| 摘要 |
PURPOSE:To obtain rare earth element with high purity at high yield and in the industrial scale by adding oxalic acid to a soln., which is obtained by adding an inorganic acid to an alloy contg. rare earth element, and adjusting pH. CONSTITUTION:The soln. dissolved alloy is obtained by allowing the alloy for magnet to dissolve into HCl, HNO3 or aqua regia of the mixture of these acids and removing the undissolved matter. The precipitate of the oxalate of the rare earth element is formed by adding the oxalic acid of 1.5-2.5 times molar mat. of the rare earth element amt. to the above-mentioned soln. and adjusting to pH 0.5-2.0 with adding a pH adjusting agent such as NH4OH. Next, the rare earth element (e.g. Sm2O3) is recovered by heat-decomposing the oxalate which is obtained by filtering, separating and crystallizing the obtained precipitate.
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