Monitoring and controlling diesel particulate matter exposure levels in an underground mine – a case study

Abstract

Underground mining operations involve the use of light and heavy-duty equipment such as pickup trucks, drill rigs and dump trucks. These equipment are powered by internal combustion engines, generating enormous exhaust fumes. The exhaust fumes contain Diesel Particulate Matter (DPM) which possess health problems to humans when inhaled. The Minerals and Mining (Health, Safety and Technical) Regulations, 2012, is silent on emission threshold in underground mines; hence, there is no established DPM standard in Ghana. Therefore the Mine Safety and Health Administration (MSHA) standards were used. This research studied the DPM exposure levels at Chirano Gold Mines Limited for the Akoti and Paboase Underground Mines for a period of two years (2016 and 2017). A total of sixty-three (63) out of eighty-two (82) workers in day shift were sampled for the analysis of DPM exposure levels. Personal DPM monitoring equipment was attached to underground workers to sample exhaust emission at working faces. CGML gathered the DPM data for 2016 while the 2017 data was collated during field studies for the thesis. A laboratory analysis was undertaken. Many of the DPM measure for both Akoti and Paboase were above the MSHA threshold limit of 160 µg/m3. Compared to the threshold limit, the percentage exceedance for the workers at Akoti Mine was: Bogger Operators (126.25%), Mechanics (70%), and Jumbo Operators (267.39%). The percentage exceedances for the workers at Paboase Mine include Blastmen (181.25%), Loader Operators (179.38%), Bogger Operators (107.72%) and ITH (114.38%). The ventilation system of the mine was also examined and revised to provide air quantity that will minimise the high DPM concentration. Using airflow analysis, it was established that increasing the air velocity to 1.3 m/s will keep the DPM to concentration at the working faces below threshold limit value (TLV) 160 µg/m3