The Thermo-Gel product in use at a firefighting demonstration at West Virginia University.
There have been many fires in coal mining’s history, each with their own severity level, their own cause and their own end result. While one may have begun as an underground equipment fire, another may have been sparked by spontaneous combustion. Every fire is different, and there is no such thing as a “textbook” mine fire.
These fires, of course, are also not a new problem; one of the most recent was at the Deer Run complex near Hillsboro, Illinois, where a combustion event in March 2015 lead to the temporary sealing of the entire mine this past April. This was after both mine officials and Mine Safety and Health Administration (MSHA) officials tried to remedy the issue by sealing specific mining areas and filling them with inert gas and other extinguishing agents.
The future of the Montgomery County operation remains unclear, and dozens of miners who have already been furloughed have moved on to other gainful employment. Deer Creek, owned by Foresight Energy and operated by Patton Mining, is a relative newcomer to the industry’s mining portfolio, opening in August 2012 with a single longwall and two continuous miner units. It produced 5.6 million tons in 2014, its last full year of production, so the losses have been significant on many levels.
Tackling mine fires from a proactive angle, including proper training of all miners in recognizing potential problems, has never been more important. Even with advanced equipment and robust ventilation systems, risks are still omnipresent.
It is unfortunate, then, that keeping a mine fire from occurring is still not a high priority for some mines. While many mine managers may never see a fire, or even the hazards leading up to one, in their careers, others will — and arming every mine worker at every level with the knowledge they need to react in the event of a fire is crucial.
“There is a steep, difficult learning curve when thermal events occur,” Sarah Dagit of Phoenix First Response (PFR) recently told Coal Age, pointing out that her organization helps to guide some of the nation’s largest mining operations through these often-unavoidable challenges. With more than 30 mine fires under the PFR team’s belt, the company has positioned itself among the top phone numbers mines want to call when a fire breaks out.
While that kind of reputation is a great honor, Dagit noted that being reactive is actually one key thing Phoenix First Response wants to change in favor of proactive approaches.
“Solving thermal events’ problems requires a depth of experience and varying expertise,” she said. “You need a real-life, hands-on firefighting background and operations-centric problem solving mindset [and cannot] rely solely on academic theory or computer modeling.”
On the surface, a fire is a fire is a fire. But add the human element, safety, and the fact that, after a finite period of time — Dagit said that after the first hour or two, many incidents become uncontrollable — the question of whether the mine will ever be the same all become paramount considerations.
With a fire that is being addressed reactively, previously there are lots of “moving parts,” as Dagit called them, to be sorted out. Among these:
How will you communicate among stakeholders? There will be a lot of information coming in that is critical and complex, and the details will be changing with nearly every moment.
How will you determine the cause, location and severity of this fire? Is all information possible being methodically and most effectively compiled?
What logistics do you need to organize? If there isn’t a firefighting firm on retainer, this could be an enormous undertaking to carry out hundreds of small to substantial tasks; simultaneously, a team still needs to develop a plan, all while the clock is ticking.
How will the mine fight the fire at the same time as it negates additional damages? This is most complicated if lives are at stake. If life and limb are not endangered, what can be done to improve the long-term impact on the mine and, by extension, surrounding community?
Factors to Keep in Mind
The dreaded event is a reality: one may have a mine fire. Stress is rising, and there are men underground (especially in the case of belt and equipment fires). What is priority one?
“There is an extremely limited window of opportunity, if any, to employ direct firefighting underground and/or evacuate everyone safely,” Dagit said. That is where that critical one- to two-hour window is key. PFR has addressed both the reactive and proactive aspects of firefighting to mines, including fire hazard awareness and training for every miner. “Whoever is closest must choose fight or flight — and the nearest man or crew may be the only viable option to attack a fire directly,” she said.
Also, on the proactive side, it prepares mine management with education about the series of anticipated events should a mine fire arise, from the first stages through the post-event investigation. Its team also has scenario-specific training and also planning for both automatic and manual fire suppression technology options.
After a mine is evacuated, the only likely access to the mine will be via ventilation shafts and boreholes.
