Abstract
In this paper, the extraction of vanadium from stone coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting with MgO was studied. The results indicated that under the conditions that the mass fraction of the particles with grain size of 0–0.074 mm in raw ore was 75%, the roasting temperature was 500 °C, the roasting time was 1 h, MgO addition was 3 wt %, the sulfuric acid concentration was 20 vol %, the liquid-to-solid ratio was 1.5 mL/g, the leaching temperature was 95 °C, and leaching time was 2 h, resulting in a vanadium leaching efficiency of 86.63%, which increased by 7.73% compared with that of blank roasting. The mechanism analysis showed that the degree of calcite decomposition was low and, thus, magnesium vanadate was more easily formed than calcium vanadate below 500 °C. Moreover, magnesium vanadate was easier to dissolve than calcium vanadate during the sulfuric acid leaching process. Thus, the vanadium leaching efficiency was enhanced by using MgO as a roasting additive below 500 °C. Additionally, at high temperature the formation of tremolite would consume calcium oxide produced from the decomposition of calcite, thus, the formation of calcium vanadate was hindered, and V2O5 would react with MgO to form magnesium vanadate. Therefore, the vanadium leaching efficiency of roasting with MgO was higher than that of blank roasting at high temperature.
Highlights
IntroductionVanadium is an important rare metal and has been widely used in ferrous and non-ferrous alloys.vanadium plays a key role in some new industries, such as chemical industry, medicine, vanadium redox batteries, and so on [1,2]
Vanadium is an important rare metal and has been widely used in ferrous and non-ferrous alloys.vanadium plays a key role in some new industries, such as chemical industry, medicine, vanadium redox batteries, and so on [1,2]
Vanadium was extracted from stone coal by roasting with MgO and leaching with sulfuric acid, and the function of MgO during stone coal roasting process was analyzed
Summary
Vanadium is an important rare metal and has been widely used in ferrous and non-ferrous alloys.vanadium plays a key role in some new industries, such as chemical industry, medicine, vanadium redox batteries, and so on [1,2]. Vanadium is an important rare metal and has been widely used in ferrous and non-ferrous alloys. Extracting vanadium from stone coal is an important way to obtain vanadium pentoxide. Most of the vanadium in stone coal mainly exists as trivalent vanadium (V(III)) which substitutes for trivalent aluminum (Al(III)) in the octahedral crystal lattice of the mica minerals as an isomorphism [6,7,8]. The trivalent vanadium in the lattice of the mica minerals cannot be directly dissolved in acid solution, which must be oxidized to a high valence state. It is necessary to break down the crystal structure of the mica minerals for extracting vanadium from stone coal. One of the effective methods commonly used is roasting [9,10]
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