Critical examination of recycled municipal solid waste incineration ash as a mineral source for portland cement manufacture – A case study

Abstract

Municipal solid waste incineration (MSWI) ash has the potential to be used as mineral feed for portland cement manufacture but is not currently used in this manner in much of the world. A scoping study was performed using samples and data from Florida, US, to assess the potential magnitude of material that may be recycled to create a viable clinker. Results indicate that MSWI ash possesses the elemental ingredients to serve as a partial kiln feed replacement. Large amounts of MSWI can be used based on mineralogy alone, but chloride and alkali content limitations decrease allowable replacement amounts, especially for fly ash. Average allowable replacement percentages that did not exceed standard chloride and alkali limits were 6.4%, 0.33%, and 1.17% for bottom ash, fly ash and combined ash, respectively. MSWI bottom ash may be the preferred material stream in the absence of pre-processing techniques such as washing. The scoping study found that available MSWI ash could supply a large amount of the current kiln feed demand, and a feasibility and cost assessment supports that both MSWI facility and cement kiln operators have justification to pursue this technology with more detailed evaluations.