Electrolytic removal of tin from ferrous scrap - using hot caustic soda soln. as electrolyte from which the tin is recovered

摘要

Tin coatings are removed from iron pieces in an oepn electrolyte bath (a), contg. a hot aq. soln. (a) of NaOH flowing in a closed circuit through the bath to a boiler, while heating (a) to >=105 degrees (105-115) degrees C., above atmos. pressure and pref. >=2 atmos., so (a) does not boil. From the boiler, (a) flows through an electrolytic sepn. tank (b) to reduce the Sn to =0.6 wt. % in soln. (a) at the temp. the pressure given above; the pressure is then reduced and the soln. fed to (a). The soln. leaving (a) pref. contains 0.6-0.8% tin, and the soln. leaving (b) pref. contains ca. 0.5% Sn, and is then recycled to (a). The pref. plant includes a tank (a) with a pump supplying a boiler followed by tank (b) contg. a stainless steel anode and cathode for removing Sn from (a), the anode pref. being formed by the tank (b). Used to remove Sn so iron or steel scrap can be melted in foundries.