DETERMINATION OF RARE EARTHS AND FLUORIDES IN RARE EARTH FLUORIDES

摘要

A technique has been developed for assaying rare earths and fluorides in re¬fractory rare earth fluoride samples. For fluoride determination, a portion of the sample is fused with NaOH in a platinum crucible and the melt is dissolved in water. The solution is transferred to a cation ex¬change column in the hydrogen form, the fluoride is eluted as HF with water, and the fluoride determination is made indirectly by titration of the HF with standard NaOH. For rare earth determination, a separate portion of sample is fused with potassium pyrosulfate and dissolved in water;the determination is made by titra¬tion with EDTA. Recommended procedures for both constituents and data from the analysis of 14 samples are presented. The relative standard deviation is 0.6% for fluorides and 0.4% for rare earths.