Washington: A new research by scientists has suggested that coal outbursts in underground mines occur through a process very similar to what happens during explosive volcanic eruptions.
Worldwide, thousands of workers die every year from mining accidents, and instantaneous coal outbursts in underground mines are among the major killers.
But although scientists have been investigating coal outbursts for more than 150 years, the precise mechanism is still unknown.
Now, a new research by scientists at the University of Michigan and Peking University in Beijing, China, has suggested that the outbursts occur through a process that resembles explosive volcanic eruptions.
“Just as magma can fragment when pressure on it is reduced, triggering an explosive eruption, gas-rich coal can also erupt when suddenly decompressed, as happens when excavation exposes a new layer of coal,” said Youxue Zhang, professor of geology, Peking University.
Zhang did much of the work on the coal outburst project in 2006 and 2007, during a part-time professorship at Peking University.
Around that time, a number of deadly coal mine accidents - in China, Russia and the United States -had made headlines, and just before leaving for China in 2006, Zhang had printed out articles about the disasters to read during his flight.
“While reading a paper describing coal outbursts as violent ejection of pulverized coal particles and gas, the similarity of coal outbursts to magma fragmentation suddenly occurred to me,” Zhang said.
When he arrived at Peking University, he discussed the idea with colleague Ping Guan, and the two decided to collaborate on experiments simulating coal outbursts.
Zhang recruited undergraduate student Haoyue Wang to help with the project, in which the researchers used a shock tube apparatus similar to the one Zhang had used in previous experiments on explosive volcanic eruptions.
Their experiments verified that coal outbursts are driven by high gas pressure inside coal and occur through a mechanism similar to magma fragmentation.
Outbursts happen only in deep mines where coal contains gas at high pressure, but as deeper coals are mined to satisfy the world’s energy demands, the risk of outbursts increases.
“Knowing the mechanism of coal outbursts is the first step toward predicting and preventing such disasters,” said Zhang.
Next, the researchers plan more experiments to verify their results. Then, they hope to capture details of the outbursts with a high-speed camera and to study a variety of coal types from different mines. (ANI)