PURPOSE: To quickly and fully regenerate a membrane performance and to reduce changing frequency of the membrane by circulating alkali metal hydroxide solution in a separating device before routine cleaning operation of the separating device.
CONSTITUTION: The used liquid is fed into a concd. vessel 1 from an acid pickling device to condense. A fine filtrating device 3 receive a concd. liquid and filtrates with a membrane 4. A filtrate recovered in a chamber 5 at the lower side of the membrane 4 does not contain non-ionized silicon but contains only a little ionized silicon content. The filtrate is sent to a thermal hydrolysis device 6 and hydrolized by heat to recover iron oxide and regenerated hydrochloric acid. When cleaning, purification is suspended and the fine filtrating device 3 is made empty. Water is sent from a cleaning water vessel 20 to rinse the device 3. Sodium hydroxide solution is sent from a sodium hydroxide solution vessel 19 to clean the device 3. The rinse is executed with water and hydrogen fluoride solution is sent from a hydrogen fluoride solution vessel 18 to clean the device 3. The rinse is executed with water to complete the cleaning.
ERUBUE BARUBAROTSUSA
RISHIYAARU PATSUDEJI
REMII NIKORU
