摘要:
热力学问题是含钒钢渣硫酸浸出反应的核心问题。针对含钒钢渣的矿物组成,对含钒钢渣硫酸浸出体系进行了热力学的计算与分析,结果表明:室温下硅酸三钙酸溶反应的很小、平衡常数很大,很容易与硫酸反应,由于该组分含量很大,势必造成大量的硫酸与之发生反应而被消耗;当终酸浓度为1×10-4 mol/L时,FeO理论上能全部被硫酸浸出,而钒在此酸浓度条件下基本不被浸出,FeO的浸出比钒具有更大的热力学趋势。依据这一结果,可设计出“选择性分段酸浸”新方法,Ⅰ段预浸除杂、Ⅱ段浸出提钒,在浸出阶段即可实现钒与主要杂质铁的分离。Eh-pH图表明,在酸性条件下钒的主要溶解相为VO2+、VO2+和V3+,而VO2+的稳定区在三个溶解相的中间,且稳定范围较大,浸出过程应尽量使钒处在VO2+的稳定区域。
关键词:
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钢渣 /
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提钒 /
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酸浸 /
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热力学分析
Abstract:
Thermodynamic problem is the core issue of the sulfuric acid leaching reactions of vanadium bearing steel slag.According to the mineral compositions in vanadium bearing steel slag,thermodynamic calculation and analysis of the steel slag leaching system were carried out in this paper.The results show that,tricalcium silicate can react with sulfuric acid easily as a result of low and high equilibrium constant of acid dissolution reactions of tricalcium silicate at room temperature.Therefore,much of sulfuric acid will certainly be consumed due to the high content of tricalcium silicate in the steel slag.FeO can be fully leached by sulfuric acid in theory while vanadium cannot be leached at the terminal acid concentration(leaching equilibrium acid concentration) of 10-4 mol/L,which indicates that the thermodynamic trend of FeO leaching is greater than that of vanadium leaching.Based on this result,a new leaching method of "selective stage leaching" can be designed,and a better selective leaching separation between vanadium and iron can be achieved significantly with pre-leaching of impurities in the first stage and leaching vanadium in the second stage.Eh-pH diagram shows that VO2+,VO2+,and V3+ are the main dissolved phases of vanadium in the acidic media,and the stable region of VO2+ is very large and just in the middle of the three dissolved phases.Thus in the leaching process,the vanadium should be controlled in the stable region of VO2+.