专业英语(L78)概要1.ppt

LESSON 1 Introduction to Mine Ventilation Part Ⅱ Mine Safety LESSON 7 Mine Gases Part Ⅱ Mine Safety LESSON 8 Coal seam methane When the water inflow area has restricted ventilation, hydrogen sulfide will build up in the area of the inflow. Levels of 100 ppm（parts per million）are rare in unventilated caverns[k?v?n] with water inflows. Although 100 ppm is not an immediately lethal[li:θ?l]concentration, extended and unprotected exposure beyond one-half hour can lead to unconsciousness[?nk?n??snis] and, ultimately, death. LESSON 7 Mine Gases When the water inflow area has restricted ventilation, hydrogen sulfide will build up in the area of the inflow. Levels of 100 ppm are rare in unventilated caverns with water inflows. Although 100 ppm is not an immediately lethal concentration, extended and unprotected exposure beyond one-half hour can lead to unconsciousness and, ultimately, death. Decomposition of organic material such as sewage[sju:id?] can lead to the formation of hydrogen sulfide if sulphur compounds are in the decaying material. Water wells with intakes at the bottom of the reservoir have brought hydrogen sulfide into the pump house with deadly results for workers. LESSON 7 Mine Gases Decomposition of organic material such as sewage can lead to the formation of hydrogen sulfide if sulphur compounds are in the decaying material. Water wells with intakes at the bottom of the reservoir have brought hydrogen sulfide into the pump house with deadly results for workers. Carbon dioxide (C02 ): Carbon dioxide is a natural metabolite produced in the human body and exhaled[eksheil] in the respiratory[resp?r?t?ri] process. In sufficient concentration, naturally exhaled carbon dioxide is hazardous. LESSON 7 Mine Gases Metabolite [mit?b?lait] n. 代谢物 Carbon dioxide (C02 ): Carbon dioxide is a natural metabolite produced in the human body and exhaled in the respiratory process. metabolite n. 代谢物 In sufficient concentrati