| 摘要 |
PURPOSE:To certainly treat a salt-containing washing liquid by rapidly and efficiently washing steel, by removing the solid salt adhered to salt bath heat- treated steel by washing the same by an ultrasonic wave while separating the washing liquid into a concn. liquid and a permeated liquid by membrane separation. CONSTITUTION:A steel material 1 which is heated in a heating furnace 2 and to which a solid salt is adhered through the salt bath heat treatment in a salt bath tank 3 is washed in a washing tank 11 provided with an ultrasonic vibrator 18 by an ultrasonic wave to remove the fixedly deposited salt by washing within an extremely short time without requiring heating. The washing liquid having the salt dissolved therein is subjected to solubilization stabilizing treatment in a pretreatment apparatus 27 through a raw water storage tank 25 and the treated liquid is further conditioned so as to be brought to a pH and a temp. suitable for membrane treatment by a pH regulator 29 and a temp. conditioner 30 while the conditioned liquid is supplied to a precise filter apparatus 31 to remove impurities such as a scale powder therein before passed through a membrane separation apparatus 35 due to a reverse osmosis method, an electrodialytic method or an ultrafiltration method. In this case, the permeated water obtained by separating the washing liquid recirculated to the washing tank 1 through a storage tank 37 to be re-used while the concn. liquid is treated in a concn. liquid drying apparatus 45 through a storage tank 41 to obtain a recovered salt 47. |
