Underground coal fires are a serious problem. Because coal deposits contain oxygen, they can continue to burn without air. This phenomenon occurs at the Lila Canyon mine in Utah, where coal has been burning for almost three months, even after miners filled the mine with nitrogen and displaced all the oxygen remaining near the fire.
The battle to save the Emery County mine enters a new phase this week when drill crews begin injecting an expanding, void-filling foam into several new wells in hopes of sealing the fire area before it floods with water becomes.
At stake are tens of millions of dollars worth of mining equipment and the fate of Utah’s most productive coal mine, which employs 238 people and supplies three power plants in Utah.
These miners have been idle since September 20, when a coal pile deep underground spontaneously caught fire, making access to the extensive underground mine unsafe. It was safely evacuated with no reported injuries, but extinguishing the fire has proved far more difficult.
Under an emergency program approved by the Bureau of Land Management on Oct. 21, mine operator Emery County Coal Resources (ECCR) has been drilling around the clock since then, drilling up to 35 holes 1,100 feet into the mine from the top of the Book Cliffs brought down. According to an environmental impact assessment, these holes will be used to seal off the fire zone and then pipe millions of gallons of water underground to extinguish the fire.
“It is not known how long it will take to extinguish the fire, but other coal fires have burned for anywhere from days to decades,” the assessment reads. “It is also difficult to quantify the impact of coal fires on regional air quality due to the inability to determine how much coal is being burned and little is known about criteria and hazardous pollutant emissions from other coal fires to use as a reference. ”
Drilling is almost complete despite some setbacks, according to Dana Dean, who directs the mining division of the Utah Division of Oil, Gas and Mining (DOGM).
“The mine is still burning. You still can’t go underground. Sealing that area with the foam will propel this, which will hopefully allow them to get underground,” Dean told the Utah Oil and Gas Board at its Dec. 7 meeting.
Meanwhile, water is already entering the part of Lila that has been actively mined, causing the operator a headache again.
“They’re still trying to save their longwall equipment from the water that’s building up in that area,” Dean said. “You’re fighting against the clock. Longwall gear is as waterproof as possible, but being under water for long periods of time is not good.”
Before the fire, Lila Canyon was producing nearly 300,000 tons of high-grade coal per month, most of which went to the Hunter and Huntington Power Stations, also in Emery County. Getting the mine back online is a top priority for state and local officials, but that could take a long time even if the fire is extinguished soon.
After the mine floods, operators may have to wait up to 120 days before entering to ensure the fire is out, according to Jurgen Brune, a professor of mining engineering at the Colorado School of Mines.
“They will continue to monitor gases through these wells, monitoring the atmosphere in the mine,” said Brune, who is not involved in firefighting. “If carbon monoxide levels continue to drop, it means the fire will eventually go out.”
There is also the question of water damage to longwall components.
“The hydraulic parts can be salvaged,” Brune said, “but everything electrical, the motor, the controls, that kind of stuff, once it gets underwater, it’s pretty much crap.”
DOGM will oversee the reclamation of the emergency wells and wells but has no authority over the firefighting operations themselves, which are overseen by the Federal Mine Safety and Health Administration (MSHA).
However, the state agency has provided public updates in the face of complete silence from the mine’s parent company, Ohio-based American Consolidated Natural Resources. The company has yet to respond to media inquiries since the fire broke out, sparking arguably the costliest emergency response involving a coal mine in Utah since the 2007 Crandall Canyon disaster, which killed six miners and three rescuers in cave-ins.
When asked for comment, MSHA directed questions to the mine operator. “The reopening of the mine is the responsibility of the operator,” said a spokesman.
Coal mines in the Book Cliffs region of Utah and Colorado are at risk of spontaneous combustion due to the chemistry of the deposits they are developing. Several mines in Colorado were closed because of such fires, and some continued to smolder for years.
In the case of Lila Canyon, the coal deposits contain pyrite or iron sulfide, according to Charles Kocsis, a professor of mining engineering at the University of Utah. Pyrite oxidizes in the presence of water and oxygen, resulting in a heat-producing chemical reaction. If the oxidizing pyrite exceeds 110 degrees Fahrenheit, it can ignite the surrounding charcoal.
“It smolders at first,” he said in a recent phone interview. “A lot of smoke is produced, but no flame.”
Kocsis, who was consulted about the fire, was told it was burning in a part of the mine that had previously been abandoned and sealed off.
“There is no human presence. You can’t even go in there,” he said. “The only option is to drill boreholes from the surface.”
At the beginning of the Lila emergency, the operator drilled three holes in the mine and then injected nitrogen, an inert gas that BLM says eventually drove all oxygen out of the mine.
Based on the data collected from these initial wells, the operator prepared the current firefighting plan, which includes extensive drilling, phenolic foam, water pumps and flooding the mine.
Kocsis believes the plan will ultimately succeed as the burning portion of the mine was abandoned and likely isolated from the rest of the mine before the fire broke out. The burning area is about two miles southeast of the mine portal at the end of Lila Canyon Road.
“In my opinion, this fire will surely be put out. How long it takes is a big question. I would say maybe a couple of months,” Kocsis said. “It takes time to understand where the fire is. Once localized, it’s easier to manage. Each mine is unique, it has a unique layout. What works at a mine site may not work here.”
In addition to the entry point holes, ECCR is drilling three more for monitoring and four more for water extraction from an inactive portion of the mine. Over a 12-month period, this water was pumped to the surface, channeled overland and channeled underground to the fire area.
There’s no way of knowing how much water would be needed, but the BLM’s environmental assessment said it would likely be hundreds of acres, far too much to haul on rough roads in winter. To move just 100 acre-feet – enough to fill 50 Olympic-size swimming pools – would require 6,300 round trips.
According to Brune, the aim is to cool the combustion area below the so-called “self-heating temperature of the burning coal” by applying water. The challenge is to ensure that the water floods the burning part of the mine.
“It’s a question of whether they have appropriate topography,” Brune said. “You can only make a puddle where there is a sink. Let’s assume they have. Then there’s a reasonable chance they can flood the part of the mine where the fire is, and that might work.”
Either way, the mine operator still has a lot to do before concrete answers come from the smoldering mine.
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https://www.sltrib.com/news/environment/2022/12/13/can-burning-emery-county-coal/ Can Utah’s Lila Canyon Coal Mine in Emery County be Saved?