Coal Mining: Simulation-Based Strategy for Oxidation Zone Control Using Inorganic Paste Backfill at the Working Face Corners

“…This study holds immense significance in mitigating air leakage in the working face and ensuring safe mining operations. While the existing literature has extensively explored inorganic paste filling materials [15][16][17][18][19][20][21][22], this article introduces an innovative approach by using mountain sand as the filling aggregate and fly ash as the filling auxiliary material, resulting in a novel mountain sand-based paste filling material. This novel material demonstrates superior self-supporting properties, a quick setting time, and the ability to fully expand and reach the ceiling, as compared to other inorganic paste filling materials.…”

“…Feng Guangming [18] developed ultra-high-water filling materials and successfully applied them to fill mining working faces, tackling the challenge of high filling costs. Liu Yong [19] conducted experiments on high-sand filling materials, using water, cement, fly ash, and wind-blown sand as inorganic filling aggregates, and determined the optimal concentration ratio suitable for water-preserving mining, significantly impacting water-preserving mining practices in western mining areas. Zhao Xuefei [20] utilized various fine-tail grains of sand as filling aggregates, examining the filling performance of cemented paste materials under different aggregates and additives, and found that substituting cement with high-alumina clay resulted in minimal changes in the compressive strength of the filling body while gradually enhancing stability in later stages.…”

Experimental investigation into the mechanical and microscopic properties of cemented aeolian sand-coal gangue-fly ash backfill

“…9, the uniaxial compressive damage of R-C-1, R-C-2, R-C-3 and R-C-4 CACFB materials is from the top to the bottom of the destruction of the penetration of the review of the relevant literature. The test block are mainly tensile damage, accompanied by a certain amount of shear damage, such as the destruction of the test block of R-C-1 as shown in the the destruction of both tensile damage and the occurrence of shear damage [30][31][32].…”