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After shutting down a cell for re-lining, we deal with the Spent Pot Lining (SPL), consisting of carbon and refractory materials. Most of SPL, which contains a lot of valuable components, remains un-used due to the difficulties associated with the extraction of such components and is transported to a landfill for industrial waste. The paper describes some efficient analytical methods used to analyze the chemical composition of SPL, including obtaining data on the qualitative composition and (or) the proportion of components in the part of the lining that is being researched, including information on the local distribution and structure of substances. The information obtained in the course of research on the impurity profile of SPL samples is necessary and important for the purpose of forecasting the service life of the cell and developing further technology for disposing or re-cycling this type of waste. The paper discusses the results obtained by different research methods: X-ray diffraction (XRD) analysis, approximate quantitative X-ray fluorescence analysis, thermogravimetric analysis (TGA), electron microscopy, which, together, provide more information on the object of researching.

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The production of aluminum by electrolysis of cryolite-alumina melts is associated with generation of process waste including gas cleaning sludge, electric filter dust, coal flotation tailings, and spent pot lining (SPL). Most of this waste is then stored in sludge fields, deteriorating the environment near aluminum works. 30 to 50 kg of spent pot lining is produced per ton of Al. The authors’ research was dedicated to finding the best reagent for solvent extraction of valuable components (fluorine in particular) in the process of SPL hydrometallurgy. To that end, the research team sampled carbon parts of lining at the RUSAL Bratsk facility in Shelekhov, Irkutsk Oblast. The following reagents were tested: 2 wt.% solutions of sulfuric acid and sodium hydroxide. Leaching lasted 60 minutes in each experiment. 2% H2SO4 solution was found to release fluorine at a higher rate. However, the resulting liquors contained sulfates, which might negatively affect the service life of equipment; for this reason, 2% NaOH solution was chosen for further leaching of fluorine from spent carbon parts of lining.