Hood type dust control systems on continuous miner (CM) in an underground bord and pillar coal mine

Abstract

The changing and stricter regulatory environment has caused the mining industries in South Africa to re-look at their individual mine health and safety departments. In 1997, after the report of the Leon Commission of Inquiry (1995), the South African Department of Minerals and Energy (DME) sent out a directive to reduce the dust concentration level to below 5 mg/m3 at the operator’s position for the sampling period. The reasons for the high levels of dust concentrations of dust are: long headings up to 35 m, inherently high dust generation rates of coal, and the increased use of highly mechanized equipment. To aid in developing systems to reduce high dust levels, a project was formulated under SIMRAC auspices with the title of “Underground Mechanical Miner Environmental Control” to address the dust problem. The project was executed in two phases. The first phase involved laboratory tests on a continuous miner model for different ventilation and spray systems at ventilation simulation tunnel at the Kloppersbos Research Center. In the second phase of the project, tests were carried out underground, based on the findings and recommendations from the simulated tests. This paper focuses on the results and findings of the hood systems, viz., retrofitted hood system and integrated hood system. The average dust concentration for the sampling period at the operator’s position for the retrofitted hood, integrated hood system-smaller scrubber and integrated hood system-larger scrubbers were 2.33 mg/m3, 6.08 mg/m3 and 5.98 mg/m3 respectively. On the other hand, the equivalent average dust concentration (TWA-CONC) for an 8- h period for the retrofitted hood, integrated hood systemsmaller scrubber and integrated hood system-larger scrubbers were 1.53 mg/m3, 5.51 mg/m3 and 4.83 mg/m3 respectively. Finally, the paper highlights the use of auxiliary ventilation systems during the tests underground.