摘要
铬酸钙盐在酸碱溶液中的溶解行为和规律对高效提取铬非常重要,为此,对CaCrO4、CaCr2O7和β-CaCr2O4生成热力学条件进行了综合分析.在保持溶液酸度恒定条件下,研究了在不同酸度、温度条件下,CaCrO4与CaCr2O7在H2SO4和NaOH溶液中的溶解规律,并分析了CaCrO4在溶液中的赋存状态.研究结果表明,在850～950℃时,CaO与Cr2O3生成CaCrO4的趋势较大,增加氧势或渣碱度均促其形成.CaCrO4在H2SO4溶液中(30～50℃)溶解率随酸度提高而增大,酸度较高时(pH=1.92～4.07)溶解率可达100%,酸度较低时(pH=5.48～7.26)溶解率最低降至50%～55%;碱性溶液中,pH值由8.5增至12时,溶解率逐渐小幅提高.提高温度后溶解率平均增加2%～5%.CaCr2O7易溶于不同浓度的H2SO4溶液,在NaOH溶液中溶解率较高;CaCrO4溶于酸或碱性溶液,存在CrO24-与Cr2O27-的平衡.
The dissolution behavior and rule of calcium chromates in acid or alkali solution are very important for efficiently extracting chromium.Therefore,the thermodynamics conditions concerning the formation of CaCrO4,CaCr2O7 and β-CaCr2O4 were comprehensively analyzed.Under the condition of keeping the constant solution,the dissolution rule of CaCrO4 and CaCr2O7 respectively in H2SO4 and NaOH solution was investigated under different acidity and temperatures.In addition,the occurrence state of CaCrO4 in the solution was studied.The results show that in the temperature range from 850 ℃ to 950 ℃,the tendency to form CaCrO4 by CaO and Cr2O3 becomes larger,which is promoted with increasing the oxygen potential and basicity of vanadium slag.In H2SO4 solution（30 ℃ to 50 ℃）,the dissolution ratio of CaCrO4 increases with increasing the acidity,reaches 100% at higher acidity（pH=1.92 to 4.07）,and falls to 50% to 55% at lower acidity（pH=5.48 to 7.26）.In alkali solution,the dissolution ratio of CaCrO4 gradually increases with increasing pH from 8.5 to 12.The dissolution ratio of CaCrO4 increases by 2% to 5% with increasing temperature.CaCr2O7 can easily dissolves in H2SO4 solution with different concentration,and its dissolution ratio in NaOH solution is higher.An equilibrium between CrO2-4 and Cr2O2-7 exists when CaCrO4 dissolves in either acidic or alkali solution.
出处
《沈阳工业大学学报》
EI
CAS
北大核心
2012年第6期639-643,共5页
Journal of Shenyang University of Technology
基金
国家重点基础研究发展计划资助项目(2007CB613503)
关键词
铬酸钙
重铬酸钙
溶解率
酸度
溶解行为
热力学
钒渣
赋存状态
calcium chromate
calcium dichromate
dissolution ratio
acidity
dissolution behavior
thermodynamics
vanadium slag
occurrence state
