(133g) Electrochemical and Chemical Mining of Municipal Solid Waste Incinerator Ash

Nowadays, in the U.S. more than 6.6 million tons of hazardous solid residue, called municipal solid waste incineration (MSWI) ash is annually generated in waste-to-energy (WTE) plants for producing electricity and reducing landfill volume. This ash cannot be further utilized for beneficial applications, so it is mostly buried and has a negative value with the cost of a disposal fee. Moreover, the economics of MSWI is challenged by the decreasing cost of renewable electricity. However, WSWI ash represents a unique opportunity for valuable element recovery, with the embodied value ranging from $100-400/tonne. We propose an electrochemical and chemical process for mining MSWI ash that utilizes electricity from the WTE plant to electrolytically produce acid and base streams for materials recovery and refining. We establish a sequential process of electrochemical extraction and chemical precipitation, and successfully recover Cu, Pb, Zn, Mg, Ca, Fe, Al, with a purified silica co-product. Recovery of >90% of the targeted elements at purities >90% is demonstrated. The industry-scale technoeconomic analysis shows our proposed technology will realize the possibility of extracting the embodied mineral value with net positive returns that significantly exceed the combined value of WTE electricity sales and landfilling cost.