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摘要: 铝电解槽炭渣是铝工业冶炼生产过程中产生的一种危险废物。炭渣的大量堆存，在浪费电解质资源的同时，也会造成大气、土壤以及水体的污染。本试验以炭渣为原料，Na2CO3为添加料，对炭渣的焙烧−水浸工艺回收炭粉和冰晶石的可行性与过程进行了研究。试验结果表明，将质量比为2.5∶1的Na2CO3与炭渣混合后置于坩埚电阻炉中，在950 ℃下焙烧2 h，炭渣中氧化铝、冰晶石和亚冰晶石被Na2CO3消耗，焙烧后混合料由C、Na2CO3、NaF、NaAlO2组成。焙烧后混合料在pH为13、浸出温度为25 ℃的条件下浸出1 h，固液分离后的浸出渣经过水洗、烘干后得到炭粉，其纯度可达89%。利用碳酸化法回收浸出液中F−，可获得主成分合格的粉状冰晶石。适当地提高焙烧温度和延长保温时间可提高炭和电解质的分离效率。研究经济而有效的炭渣处理方法，不仅可以解决炭渣带来的环境污染问题，还对社会的可持续发展产生深远影响。Abstract: Carbon residue in aluminum electrolytic cell is a kind of hazardous waste produced during the smelting and production process of the aluminum industry. Approximately 10 kg of carbon residue is produced for every ton of primary aluminum produced. China’s primary aluminum output was as high as 35.04 million tons in 2019, so its carbon residue production was about 350,000 tons. The accumulation of a large amount of carbon residue wastes electrolyte resources, as well as causes air, soil, and water pollution. Additionally, carbon residue was listed on the National Hazardous Waste List in 2016. Therefore, the treatment of carbon residue needs to be solved urgently. In this experiment, the characteristics of carbon residue were introduced, and it was used as the raw material to study the process feasibility of recovering carbon powder and cryolite by the roasting-water leaching process of carbon residue with Na2CO3 as the additive. Na2CO3 with a mass ratio of 2.5∶1 was mixed with carbon residue, placed in a crucible-resistance furnace, and then baked at 950 ℃ for 2 h. Test results show that the alumina, cryolite, and sub-cryolite in the carbon residue are consumed by Na2CO3, and the mixture after roasting consists of C, Na2CO3, NaF, and NaAlO2. After roasting, the mixture is leached for 1 hour with a pH of 14 and at a leaching temperature of 25 ℃. The purity of the recovered carbon powder after solid-liquid separation can reach 89%. The carbonation method is used to recover F− in the leachate to obtain powdered cryolite with qualified main components. Properly increasing the roasting temperature and extending the holding time can improve the separation efficiency of carbon and electrolyte. Research on economical and effective carbon residue treatment methods can not only solve the environmental pollution caused by carbon residue, but it can also have a profound impact on the sustainable development of society.
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Key words:
- carbon residue /
- aluminum electrolysis /
- electrolyte /
- carbon powder /
- cryolite
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图 4 炭渣焙烧−水浸试验原理图
Figure 4. Principle diagram of carbon residue roasting−water immersion test
图 5 焙烧试验主要反应热力学计算曲线
Figure 5. Main reaction thermodynamic calculation curve of roasting test
图 7 炭渣（a）和焙烧混合料（b）的SEM-EDS图
Figure 7. SEM-EDS mapping of carbon residue (a) and roasted mixture (b)
图 8 不同温度下Al−H2O 的E−pH图。（a）25 ℃；（b）50 ℃；（c）75 ℃；（d）100 ℃
Figure 8. E−pH diagram of Al−H2O at different temperatures: (a) 25 ℃; (b) 50 ℃; (c) 75 ℃; (d) 100 ℃
图 9 950 ℃时保温时间与混合料质量损失的关系
Figure 9. Relationship between the holding time and mass loss of the mixture at 950 ℃
a—m[Na2CO3]=7.5 g, m[carbon residue]=3 g; b—m[Na2CO3]=7 g, m[carbon residue]=3.5 g; c—m[Na2CO3]=5.25 g, m[carbon residue]=5.25 g
图 10 焙烧2 h时焙烧温度与混合料的质量损失的关系
Figure 10. Relationship between the roasting temperature and mass loss of the mixture at 2 h roasting
