Improvements in Separation Procedures.

摘要

1,180,921. Yttrium separation. THORIUM Ltd. 19 Jan., 1967 [4 Feb., 1966], No. 4952/66. Heading C1A. A batch method for separating yttrium ions from rare earth metal ions comprises: (a) multistage counter-current extraction between (i) an aqueous solution of inorganic acid salts of rare earth metals and of yttrium and (ii) a hydrocarbon solution of a branched chain carboxylic acid (the acid being branched at the C-atom adjacent the -COOH group) containing ions of yttrium and of rare earth metals, the extraction being carried out under conditions such that any solutes which leave each end of the extraction apparatus are continuously returned to that end whence they were derived; (b) stopping the counter-current solvent flows when sufficient separation has been achieved and emptying one or more stages of the extraction system containing yttrium ions together with some rare earth metal ions as impurities; (c) isolating the yttrium and rare earth values thus obtained, and where necessary converting to nitrates; (d) multistage counter-current extraction between (i) a solution of yttrium and rare earth metal nitrates in tributyl phosphate and (ii) an aqueous solution of said nitrates, the extraction again being carried out under conditions such that any solutes which leave each end of the extraction apparatus are continuously returned to that end from which they were derived; (e) stopping the counter-current solvent flows when sufficient separation has been achieved, and emptying one or more stages of the extraction apparatus containing a suitably pure solution of yttrium ions. Specified inorganic acid salts in stage (a) are nitrates and chlorides. When the salts in stage (a) are nitrates, the process may be conducted in the stages as before, but using the solvent pair (d(i)) and (d(ii)) in stage (a) and the solvent pair (a(i)) and (a(ii)) in stage (d). The carboxylic acid (stage a(ii)) may be a secondary acid (e.g. a naphthenic acid) or a tertiary acid containing 8-20 C-atoms, dissolved in xylene, kerosene or trimethylbenzenes. The tributyl phosphate used in stage (d) may also be dissolved in an organic solvent, e.g. trimethylbenzenes. The nitrate concentration in stage (d(ii)) is preferably not more than 160 g./l. expressed as oxides. Reference is made to Specification 1,026,791, which deals with the concept of "total reflux" used in this separation process.