Abstract
This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans). Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD) patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS) element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.
Highlights
Vanadium, a significant rare metal, has gained extensive attention due to its widely industrial applications, especially in ferrous and nonferrous alloy productions, catalysts and batteries [1,2].Vanadium-bearing shale is widely distributed in many southern provinces of China and is an important vanadium resource in China [3]
The vanadium leaching efficiency of 62% was achieved in 1.2 days
The vanadium leaching efficiency decreased to 24% in 10 days
Summary
A significant rare metal, has gained extensive attention due to its widely industrial applications, especially in ferrous and nonferrous alloy productions, catalysts and batteries [1,2]. It has been proven to be an effective, low-cost and eco-friendly way to process various minerals and wastes [9,10,11,12] It is based on the interaction of microorganisms with metal sources for the transformation of organic or inorganic acids (protons), oxidation and reduction reactions and the excretion of complexing agents [13]. In a number of studies using A. ferrooxidans, the feasibility of bioleaching of different metals from silicate minerals was shown in lab-scale. Metals in these minerals are mainly leached via sulfuric acid and ferric ion produced by microorganisms [16,17,18]. X-ray diffraction (XRD) and scanning electron microscopy-energy disperse X-ray spectrometry (SEM-EDS) analysis were conducted to reveal the vanadium bioleaching behavior
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