Such passages are caused by unreasonable exploration or exploitation and should be eliminated.
First, the top plate crashes the crack channel
Water-permeable cracks caused by caving mining, such as reaching the overlying.......
In the refining of crude lead , bismuth is the most difficult impurity to remove. Some foreign plants often use calcium and magnesium to remove bismuth. Since the lead.......
In recent years, as the world economy, China's gold reserve has reached 1054 tons. At present, China's gold resources are 1.5 to 20,000 tons, and the reserves of gold are 4634 tons, including 2,786 tons of rock gold, 593 tons.......
Coal gangue is coal production process in the garbage, solid waste is a major coal, many mines around there are mountains of coal waste, not only pollute the environment, but also occupy large tracts of land, the country.......