METHOD FOR CLEANING VOLATILE RUTHENIUM

摘要

PURPOSE:To allow a removal treatment with a simple treatment and high efficiency by incorporating nitrous acid ions into a cleaning liquid at the time of cleaning an off-gas contg. RuO4 with cleaning water and absorbing and removing the above-mentioned RuO4 into the cleaning liquid. CONSTITUTION:The off-gas is supplied from an off-gas supplying system 1 into a cleaning column 2 and the cleaning liquid contg. the nitrous acid ion is injected from a cleaning liquid supplying system 5 onto a tray 4 of the uppermost state. The cleaning liquid supplied from the cleaning liquid supplying system 5 and the off-gas come into gas-liquid contact in the respective trays 4 provided in the cleaning column 2 and migrate the volatile ruthenium in the off-gas into the cleaning liquid. The cleaning liquid absorbing the volatile ruthenium is discharged to a waste liquid discharge port 8 in the bottom of the cleaning column 2. The solubility of the volatile ruthenium in the cleaning liquid is increased by adding the nitrous acid ion into the cleaning liquid and, therefore, the decontamination of the volatile ruthenium from the off-gas is executed with the high efficiency.