铝电解槽废旧阴极处置过程中F~-的迁移规律

发布时间：2018-05-17 21:45

  本文选题：铝电解槽废旧阴极 + 氟化物　； 参考：《西安建筑科技大学》2015年硕士论文

【摘要】：随着我国电解铝产量的大幅度提高,铝电解槽每年排放的废旧阴极材料也随之逐年增长。废旧阴极中含有大量的可溶氟化物,属于危险固体废弃物。露天堆放或直接填埋时,会对周围生态环境造成严重污染。同时,其中含有的氟化物会对浮选工艺产生严重的影响。因而提出先浸出,后浮选的工艺,去除其中可溶氟化物,使其由危险固废转化为一般固废,以优化浮选工艺。所以,研究废旧阴极处置过程中F-的迁移规律,具有重要的理论和应用价值。本文所用原料取自山西运城某铝电解生产企业大修期间新拆卸的铝电解槽废旧阴极材料,通过矿相分析、XRD检测以及元素分析等多种手段,充分了解其主要组成部分,分析其中氟化物的存在形式。通过对其进行粗碎、细碎、浸出后,得到较优的浸出实验条件,同时对其浸出含氟废水进行无害化处理。浸出之后,对于浸出渣,可作为非危险固体废弃物直接排放,也可通过浮选工艺进行分选,最终对浮选精矿进行回收利用。通过实验研究,主要得出以下结论:(1)铝电解槽废旧阴极材料主要以C、Na3AlF6、NaF、CaF2等形式存在,其中碳含量高达68.58%,其余为电解质,且氟化物主要以Na3AlF6、CaF2、NaF三种形式存在,其中常温下NaF为主要的可溶氟化物。(2)较优浸出实验条件为:浸出剂为水,粒径为0.075~0.096mm,液固比为55:1,浸出温度为85℃,浸出时间为2h。其中可溶F-最大浸出量为11.25%,占理论可溶F-的97.8%。(3)浸出渣XRD检测分析结果表明:废旧阴极中的NaF已经基本全部溶解到溶液中,此时浸出渣中的F-可以控制在危险固体废弃物限制的含量以内,可予以排放,也可通过浮选工艺进行回收利用。(4)对其浸出高浓度含氟废水进行处理,实验结果表明:采用CaCl2沉淀法和硫酸铝沉淀法可将可溶F-浓度降到10mg/L以下,达到国家废水排放标准,最高可溶F-脱除率均为99.5%,但前者最终溶液显中性,后者显酸性;而CaO沉淀法和超滤法均无法处理达标。综合对比,采用Ca Cl2沉淀法处理含氟废水为最佳处理实验方法。(5)对于浮选后的精矿,采用在原厂阴极中适量添加的方法进行回收利用。实验结果表明:在原厂阴极中加入20%的沥青和适量浮选精矿,经过焙烧后,其电阻率明显增长,且可以达到使用标准。同时,浮选精矿不宜配入过多,否则电阻率会超出阴极使用的规定范围。本研究结果对废旧阴极的储运、选分、提纯以及废水处理等均具有参考价值。
[Abstract]:With the increase of electrolytic aluminum production in China, the waste cathode material discharged by aluminum reduction cell increases year by year. The waste cathode contains a large amount of soluble fluoride, which is a hazardous solid waste. Open-air stacking or direct landfill will cause serious pollution to the surrounding ecological environment. At the same time, the fluoride contained therein will have a serious effect on the flotation process. Therefore, the process of leaching first and then floatation is put forward to remove soluble fluoride from dangerous solid waste to general solid waste in order to optimize flotation process. Therefore, it is of great theoretical and practical value to study the law of F- migration in the process of waste cathode disposal. The raw materials used in this paper are taken from the waste cathode material of aluminum electrolytic cell that was newly disassembled during the overhaul of an aluminum electrolysis production enterprise in Yuncheng, Shanxi Province. The main components of the material are fully understood by means of phase analysis, XRD detection and element analysis, etc. The existing forms of fluoride were analyzed. After coarse, fine and leaching, the optimum leaching conditions were obtained, and the wastewater containing fluorine was treated innocuously at the same time. After leaching, the leachate slag can be directly discharged as non-hazardous solid waste, or can be separated by flotation process, and the flotation concentrate can be recycled. The main conclusions are as follows: (1) the waste cathode materials of aluminum reduction cell mainly exist in the form of Con Na 3AL F 6 and NAF F 2, in which the carbon content is as high as 68.58%, the rest is electrolyte, and the fluoride mainly exists in three forms, Na 3AL F 6, CaF 2N NAF, etc. The optimum leaching conditions are as follows: the leaching agent is water, the particle size is 0.075 渭 m, the liquid-solid ratio is 55: 1, the leaching temperature is 85 鈩，

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