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Leaching of spent pot - lining with aluminum anodizing wastewaters / Diego F. Lisbona in Industrial & engineering chemistry research, Vol. 51 N° 25 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8366–8377 Titre : Leaching of spent pot - lining with aluminum anodizing wastewaters : Fluoride extraction and thermodynamic modeling of aqueous speciation Type de document : texte imprimé Auteurs : Diego F. Lisbona, Auteur ; Christopher Somerfield, Auteur ; Karen M. Steel, Auteur Année de publication : 2012 Article en page(s) : pp. 8366–8377 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermodynamic  Aqueous  speciation Résumé : The cotreatment of spent pot-lining (SPL), a high fluoride (20 wt %), and cyanide (up to 1 wt %) waste generated in aluminum smelting, and Al3+ wastewaters generated by the aluminum anodizing industry was identified in this work as a treatment alternative that holds the potential to virtually remove the need for purchasing chemical reagents while keeping carbon dioxide emissions to a minimum. The process proposed involves fluoride leaching with anodizing wastewaters and precipitation of AlF2OH by treatment with caustic waste from the aluminum anodizing industry. AlF2OH can be directly injected into fluidized beds that are used to convert Al(OH)3 to AlF3. Since AlF3 is used in primary aluminum smelting, aluminum and fluoride from aluminum industry wastes such as SPL and anodizing wastewaters are recovered in a form that can be readily used as a feedstock in the aluminum industry. In this paper, the results of SPL leaching studies using aluminum anodizing waste are presented together with a model of the solution equilibria, which has been used to interpret experimental observations. Mild leaching temperatures were used and no chemical reagents other than anodizing waste were necessary to extract the soluble fluoride. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3006353 [article] Leaching of spent pot - lining with aluminum anodizing wastewaters : Fluoride extraction and thermodynamic modeling of aqueous speciation [texte imprimé] / Diego F. Lisbona, Auteur ; Christopher Somerfield, Auteur ; Karen M. Steel, Auteur . - 2012 . - pp. 8366–8377. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8366–8377 Mots-clés : Thermodynamic  Aqueous  speciation Résumé : The cotreatment of spent pot-lining (SPL), a high fluoride (20 wt %), and cyanide (up to 1 wt %) waste generated in aluminum smelting, and Al3+ wastewaters generated by the aluminum anodizing industry was identified in this work as a treatment alternative that holds the potential to virtually remove the need for purchasing chemical reagents while keeping carbon dioxide emissions to a minimum. The process proposed involves fluoride leaching with anodizing wastewaters and precipitation of AlF2OH by treatment with caustic waste from the aluminum anodizing industry. AlF2OH can be directly injected into fluidized beds that are used to convert Al(OH)3 to AlF3. Since AlF3 is used in primary aluminum smelting, aluminum and fluoride from aluminum industry wastes such as SPL and anodizing wastewaters are recovered in a form that can be readily used as a feedstock in the aluminum industry. In this paper, the results of SPL leaching studies using aluminum anodizing waste are presented together with a model of the solution equilibria, which has been used to interpret experimental observations. Mild leaching temperatures were used and no chemical reagents other than anodizing waste were necessary to extract the soluble fluoride. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3006353

Treatment of spent pot-lining with aluminum anodizing wastewaters / Diego F. Lisbona in Industrial & engineering chemistry research, Vol. 51 N° 39 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 39 (Octobre 2012) . - pp 12712–12722 Titre : Treatment of spent pot-lining with aluminum anodizing wastewaters : Selective precipitation of aluminum and fluoride as an aluminum hydroxyfluoride hydrate product Type de document : texte imprimé Auteurs : Diego F. Lisbona, Auteur ; Christopher Somerfield, Auteur ; Karen M. Steel, Auteur Année de publication : 2012 Article en page(s) : pp 12712–12722 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Wastewaters  Hydroxyfluoride Résumé : Wastewaters generated by the aluminum anodizing industry have been identified as a source of acid, Al3+, and caustic values that could be used for the treatment of spent pot-lining (SPL) generated in primary aluminum smelting. In this paper, recovery of aluminum and fluoride values as an aluminum fluoride product that could be converted into smelter grade (SG) AlF3 for recycling in aluminum smelting is reported. Experimental observations were contrasted with a thermodynamic model of the solution equilibria and new values for the solubility product of AlF2OH·1.4H2O, 10–15 at 30 °C and 10–23.8 at 50 °C, are reported. Neutralization of leachates obtained from SPL treatment with aluminum anodizing acid wastewaters was performed using 2 M NaOH and, alternatively, waste caustic solutions from the aluminum anodizing industry. pH-static precipitation with 2 M NaOH successfully recovered 92 wt % of the solubilized fluoride as AlF2OH·1.4H2O at pH 4.0 and 70 °C, although a hydrolyzed Na5Al3F14-like product (3–5 wt % Na) coprecipitated. Seeded heterogeneous nucleation of AlF2OH·1.4H2O on SG Al(OH)3 yielded a product that could be acceptable to AlF3 manufacturers, meeting specifications for particle size and phosphorus and silicon content. Caustic wastewaters from the aluminum anodizing industry were identified as suitable to provide the caustic values required for precipitation, providing that Al concentration is decreased by aging the solutions under seeded conditions. The use of caustic waste from the aluminum anodizing industry to treat the SPL leachates obtained with acidic anodizing waste totally removes the need of chemical reagents for SPL treatment and fluoride recovery. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3013506 [article] Treatment of spent pot-lining with aluminum anodizing wastewaters : Selective precipitation of aluminum and fluoride as an aluminum hydroxyfluoride hydrate product [texte imprimé] / Diego F. Lisbona, Auteur ; Christopher Somerfield, Auteur ; Karen M. Steel, Auteur . - 2012 . - pp 12712–12722. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 39 (Octobre 2012) . - pp 12712–12722 Mots-clés : Wastewaters  Hydroxyfluoride Résumé : Wastewaters generated by the aluminum anodizing industry have been identified as a source of acid, Al3+, and caustic values that could be used for the treatment of spent pot-lining (SPL) generated in primary aluminum smelting. In this paper, recovery of aluminum and fluoride values as an aluminum fluoride product that could be converted into smelter grade (SG) AlF3 for recycling in aluminum smelting is reported. Experimental observations were contrasted with a thermodynamic model of the solution equilibria and new values for the solubility product of AlF2OH·1.4H2O, 10–15 at 30 °C and 10–23.8 at 50 °C, are reported. Neutralization of leachates obtained from SPL treatment with aluminum anodizing acid wastewaters was performed using 2 M NaOH and, alternatively, waste caustic solutions from the aluminum anodizing industry. pH-static precipitation with 2 M NaOH successfully recovered 92 wt % of the solubilized fluoride as AlF2OH·1.4H2O at pH 4.0 and 70 °C, although a hydrolyzed Na5Al3F14-like product (3–5 wt % Na) coprecipitated. Seeded heterogeneous nucleation of AlF2OH·1.4H2O on SG Al(OH)3 yielded a product that could be acceptable to AlF3 manufacturers, meeting specifications for particle size and phosphorus and silicon content. Caustic wastewaters from the aluminum anodizing industry were identified as suitable to provide the caustic values required for precipitation, providing that Al concentration is decreased by aging the solutions under seeded conditions. The use of caustic waste from the aluminum anodizing industry to treat the SPL leachates obtained with acidic anodizing waste totally removes the need of chemical reagents for SPL treatment and fluoride recovery. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3013506