Abstract
The selective leaching of vanadium and iron has been one of the main concerns in the field of vanadium recovery from stone coal, but the source of iron ions and their release characteristics were still unclear. In this work, the dissolution of pyrite and its roasted product, under conditions in accordance with the vanadium leaching process from stone coal by blank roasting-acid leaching, were studied. The results indicated that the leaching performances of V and Fe in stone coal were significantly correlated, with both depending on the leaching parameters of the H2SO4 concentration, the leaching temperature, the leaching time and the solid to liquid ratio. Under air conditions, with a roasting temperature of 700 °C, the roasted product of pyrite was hematite. Approximately 45% of the roasted product dissolved at its optimal leaching condition—35% higher than that of the raw pyrite. However, any further improvement was difficult, due to the difference in texture between its outer sphere and inner core. The results demonstrated that the roasting treatment led to a significant increase in the release of iron ions during the vanadium leaching process. The pre-removal of pyrite from the raw ore was necessary to reduce the concentration of iron ions in the leachate.
Highlights
Stone coal is a unique vanadium resource with a massive reserve in China, and the extraction of vanadium from stone coal has attracted attention for a long time
Especially iron ions, are inevitably leached along with the vanadium, which is detrimental to its subsequent purification and enrichment, and increases the cost of vanadium recovery [5]
The leaching behaviors of V and Fe from stone coal both depended on the following leaching parameters: the concentration of sulfuric acid, the leaching temperature, the leaching time and the solid to liquid ratio
Summary
Stone coal is a unique vanadium resource with a massive reserve in China, and the extraction of vanadium from stone coal has attracted attention for a long time. Muscovite is the primary vanadium-bearing mineral in stone coal because the V3+ substitutes the Al3+ from the dioctahedral structure as an isomorphism in muscovite [1,2]. It is challenging to extract vanadium from stone coal. Blank roasting-acid leaching is an effective technique to recover vanadium from stone coal. Especially iron ions, are inevitably leached along with the vanadium, which is detrimental to its subsequent purification and enrichment, and increases the cost of vanadium recovery [5]. The concentration of iron ions is 2.0–4.0 times higher than that of the vanadium ions in the leachate [6,7,8]. The separation of vanadium and iron ions has been one Minerals 2020, 10, 526; doi:10.3390/min10060526 www.mdpi.com/journal/minerals
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