摘要:
采用溶析结晶法制备偏钒酸钾,确定高钒浓度下偏钒酸钾存在酸度范围。试验结果表明,钒浓度150 g/L,pH值7.6~8.5,溶析结晶法制备偏钒酸钾时溶析剂采用乙醇、加入量按体积比1:1,搅拌60 min,结晶钒收率大于95%,偏钒酸钾纯度98%以上。在溶析结晶过程中结晶收率与溶析剂配比、结晶前钒浓度、结晶时间关系密切;结晶晶体中的铬随结晶前液钒浓度增加而增加,不随结晶时间的变化而变化,硅随结晶时间的增加而降低,不随结晶浓度的变化而变化,同时通过控制溶析剂加入量可控制结晶粒度。
关键词:
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偏钒酸钾 /
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溶析结晶 /
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硅 /
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铬 /
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收率
Abstract:
Potassium metavanadate(KVO3) was firstly prepared by solventing-out crystallization,and the proper acidity range for crystallization from high-vanadium solution was determined.The results show that KVO3 owning purity more than 98% can be obtained with vanadium recovery rate more than 95%,under the conditions of 150 g/L vanadium concentration,7.6~8.5 solution pH,ethanol as precipitation agent with volume ratio of 1:1 to the vanadium solution,and stirring for 60 min.The recovery rate for crystallization is closely related to the volume ratio of precipitation agent,vanadium concentration of mother liquor and crystallization time.The chromium content in the obtained crystals increases with rise in vanadium concentration of mother liquor and is not affected by crystallization time.However,the silicon content in the crystals decreases with increase in crystallization time and not change with vanadium concentration in mother liquor.Moreover,the particle size of crystals can be controlled by addition amount of precipitation agent.