HOHHOT, March 24 (Xinhua) -- Chinese mining experts are still unable to control a water flowing into a coal mine where 32 workers were killed in a flooding accident on March 1 in north China's Inner Mongolia Autonomous Region.
"Large pumping machines have been working day in and day out pumping water out of the Luotuoshan mine at 3,850 cubic meters per hour since the accident. However, the amount of water in the mine remains at 100,000 cubic meters," said Hu Weiyue, a coal science expert.
By Wednesday, more than 1.06 million cubic meters of water had been pumped out from the flooded mine, he said.
Hu said workers had met the so-call "underground current", or Ordovician limestone water, which came from Ordovician geological structure formed 400 million to 500 million years ago.
"It is very rare to see Ordovician water outbursts in arid northwest China regions. Actually, it is the first time that we have seen such a large scale Ordovician water inrush in the region," said Hu, who is also deputy director of the Xi'an Research Institute of the China Academy of Coal Science.
The rescue work, the country's largest coal mine rescue mobilization, took 14 days and involved 40 professional rescue teams comprising 20,384 people, said Hu.
Lan Yi, spokesman of the rescue headquarters, declared the rescue efforts ended on March 14, as no signs of life had been detected during the two-week rescue.
Cao Anya, director of the Inner Mongolia Coal Mine Production Safety Bureau, said the accident was a warning for coal mining workers to review studies of the hydrogeological structure in the region.
He said an investigation by the bureau found the threat of Ordovician water could affect 32 mines in the western area of Inner Mongolia.
Professor Hu said workers were trying to seal the 400-meter deep flooded mine with a mixture of cement, rubble and water-glass. However, the mixture had no obvious effect on blocking the water inrush.
Rescue headquarters spokesman Lan Yi said workers hoped to seal the mine pit by April 4 with 50 million cubic meters of prepared sealing materials. By Wednesday, a fifth of the materials had been put in.
"Filling a flooded coal mine is still a conundrum worldwide. We cannot be sure whether the current effort can solve the problem," he said.
Inner Mongolia is China's coal heartland. Its verified coal deposits of 732 billion tonnes is much greater than the 250 billion tonnes in Shanxi Province, China's biggest producer of the fossil fuel.
Its coal output hit 600 million tonnes in 2009. The output is projected to be about 700 million tonnes in 2010.
The Luotuoshan Coal Mine is owned by Wuhai Energy Co. Ltd. under Shenhua Group Corp. Ltd., the country's largest coal producer.
Construction of the mine started in 2006. It is designed to produce 1.5 million tonnes of coal a year.