Abstract
An integrated hydrometallurgical process was used for the zinc leaching and purification from a zinc ore containing 9.75 wt% zinc. The zinc minerals in the ore were hemimorphite, willemite, and calcophanite. Main gangue minerals were quartz, goethite, hematite, and calcite. Central composite design (CCD) method was used to design leaching experiments and the optimum conditions were found as follows: 30% of solid fraction, 22.05% sulphuric acid concentration, and the leaching temperature of 45 °C. The PLS containing 35.07 g/L zinc, 3.16 g/L iron, and 4.58 g/L manganese impurities was produced. A special purification process including Fe precipitation and Zn solvent extraction was implemented. The results showed that after precipitation of iron, Zn extraction of 88.5% was obtained with the 2 stages extraction system composed of 30 vol% D2EHPA as extractant. The overall Zn recovery from the ore was 71.44%. Therefore, an appropriate solution containing 16.6 g/L Zn, 0.05 g/L Fe, and 0.11 g/L Mn was prepared for the electro-winning unit without using the roasting and calcination steps (conventional method), which result in environmental pollution.
Highlights
An integrated hydrometallurgical process was used for the zinc leaching and purification from a zinc ore containing 9.75 wt% zinc
The x-ray powder diffraction (XRD) results showed that the dominant minerals in the ore are quartz (SiO2), hematite (Fe2O3), goethite (FeO(OH)), willemite (Zn2SiO4), hemimorphite (Zn4Si2O7(OH)2·H2O), dolomite (CaMg(CO3)2), cryptomelane (K(Na)Mn8O16), and calcite (CaCO3)
It was observed that metallic minerals in the polished sections are iron minerals mainly as hematite and goethite, manganese-zinc minerals mainly as calcophanite and hetaerolite (ZnMn2O4), manganese mineral as pyrplozite, and zinc minerals mainly as willemite and hemimorphite
Summary
An integrated hydrometallurgical process was used for the zinc leaching and purification from a zinc ore containing 9.75 wt% zinc. The zinc oxide ores usually contain several different minerals including zincite (ZnO), smithsonite ( ZnCO3), hydrozincite (2ZnCO3·3Zn(OH)), hemimorphite ( Zn4Si2O7(OH)2·H2O), and willemite ( Zn2SiO4)[2]. The main advantages of alkaline leaching are lower iron dissolution and lack of silica gel formation[16]. This method does not have the ability for dissolving of hemimorphite m ineral[8]. The Skorpion zinc processing method demonstrated the viability of the production of zinc from zinc oxide ores, using hydrometallurgical route including the leaching, solvent extraction, and electro-winning p rocess[18,19]. Faculty of Environment and Chemical Engineering, Duy Tan University, Da Nang 550000, Viet Nam. *email: Scientific Reports | (2021) 11:1566
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