Mining Market Sector & Biodiesel

Click here for the June 2009 Clean Cities Factsheet Titled "Biodiesel Clears the Air in Underground Mines."

Brief overview of the US 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.  Table 1 presents general types of mining operations (by mineral) in the United States along with estimated total distillate fuel consumption (thousand barrels per year).

Mining operations are also classified as above-ground (surface) mining and underground mining operations and the underground mining sector is the chief focus of the biodiesel industry due to the primary use of diesel fuel to power machinery underground and emissions from that machinery that has a direct effect on worker respiratory health.    

Figure 1 shows the geographic location of the five general mining categories.  For a complete listing of types and number of mines by state please see http://www.cdc.gov/niosh/mining/statistics/tables/m1.html.  A breakdown by type of mining operation (metal, non-metal, stone, sand and gravel, coal), name of mine, location, address and contact information within an individual state can be obtained at http://www.msha.gov/drs/asp/extendedsearch/minesbystatecommodity.asp

Table 1.  Distillate (light) grade numbers 1, 2, 3, and light diesel fuel used as a fuel (000 bbls) in various (reference:  http://www.census.gov/prod/ec02/ec0221sm1.pdf)

Figure 1.  Location of various mining operations.

Background - Mining and Worker Health

Since the 1960s, there have been a number of epidemiological studies concerned with the relationship between diesel particulate matter (DPM) and worker health in underground mines.  The US Department of Labor - Mine Safety and Health Administration (MSHA) has mandated strict diesel particulate matter (DPM) exposure limits for metal and nonmetal underground miners which have tightened significantly in the past two years.  DPM is a component of diesel exhaust, are usually less than one micron (one millionth of a meter), and are burned and unburned hydrocarbons as well as oxides of sulfur, nitrogen, and metal fragments.  DPM carbon components include vapor phase hydrocarbons (OC) and elemental carbon (EC) the sum of which is the total carbon (TC).  Elemental carbon comprises a little over three-quarters (~77%) of total DPM carbon (TC).  DPM is strongly believed to impact underground worker health.  By limiting worker exposure of DPM to certain prescribed levels over a set timeframe, worker health will be vastly improved.  Figure 2 presents a visual of DPM and its carbon components. 

Beginning in the 1990 the United States Department of Labor’s Mining Safety and Health Administration (MSHA) began initiating rulemaking to limit DPM exposure, expressed in micrograms per meter cubed (µg/m3) in underground metal and non- metal mines.  In 2001, MSHA issued an interim rule that set the permissible exposure limit (PEL) of DPM to 400TC µg/m3 (~308EC µg/m3) with the condition that by May 2008 a more stringent DPM PEL would be enacted reducing DPM levels to 160TC µg/m3.  

Figure 2.  Diesel particulate matter (DPM) carbon constituents and relative      
                 percentages in DPM (figure courtesy of Bill Pomroy, MSHA).

The MSHA compliance guide at http://www.msha.gov/REGS/COMPLIAN/Guides /MNMDPM / MNMdpmcompguide.pdf has complete detail on the DPM regulations.  Figure 3 provides a brief summary of the MSHA final rule.

Figure 3.  General overview of the MSHA final proposed rule.
 (figure courtesy of Bill Pomroy, MSHA).

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.  In addition, 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.  While other means exist to reduce underground DPM levels, at present no other technology or fuel that can provide the emissions reduction benefits to match certain biodiesel blends at a competitive cost.

Use of biodiesel to control DPM – Reductions in DPM concerning biodiesel use in underground mines

Biodiesel in a conventional diesel engine has demonstrated substantial reductions of unburned hydrocarbons, carbon monoxide, and particulate matter.  Biodiesel decreases the solid carbon fraction of particulate matter (since the oxygen in biodiesel enables more complete combustion to CO2), eliminates the sulfate fraction, while the soluble (hydrocarbon) fraction stays the same or is increased.

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 4 and 5 provide examples of EC reductions at two mines sampled by MSHA.  Based on data presented in the figures below, biodiesel definitely had a definite affect on EC reductions, but it must also be noted that differences in ventilation rates and work/load cycle over the same period of time may also have played a role in these EC reductions as well.

    
Figures 4 and 5.  EC reductions with 100% biodiesel versus conventional diesel
fuel in two underground mining applications (figures courtesy of Bill Pomroy, MSHA).

For more information, contact Richard Nelson at the National Biodiesel Board offices.

Please assist us in advancing the biodiesel
product and in keeping this site current and
informative by completing a short survey.