Abstract
In-mine studies were conducted as part of a collaborative study with the U.S. Bureau of Mines to assess the effects of diesel emission after-treatment control devices on mine air quality. An oxidation catalytic converter (OCC) was replaced with a combined catalyzed diesel particulate filter (CDPF) and OCC unit in one mine, designated mine Q. In a second mine, designated mine T, the OCC was replaced with a CDPF. In each mine, emissions from one diesel-powered mine vehicle were monitored with the two control configurations. In mine Q, the vehicle studied was an Elphinstone R1500 load-haul-dump vehicle equipped with a Caterpillar 3306 PCTA diesel engine used to move ore from a drawpoint to an ore pass. In mine T the vehicle studied was a Tamrock model 2S-TR1 diesel-hydraulic, roof-bolting jumbo powered by a 61-kW (82-hp) Deutz F6L912W diesel engine, which used diesel power to install roof bolts. Control efficiencies for diesel particulate matter (DPM) concentrations in the vicinity of the mine vehicle operator, calculated as the percentage reduction in concentration in the condition with the CDPF installed, were 61 percent for mine Q and 82 percent for mine T. Control efficiencies for tailpipe DPM were 95 percent for mine Q and 74 percent for mine T. Control efficiencies as determined from calculated air quality index (AQI) values were 32 percent for mine Q and 63 percent for mine T; exhaust quality index (EQI) control efficiencies were 85 percent for mine Q and 30 percent for mine T. The AQI and EQI values provide measures of the health effects of combined concentrations of DPM and gaseous emissions in the mine ambient air. Control efficiencies for DPM and DPM-associated organics (including polynuclear aromatic hydrocarbons) collected with high-volume samplers were about 70 percent or greater in both mines. Mutagenic activity decreased by an amount approximately equal to the decrease in DPM in mine T, but increased by over 100 percent in mine Q. These findings indicate that replacement of an OCC with a CDPF or with a combined CDPF and OCC had overall positive effects on the mine air quality, but the increased mutagenicity in the DPM from mine Q suggests that further study is needed.