Many fires that PFR has seen over the years, Dagit noted, have been due to spontaneous combustion or combustion in a remote gob, which is not only difficult to pinpoint but also usually complicated or impossible to reach. As management learned more about the event, more coordination and communication will be needed. A team that begins with the mine’s management will rapidly grow to corporate management, then state and national agencies, and potentially mine rescue teams, private contractors, trucking and logistics. Often labor representatives, financial backers, and insurance companies will become a part of this circle in the ensuing hours and days.
Make quick ties with the MSHA officials once they are on-site. Keep in mind, however, that one’s perspective and that of the federal team may vary widely.
“[They have] extensive centralized experience with the technical side of mine fires and explosions; they are involved with almost every event and have a coordinated team of people at all times,” Dagit said, noting that it is not feasible or practical for mines to have in-house firefighting experts available on-call to answer questions, so pooling expertise at this stage can make a sizeable difference.
“PFR’s involvement benefits mining companies by deepening and expediting available resources, drawing on decades of expert fire and emergency response experience, working in the mine’s best interest as priority one. We offer one of the most centralized resources for this expertise in the world — no other private organization in the Americas offers access to such comprehensive emergency response experience,” Dagit said, noting that the company has been called to fire events across the world over the years in coal as well as metal/non-metal and tunneling sites.
Once management has been in touch with PFR, the first order of business is to determine specific priorities for that mine, not just providing technical support. There will be obstacles and challenges throughout the process, and having a partner in the effort can not only save time but also money and stress. Dagit said their missions have been modeled after the “one phone call” concept for mine rescue stations worldwide. Some of the most common aspects of past fires that PFR has managed have included borehole drilling, contracting and placement of nitrogen membrane units, use of fire foam/ThermoGel, formulating a strategy for underground flooding, issues associated with ventilation seals and remote sealing, and even public relations support. For gas analysis, the company can liaise with MSHA’s lab for on-site , or in most cases mines contract PFR’s mobile gas chromatograph (GC) laboratory to work on-site. (PFR is the only firm in North America that offers the latter).
Paradigm Shift: Reactive to Proactive
As Dagit noted, there is still much work to be done before the industry as a whole embraces the most effective tactics to proactively fighting fires. What coal as a community has become good at, however, is taking much insight from the experiences of others — both positive and negative. For that reason, PFR will continue to offer mines both reactive firefighting methods as well as those proactive options that can keep operations out of the line of fire — quite literally — in the long-term.
Gas Analysis (Reactive)
One primary example of an ongoing capability for the company is gas analysis. “The need for gas chromatograph analysis is consistently one of the most surprising factors to operators during an event,” she said. “It is probably the most central piece of decision-making guidance in most thermal events. Handheld monitor results are not sufficient to guide decision-making, as the infrared technology can inaccurately read and misidentify similar gas molecules.”
Dagit also stressed that these handhelds also do not cover gases like ethylene and acetylene, both of which can indicate a presence of combustion.
“At almost every thermal event in the last 10 years, mines have opted to contract PFR’s mobile gas chromatograph laboratory, even when government laboratories are present,” she said. “Having two sets of samples analyzed provides all stakeholders with confirmation of gas results’ accuracy. Being certain of the gas chromatograph analysis is critical, as the results serve as one of the biggest factors in decision-making to effectively combat the fire, plan re-entry [and other issues].”
Two sets of data enable comparison to ensure both laboratories are properly calibrated and that accurate results are being used to make critical decisions. On the other hand, when the two sets of data do not match, it allows for identification of potentially inaccurate data or other issues (such as sample bags with small holes or leaky valves).
Jet Engines (Reactive)
PFR introduced jet engine technology for mine firefighting in the early 2000s, Dagit said, and the company remains the only U.S. company to deploy the system, which can create as much as 60,000 cubic feet per minute (cfm) of cooled, inert air with less than a 1-2% oxygen content via existing ventilation shafts.
“We have successfully extinguished two fires where loss of mine was a real threat and other measures failed or were not viable to attempt,” she explained. Because a presence of residual carbon monoxide can sometimes delay re-entry into a mine, this option is rarely employed; however, it is still considered a highly effective measure to avoid long-term or even a permanent closure of the mine.
Membrane Nitrogen Application (Reactive)
Most significant thermal events will use membrane nitrogen generation as a primary component. To apply it, nitrogen (with less than 5% oxygen content) enters the mine via ventilation shafts and boreholes. PFR’s preferred partner employs a technology to enable production of nitrogen with less than 2%, a level extremely difficult to achieve that cannot be expected from the average membrane unit or operating crew, Dagit noted.
