Safety science and engineering department Wang Zhao

the five natural disasters in mines As we all know, coal miners can earn more money than other workers, but their lives are more dangerous ,too. Generally speaking, there are five natural disasters in mines : mine gases(矿井瓦斯)、mine fire disasters(矿井火灾)、mine dust disasters(矿尘灾害)、mine water disasters(矿井水灾) 、roof disasters(顶板事故 ).

the five natural disasters in mines

Mine gases In this PowerPoint, I mainly talk about mine gases. first: the definition of mine gases second: the disaster of mine gases third: gas drainage(瓦斯抽放 )

The definition of mine gases Generalized：the generic terms of toxic gases which run into the mining space . 广义：井下除正常空气的大气成份以外,涌向采矿空间的各种有毒、有害气体总称。英文为Gas

The definition of mine gases Chivalrous ：the generic terms of mixed gases which produce in the process of coal mine production，it is mainly made up of CH4. 狭义：煤矿生产过程中从煤、岩内涌出的，以甲烷为主要成份的混合气体总称。CH4。英文为Methane

The disaster of mine gases The gas is one of the most important factors that endangers the produce in mines. On some certain conditions, Gas can cause choking gas burning gas explosion gas emission coal and gas outburst

gas drainage Now we have known that gases are very dangerous to coal miners. So it is necessary to drain the gases from the mine. In order to drain gases from coal seams, several different techniques are used.

gas drainage Within coal mines, gas is drained ahead of the mining by drilling holes along the coal seams. Boreholes from the surface are also drilled into the mined out areas to drain gas from collapsed areas. 煤矿中，开采前，深煤层打钻孔，预抽煤层中的瓦斯。从地面往开采过的区域打钻孔，以抽放塌陷区域的瓦斯。

gas drainage These methods of pre-drainage and post-drainage have only been partially success-ful in controlling the gas inflow into mine. Increases in coal production and the attendant increases in the depth of mining will result in even greater levels of gas. 这些预抽和后抽的方法，只能部分成功地控制瓦斯涌入到煤矿中。煤矿产量的增加及开采深度的增大，将导致瓦斯等级更高。

gas drainage Surface pre-drainage techniques may provide a solution to mining problems and also provide a method of recovering the gas by itself for commercial uses. 地面预抽方法提供一种解决开采问题的途径，同时提供一种回收瓦斯商业用途的方法。

gas drainage Fracturing the coal seams with hydraulic pressure within boreholes (hydraulic fracture stimulation) may represent the method of highest potential for the development of a gas drainage industry. 在钻孔内使用水压压裂煤层（水力压裂模拟）可以代替高压电的方法，这是瓦斯抽放行业中的进展。

gas drainage At present, the gas drainage quantity of China only accounts for 20％ of the total gas emission. The flow law of gas is still studied, as well as the increase of the permeability of coal and the improvement of the drainage technology, in order to improve the gas drainage quantity. 目前中国瓦斯抽放量只占抽放瓦斯矿井全部涌出量的20％。正在研究瓦斯流动规律，加大煤层的透气性和改进抽放技术，进一步提高瓦斯抽放量。

That’s all! Thank you！