Separation of fluorine and aluminum from secondary aluminum dross by calcium-cured alkali roasting-water leaching
(1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China)
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China)
Abstract: A combined strategy of calcium-cured alkali roasting and water leaching was devised to treat secondary aluminum dross. The effects of calcium oxide dosage, sodium hydroxide dosage, roasting temperature, and time on aluminum extraction behavior and fluorine curing behavior were studied. Under optimal experimental conditions: roasting temperature of 1000 °C, Al？NaOH mole ratio of 1？0.6, F？CaO mole ratio of 1？2.5, and roasting time of 2.0 h, fluorine and aluminum were separated, with 99.98% of the fluoride solidified and 52.97% of the aluminum extracted. The sodium aluminate products obtained by evaporation and crystallization from leaching solution met the industrial standards of China. The aqueous residue can be used as a raw material for quick-setting cement. Overall, this study provides an effective and environmentally friendly strategy for the treatment of secondary aluminum dross.
Key words: secondary aluminum dross; calcium-cured alkali roasting; separation; fluorine; aluminum; sodium aluminate; clean production