Comprehensive evaluation of the effectiveness on metals recovery and decontamination from MSWI fly ash by an integrating hydrometallurgical process in Guangzhou

Municipal solid waste incineration (MSWI) fly ash generally contains substantial toxic elements which can be easily released into the environment, giving rise to serious environmental contaminations. In order to dispose of these harmful fly ashes safely and feasibly, an advanced and reliable strategy is needed. This work presented an integrated method designed for recycling of valuable copper (Cu) and zinc (Zn) through hydrochloric acid leaching and sequential extraction (using LIX 860N-I and Cyanex 572 for Cu and Zn as extractants, respectively) and clean-up of cadmium (Cd) and lead (Pb) in consequential waste effluent by adsorption with a versatile material – bundle-like hydroxyapatite (B-HAP). The method was applied in the pilot scale tests with recovery yields of 95% and 61% for Cu and Zn, respectively. Additionally, satisfied removal efficiencies of Cd and Pb (over 95% for both) were realized, reaching the acceptable emission level for Cd and Pb in China. A scenario based on the latest MSW data in 2018 in Guangzhou was assessed through the integrated pilot experiment. The evaluation demonstrates a reduction of a $ 20.8 million cost; over 48.2 k GJ of energy consumption and 5800 tons of CO2 emission can be reduced in 2018, comparing to that landfilled in hazardous waste sites, which reveals great benefits. The valuable metal recovery in combination with decontamination of toxic elements/substances as a complete and combined process gives a promising fly ash treatment strategy in future