Stone coal, a kind of important vanadium-bearing resources in China, accounts for about 87% of the domestic reserves of vanadium. But the currently developed techniques to extract vanadium from stone coal are all confronted with environmental problems. For example, large quantities of caustic or greenhouse gases discharged in the oxidizing roast process, enormous consumptions of acid or alkali in the leaching step and massive tailings containing toxic V5+ ions. With a view to solve those problems, an innovative process for pre-concentration of vanadium from stone coal was designed and confirmed on a laboratory scale. The distinct features of this design are as follows. Firstly, the environment-friendly Fe2O3 is selected as a capturer of vanadium. Secondly, the natural reducing property of stone coal is utilized to promote the formation of magnetic V-rich phase, Fe2VO4. Thirdly, a high-grade vanadium concentrate is obtained by magnetic separation method. The practicability of this design was confirmed using industrial stone coal on a laboratory scale. When 10 mass% Fe2O3 relative to stone coal was added and roasted at 1200 degrees C for 3 h, a high-grade concentrate containing vanadium higher than 14 mass% was obtained, and more than 91% of the total vanadium in stone coal was recovered.
Stone coal; Vanadium; Pre-concentration; Reducing roast; Magnetic separation