Research on extraction of cerium from rare-earth metals concentrate solutions by electrochemical and extraction methods

In order to extract cerium from rare-earth metals (REM) recovered from Russian raw materials, the following modern domestic equipment was selected: OXITRON-58L-O2 diaphragm electrolyzer manufactured by LLC «Delfin Aqua» with the purpose of Ce(III) to Ce(IV) oxidation; EC-10FA centrifugal extractor manufactured by LLC «LIT» with the purpose of Ce(IV) extraction from the sum of REM. These units were used in the studies performed to identify conditions that would lead to cerium oxidation to a 4-valent state with the electrochemical method as well as to recover and clean Ce(IV) from rare-earth metals with the solvent extraction method. The experiments were performed with standardized test solutions of cerium nitrate and process solutions obtained using loparite concentrate from the Solikamsk Magnesium Plant. The conditions were identified and equipment operation modes were designed in order to enable the chosen electrolyzer model to achieve a degree of cerium oxidation in REM process solutions over 99 % at power consumption below 0,8 kW/h per 1 kg of CeO2, and extract cerium from REM concentrate solution using the laboratory cascade of 20 centrifugal extractors with further production of 99,6 % pure CeO2.