The invention relates to a technology for purifying
scandium,
titanium and
vanadium from an acid solution step by step. According to the technology, the acid solution obtained by leaching
red mud through
sulfuric acid is subjected to three-time extraction work, and an extraction organic phase is composed of a P507 extraction agent, a TBP synergist and sulfonated
kerosene; in the first-time extraction process, the acid solution is directly subjected to
scandium extraction and enrichment without pH value adjustment, after two-phase separation, a
scandium-enriched organic phase and a
titanium and
vanadium containing solution are obtained, the scandium-enriched organic phase is subjected to
sulfuric acid scrubbing and reverse extraction of
sodium hydroxide, and scandium-enriched liquid is obtained; after the
titanium and
vanadium containing solution is subjected to pH value adjustment, the second-time extraction work is conducted for enrichment and separation of titanium, after two-phase separation, a titanium-enriched organic phase and a vanadium-containing solution are obtained, and after the titanium-enriched organic phase is subjected to
sulfuric acid scrubbing and reverse extraction of
hydrofluoric acid, titanium-enriched liquid and the vanadium-containing solution are obtained; and after the vanadium-containing solution is subjected to pH value adjustment and reducing treatment, the third-time extraction is conducted, and after two-phase separation, a vanadium-enriched organic phase and
raffinate are obtained. The technology has the beneficial effects that the separation efficiency is high, the enrichment multiple is large, the technology is simple, and the number of the kinds of extraction agents is small.