TY - JOUR A1 - Peplinski, Burkhard A1 - Adam, Christian A1 - Michaelis, Matthias A1 - Kley, Gerd A1 - Emmerling, Franziska A1 - Simon, Franz-Georg T1 - Reaction sequences in the thermochemical treatment of sewage sludge ashes revealed by X-ray powder diffraction - A contribution to the European project SUSAN N2 - The sequence of reactions accompanying the thermochemical treatment of an iron- and aluminium-bearing sewage sludge ash was ascertained by investigating two systematic series of samples. The ash was thermochemically treated in a lab-scale rotary furnace after mixing it with a chlorine-donor, either CaCl2 or MgCl2. Within each of these two sample series only a single process parameter, the reaction temperature, was varied, namely between 350 and 1050°C. It was found, that among the numerous crystalline phases present in the raw ash only quartz and hematite continue to exist after thermochemical treatments carried out at 1050°C, whereas all other components undergo at least one decomposition-recrystallization cycle. Some of the components re-crystallize even several times. It was proved that the restructuring of the calcium- and phosphorus-bearing mineral phases proceeds via the formation of chlorspodioside, Ca2PO4Cl. The influence of the type of chlorine-donor on the final product was elucidated in detail and - to the best of our knowledge - for the first time crystalline AlPO4 was found in a sewage sludge ash and its decomposition was investigated, too. KW - XRD KW - Phosphorus recovery KW - Sewage sludge ash KW - Urban mining KW - Fertilizers PY - 2009 U6 - https://doi.org/10.1524/zksu.2009.0068 SN - 0930-486X VL - 30 EPDIC 2008 SP - 459 EP - 464 PB - Oldenbourg CY - München AN - OPUS4-20562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -