Application of the Microwave and Ultrasonic Combined Technique in the Extraction of Refractory Complex Zinc Ore

Abstract

This paper proposes a combined microwave and ultrasonic technique that aims to extract the refractory mineralogical properties of complex zinc ore. This technique consists of two steps: microwave-assisted phase transformation and ultrasonic-assisted complexation leaching. During the microwave-assisted phase transformation step, the refractory zinc phases transform into manageable phases using doping oxidation agents. In the ultrasonic-assisted complexation leaching step, the effect of NTA3 on Zn2+ species distribution is explored. The results show that microwave roasting with 20% Na2O2 at 600 °C for 15 min adequately transforms ZnS, ZnCO3 and Zn2SiO4 into ZnO and avoids the generation of Zn2SiO4. Further, 0.5 mol/L NTA3− (nitrilotriacetic acid) is especially effective as a complex additive for complexes with Zn2+ as Zn (NTA)24−. The ultrasonic technique can reduce the diffusion resistance and open the products in the leaching process, improving zinc leaching by 4.7%. The degree of zinc recovered from zinc ore can reach 91.4% when leach is assisted with 225 W ultrasonic force at 80 °C for 75 min. This paper shows great potential for the green extraction of non-traditional zinc-containing resources.