Application and prospect of coal gangue slurry filling technology

In order to realize in-situ, green and large-scale disposal of coal gangue, coal gangue slurry filling technology, as a new filling technology, has been rapidly developed and applied in recent years. This paper systematically reviews and summarizes the landmark achievements and key technologies of coal gangue slurry filling at different stages, such as the proposal of the technical framework, the formation of the theoretical system of slurry filling, the application of engineering demonstration and the innovation of technology iteration, and forms three filling methods, namely, high-level grouting, low-level grouting and adjacent grouting. The “intervention theory” of coal gangue slurry flow in goaf caving zone and the “three degrees and one field” theory of slurry pipeline transportation have been established, and the first demonstration project of coal gangue underground slurry filling and surface slurry preparation + underground adjacent grouting filling has been successfully carried out at home and abroad; This paper expounds the technical system of coal gangue slurry filling, and discusses the key technical core issues of coal gangue high-efficiency grading crushing, slurry precise preparation, slurry pipeline transportation and end filling, focusing on the process flow of coal gangue crushing, water slurrying of finished gangue powder, slurry pumping preparation and underground target area filling. The technical principles and application scenarios of key equipment such as crushing equipment, screening equipment, metering equipment, mixing equipment and pumping equipment are analyzed; Based on the engineering background of small space, multi-equipment and high capacity of coal gangue slurry filling in Zhangjiamao Coal Mine, the layout of different systems such as surface slurry making, pipeline transportation, underground filling and intelligent control of coal gangue slurry filling was innovatively developed and designed, and the annual filling amount of coal gangue could reach 554 000 tons, forming a demonstration of coal gangue slurry filling engineering. In the future, the coal gangue slurry filling technology will be further studied and developed in the direction of small and lightweight equipment, highly integrated system, iterative and innovative technology, which will provide technical support for the construction of green coal mining technology system and the realization of the national carbon peaking and carbon neutrality goal.