Introduction of safety engineering

1. Introduction of safety engineering • Producer: Wang qiyu • Group: the fifth group

2. Safety Department • My name is Wang qiyu. I come form safety science and engineering department. • It is well known that safety department is the best at Henan Polytechnic University. What is more, it is very important for people to be safe.

3. Safety Department • Ventilation and methane are two special characters of safety department. • There are many safety professors who are national level. • The students of safety department find jobs easily and make a lot of money. • But their jobs are very hard and dirty.

8. outburst • Natural phenomena of sudden gas and rock mass outbursts, such as volcano eruptions, geysers, huge bursts of water saturated with CO2, out of the reservoirs in former volcano craters have been known for a long time. As mining activities upset the natural balance in the rock mass containing the substances that undergo phase transitions, the outbursts of rock and gas may occur.

9. Their occurrences in mines have been records for more than 150 years. Attempts have been made to provide an adequate explanation of these processes. Increasing frequency of outburst occurrence after World War 2 called for still more extensive research.

10. Coal and gas outburst problems have been exacerbated significantly over the past decade because of higher productivity and the trend towards recovery of deeper coal seams. However, despite of great efforts, surprisingly little progress has been made towards understanding outburst mechanism. Prediction techniques continue to be unreliable and unexpected outburst incidents are still a major concern for underground coal mining.

11. In China outbursts occur in a number of coal fields and in a large number of mines. In fact, the largest number of outbursts have been recorded in China. The most important coal fields where outbursts occur are in the provinces of Shanxi (Yangquan) ; Liaoning (Beipiao) ; henan (jiaozuo) ; Chongqing (Nantong and Songzao) and Hebei (Kailuan) .

12. Coal and gas bursts are differentiated in China into four categories: • Coal bursts with no gas • Gas bursts • Coal and gas outbursts • Rock and gas outbursts

13. Methane exists within coal in two distinct forms, generally referred to as free gas and adsorbed gas. The free gas comprises molecules that are, indeed, free to move within the pores and fracture network.

14. 存在于煤中的瓦斯有两种截然不同的形式，通常称为自由状态瓦斯和吸附状态瓦斯。自由状态瓦斯由分子组成，这些分子实际上能够自由地在微孔中和裂隙网中移动。存在于煤中的瓦斯有两种截然不同的形式，通常称为自由状态瓦斯和吸附状态瓦斯。自由状态瓦斯由分子组成，这些分子实际上能够自由地在微孔中和裂隙网中移动。

15. Porosities of coals have been reported from 1 to over 20 percent. However, those values depend upon the chosen definition of porosity and the manner in which it is measured. Absolute (or total) porosity is the total internal voidage divided by the bulk volume of a sample and may be difficult to measure accurately.

16. 据报告，煤的孔隙率从1%到20%以上。然而，这些数值的大小倚赖于孔隙率所选择的定义和它测量的方式。绝对（或总）孔隙率指的是样品内部总的孔隙度除以体积；绝对孔隙率可能难以准确测量。据报告，煤的孔隙率从1%到20%以上。然而，这些数值的大小倚赖于孔隙率所选择的定义和它测量的方式。绝对（或总）孔隙率指的是样品内部总的孔隙度除以体积；绝对孔隙率可能难以准确测量。

17. Effective (or macroscopic) porosity is the ratio of interconnected void space to the bulk volume. The latter definition is more useful in the determination of recoverable gas from a seam.

18. 有效（或者宏观）孔隙率指的是相互连接空隙与总体积的比率。有效孔隙率在查明煤层中可利用瓦斯时比较有用。有效（或者宏观）孔隙率指的是相互连接空隙与总体积的比率。有效孔隙率在查明煤层中可利用瓦斯时比较有用。

19. thank you