Abstract
In order to figure out the decomposition of muscovite and the release mechanism of vanadium from vanadium shale in the alkaline fusion process, the process of vanadium release and roasting kinetics by alkaline fusion was studied. It was found that the addition of sodium hydroxide made the muscovite convert into the sodium silicate and gehlenite. This process promoted the dissolution of silicon and the destruction of muscovite, which could facilitate the release of vanadium. The kinetic analysis indicated that the controlling step of vanadium transformation reaction is changed from chemical reaction control to diffusion control with the increase of roasting time. Compared to the diffusion controlling step, the vanadium related chemical reaction was completed in the first period. The alkaline fusion reaction enhanced the decomposition of muscovite, which could accelerate the release of vanadium and reduce the dependence on high temperature and time in the roasting process. The apparent activation energies of chemical reaction control and diffusion control were 42.24 kJ molâ1 and â9.553 kJ molâ1, respectively. The kinetic model of vanadium extraction from vanadium shale using alkaline fusion could be finally established.
Highlights
Vanadium plays significant roles in many fields because of its good properties [1,2,3]
The alkaline fusion process had an efficient extraction of vanadium from the vanadium shale though drawing molten alkali to produce local deformation of muscovite particles for a complete decomposition of the muscovite
The vanadium shale alkaline fusion kinetic analysis showed that the early stage of the roasting process is controlled by chemical reaction, but the reaction process transformed into diffusion control quickly
Summary
Vanadium plays significant roles in many fields (such as ferrous and nonferrous alloy production, catalysts and redox flow batteries) because of its good properties [1,2,3]. Direct acid leaching and roasting-leaching processes are the main technologies for extracting vanadium from vanadium shale and have been widely adopted in recent years. The most important problem is that the sulfuric acid leaching process lacks effectively break the V-bearing lattice of mica minerals, resulting in a lower vanadium leaching efficiency. A series of novel composite roasting additive-acid leaching processes have been developed by researchers from our research group [15,16]. Their industrial application and feasibility are still to be further researched. As an effective and environmentally friendly technique, the use of alkaline fusion in the mineral and metallurgy fields is increasingly attracting attention. The lattice bonding structure and the particle morphology were employed to explain the mechanism of muscovite structure collapse and vanadium release mechanism in vanadium shale by alkaline fusion
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