Mswi Bottom Ash Characterization And Resource Recovery Potential Assessment

Municipal solid waste incineration (MSWI) bottom ash contains valuable components that can be recovered as secondary materials, such as ferrous and non-ferrous metals, some rare earth elements, glass etc. Metal-free mineral fraction can be used in construction industry as a substitute for natural materials. Important benefit of bottom ash recycling for the plant operator is also in reduction of fees for solid residuals landfilling. The composition of bottom ash is highly dependent on the composition of incinerated waste but in average can be around 5-13% ferrous metals, 2-5% non-ferrous metals, 15-30% glass and ceramics, 1-5% unburned organics and 50-70% mineral fraction. Several incineration plants in Europe are equipped with advanced systems for metals recovery, mostly based on magnetic separation of ferrous metals and separation of non- ferrous metals usually by eddy-current separators.To assess the possibilities of the bottom ash treatment in the Czech Republic it is necessary to obtain data about the bottom ash composition and evaluate its resource recovery potential. This paper summarizes characteristics of bottom ash samples from waste-to-energy plant in Prague. Emphasis of the study was primarily placed on the material composition. Bottom ash samples were dried and sieved into eight size fractions in the first step. It must be said that particle size distribution plays a decisive role for further utilization of bottom ash. In the second step, individual size fractions were sorted, using magnetic separation and the set of grinding, sieving, and manual separation processes, into the following materials: glass, ceramics and porcelain, magnetic particles with ferrous scrap, non- ferrous metals, unburned organic material, and residual fraction.