Selective recovery and separation of Zr and Hf from sulfuric acid leach solution using anion exchange resin

Abstract

Apart from zircon and baddeleyite, some other minerals also contain amounts of Zr and Hf, and H2SO4 can be the best candidate leachate for their recovery. The subsequent step in the process would be the recovery and separation of Hf and Zr from the resulting leach solution together with impurities. This reported study focused on the recovery process following the leaching of Zr and Hf from a eudialyte residue after REEs extraction. The chemistry of the solution was studied to determine the feasibility of different methods, and based on the results, an anion exchange resin was chosen to selectively recover Zr and Hf from the acidic sulfate solution. Batch and continuous ion exchange experiments using a strong anionic resin (MP600) were performed to develop the ion exchange process. The experimental results showed that Zr and Hf can be selectively recovered over other impurities. In the process of the adsorption of Zr and Hf, the bed volume reached 6 using the feed solution at a pH 0.94 at 25 °C with a contact time of 2 h. Pure Zr sulfate solution was used to scrub the load resin, after which the loaded resin was easily eluted using 10% NH4HCO3 + 1 mol/L NH4OH solution. This produced 21.23 g/L Zr, 0.03 g/L Hf, 0.01 g/L Fe, 0.01 g/L Al, 0.02 g/L Nb and < 0.001 g/L Ca in the eluate. The impurity removal from the leachate and the enrichment of Zr were achieved by the process.