拜耳法生产氧化铝中脱锌的研究

发布时间：2018-05-21 08:51

本文选题：铝酸钠溶液除锌 + 硫化钠　；参考：《昆明理工大学》2017年硕士论文

【摘要】：氧化铝的纯度是影响原铝质量的主要因素,同时也影响电解过程的技术经济指标。锌是比铝更正电性元素,会在电解过程中优先铝在阴极析出而使铝锭的质量降低。论文针对云南铝土矿含锌较高,生产中常出现锌含量偏高的现象,对拜耳法生产氧化铝中锌的脱除进行了研究。在查阅和总结国内外相关文献资料的基础上,对硫化物脱锌过程进行了深入分析。利用E-pH图探究了 S、Zn元素在碱性溶液中的行为;通过热力学计算,分析了 pH值对硫化钠脱锌的影响,确定了适合拜耳液脱锌的工艺环节;研究了硫化钠、二硫代氨基甲酸盐和高硫铝土矿三种脱锌方法。实验研究表明:利用用硫化钠—絮凝法脱锌时,Na2S用量0.5 g/L、反应时间120 min、反应温度60℃、絮凝剂添加量0.1%的条件下,可将铝酸钠溶液中锌杂质从70mg/L降至10mg/L;添加硫化钠的同时添加ZnS晶种,可以提高脱锌效率,减少S2-引入,最佳条件为反应温度60℃,反应时间90min,Na2S用量0.4g/L,ZnS晶种用量40mg/L,可将铝酸钠溶液中锌杂质从70mg/L降低到15mg/L以下;在沉降过程中添加硫化钠脱锌,仅用0.5g/L浓度Na2S,就可将铝酸钠溶液中的锌杂质从70mg/L降低到7mg/L,脱锌效果明显。利用二硫代氨基甲酸盐法脱锌时,在二甲基二硫代氨基甲酸钠0.8g/L、反应时间120min、反应温度80℃、絮凝剂添加量0.1%的条件下,铝酸钠溶液中锌杂质可降至15mg/L以下。在溶出过程添加高硫铝土矿,添加比例为10%～20%时,也能达到较好的脱锌效果,溶出液中的锌杂质从30mg/L降至15mg/L以下,符合生产要求。
[Abstract]:The purity of alumina is the main factor affecting the quality of the original aluminum, and it also affects the technical and economic indicators of the electrolytic process. Zinc is a more positive element than aluminum, and the quality of the aluminum ingot is reduced by the precipitation of the first aluminum in the electrolysis process. The paper has a high zinc content in Yunnan bauxite, and the phenomenon of high zinc content often appears in the production. The removal of zinc from alumina by ear method was studied. On the basis of consulting and summarizing the relevant documents at home and abroad, the process of zinc dezincing was deeply analyzed. The behavior of S and Zn in alkaline solution was explored by using E-pH diagram. The effect of pH value on dezincing of sodium sulfide was analyzed by thermodynamic calculation, and the suitability for the dezincing of sodium sulfide was determined. Three dezinnation methods of sodium sulfide, two thiocarbamate and high sulphur bauxite are studied in the process of dezinking of Bayer liquid. The experimental study shows that the dosage of Na2S is 0.5 g/L, the reaction time is 120 min, the reaction temperature is 60, and the adding amount of flocculant is 0.1%, and the zinc impurities in sodium aluminate solution can be from 70 under the condition of sodium sulfide flocculation. Mg/L is reduced to 10mg/L, and the addition of ZnS crystal with sodium sulfide can increase the dezine efficiency and reduce the introduction of S2-. The optimum condition is 60 C, 90min, Na2S dosage 0.4g/L, ZnS seed dosage 40mg/L, and the zinc impurities in sodium aluminate solution can be reduced from 70mg/L to 15mg/L below. In the process of sedimentation, the addition of sodium sulfide is only 0. The concentration of.5g/L in Na2S can reduce the zinc impurities in sodium aluminate solution from 70mg/L to 7mg/L, and the dezinnation effect is obvious. With two thiocarbamate dezinnation, the zinc impurities in sodium aluminate solution can be reduced to 15mg/L under the conditions of two methyl two sodium thiocarbamate 0.8g/L, reaction time 120min, reaction temperature 80, and 0.1% flocculant. The addition of high sulphur bauxite in the dissolution process can achieve better dezinion effect when the proportion is 10% to 20%, and the zinc impurity in the solution is reduced to less than 15mg/L from 30mg/L, which is in line with the production requirements.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ133.1

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