常温常压下含钒钢渣直接硫酸浸钒的研究

Direct Leaching of Vanadium from V-Bearing Steel Slag with Sulfuric Acid under Normal Temperature and Pressure

含钒钢渣可作为提钒的重要原料。首先,对某含钒钢渣的性质进行了分析,结果表明,含钒钢渣中钙、铁含量很高,这将会导致直接硫酸浸钒时酸耗较高;含钒钢渣中的钒主要以酸溶的V4+形式存在,无需焙烧氧化、可直接酸浸溶出提钒;含钒钢渣中的钒弥散分布于多种矿相中,其中钙钛氧化物为最主要的含钒矿物。然后,依据含钒钢渣的性质特点,采用常温常压下直接硫酸浸出法从中提钒,并考察了各主要因素对钒浸出率的影响和内在原因,结果表明,硫酸用量、搅拌与否对钒的浸出有显著影响,时间、液固比及搅拌强度的影响较小,细度达到-74μm占60%后即可保证较高的浸出率。最终,常温常压下,在最佳条件硫酸用量90%、时间2 h、细度-74μm占60%、液固比4∶1、搅拌强度200 r·min-1时,钒浸出率高达94.10%,与传统提钒方法相比,浸钒指标大幅提升。常温常压下直接硫酸浸出法可省去复杂的焙烧系统、突破氧压酸浸的局限,流程简单、作业环境好、浸出指标高;但该法酸耗较高,如何降低酸耗,值得进一步研究。

V-bearing steel slag could be used as the key raw materials for vanadium extraction. Firstly, the properties of a V-bearing steel slag were analyzed. The results revealed that, the content of calcium and iron in V-bearing steel slag was very high, which would lead to the high acid consumption during direct leaching of vanadium with sulfuric acid. And most vanadium in V-beating steel slag ex- isted in the form of V（ IV ） which was soluble in acid solution, so the technology of direct acid leaching without oxidation roasting was feasible for vanadium extraction. And vanadium in V-bearing steel slag was dispersed in a variety of mineral phases and Ca-Ti oxide was the dominant mineral containing vanadium. Then, according to properties of V-bearing steel slag, a method of direct leaching with sulfuric acid under normal temperature and pressure was adopted to extract vanadium, and the effects of main factors on vanadium leac- hing rate, as well as inherent reasons of effects, were investigated. The results showed that sulfuric acid dosage and stirring or not had significant influence on leaching of vanadium, while time, liquid-solid ratio and stirring speed had unremarkable influence, and high leaching rate could be obtained just at the fineness of -74 μm accounting for more than 60%. Finally, under normal temperature and pressure, at the optimum conditions of sulfuric acid dosage of 90%, time of 2 h, fineness of - 74 μm accounting for 60%, liquid-solid ratio of 4： 1, stirring speed of 200 r·min-1 , the vanadium leaching rate reached 94. 10%, which was much higher than that of tradi- tional vanadium extraction methods. The method of direct leaching with sulfuric acid under normal temperature and pressure could leave out the complex roasting system and overcome the limitation of oxygen pressure acid-leaching, and it had the advantages of easy process, high leaching rate and environmental friendliness. However, acid consumption of this method was very high, and how to re- duce acid consumption should be further studied.