Detoxification of spent cathode carbon blocks from aluminum smelters by joint controlling temperature-vacuum process

Xie, Mingzhuang; Li, Rongbin; Zhao, Hongliang; Liu, Wei; Lu, Tingting; Liu, Fengqin

doi:10.1016/j.jclepro.2019.119370

Cited by 64 publications

(11 citation statements)

References 15 publications

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“…However, the massive consumption of high-quality graphite carbon from the spent cathode carbon causes it difficult to be carried out in an industrial application. In the vacuum evaporation process, the temperature and vacuum pressure affects the fluoride and cyanide removal rates greatly [10,11,15]. The soluble fluoride content could be reduced to 3.5 mg/L and the cyanide was completely decomposed under the conditions of vacuum pressure of 3000 Pa and temperature of 1700°C.…”

Section: Introductionmentioning

confidence: 99%

“…The soluble fluoride content could be reduced to 3.5 mg/L and the cyanide was completely decomposed under the conditions of vacuum pressure of 3000 Pa and temperature of 1700°C. However, the huge energy consumption restricts this vacuum evaporation process for an industrial application [15]. Through a hydrometallurgical method, the carbon and electrolyte components can be effectively recovered from the spent cathode carbon, and in additional the purity of the obtained carbon exceeds 95% [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Tian

2022

J min metall B Metall

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The fluorides from spent carbon cathodes could be effectively solidified in a molten copper smelting slag (FeO-Fe3O4-SiO2-CaO-Al2O3) in forms of CaF2 and Ca4Si2F2O7. The results of thermodynamic analysis, chemical analysis, and XRD and EPMA analyses showed that the F solidification efficiency increased with the CaO amount and decreased with the addition of Al2O3 and SiO2. In addition, it was noteworthy that the F solidification efficiency decreased with an excessive CaO amount, which could be ascribed to the consumption of SiO2 through forming CaSiO3 and Ca3Si2O7. It restricted the solidification of the fluoride into Ca4Si2F2O7. Under the conditions of melting temperature of 1300?C, residence time of 60 min and N2 flow rate of 40 ml/min, the optimum CaO and NaF amounts were found to be 20 wt.% and 6 wt.% respectively, in which the F solidification efficiency in the copper smelting slag of FeO-Fe3O4-SiO2-CaO-Al2O3 obtained 98.35%.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Tian

2022

J min metall B Metall

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“…The typical service life of the modern reduction cell is about 2500–3000 days. About 24–30 kg of SPL is generated for every ton of primary aluminum and about 1.7 million tons of SPL are discharged per year. , Although the copper slag and SPL are solid wastes, they contain many valuable elements, such as copper, cobalt, and carbon. Therefore, the key issue for processing these solid wastes is effective harmless treatment and economic recycling.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, considerable quantities of harmful and toxic components are adsorbed in SPL. − The efficient utilization and recycling of SPL has become an urgent problem in the aluminum industry. The fluoride in SPL can be completely removed by hydro-processing, and high temperature >1973 K or high vacuum is required for pyro-processing, which has a high requirement for the equipment. ,, …”

Section: Introductionmentioning

confidence: 99%

Recovery of Copper and Cobalt from Converter Slags via Reduction–Sulfurization Smelting Using Spent Pot Lining as the Reductant

Zhao

Hong

et al. 2021

ACS Sustainable Chem. Eng.

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Large amounts of solid wastes are produced in copper and aluminum smelting processes, which not only cause losses of valuable resources but also threaten the ecology and environment. In this study, a reduction−sulfurization smelting method was used for recovering Cu and Co from converter slags by using spent pot lining (SPL) as the reductant. CaO was added to fix the fluorine from SPL into the cleaned slag. Thermodynamic analysis and experiments were performed to verify the feasibility and determine the optimal conditions of this smelting process. The optimum reductant addition of spent cathode carbon block (SCCB) and spent SiC side block (SSCB) was 8−12 wt %, and the copper and cobalt recovery reached more than 98 and 96%, respectively. The addition of 10 wt % CaO for SCCB improved slag viscosity and promoted the separation between slag and matte/alloy and fixed fluorine in the cleaned slag in the form of insoluble calcium fluoride. The metallized Cu−Co matte was obtained, in which Cu mainly existed in the form of sulfide and Co mainly existed in the form of an iron cobalt alloy.

