Featured Research

from universities, journals, and other organizations

Coal-mining Hazard Resembles Explosive Volcanic Eruption, Study Shows

Date:
October 1, 2009
Source:
University of Michigan
Summary:
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.

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.

New research by scientists at the University of Michigan and Peking University in Beijing, China, suggests that the outbursts occur through a process very similar to what happens during explosive volcanic eruptions. The research is described in a paper in the October issue of the journal Geology.

"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, whose previous work on volcanic eruptions, Africa's "exploding lakes" and theorized methane-driven ocean eruptions set the stage for the current research.

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.

Before an explosive volcanic eruption, magma (molten rock in Earth's crust) contains a high concentration of dissolved gas, mainly water vapor. When pressure on the magma is reduced, as happened in the 1980 eruption of Mount St. Helens when overlying rock was suddenly removed, gas bubbles in the magma rapidly expand. Pressure is higher inside the bubbles than in the surrounding magma, and when pressure on the bubble walls builds to the breaking point, the bubbles burst and the magma fragments into pieces in an explosive eruption.

In deep coal beds, coal contains high concentrations of the gases carbon dioxide and methane. When a coal seam is exposed, pressure on the coal is reduced, but pressure on the gas inside the coal remains high. When the resulting stress exceeds the coal's strength, the coal fragments, releasing high-pressure gas that suddenly decompresses, ejecting outward and carrying pulverized coal with it.

The first recorded coal outburst was in France in 1834. Since then, outbursts have occurred in China, Russia, Turkey, Poland, Belgium, Japan and about a dozen other nations. They 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.

The research was funded by Peking University, the Chinese National Science Foundation and the U.S. National Science Foundation.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University of Michigan. "Coal-mining Hazard Resembles Explosive Volcanic Eruption, Study Shows." ScienceDaily. ScienceDaily, 1 October 2009. <www.sciencedaily.com/releases/2009/10/091001081219.htm>.
University of Michigan. (2009, October 1). Coal-mining Hazard Resembles Explosive Volcanic Eruption, Study Shows. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2009/10/091001081219.htm
University of Michigan. "Coal-mining Hazard Resembles Explosive Volcanic Eruption, Study Shows." ScienceDaily. www.sciencedaily.com/releases/2009/10/091001081219.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins