Title: Theoretical equation of initial top-coal boundary in longwall top-coal caving mining

Authors: Weijie Wei; Zhengyang Song; Jinwang Zhang

Addresses: College of Resource and Safety Engineering, China University of Mining and Technology, Beijing, Beijing 100083, China; Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083, China ' TU Bergakademie Freiberg, Freiberg 09599, Germany; College of Resource and Safety Engineering, China University of Mining and Technology, Beijing, Beijing 100083, China ' College of Resource and Safety Engineering, China University of Mining and Technology, Beijing, Beijing 100083, China; Coal Industry Engineering Research Center of Top-coal Caving Mining, Beijing 100083, China

Abstract: The theoretical equation of initial top-coal boundary (ITCB) is one of the fundamental problems of top-coal drawing law in longwall top-coal caving (LTCC) mining. The granular mechanical model of ITCB is established based on loose medium flow field theory. By analysing the stressed top-coal on ITCB along the section of coal seam thickness and face advancement directions, the theoretical equation of ITCB is deduced respectively in the two conditions of first gangue drawing out and excessive gangue drawing out. The theoretical equation is further modified by a correction coefficient k, which is given by a large number of experimental data. Meanwhile, it is found that the ITCB at excessive gangue drawing out condition is in the special shape that "the top opening is elliptical and the bottom opening is rectangle". The theoretical equation of ITCB can provide meaningful guidance to the improvement of top-coal recovery ratio in LTCC.

Keywords: LTCC; longwall top-coal caving; ITCB; initial top-coal boundary; granular mechanics; theoretical equation; top-coal drawing law; PFC simulation.

DOI: 10.1504/IJMME.2018.091972

International Journal of Mining and Mineral Engineering, 2018 Vol.9 No.2, pp.157 - 176

Available online: 21 May 2018 *

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