Detoxication of barium ferrite magnet scrap - by adding sodium sulphate to aq. sludge of scrap, to produce insol. barium sulphate

摘要

The scrap is treated with sulphate ions so that the water-soluble barium cpds. in the scrap are converted to insol. BaSO4, and the sulphate ions are pref. obtd. by adding sodium sulphate to the scrap. The magnets are made starting from BaCO3 and Fe2O3, the scrap occurs at many prodn. stages, e.g. after mixing and milling the raw materials or grinding the finished magnets. The scrap generally exists as an aq. sludge contg. BaCO3 which has solubility in water of ca. 20 mg/l and is toxic, and should not enter the drains. By adding Na2SO4, the Ba cpds. are converted to BaSO4 which has solubility in water of only ca. 2.3 mg/l. Other sulphates or H2SO4 can be used instead of Na2SO4.