Molybdenum extn. and purificn from aq. solns. for uranium@ industry - by organic solvent extn. with two component system contg. prim. and sec. extractants of di:alkyl phosphoric acid and phosphine oxide

摘要

The extn. comprises contact of the aq. soln. with an organic solvent contg. prim. extractant(s) i.e. di-alkyl phosphoric acid and sec. extractant(s) which may be a tert. amine or quat. ammonium salt, tributyl phosphate or a phosphine oxide which selectively extracts Mo into the organic solvent. After contact of the aq. soln. of CaMoO4 in H2SO4 with the organic phase, the following steps are pref. 1) the organic layer is washed with dil. H2SO4 (opt. without ascorbic acid) and 2) the Mo is re-extracted from the washed organic layer by means of ammonia soln. This enables continuous operation of the extn. the organic solvent and aq. soln. circulating counter-currently and the aq. wash soln. is recycled to the initial Mo-contg. aq. soln. after the re-extn. of Mo by the NH3 soln. the organic solvent may be treated by conducting with an H2SO4 soln. to re-acidify it to reuse as an extractant. The prim. extractant is pref. di(2-ethyl hexyl)phosphoric acid (HDEHP). The sec. extractant is pref. dihexyl-methoxy-octyl phosphine oxide (POX 11), a mixt. of phosphine oxides with di-symmetric 6-8C chains, or a tert. amino salt. Or the sec. extractant is tributyl phosphate. The ratio of prim. to sec. extractant is pref. 4:1. The activity of the aq. H2SO4 soln. is pref. at leasdt 0.5N, and if tributyl phosphate is used, the activity may be at least 2N and if POX 11 is used, the acid value may be at least 1.5N. If a reducing agent (ascorbic acid) is used, the concn. may be 0.001-0.02 mol. per l of aq. soln. USE/ADVANTAGE - The extn. is used in the uranium industry and hydrometallurgical prodn. to produce carbonated solns. contg. W and various other metals e.g. Mo and it is necessary to separate these from W. Initial sepn. is after acidified by pptn. with lime producing impure calcium molybdate.