Every day, around the world, some of the bravest souls on earth go below the surface, trusting the equipment they are outfitted with to get their work done and come out alive. Coal mining is unquestionably one of the dirtiest jobs around, and one of the most dangerous.
Invisible gases lurking underground introduce the potential dangers of poisoning by toxic gas exposure, suffocation due to lack of oxygen, and fire or explosion caused by combustible gases. A toxic or combustible gas can be colorless and odorless, and reduced oxygen levels are invisible. Measurement and control of the environment is intended to prevent the occurrence of mine fires, unplanned explosions, and occupational illnesses or injuries.
Dangerous mine gases
The dangers associated with certain mine gases are some of the most documented health and safety hazards in the mining industry. Following the Sago Mine accident in West Virginia on January 2, 2006, there was much discussion regarding the levels of carbon monoxide and methane contributing to the deaths of 12 miners. Questions regarding the delay of the mine rescue attempts brought to light the complications when hazardous gases are involved.The following statement was issued by the Mine Safety & Health Administration (MSHA) regarding the delay:
“A mine explosion had occurred and methane gas appeared to be the fuel. Initial instrument readings at the mine portals indicated that 500 ppm of carbon monoxide and 11/2% concentration of methane were exiting the mine through the ventilation current. Carbon monoxide is an indicator of a possible fire and methane is an explosive gas. The gas readings collected were indicators that it was not safe to send people into the mine because of the potential for a second explosion. Safe entry into the mine could not be accomplished until trending of the carbon monoxide and methane gases indicated an active fire was not present.”
Methane, a combustible gas naturally occurring in coal mines, commonly builds up over time, often in newly mined areas. The deadly gas is released from the layers of the rock bed or from the coal seam itself. Methane is lighter than air and tends to migrate upwards. Without proper ventilation, methane gas accumulation will displace the oxygen in the air, resulting in an atmosphere that is not only highly explosive but hazardous to your health. Atmospheres with oxygen concentrations below 19.5 percent can have adverse physiological effects, and atmospheres with less than 16 percent oxygen can become life-threatening.
The need for monitoring
Recognizing the detrimental effects of a methane-rich, oxygen-deficient atmosphere emphasizes the need to monitor the air prior to working in the environment. Initial rudimentary methods for determining if the atmosphere was fit for humans included using caged canaries, open-flame lanterns on caps, and hand-carried flame safety lamps. All were precursors to electronic devices, commonly known as gas monitors or multi-gas detectors.Open-flame lanterns and the flame safety lamp utilized the fire triangle as the principle of operation. A flame requires fuel, an ignition source and oxygen to burn. The flame safety lamp used a naphtha fuel fed wick housed inside of a glass tube with precision markings to gauge the propagation of the flame. This flame interacted with the ambient air and would increase in intensity if there was combustible gas in the area and would decrease if levels of oxygen were substandard. The rings in the glass were used to establish these levels. Flame safety lamps were effective but required significant maintenance to keep them operating properly, not to mention the dangers of having an open flame in a potentially explosive atmosphere.
Thankfully, technology and safety are at the forefront of the coal mining standards these days.
Mission and commitment
On June 16, 2006, the Mine Improvement and New Emergency and Response (MINER) Act was signed into law — the first major update to the Mine Safety & Health Act put into place in 1977. Long overdue, the MINER Act is the most significant mine safety legislation in the last 30 years. Fast-tracked through the system, the Act was a direct result of the multiple fatalities in the coal mining industry, culminating with the Sago Mine accident.“All underground coal mines must have the materials necessary to save and preserve lives after a serious accident,” MSHA stated when it brought in the MINER Act. The government set forth a mission and commitment that the “best and most practicably available equipment and technology are being deployed — and continuously upgraded — to maximize mine rescue responses and miner survivability in the wake of mine accidents.”
In conjunction with the MINER Act, legislation put into place on December 8, 2006, addresses a new requirement for operators regarding the availability and use of multi-gas detectors in underground mines. In the Code of Federal Regulations, Title 30 CFR Part 75 helps assure that miners, mine operators and MSHA will be able to respond quickly and effectively in the event of an emergency.
The final rule of Title 30 CFR Part 75 Section 1714.7 addresses the following:
a) A mine operator shall provide an MSHA-approved, handheld, multi-gas detector that can measure methane, oxygen and carbon monoxide to each group of underground miners and to each person who works alone, such as pumpers, examiners and outby miners.
b) At least one person in each group of underground miners shall be a qualified person under Sec. 75.150 of this part and each person who works alone shall be trained to use the multi-gas detector.
c) Multi-gas detectors shall be maintained and calibrated as specified in Sec. 75.320 of this part.
Regs already in place
Regulatory requirements for the use of gas detection in underground mining are not new. A multi-gas monitor, with a minimum of three sensors installed, is the tool of choice for the mine examination of the area prior to the shift start and entry of mine workers. Legislation dating back to the Federal Mine Safety and Health Act of 1977 (Mine Act) states that no person other than certified examiners may enter or remain in any underground area unless a pre-shift examination has been completed, including testing the atmosphere with a multi-gas monitor.Federal regulations regarding the use of gas detection equipment clearly are intended to reduce fatalities in an industry that has less than ideal working conditions and to increase the chances of survival in the event of mine emergencies.
