Consecutive complexometric titration of thorium and rare earths in ores. (Kuang shi zhong du he xi tu de lian xu luo he di ding).

摘要

The major problem present in the EDTA consecutive complexometric titration of thorium and rare earths lies in the fact that during the adjustment of pH 5--6 for the titration of rare earths and after the titration of thorium, because of the formation of the colored ternary coordination compound of Th-EDTA-indicator, the indicator is sealed and it is impossible to identify the end point. In order to solve this problem, in the present article, selection has been made of the indicator and conditions concerning the complexometric titration, and the conditions for the sedimentation separation with oxalate of macro thorium and rare earths in the ore as well. The experimental results indicate that the optimum acidity of the sedimentation with oxalate is pH 1.5--2.5. (ERA citation 15:034092)