Rare earth oxalates hydrous

From the diluted acid solutionf the rare earth oxalates are precipitated by the addition of a small excess of hot concentrated oxalic acid solution. Usually about 2 kg. of oxalic acid is required. The precipitated oxalates are thoroughly washed with hot water, converted to hydrojis oxides by boiling with concentrated sodium hydroxide solution (see synthesis 12D) and the washed hydrous oxides dissolved in the least amount of concentrated (16 N) nitric acid (about 21.). This solution is then diluted to 121. 

The cerium may now be removed from this solution by the bromate method (synthesis 14). Then the resulting solution is treated as before with excess oxalic acid or sodium suKate, the precipitates are again converted to hydrous oxides, and the latter are again dissolved in nitric acid. The rare earths from monazite are generally converted to double magnesium nitrates, 3Mg(N03)2-2(R.E.)-(N03)3 24H20 (synthesis 15), for preliminary fractionation. The rare earths from xenotime, after complete removal of cerium, may be converted to bromates (synthesis 17), and fractional crystallization of these salts may be commenced. 

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