CMA

52 stack at the kiln end ( ue) were analysed or the PCDD/Fs and HMs as Hg, Tl, Cd, Pb, As, Be, Cr, Sb, Cu, Co, Mn, Ni, V, Zn, Mo, Ba. The sampling points and major test parameters are shown in Figure 3. Distribution of heavy metals and PCDD/Fs in the water washing and co-processing of MSWI y ash in cement kiln were studied. Co-processing of DWFA did not in uence on the release of PCDD/Fs; baseline and co-processing values ranged from 0.022 to 0.039 ng-TEQ/N m3, and from 0.01 to 0.031 ng-TEQ/N m3, respectively. The destruction ef ciency for PCDD/Fs in MSWI y was 82.6%. Stack emission of Hg seems correlated with feeding rate of MSWI y ash, further veri cation study shall be carried out. Co-processing of DWFA had no observable impact on heavy metal content of clinker except for Cd, Pb and Sb (which came from DWFA). This technology seems to be an environmentally sound option for the disposal of MSWI-FA. Conclusion Ever increasing waste generation coupled with a move towards effective waste management strategies posits MSWI as a preferred technology for waste volume reduction and energy production. The residual ash leftover from the incineration process is a potential substitute for the raw materials traditionally used in cement production. Several studies have been published on the topic of MSWI ash incorporation into cement production, but a critical gap in the literature is the lack of a comprehensive overview of the published science regarding this practice. Existing studies suggest viable addition of untreated MSWI ash addition is limited to below 10%, but control of harmful substances may increase viable addition to around 30–50%, with some exceptions. The literature points to a variety of implications of this recycling process • Generally, MSWI ash has the Ca, Si, Fe, and Al necessary for cement production, but may be severely limited as a raw material substitute due to its high chloride and alkali content that leads to deleterious reactions within the production process as well as the final product. Figure 4. PCDD/F mass balance during pre-treatment and co-processing in the cement kiln (Yan et al, 2018) • Pre-treatment of the ash is recommended (or required) before it is used as a cement kiln feed; this is often a water-washing process. • MSWI ash contains several trace elements that are not found in traditional kiln feed materials, and these trace elements have documented impacts on cement performance. • Using MSWI ash as a raw material generally creates the necessary clinker mineralogy without issue, with some parameters differing slightly. • Impacts on cement performance are highly variable, with a negative trend associated with increasing ash addition. • Trace metals are generally stabilized in clinker, but total trace element content may be an issue for end of life recycling opportunities and could impact clinker phase formation. • Trace elements have variable volatility dependent on kiln operating conditions and the ability to form volatile salts with low boiling points. • CO2 emissions are mitigated by the introduction of MSWI ash, and life cycle assessments point to MSWI ash kiln feed as an environmentally favourable and cost-effective management strategy. Drying flue Water Water is circularly used PCDD/F mass flow Industrial salt Raw Meal CKD is recirculated into silo of Raw Meal Flue gas Clinker Cement kiln dust (CKD) MSWI fly ash Pretreatment Cement kiln Co-processing Coal