| 摘要 |
<p>PROBLEM TO BE SOLVED: To recover most fluoride in waste gas to economically treat a gas containing a material to be treated by previously removing impurity components except a chemically stable fluoride in the waste gas, concentrating the fluoride with membrane separation to recover and decomposing a trace quantity of the remaining fluoride in the treated waste gas. SOLUTION: A 1st membrane separation device 2 and a 2nd membrane separation device 3 are mounted in the poststage of a pre-treatment equipment 1 and the gas containing the fluoride concentrated in the 1st membrane separating device 2 is introduced into the 2nd membrane separation device 3 through a passage 4 to concentrate the fluoride in 2 stages. The fluoride concentrated in the non-permeated gas side in the 2nd membrane separation device 3 is recovered in a vessel 5 and sent to a purifying equipment. And a fluoride decomposition column 7 for decomposing the fluoride in the gas is provided in a passage 6 for discharging the gas permeated through both membrane separation devices 2, 3. As a result, the chemically stable fluoride in the waste gas discharged from a semiconductor production process is efficiently recovered and a trace quantity of the remaining fluoride is also effectively decomposed.</p> |