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“…15 In the pyrometallurgical process, most of the fluoride is volatilized under hightemperature and vacuum conditions, and cyanide is oxidized and decomposed. 16,17 However, CaF 2 and silicate with a high melting point and a low vapor pressure are difficult to separate at low temperatures. 17 Recently, the co-utilization of SCC with other solid wastes such as red mud, textile sludge, and coal gangue has attracted widespread attention.…”

Section: ■ Introductionmentioning

confidence: 99%

Detoxification and Recovery of Spent Carbon Cathodes via NaOH–Na₂CO₃ Binary Molten Salt Roasting–Water Leaching: Toward a Circular Economy for Hazardous Solid Waste from Aluminum Electrolysis

Yao

Xiao

Mao

et al. 2020

ACS Sustainable Chem. Eng.

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The conversion of solid waste into secondary resources has become a prerequisite for the sustainable development of the industry. This study focused on the development of the detoxification process for spent carbon cathode (SCC) without environmental pollution risks and the exploration of the recycling direction of recovered carbonaceous materials. First, the mechanism of thermodynamic conversion and decomposition of toxic substances was explored. Parameters of NaOH–Na2CO3 binary molten salt roasting were optimized through an orthogonal design and a single-factor experiment, and gas release behavior during detoxification treatment was investigated. Results showed that most of the fluoride and cyanide were dissociated and decomposed, and the leaching concentration of fluoride and cyanide was as low as 7.58 and 0.12 mg/L after detoxification treatment, respectively. Then, a multistage recovery process of fluorine from fluorine-containing leachate was designed, and the comprehensive utilization of exhaust gas and the recycling of the reaction reagent were realized simultaneously. The possibility of recovering graphitized carbon blending to prepare carbon anodes was discussed in detail, and the catalytic mechanism of main impurity elements on the O2/CO2 reactivity of carbon anodes was investigated via density-functional-based tight binding (DFTB). The results showed that the Boudouard reaction and carbon–O2 reaction were affected because of the presence of Ca or Na, and the recovered graphitized carbon with a low blending ratio was more suitable for the preparation of carbon anodes. Finally, an economic benefit analysis was conducted to evaluate the industrial application potential of the proposed detoxification treatment. Compared with landfills, the proposed process reduced the disposal cost while eliminating environmental pollution risks and realized the on-site recovery and reuse of valuable components, showing considerable environmental and economic benefits.

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Detoxification of spent cathode carbon blocks from aluminum smelters by joint controlling temperature-vacuum process

Cited by 64 publications

References 15 publications

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Recovery of Copper and Cobalt from Converter Slags via Reduction–Sulfurization Smelting Using Spent Pot Lining as the Reductant

Detoxification and Recovery of Spent Carbon Cathodes via NaOH–Na₂CO₃ Binary Molten Salt Roasting–Water Leaching: Toward a Circular Economy for Hazardous Solid Waste from Aluminum Electrolysis

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Detoxification of spent cathode carbon blocks from aluminum smelters by joint controlling temperature-vacuum process

Cited by 64 publications

References 15 publications

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

Recovery of Copper and Cobalt from Converter Slags via Reduction–Sulfurization Smelting Using Spent Pot Lining as the Reductant

Detoxification and Recovery of Spent Carbon Cathodes via NaOH–Na2CO3 Binary Molten Salt Roasting–Water Leaching: Toward a Circular Economy for Hazardous Solid Waste from Aluminum Electrolysis

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Detoxification and Recovery of Spent Carbon Cathodes via NaOH–Na₂CO₃ Binary Molten Salt Roasting–Water Leaching: Toward a Circular Economy for Hazardous Solid Waste from Aluminum Electrolysis