Dust transport behaviour in the Nanwenhe extra-large stepped underground metal mine stope

Abstract

This paper is aimed at studying the dust behaviour of a super-large stepped stope, which is essential in reducing the dust hazards and setting up effective dust control facilities. In this paper, a three-dimensional model is established for the super-large stepped stope of Nanwenhe. Based on the theory of gas-solid two-phase flow, the Fluent software was applied to carry out a numerical simulation of the air flow distribution in the stope and the dust concentration distribution from multiple dust sources. The simulation results reveal that air flow is affected by the roof fault, resulting in it being diverted to the connecting roadway of the return air roadway, the roof of the lower stope and the interior of the stope. A part of the air flow flows back to the upper stope operation area at a speed of 0.3–0.6 m/s. The dust produced by the shovelling and dumping operations forms a high concentration dust belt with a length of 41 m, a width of 3.6 m and an average concentration of over 260 mg/m³. A portion of the dust flows back to the operation area by bypassing the ore pillar, with a concentration of 60–80 mg/m³. The reliability of our simulation method was verified by field measurements of the air flow velocity and dust concentration. Finally, a new intelligent wind-fog combined dust removal system was designed according to the dust concentration distribution, which achieved an overall dust removal efficiency of 76.9%. These research results provide certain references for the study of dust migration law in underground metal mines and the development of dust removal equipments.