Recovery of iron by jarosite crystallization and separation of vanadium by solvent extraction with extractant 7101 from titanium white waste liquid (TWWL)

摘要

The jarosite crystallization and new extractant system for extractant 7101 was used to separate iron and extract vanadium from titanium white waste liquid (TWWL). The influence factors and mechanisms of crystallization and solvent extraction were investigated and analyzed using SEM-EDS, XRD, FT-IR, solution thermodynamic theory and extraction isothermal curve. More than 97% of iron was precipitated with the following conditions: potassium chlorate 15 g/L, pH value of 1.6, temperature of 95 °C and time of 90 min, in which the crystallization product was jarosite with a purity of 99.5%; the pH value of the solution decreased after precipitation. The extraction efficiency of vanadium reached 88.6% with 10% Fe, 5% Al(III) but less for Mg(II), K(I) and Na(I) under the conditions X_(7101)of 0.5, pH value of 2.0, time of 4 min and stirring speed of 40 r/min. The extraction of metal ions occurred in the order V(V) > Fe(III) > Al(III) > Mg(II) > K(I). Vanadium minimally existed as H_(2)V_(10)O_(28)~(4-)at pH 2.0, and the functional groups NH and C–N contributed to vanadium extraction using the extractant 7101. Four stages extraction and three stages of re-extraction were predicated by McCable–Thiele plots.