Efficient Vanadium Extraction from Shale with High Silicon Content Using a Short Flow Process by Roasting-Water Leaching: Laboratory and Industrial Scale Research

摘要

With increasing demand for vanadium (V) products in recent years around China, the V utilization from V-bearing shale becomes very important. The V extraction from a shale in Shiyan, Hubei, China was systematically studied. For laboratory experiment, more than 75% of the V can be leached under the experimental conditions of the roasting temperature of 800 degrees C to 830 degrees C, the mass ratio of Na2CO3 to NaCl of 7:3-5:5, the composite additive (Na2CO3-NaCl) total dosage of 9 wt.% and the roasting time of 3 h. The microstructure analysis shows that the composite additive can thoroughly destroy structures of silicate minerals (muscovite/illite) during roasting, releasing the V from shale. The phase analysis indicates that albite (NaAlSi3O8) and water-soluble sodium vanadate (NaVO3 and Na4V2O7) were formed during roasting. For industrial test and commercial application, the V leaching efficiency maintained at 80%-85% under the conditions of the roasting temperature of 820 degrees C-830 degrees C, the composite additive (Na2CO3-NaCl) total dosage of 9 wt.%, the mass ratio of Na2CO3 to NaCl of 7:3 and the roasting time of 3 h. The NaCl dosage was as low as 2.7 wt.%. More than 99% of the V was recovered in the V precipitation process and the obtained V2O5 product had a purity of 98.2 wt.%-98.6 wt.% in commercial application.

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