Hydrothermal crystallization of jarosite and natrojarosite from acid leaching solution of zinc oxide dust

Abstract

ABSTRACTThe separation of Zn and Fe, K, and Na ions remains a challenge in the recovery process of Zn-containing secondary resources. A hydrothermal process without adding neutralizer was developed to remove Fe, K, and Na ions from the leaching solution of zinc oxide dust. Results showed that Fe and K ions were synchronously eliminated, yielding low-contaminant jarosite products with excellent crystallinity and rosette-like morphology under the following conditions: gas pressure = 1.6 × 106 Pa, agitation speed = 600 rpm, reaction time = 3 h, and temperature ranges at 368.15 K−423.15 K. The removal efficiency of Fe and K ions reached 99.8% and 97.7%, respectively. The obtained low-contaminant jarosite contained Fe 31.09%−31.98%, Zn 1.05%−1.24%, S 12.33%−12.71%, K 6.12%−6.46%, and Na 0.44%−0.87%. Additionally, the Na ions in the leaching solution precipitated can also along with Fe ions, forming low-contaminant natrojarosite products containing Fe 31.36%−35.66%, Zn 1.60%−1.88%, S 10.66%−12.56%, Na 2.85%−3.26% and K 0.74%−0.85%. The optimal hydrothermal temperature for the removal of Fe, K, and Na ions while minimising energy consumption was determined to be 393.15 K. The low-contaminant jarosite and natrojarosite products possess potential applications in the field of yellow pigments, building materials, iron and arsenic removal, adsorption materials, catalytic materials, etc.