| 摘要 |
PURPOSE:When iron oxide is recovered from waste solution containing Fe ions such as waste solution from iron acid rising, the iron oxide is treated in a specific manner to remove P and F, resulting in production of high-purity iron oxide. CONSTITUTION:Fe ions in waste water after rising iron materials with acid are extracted with an organic solvent composed of a phosphorus-containing extracting agent such as alkyl phosphate and a petroleum hydrocarbon diluent and a fluoride releasing solution is used to precipitate the Fe ions in the form of ammonium ferrofluoride or crystals of iron fluoride. The precipitates are separated and roasted in the air to recover iron oxide. In this iron oxide, the P from the extracting agent and F remain, because the decomposition of the salt is insufficient, and so the iron fluoride crystals are rinsed with the same hydroacarbon as that of the diluent to reduce the P content. Further, the reasting temperature is raised up to 700-900 deg.C to promote the decomposition of the crystals to give iron oxide of high purity of reduced F content.
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