Highly efficient recovery and clean-up of four heavy metals from MSWI fly ash by integrating leaching, selective extraction and adsorption

• Published in: Journal of cleaner production Vol. 234; pp. 139 - 149
• Main Authors: Tang, Jinfeng, Su, Minhua, Wu, Qihang, Wei, Lezhang, Wang, Nana, Xiao, Enzong, Zhang, Hongguo, Wei, Yongjun, Liu, Yingkui, Ekberg, Christian, Steenari, Britt-Marie, Xiao, Tangfu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 10.10.2019
• Subjects: Cadmium/lead; Copper/zinc; Detoxification; Hydrometallurgy; Metal recovery; MSWI fly ash; MSWI fly ash; Metal recovery; Cadmium/lead; Copper/zinc; Detoxification; Hydrometallurgy
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2019.06.198

Municipal solid waste incineration (MSWI) fly ash contains significant amounts of heavy metals (e.g., Cd, Cu, Pb and Zn) and is therefore considered to be a hazardous waste requiring proper treatment prior to its disposal. In this work, an integrated hydrometallurgical process for treatment of MSWI fly ash was evaluated. Valuable metals, e.g. Cu and Zn, were first recovered by combining leaching and extraction sequentially. In the next step, the t removal of Cd and Pb from the remaining leachate using four types of iron-based adsorbents was evaluated. The leaching was optimized with respect to pH, leaching time and liquid to solid ratio. A test done under optimal conditions gave metal releases of 100% and 80% for Cu and Zn as well as 100% and 85% for Cd and Pb, respectively. The resulting leachate was contacted with organic phases based on kerosene containing the extractants LIX860N–I for Cu extraction and Cyanex 572 for Zn extraction in two consecutive steps. Efficient extractions were achieved, thus demonstrating that the combination of leaching and extraction can be successfully used for the recovery of Cu and Zn. Adsorption of heavy metal ions on various iron based sorbents to detoxify the aqueous effluent from the extraction showed good removal efficiency (more than 95%) for both Cd and Pb. The results of this study show that the proposed integrated process is a promising tool that can be used in the strategy for metal recovery and detoxification of MSWI fly ash. [Display omitted] •A integrated method for recovery and clean up of metals from fly ash was developed.•Enhanced leaching gave a high yields of Cu (100%) and Zn (>80%) with HCl.•Removal of Cd and Pb in wastewater was proposed by adsorption.•A removal efficiency of >95% for both Cd and Pb was achieved.•The adsorption kinetics well followed the pseudo-second-order model.