The advantage to this option is that it can reach remote areas of the mine to remove the oxygen component from what is often referred to as the “fire triangle”: heat, a fuel source and oxygen.
“Where and how to apply nitrogen effectively requires scientific and engineering analysis, and drawing on experience of previous fires to evaluate all known information about conditions on an ongoing basis,” she noted. “It is not as simple as picking some boreholes and pumping nitrogen into the mine. These factors apply to liquid nitrogen and liquid carbon dioxide as well.” One important note on this avenue of firefighting is that nitrogen units are often moved from borehole to borehole several times so that it can be the most effective. Sometimes, that means mines may need to drill new boreholes.
Extinguishing Belt Fires (Reactive)
It is one of the most prevalent hazards that can result in a mine fire; just the right conditions can quickly turn a running belt ablaze. PFR has coordinated the extinguishment of underground belt fires in the past where an initial direct attack has not brought the flames under control.
A belt or similar fire can easily spread and heat embed into surrounding coal, similar to one past case the company tackled with an operator. That led to longer-term efforts to combat the fire from above the ground.
“Success was achieved with input from mine management and PFR’s team, with recommendations for drilling of new boreholes; engineered ventilation circuits guided by gas analysis by gas chromatograph analysis; water cooling strategies; custom-designed, down-hole application of fire suppression products; and extensive utilization of membrane nitrogen,” Dagit said, adding that the company also assisted with post-event investigation, where it recommended specific courses of action for fire prevention and general safety.
Mine Gas History (Proactive)
PFR can attest to multiple thermal events that have actually been prevented using proactive, routine gas sampling and gas chromatography before a problem ever arises. This has especially been the case in the western coalfields, where elevated levels of CO and methane are routine and do not always indicate an initial direct attack of a mine fire. What’s more, these levels can easily be managed with an appropriate mining plan, which the company has helped others to establish.
This is done by routinely taking gas samples in bags or syringes at key ventilation and production locations mine-wide, then analyzing them with a gas chromatograph for oxygen, carbon dioxide, carbon monoxide, methane, ethylene, acetylene, hydrogen and nitrogen at molecular levels; the technology can read all of these as low as parts per billion, not just parts per million.
The use of mine gas histories via routine sampling and a gas chromatography lab is one of the most efficient proactive firefighting methods.
With an independent laboratory, mines can ensure defensible results that would be accepted for consideration by responding agencies should a thermal event ever occur. Additionally, graphing these trends and monitoring them over time can help an operation to identify and eliminate potentially developing events.
“Having a MGH (mine gas history) has also proved to save time and millions of dollars for mines that experience heatings or fires,” Dagit said. One example of this has been with carbon monoxide levels, a main consideration for mine re-entry.
“Previous handheld gas monitor readings are not often accepted as proof of a mine’s pre-fire ambient environment,” she noted. “Mines that have slightly elevated CO levels on a regular basis and can prove it with gas chromatograph data are more likely to resume production days or weeks sooner after an event. Otherwise, months of gas monitoring showing low and unchanging levels of potential ‘fire gases’ can be required before agencies will authorize re-entry.”
MGH is simple; just one to four samples monthly with a 24-hour results return can provide operations, regardless of their pasts, to see a comprehensive and personalized database of typical gas behaviors and also give management a custom protocol and its workers the best hands-on-training for their specific situation.
One question mines often propose to the company is, “Why do we need MGH? Our mine isn’t gassy and we have 120-psi seals.” Dagit said that ongoing monitoring is vital to all mines, even those without a history of gas problems, and PFR’s method extends far beyond mere seal regulations and ventilation plan compliance.
“It enables proactive management to prevent and detect dangerous underground events and fires, minimize production delays [and] manage underground conditions to maximize safety,” she said.
“Even mines that do not have gas issues encounter tough situations. Knowing the ‘before’ is key to best manage the ‘now.’”
Goals and Benefits of Mine Gas
- Establish a baseline history of mine conditions.
- Regularly monitor mine conditions at sample points.
- Operate a GC under high sample load during combustion events and emergencies.
- No bias argument if litigation occurs.
- Respected data by government agencies.
- Low cost (as low as a few hundred dollars per month)