Two-step process to recover metal and mineral residues from municipal solid waste incinerated (MSWI) ashes

The utilization potential of mineral fractions after metal recovery from fly ash and air pollution control residues from a municipal solid waste incineration plant was studied. Chemical leaching using acidic (H2SO4), and alkaline (NaOH) solutions was applied for metal recovery from fly ash and air pollution control residues from a municipal solid waste incineration plant. Subsequently, the feasibility of recycling both untreated and treated samples in cementitious materials was evaluated. This study aims to investigate the influences of chemical leaching on the structures and properties of MSWI residues as well as examine the utilization potential in cementitious materials of mineral residues after leaching, and their environmental risk. The use of acidic and alkaline leachants had good efficiency in critical metal recovery and unvalued/hazardous metal removal: 99 % of As, 72–80 % of Cd, 47–60 % of Zn, Cu, Co or Mn. After leaching, the chemical composition, physical properties, and mineralogical phases of the incinerated residues were substantially modified. The postleaching mineral residues showed potential for use in supplementary cementitious materials with enhanced reactivity and control of hydration kinetics. The compressive strength of cement pastes using 20 % of MSWI residues can obtain 14 MPa after 7 days. Detrimental impacts from potential toxic elements in incinerated residues can be alleviated through chemical leaching.