a—m[Na2CO3]=7.5 g, m[carbon residue]=3 g; b—m[Na2CO3]=7 g, m[carbon residue]=3.5 g; c—m[Na2CO3]=5.25 g; m[carbon residue]=5.25 g
图 11 浸出时间与炭粉纯度的关系
Figure 11. Relationship between leaching time and carbon powder purity
图 12 试验Ⅶ（a）和Ⅷ（b）所得炭粉的X射线衍射物相分析
Figure 12. X-ray diffraction phase analysis of carbon powder obtained in Ⅶ(a) and Ⅷ(b)
图 13 试验Ⅷ所得冰晶石的X射线衍射物相分析
Figure 13. X-ray diffraction phase analysis of cryolite obtained in Experiment Ⅷ
图 14 试验Ⅷ所得炭粉（a, b）和冰晶石（c, d）的SEM图
Figure 14. SEM images of carbon powder (a, b) and cryolite (c, d) obtained from test Ⅷ
表 1 炭渣主要成分（质量分数）
Table 1. Main components of carbon residue
% Sample
numberC Na Al F O K Li Mg Ca Total Sample 1 30.1 16.53 11.69 33.55 — 0.11 0.002 0.3 1.14 93.422 Sample 2 29.2 16.67 10.92 34.7 — 0.1 0.002 0.33 1.21 93.132 
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表 2 炭渣焙烧试验参数及炭粉产物纯度
Table 2. Roasting test parameters of carbon residue and purity of carbon powder
Test Components Roasting temperature/
℃Holding time/
hThe quality of carbon
powder/gPurity of carbon powder/
%Exp. Ⅰ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 800 1 5.51 55 Exp. Ⅱ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 850 1 5.28 56 Exp. Ⅲ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 900 0.5 3.99 70 Exp. Ⅳ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 900 1 3.69 72 Exp. Ⅴ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 900 1.5 3.71 73 Exp. Ⅵ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 900 2 3.52 76 Exp. Ⅶ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 950 1 3.48 84 Exp. Ⅷ m[carbon residue] = 10 g, m[Na2CO3] = 25 g 950 2 2.95 89
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参考文献
[1] Grjothem K, Welch B J. Aluminium smelter technology. Dusseldorf: Aluminium-Verlag, 1980 [2] Xu H F, Fan L J, Zhang Y, et al. Analysis of sources of carbon residue and its control methods. Carbon Tech, 2009, 28(6): 41 doi: 10.3969/j.issn.1001-3741.2009.06.009许海飞, 樊利军, 张阳, 等. 炭渣来源及其控制方法分析. 炭素技术, 2009, 28(6):41 doi: 10.3969/j.issn.1001-3741.2009.06.009 [3] Hume S M, Utley M R, Welch B J. The influence of low current densities on anode performance. Light Metals. 1992: 687 [4] Zhao D F, Yang Y Z. Analysis on the harmfulness of carbon slag in aluminum electrolysis production. Sci Technol Innov Her, 2013, 10(10): 154 doi: 10.3969/j.issn.1674-098X.2013.10.100赵东方, 杨玉卓. 探析铝电解生产中碳渣的危害性. 科技创新导报, 2013, 10(10):154 doi: 10.3969/j.issn.1674-098X.2013.10.100 [5] Zhang B S. The harm of carbon slag in aluminum electrolysis production. Xinjiang Nonferrous Metals, 2013, 36(1): 70张保社. 碳渣在铝电解生产中的危害. 新疆有色金属, 2013, 36(1):70 [6] Li C Z. Causes of carbon slag formation in aluminum electrolysis production and its treatment methods. Qinghai Sci Technol, 2008, 15(4): 74 doi: 10.3969/j.issn.1005-9393.2008.04.032李长珍. 铝电解生产中炭渣生成的原因及其处理方法. 青海科技, 2008, 15(4):74 doi: 10.3969/j.issn.1005-9393.2008.04.032 [7] Wen L G, Sun H L, Li J Y. Synthetic analysis of the recovery and utilization for carbon slag from aluminium electrolysis in Qingtongxia aluminum plant in Ningxia. Inn Mong Petrochem Ind, 2019, 45(6): 13 doi: 10.3969/j.issn.1006-7981.2019.06.005温铝刚, 孙海璐, 李京彦. 宁夏青铜峡铝厂铝电解炭渣回收利用综合分析. 内蒙古石油化工, 2019, 45(6):13 doi: 10.3969/j.issn.1006-7981.2019.06.005 [8] Lu H M, Qiu Z X. Comprehensive utilization of carbonaceous slag from aluminium reduction cells. Multipurp Util Miner Resour, 1997(2): 45卢惠民, 邱竹贤. 铝电解槽炭渣的综合利用研究. 矿产综合利用, 1997(2):45 [9] Liu Y Q, Ji F W. Hazard analysis and control of carbon slag in aluminum electrolysis production. World Nonferrous Met, 2013(12): 30刘永强, 姬凤武. 