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针对钼酸盐深度除钒,计算并绘制了Mo(VI)-V(V)-H_2O系中存在的各种单核离子、同多酸根离子、杂多酸根离子随pH以及浓度变化的热力学平衡图,并全面分析了其变化规律,随后利用热力学计算对现有的钼酸盐深度除钒工艺进行了理论分析。研究结果表明,在pH下降的过程中,VO_4~(3-)会率先转变为聚合的偏钒酸根离子,而钼则在相对较低的pH下才会形成聚合离子,并且聚合开始时p H还会随着钼浓度的下降而降低。当pH=2.0~5.5时体系中会形成大量的钼钒杂多酸根离子。低浓度钼钒混合溶液会在强酸性条件下形成MoO_2~(2+)和VO_2~+,但钒形成阳离子的能力要强于钼。目前钼酸盐深度除钒的工艺从原理上可归为两类,即利用钒在弱碱性范围内会优先生成聚合离子以及利用酸性条件下钒更易生成阳离子的性质。通过热力学平衡计算,可较为准确地对这些工艺在处理不同浓度料液时的最佳pH范围进行预测。
According to the depth of vanadium removal, the thermodynamic equilibriums of various mononuclear, isopolyacid and heteropolyacid ions in the Mo (VI) -V (V) -H 2 O system were calculated and plotted as a function of pH and concentration Figure, and a comprehensive analysis of its variation, and then the use of thermodynamic calculations of the existing molybdate deep vanadium removal process were analyzed. The results show that VO_4 ~ (3-) will convert to polymerized metavanadate ions first, while molybdenum will form polymerized ions at a relatively low pH, and at the beginning of polymerization, p H It will also decrease as the concentration of molybdenum drops. When pH = 2.0 ~ 5.5, a large amount of molybdovanadophosphoric acid ions are formed in the system. Low concentrations of molybdenum-vanadium mixed solution will form MoO 2 2+ and VO 2 + in strong acidic conditions, but the ability of vanadium to form cations is stronger than that of molybdenum. At present, the deep vanadium removal process of molybdate can be divided into two types in principle, that is, the use of vanadium in the weak alkaline region will give priority to the formation of polymeric ions and the use of acidic conditions, vanadium is more likely to generate cationic properties. Thermodynamic equilibrium calculations allow for a more accurate prediction of the optimal pH range of these processes for treating different concentrations of feedstock.