Research on Treatment of Cinder from Aluminum Electrolysis Cell Using Na2CO3
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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,大量炭渣的堆存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和过程进行了研究。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2h。试验结果表明,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1h,固液分离后的固体烘干得到炭粉,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,而且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. The accumulation of a large amount of carbon residue wastes electrolyte resources, as well as causing air, soil and water pollution. In this experiment, carbon residue was used as raw material and Na2CO3 was used as additive to study the feasibility and process of recovering carbon powder and cryolite by the roasting-water leaching process of carbon residue. The carbon residue with a mass ratio of 2.5:1 was mixed with Na2CO3, then placed in a crucible-resistance furnace, and baked at 950°C for 2h. The test results show that the alumina, cryolite and sub-cryolite in the carbon residue are consumed by Na2CO3, and the mixture after roasting is composed of C, Na2CO3, NaF, and NaAlO2. After roasting, the mixture is leached for 1 hour when the pH of 14 and leaching temperature of 25°C. 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 also have a profound impact on the sustainable development of society.
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Key words:
- carbon residue /
- Aluminum electrolysis /
- Carbon powder /
- Cryolite
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