Resource utilization strategies for spent pot lining: A review of the current state

Structure characteristics and adsorption performance of graphene oxide prepared by spent carbon cathode-an ultra-low temperature graphitized carbon material

Spent carbon cathode (SCC) is a hazardous waste from the aluminum electrolysis industry. It is commonly used as a carbon source in the current disposal and recovery strategies, such as combustion, or as a reductant for smelting. The novelty of this study is to propose a strategy for recycling SCC as a graphite resource and to investigate the unique structural characteristics and adsorption properties of graphene oxide produced from this low temperature graphitized carbon. The adsorption kinetics and isotherms of SCC-GO on methylene blue (MB) were studied and compared with the GO prepared from natural flake graphite (NFG) and artificial graphite (AG). The results show that SCC-GO exhibits the highest adsorption rate and adsorption capacity (647.83 mg/g) for MB, which is much higher than NFG-GO (451.22 mg/g) and AG-GO (533.12 mg/g). The analysis of the spectroscopy and morphology confirmed that SCC-GO has a high degree of crystal defects, oxidation, and surface wrinkle. Overall, this study reveals the unique structure of SCC-GO and highlights its significant scientific and application potential as an ultra-low temperature graphitized carbon. This research is also significant for recycling aluminum electrolytic cathode solid waste in the form of a graphite source.

Measurement and control of containing-fluorine particulate matter emission during spent pot lining combustion detoxification process

The particle size distribution (PSD), composition, morphology, and formation mechanism of particulate matter (PM) released from the combustion of spent pot lining with and without CaSiO₃ were investigated. The results showed that NaF and Na₃AlF₆ were found to be the main compositions of PM, and the particle size distribution of PM shows a bimodal distribution. CaSiO₃ substantially inhibited the emission of PM by transforming NaF, Na₃AlF₆, and CaF₂ into stable Ca₄Si₂O₇F₂. Moreover, CaSiO₃ also limited the formation of high hazardous PM_0.2 by providing SiO₂, Al₂O₃, and NaAlSiO₄ with high melting points as the core of promoting the growth of PM in particle size.

Recovery of carbon and cryolite from spent carbon anode slag of electrolytic aluminum by flotation based on the evaluation of selectivity index

One of the main electrolytic aluminum production costs is the consumption of carbon anodes, and carbon anode slag is a common hazardous waste in the aluminum industry. In this work, electrolytic aluminum carbon anode slag was separated by flotation. Using the selectivity index (SI) as an indicator, the influencing factors of the carbon slag flotation process were optimized, and the separation performance of carbon and cryolite in the carbon anode slag was investigated. The raw carbon anode slag was ground for 40 min to achieve dissociation of the cryolite from the carbon, the optimized SI value was then used to determine the optimal flotation test conditions. The test results showed that the SI value under the optimal grinding flotation was approximately four times larger than the value of direct flotation. This indicated that carbon anode slag had a better flotation selectivity under the grinding flotation, which significantly improved the flotation performance.