Page 223 - Advances In Productive, Safe, and Responsible Coal Mining

202 Advances in Productive, Safe, and Responsible Coal Mining

equipment used in an underground coal mine must be approved by MSHA. Under-
ground coal mine diesel equipment has been categorized by MSHA into two types:
Type (I) permissible diesel equipment and Type (II) nonpermissible equipment.
Type (I) permissible equipment is required in those underground mines that
potentially have methane gas and/or coal dust explosive mixtures. Permissible equip-
ment is mainly used in areas of the mine that are inside the last open crosscut (called
inby areas). Permissible equipment consists mainly of heavy-duty (HD) production
equipment that must be explosion proof and have stringent requirements for exhaust
cooling systems and surface temperature controls. As of July 2002, according to
MSHA, the requirement for each piece of permissible diesel equipment used in
any underground coal mine is a maximum emission of 2.5g/h. of DPM [16]. Most
permissible diesel equipment use exhaust filtration systems in order to meet the
MSHA requirement of 2.5g/h.
Type (II) nonpermissible diesel equipment can be used in the areas of the under-
ground coal mines where use of permissible equipment is not essential. Non-
permissible equipment does not require surface temperature and exhaust cooling
controls. MSHA further categorizes nonpermissible diesel equipment into two types:
(a) nonpermissible light-duty (LD) equipment and (b) nonpermissible HD equipment
[16]. As of January 2005, MSHA requires that each nonpermissible HD diesel equip-
ment used in an underground coal mine must emit <2.5g/h. of DPM and each
nonpermissible LD diesel-powered equipment added in an underground coal mine
after May 2001 must emit <5.0g/h. of DPM [16]. Other diesel engine vehicles, which
meet the US Environmental Protection Agency (EPA) emission standards, are consid-
ered in compliance with LD provisions, even if they exceed DPM emissions of 5.0g/h.
LD diesel engines that meet US EPA standards and emit >5.0g/h. can be an important
source of DPM in the underground coal mine air [17] even though MSHA regulations
allow their usage without emission control.

11.4.2 Impact on M/NM mines
After July 2001, MSHA requires that any diesel-powered engine introduced in a
metal-nonmetal mine in the US must be either certified to meet or exceed the partic-
ulate matter (PM) emission requirements specified by the EPA [32]. This requirement
does not pertain to diesel engines used in ambulances or in firefighting equipment as
these vehicles are used according to the mine’s firefighting and evacuation plans.

11.5 US DPM regulations and permissible exposure
limits (PELs)

MSHA published two rules related to miners’ exposure to DPM in underground coal
[16] and M/NM mines [32]. These regulations, implemented in the two mining sec-
tors, differ significantly in term of implementation and DPM exposure determinations.
The DPM regulatory approach implemented in M/NM mines is focused on monitoring
DPM exposure in mine atmospheres. They encourage the use of personal protective
equipment (PPE) and different administrative and engineering controls. The US DPM