Consol Energy’s Pramod Thakur, speaking on behalf of his research team comprising of the West Virginia Coal Association’s (WVCA) Chris Hamilton and United Mine Workers of America’s (UMWA) Dennis O’Dell, presented on West Virginia’s diesel regulations at the recent US/North American Mine Ventilation Symposium held at Penn State.

According to the researchers, there are approximately 3000 diesel engines in use throughout US mines, with 45% of coal production from underground operations.

With the statistics showing diesel consumption is consistently increasing since its introduction in the 1930s, Thakur said mines can benefit from the advantages of diesel: mine safety and productivity, negation of electric shock, fire and explosion hazards, personal injury reduction through more efficient load carrying and improved face ventilation.

However, he said the use of diesel engines does involve a few drawbacks – most importantly, the contamination of mine ventilation air. Thakur said this was something industry could not only improve upon, but could control through state emissions regulations.

With the main components of diesel exhaust being gaseous emissions and diesel particulate matter (DPM), threshold limit values (TLVs) were established by the US Government some years ago and adopted by the Mine Safety and Health Administration (MSHA). DPM standards are set on a country-by-country basis.

Plans for West Virginia’s regulations (now known as Title 196, Series 1 of WV Underground Mine Laws and Regulations) started early, after the State Governor formed the WV Diesel Equipment Commission in 1997. Formed for the purpose of identifying ways to minimise emissions underground, the group examined engines commonly used in standard equipment such as shuttle cars and personnel transport carriers as well as the efficiency of numerous after-treatment devices.

“Based on these findings and the contents of federal and other states’ diesel regulations, the commission reached a consensus that the best way to control DPM in coal mines and tunneling was to take an integrated approach,” the researchers said.

These included DPM generation reduction through the use of approved clean engines and diesel fuel; generated DPM collection and combustion via the use of a catalytic converter; DPM dilution by means of an adjusted amount of ventilation air provided to the engine; periodic monitoring of engines’ gaseous emissions; routine record keeping and maintenance; and sufficient training for operators, engineers and maintenance staff.

While the resulting WV diesel regulations are quite detailed, below are Thakur and the research team’s highlights:

• Clean engines: All must be MSHA certified. Under a maximum fuel-to-air ratio, they will not exceed a 75 CFM plate ventilation rate.
• Diesel fuel: All must meet EPA regulations for over-the-road fuel as well as ASTM D 975.
• Exhaust emission control and conditioning system: All of these systems must be laboratory-evaluated with an ISO 8178-1 8-mode test resulting in concentrations at or below 120 microgram/m3 diluted average.
• Exhaust control system: All must include a 75%-or-higher efficiency DPM filter, an oxidation catalyst decreasing tailpipe concentrations of carbon monoxide to 100ppm or less and a reduction of exhaust temperature to a point below 320 degrees Fahrenheit. Other requirements for the system include spark and flame arrestors, sampling ports, performance and diagnostics available on the machine itself and automatic shutoff.
• Ventilation requirements: While complex, the three vital outlines of the regulation require adequate ventilation to ensure ambient exhaust concentrations remain within the thresholds of 35ppm for carbon monoxide, 25ppm for metric oxide, and 3ppm for nitrogen dioxide. If concentrations reach 75% of TLV in this instance, an operation could face corrective action. Also, minimum ventilation and the MSA approval plate ventilation would be the same and, for areas utilizing multiple engines, regulations were also adjusted.

The commission also developed and put into place a diesel-powered equipment package approval process for those operations planning to add machines. An application must be submitted to the WV Office of Miners’ Health, Safety and Training for review.

The form is very exact and detailed, according to the group. Some of the information that must be detailed includes inventory sheets for all proposed packages to be used; OEM/model/serial of all incoming packages; rated horsepower and rpm information; ventilation rate; efficiency rating of after-treatment devices; and the results of the system’s ISO 8178-1 8-mode test with DPM emissions listed in grams per hour.

While the state regulations also include the submission of a copy of subsections 196-1-8 to 196-1-27 of the current regulations, the researchers said plans are under way to simplify that documentation.

With approximately 60 diesel engines in use throughout West Virginia’s underground mines, the researchers hoped the sector would recognise the benefits of using diesel equipment and that diesel use would eventually phase out trolley wire equipment.

“Many other states have formulated diesel laws/regulations to supplement federal laws/regulations. It is hoped that other states without diesel regulations can use [these] as a model to write their own.”