Abstract
Zinc has wide industrial applications; consequently, its extraction procedures have been extensively studied. Hydrometallurgy is one of the most common methods employed for zinc recovery. However, the electrooxidation of sphalerite and the effect of the pyrite content in the concentrate have not been investigated; thus, in this work, zinc recovery from low-iron sphalerite mineral with a relatively high pyrite content (EBHSS), in a sulfate medium was further explored. The reaction mechanism of the anodic dissolution of the EBHSS mineral was established by microelectrolysis using mineral carbon paste electrodes; these results were used to determine adequate conditions for the macroelectrolysis of the sample. The macroelectrolysis indicated that EBHSS has a low electrodissolution rate; additionally, different analyses of the species produced in the macroelectrolysis showed that the ohmic drop registered in the collector had no influence in the passivation of the EBHSS surface. It was also determined that the dissolution of EBHSS was driven by the charge transfer of the sphalerite particles, which are not very efficient for electronic conductivity. Experiments using doped EBHSS led to an increase of the electrodissolution rate, which consequently increased the recovered zinc.
Highlights
Zinc is an important base metal required for various industrial applications [1]
The pyrite addition increased the associated oxidation current density (J) at any pH and concentration. These results suggested that the presence of pyrite in the EBHSS samples contributed to its electrooxidation when elevated potentials such as 1 V were applied at pH = 7 (Figure 2a); pH = 2 (Figure 2b) and 1.7 M H2SO4 (Figure 2c)
The electrochemical response of two zinc sulphide concentrates was initially studied, one with a high iron content in solid solution (EAHSS) and the other with a low iron content in solid solution (EBHSS), both concentrates with an amount of iron as pyrite
Summary
Zinc is an important base metal required for various industrial applications [1]. It is mainly recovered from primary sulfide concentrates, sphalerite (ZnS) being the primary ore [2,3]. Pyrometallurgical processes have traditionally been used for recovering metal from mineral concentrates, since these processes have metal recovery efficiencies of up to 99%. These methods involve several steps, including roasting, carbothermic reduction, reduction of sulfide ores, or metallothermic reduction, depending on the ore composition [8,9]. The production of sulfur dioxide and solid particles suspended in the air during combustion make these processes unfriendly to the environment [10,11]
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