Pre-Concentration of Vanadium from Stone Coal by Gravity Using Fine Mineral Spiral
Due to the low grade of V2O5 in stone coal, the existing vanadium extraction technologies face challenges in terms of large handling capacity, high acid consumption and production cost. The pre-concentration of vanadium from stone coal before the extraction process is an effective method to reduce cost. In this study, detailed mineral characterization of stone coal was investigated. It has been confirmed that the vanadium mainly occurs in muscovite and illite. A significant demand for an effective pre-concentration process with simple manipulation for discarding quartz and other gangue minerals is expected. Based on the mineralogical study, a new vanadium pre-concentration process using a fine mineral spiral was investigated. The experimental results showed that the separation process, which was comprised of a rougher and scavenger, could efficiently discard quartz, pyrite and apatite. A final concentrate with V2O5 grade of 1.02% and recovery of 89.6% could be obtained, with 26.9% of the raw ore being discarded as final tailings.
A novel approach for pre-concentrating vanadium from stone coal ore
Abstract 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 °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.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.