Study On Recovery Of Scandium From Sulfuric Acid Medium Based On Trialkyl Phosphine Oxide

Scandium is an important strategic resource,which is widely used in electronics,aerospace,chemical industry and other fields with its excellent performance.Scandium resources are distributed very dispersedly,and there are few independent minerals,which are mainly recovered as by-products.At present,most of the scandium oxide produced in China comes from the waste acid produced in the process of producing titanium dioxide by the sulfuric acid method,in which the scandium content is about 6-15 mg/L.Because titanium white waste acid contains a large number of impurity elements such as Ti,Fe,Zr and rare earth elements,which seriously affects the separation of scandium and the purity of SC2O3.So it is of practical significance to study the separation of scandium from the sulfuric acid medium.Based on neutral phosphine extractant trialkyl phosphine oxide(TRPO),the separation behavior and mechanism of scandium by TRPO in the sulfuric acid medium were studied by adsorption.In this paper,macroporous silicon-based adsorbent TRPO/SiO2-P was synthesized by vacuum impregnation with SiO2-P as the carrier.In addition,the adsorbent was characterized by SEM-EDS,TG-DSC,BET and IR,and he results showed that the effective load of TRPO in TRPO/SiO2-P was 31 wt%.The effects of sulfuric acid concentration,contact time,experimental temperature,competitive ions and Sc ion concentration on the adsorption behavior of TRPO/SiO2-P for scandium were studied by batch adsorption experiments,and the optimum adsorption conditions were determined.The dynamic column separation experiment was carried out on the basis of the static experiment,and the continuous separation of scandium was studied.Finally,the adsorption mechanism was explored by IR,XPS and IC,and the adsorption reaction model of scandium by TRPO/SiO2-P was obtained.The results show that under 5 M H2SO4,TRPO/SiO2-P has good selectivity for Sc and has no adsorption capacity for impurity elements such as Fe,Al,Mg and rare earth elements in solution.The adsorption of titanium ion by TRPO/SiO2-P can be inhibited by adding hydrogen peroxide to the solution.When the concentration of sulfiuric acid is 5 M,the contact time is 180 min and the experimental temperature is 25?,the adsorption effect of TRPO/SiO2-P on scandium is the best,and the saturated adsorption capacity for scandium is 13.3 mg/g.Dynamic column separation experiments show that TRPO/SiO2-P can separate scandium and other common competing ions from sulfuric solution.These results indicate that TRPO is a promising candidate material for the separation and purification of scandium from the sulfuric acid solution.