Background on the Mining Sector
The mining sector in the United States is generally comprised of those entities that extract naturally-occurring materials such as crude oil, minerals, or metals from the Earth. Mining operations are generally classified as above-ground (surface) mining and underground mining operations and the underground mining sector is a chief focus of the biodiesel industry due to the primary use of diesel fuel to power machinery underground and diesel particulate emissions from that machinery which has a direct effect on worker respiratory health.
The US Department of Labor – Mining Safety and Health Administration (MSHA) is directly responsible for insuring the health of the nation’s underground mining workers. One key aspect involves controlling their exposure to diesel particulate matter resulting from the combustion of petroleum-based fuels such as diesel fuel in equipment used to mine metals and non-metals in underground mines. To control exposure to acceptable levels, MSHA in 2006 set forth health standards limiting diesel particulate matter emissions in underground mining operations. The full rule can be found here: http://cfr.vlex.com/vid/57-limit-diesel-particulate-matter-19690228.
Specifically, from May 20, 2008, a miner's personal exposure to diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift airborne concentration of 160 micrograms of total carbon (TC) per cubic meter of air (160TC μg/m3) which is a significant decrease from 2007, which set the limit at 350TC μg/m3. MSHA measures the total carbon level as elemental carbon (EC) which is the TC level divided by 1.3. Therefore, 160TC μg/m3 becomes roughly 123EC μg/m3.
There are a number of control strategies underground mines can take to achieve this level such as increased ventilation, installing newer engines with better exhaust profiles or use of environmental cabs, and the use of biodiesel in high blend levels. Because of this ruling, operators of underground mines where exposure to elevated levels of DPM are prevalent must install controls to keep DPM levels below the mandates 160TC μg/m3. The MSHA recognizes the use of biodiesel as an accepted method for accomplishing DPM reductions in underground mines.
Why Biodiesel is Important to the Mining Sector
Biodiesel has been shown by MSHA in their underground testing and in numerous underground mining applications at various blend levels to consistently help meet or exceed DPM PEL criteria, thereby significantly improving worker health. MSHA has continually endorsed biodiesel in national workshops and meetings as a viable means of reducing total and elemental carbon levels in underground mines and meeting the required exposure limits. Information provided by MSHA on biodiesel, its application in a number of underground mines, and reductions in DPM achieved can be found here: http://www.msha.gov/01-995/Dieselpartmnm.htm.
Use of biodiesel to control diesel particulate matter – reductions in underground mines
Biodiesel in a conventional diesel engine has demonstrated substantial reductions of unburned hydrocarbons, carbon monoxide, and particulate matter when compared to conventional diesel fuel. Because of the emissions characteristics of biodiesel, MSHA has been actively involved over the past several years in conducting TC and EC emissions sampling from machinery that has utilized only standard #2 diesel and various blend levels of biodiesel, most notably B100. Sampling in a number of underground metal and non-metal mines by MSHA has found significant reductions in EC levels occur with increased biodiesel blend levels and total levels of emission reduction is a function of a number of factors such as machinery type, biodiesel feedstock and blend level, and existing mine ventilation. Figures 1 through 4 provide examples of EC reductions at four separate underground mines across the United States sampled by MSHA. Based on data presented in the figures below, biodiesel definitely had a definite affect on EC reductions.
Figures 1 and 4. EC reductions with 100% biodiesel versus conventional diesel fuel in two underground mining applications (figures courtesy of Bill Pomroy, MSHA).