铝电解生产中炭渣的危害分析与控制. 世界有色金属, 2013(12):30 [10] Huang Y K, Xiao H Z, Peng D Q. Formation and distribution of carbon slag in aluminum electrolyte melt and its separation measures. Light Met, 1994(10): 23黄英科, 肖辉照, 彭德泉. 铝电解质熔液中碳渣的形成和分布及其分离措施. 轻金属, 1994(10):23 [11] Jin R Y, Wang Y M. The cause of carbon residue increase in aluminum plant and its prevention. Shanghai Met (Nonferrous Fascicule) , 1992, 13(4): 54金瑞玉, 王玉明. 铝厂碳渣增多的原因及其预防. 上海金属(有色分册), 1992, 13(4):54 [12] Xie Y M. Impact of carbon residue to the aluminum electrolysis production. Gansu Metall, 2014, 36(4): 32 doi: 10.3969/j.issn.1672-4461.2014.04.010谢叶明. 碳渣对铝电解生产的影响. 甘肃冶金, 2014, 36(4):32 doi: 10.3969/j.issn.1672-4461.2014.04.010 [13] Peng J P, Liang C, Di Y Z, et al. Method for Treating Anode Carbon Residue of Aluminum Electrolytic Cell by Using NaCl Molten Salt Extraction Method: China Patent, CN110938838A. 2020-3-31彭建平, 梁诚, 狄跃忠, 等. 利用NaCl熔盐萃取法处理铝电解槽阳极炭渣的方法: 中国专利, CN110938838A. 2020-3-31 [14] Peng J P, Liang C, Wei Z, et al. Method for Treating Anode Carbon Residue of Aluminum Electrolytic Cell by Using NaOH Molten Salt Method: China Patent, CN110775955A. 2020-2-11彭建平, 梁诚, 魏征, 等. 一种利用NaOH熔盐法处理铝电解槽阳极炭渣的方法: 中国专利, CN110775955A. 2020-2-11 [15] Zhao R M, Yu Z L, Li S H. The recycling experimental study on aluminum electrolysis carbon residues. Yunnan Metall, 2015, 44(1): 15 doi: 10.3969/j.issn.1006-0308.2015.01.004赵瑞敏, 于站良, 李顺华. 铝电解炭渣回收利用实验研究. 云南冶金, 2015, 44(1):15 doi: 10.3969/j.issn.1006-0308.2015.01.004 [16] Kang N. Flotation of aluminum electrolytic carbon slag. Light Met, 2002(6): 42 doi: 10.3969/j.issn.1002-1752.2002.06.012康宁. 铝电解碳渣的浮选. 轻金属, 2002(6):42 doi: 10.3969/j.issn.1002-1752.2002.06.012 [17] Xue W Q, Hou X. Recycling and utilizing technology on aluminium electrolytic carbon dross. World Nonferrous Met, 2002(8): 35薛伍芹, 侯新. 铝电解炭渣回收利用技术. 世界有色金属, 2002(8):35 [18] Mei X Y, Li J, Yu Z L. The research on recycling carbon residue by Floatation process. Light Met, 2016(4): 28梅向阳, 李俊, 于站良. 浮选法回收利用碳渣实验研究. 轻金属, 2016(4):28 [19] Chai D P, Hou G H, Huang H B. Experimental study on the treatment of aluminum reduction carbon residue by vacuum metallurgy. Light Met, 2016(4): 25柴登鹏, 候光辉, 黄海波. 真空冶金法处理铝电解碳渣试验研究. 轻金属, 2016(4):25 [20] Feng N X, Wang Y W. Method for Separating and Recovering carbon and Electrolyte Components from Carbon-containing Solid Waste Material of Molten Aluminum Electrolysis: China Patent, CN104894600A. 2015-9-9冯乃祥, 王耀武. 一种从铝熔盐电解含炭固体废料中分离回收炭和电解质组分的方法: 中国专利, CN104894600A. 2015-9-9 [21] Chen X P, Zhao L, Luo Z S. Study on recycling process for electrolyte in carbon dust from reduction cells. Light Met, 2009(12): 21陈喜平, 赵淋, 罗钟生. 回收铝电解炭渣中电解质的研究. 轻金属, 2009(12):21 [22] Chen X P, Li W X, Wang Y. Method for Extracting Electrolyte from Carbon Slag of Aluminum Electrolysis Anode: China Patent, CN101063215A. 2007-10-31陈喜平, 李旺兴, 王玉. 一种提取铝电解阳极碳渣中电解质的方法: 中国专利, CN101063215A. 2007-10-31 [23] Li W X, Chen X P, Liu F Q, et al. Process for Recovering Fluoride Salt from Aluminium Electrolyzing Carbon Slag: China Patent, CN1587028A. 2005-3-2李旺兴, 陈喜平, 刘凤琴, 等. 一种回收铝电解阳极碳渣中氟化盐的方法: 中国专利, CN1587028A. 2005-3-2 [24] Li M J, Shi Z H, Zheng C F, et al. Investigation into direct synthesizing cryolite by sodium aluminate. Conserv Util Miner Resour, 2008(4): 36 doi: 10.3969/j.issn.1001-0076.2008.04.010李民菁, 史智慧, 郑朝付, 等. 铝酸钠溶液直接合成冰晶石的研究. 矿产保护与利用, 2008(4):36 doi: 10.3969/j.issn.1001-0076.2008.04.010 -
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