The diffusion of dust in a fully-mechanized mining face with a mining height of 7 m and the application of wet dust-collecting nets

Abstract

In order to gain a more in-depth knowledge of the diffusion and pollution rules of dust from multiple sources in a fully-mechanized mining face with a mining height of 7 m, and design some effective dust-suppression measures. This study focuses on the No. 22305 fully-mechanized mining face in the Bulianta Mine, and employs CFD-Fluent software for conducting numerical simulations on the dust concentration's distribution in the respiratory zone on the footway. According to the results of the numerical simulations: due to an air leakage around the air-intake corner, the airflows in the goaf moved in a spiral pattern; they then moved stably in the goaf because of an air leakage between the hydraulic supports parallel to the coal cutter; the dust produced in the coal cutting and support movement processes were superposed on the leeward side of the coal cutter, and a dust belt, with a length of approximately 36 m and a concentration of over 2850 mg/m3, was formed; at 0–120 m on the leeward side of the coal cutter, the dust concentration at the respiratory height exceeded 1700 mg/m3 and exhibited no significant settlement along the way; and dust concentrations at the mining height range of 0–1.55 m and 5.55 m–6.80 m were higher than those at a mining height range of 1.55–5.55 m. Accordingly, a novel dust removal system, comprising wet roller-shutter, dust-collecting nets in the coal mining area and full cross-section, wet dust-collecting nets in the return airway, was designed. The field measurement results show that the overall dust-removal efficiency of this system was 69.6%.