Abstract

The large mining height fully mechanized top-coal caving mining technique has developed rapidly and become the most extensively used mining method for ultra-thick coal seams. The arching of coal/gangue and the drawing out of gangue are peculiar phenomena in the process of fully mechanized top-coal caving mining, which not only affects the recovery of top-coal, but also affects the quality of the coal. This paper studies the arching phenomenon in top-coal caving mining process of ultra-thick coal seam. A series of laboratory granular material simulation experiments were performing and a top-coal arching model in the framework of mechanics was established to explore the formation characteristic of arches and their effects to top-coal loss. Then the countermeasures against the arches and technology path of intelligent mining based on improving top-coal recovery were put forward and performed in practice. The results show that the recovery ratio of top-coal has increased nearly 6%, and increased the production efficiency at the same time. The research on arching mechanism and removing strategies of dynamic random arches effectively improves the efficiency of fully mechanized top-coal caving mining in ultra-thick coal seams, and provides the foundation for the realization of intelligent top-coal caving mining technology.

Highlights

  • In China, fully mechanized top-coal caving mining in ultra-thick coal seams has developed rapidly in the past 10 years [1,2,3,4]

  • The application of intelligent working faces has been studied in China, which will greatly promote the development of coal intelligent mining technology, especially in the research of fully mechanized top-coal caving intelligent mining [12,13,14,15,16,17]

  • The main issues are the arching law, arch structure characteristics, the influence of arches to the smoothness of coal/gangue flow and loss of top-coal. It is of great significance for improving the recovery ratio of top-coal and solving the key problem in fully mechanized intelligent top-coal caving mining in ultra-thick coal seams [21,23]

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Summary

Introduction

In China, fully mechanized top-coal caving mining in ultra-thick coal seams (especially in 14–20 m ultra-thick coal seams) has developed rapidly in the past 10 years [1,2,3,4]. The application of intelligent working faces has been studied in China, which will greatly promote the development of coal intelligent mining technology, especially in the research of fully mechanized top-coal caving intelligent mining [12,13,14,15,16,17]. The main issues are the arching law, arch structure characteristics, the influence of arches to the smoothness of coal/gangue flow and loss of top-coal It is of great significance for improving the recovery ratio of top-coal and solving the key problem in fully mechanized intelligent top-coal caving mining in ultra-thick coal seams [21,23]. Countermeasures against the arches and technologies of intelligent mining were performed in practice to test the feasibility

Engineering Background
Experiment Design
Experiment and Analysis
Probability
Characteristics of Arches as followings:
Arching
Trajectories
Removing Strategies of DRA
Removing
10. Fragment
Discussion
Findings
Conclusions
Methods

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