Investigation of Carbon Mineralization and Copper Recovery from Municipal Solid Waste Incineration Bottom Ash Using a Recyclable Solvent Glycine

Abstract

Municipal solid waste incineration bottom ash （MSWIBA） contains abundant alkaline minerals and valuable metals such as copper, making it a promising feedstock for both carbon mineralization and copper recovery. However, the simultaneous implementation of CO2 sequestration and copper recovery from MSWIBA remains relatively unexplored, and the pathways of metal migration, leaching behavior, and impurity precipitation have not yet been fully clarified. Therefore, in this study, an indirect carbon mineralization process using a recyclable glycine-based solvent was developed to achieve simultaneous CO2 sequestration and copper recovery from MSWIBA. The effects of glycine concentration, temperature, and aeration conditions on the leaching behavior of Ca and Cu were investigated. Carbonation was conducted under controlled pH conditions, and the CaCO3 polymorph was identified by powder X-ray diffraction （PXRD）. We confirmed that Cu leaching efficiency increased from 24.2% to 45.0% under high-temperature and aeration conditions. In addition, CaCO3 precipitation efficiency increased from 84.11% to 95.47%, and vaterite was identified as the dominant CaCO3 polymorph after 5 min of CO2 blowing at pH 8.5. Cu was selectively precipitated, achieving a recovery efficiency of 66.83% using a sulfide salt at a Cu/S molar ratio of 1:2. After metal removal, glycine could be reused in subsequent leaching cycles without significant loss of efficiency. The proposed process offers a sustainable and cost-effective strategy for MSWIBA valorization, which contributes to carbon neutrality and the circular economy.