The carbon residue is a hazardous waste generated by the aluminum electrolysis production process, which contains a large amount of electrolyte fluoride salts. In order to recover the electrolyte components in carbon residue, this paper proposes a new method of using carbon residue to prepare aluminum fluoride by converting NaAlF and NaAlF in carbon residue into aluminum fluoride to realize the recycling of fluoride in carbon residue. In the initial step, optimal parameters for carbon removal during roasting have been determined, including an oxygen flow rate of 7 g/min, a roasting temperature of 670 °C, and a roasting time of 80 min. The roasted clinker is obtained, and the removal rate of carbon reaches 99.95 % while the loss rate of fluorine is 0.48 %. In the second step, the mix anhydrous Al(SO) with roasted clinker for roasting. The optimal roasting temperature of 670 °C, the time of 10 min, and the mass ratio of anhydrous Al(SO) to roasted clinker of 5:5 could convert fluoride to AlF products, with a conversion rate of 99.76 % and a loss rate of fluorine of 1.05 %. Finally, by removing sulfate impurities through water leaching for 15 min at 35 °C and with a liquid-solid ratio of 6 ml/g, the loss rate of fluorine is 3.98 %. This process yields AlF with a purity of 94.30 %. The recovery rate of fluorine in the whole process is 94.56 %, which successfully achieves the recycling of fluorine in the carbon residue to obtain AlF products.

中文翻译：

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铝电解槽炭渣焙烧浸出法制备氟化铝

炭渣是铝电解生产过程中产生的危险废物，其中含有大量的电解质氟化盐。为了回收炭渣中的电解质成分，本文提出了利用炭渣制备氟化铝的新方法，通过将炭渣中的NaAlF和NaAlF转化为氟化铝，实现炭渣中氟化物的回收利用。在第一步中，确定了焙烧过程中除碳的最佳参数，包括氧气流量7 g/min、焙烧温度670 ℃、焙烧时间80 min。得到的焙烧熟料，碳去除率达到99.95%，氟损失率为0.48%。第二步，将无水Al(SO4)与焙烧熟料混合进行焙烧。最佳焙烧温度为670 ℃、时间为10 min、无水Al(SO)与熟料质量比为5:5时，氟化物转化为AlF产物，转化率达99.76%，损失率较低。氟含量为1.05%。最后通过35℃、液固比6ml/g水浸15min去除硫酸盐杂质，氟损失率为3.98%。该过程产生纯度为 94.30% 的 AlF。整个过程氟的回收率为94.56%，成功实现了炭渣中氟的回收利用，得到AlF产品。