TY - JOUR A1 - Adamczyk, Burkart A1 - Brenneis, Rudolf A1 - Adam, Christian A1 - Mudersbach, D. T1 - Recovery of chromium from AOD-converter slags N2 - Slags from the production of high-alloyed steel contain both chemically bound chromium (mainly as Cr2O3) in the mineral fraction and elemental chromium in the metallic remainders. Thermochemical post treatment of the slag in an electric arc furnace under reducing conditions enables the nearly complete recovery of the total amount of chromium in form of a metallic alloy. The best results were achieved by resistance melting (submerged electrodes) with addition of a reducing agent into the melt. The efficiencies of the reducing agents carbon, aluminium, silicon (as ferrosilicon) and silicon carbide were investigated and compared. As aluminium is the strongest reducing agent, it is less selective and reduces much more SiO2 than Cr2O3. While SiC shows only low reactivity because of its high thermal resistance, carbon and silicon had the highest reducing potentials: More than 97% of the chemically bound chromium can be recovered by application of these reducing agents. Due to the high temperature required for the reduction of the chromium compounds, the reduction of SiO2 as an undesired side reaction cannot be avoided. However, compared with mechanical procedures that are limited to the recovery of the metallic remainders, the total chromium recovery can be significantly increased by the described reductive melting procedure. KW - Arc furnace KW - By-product KW - Chromium recovery KW - High-alloyed steel KW - Reductive melting KW - Slag treatment KW - Slag KW - Thermochemical treatment PY - 2010 DO - https://doi.org/10.1002/srin.201000193 SN - 1611-3683 SN - 0177-4832 VL - 81 IS - 12 SP - 1078 EP - 1083 PB - Verl. Stahleisen CY - Düsseldorf AN - OPUS4-22898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Oliver A1 - Grabner, Angela A1 - Adam, Christian T1 - Complete survey of German sewage sludge ash N2 - The amount of sewage sludge produced worldwide is expected to further increase due to rising efforts in wastewater treatment. There is a growing concern against its direct use as fertilizer due to contamination of the sludge with heavy metals and organic pollutants. Incinerating the sludge degrades organic compounds almost completely and concentrates heavy metals and phosphorus. However, the sewage sludge ash (SSA) is almost completely disposed of and with it all resources are removed from the economic cycle. Comprehensive knowledge of the composition of SSA is crucial to assess the resource recovery potentials. We conducted a survey of all SSA emerging in Germany and determined the respective mass fractions of 57 elements over a period of one year. The median content of phosphorus was 7.9%, indicating an important recovery potential. Important trace elements were Zn (2.5 g/kg), Mn (1.3 g/kg), and Cu (0.9 g/kg). Mass fractions of technology metals such as V, Cr, Ga, Nb, and rare earths were comparatively low. Considering the possible use of SSA as secondary raw material for fertilizer production it should be noted that its Cd and U content (2.7 mg/kg and 4.9 mg/kg respectively) is significantly lower than that of rock phosphate based mineral fertilizers. PY - 2014 DO - https://doi.org/10.1021/es502766x SN - 0013-936X SN - 1520-5851 VL - 48 IS - 20 SP - 11811 EP - 11818 PB - ACS Publ. CY - Washington, DC AN - OPUS4-32646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Adam, Christian A1 - Brenneis, Rudolf A1 - Adamczyk, Burkart T1 - Möglichkeiten der thermochemischen Behandlung von Reststoffen KW - Thermochemische Stofftrennung KW - Wertstoffrückgewinnung PY - 2010 DO - https://doi.org/10.1002/cite.201050012 SN - 0009-286X SN - 1522-2640 VL - 82 IS - 9 SP - 1579 EP - 1580 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-22004 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gentzmann, Marie A1 - Paul, Andrea A1 - Serrano, Juan A1 - Adam, Christian T1 - Understanding scandium leaching from bauxite residues of different geological backgrounds using statistical design of experiments N2 - The leaching behavior of scandium (Sc) from bauxite residues can differ significantly when residues of different geological backgrounds are compared. The mineralogy of the source rock and the physicochemical environment during bauxitization affect the association of Sc in the bauxite i.e., how Sc is distributed amongst different mineral phases and whether it is incorporated in and/or adsorbed onto those phases. The Sc association in the bauxite is in turn crucial for the resulting Sc association in the bauxite residue. In this study systematic leaching experiments were performed on three different bauxite residues using a statistical design of experiments approach. The three bauxite residues compared originated from processing of lateritic and karstic bauxites from Germany, Hungary, and Russia. The recovery of Sc and Fe was determined by ICP-OES measurements. Mineralogical changes were analyzed by X-ray-diffraction and subsequent Rietveld refinement. The effects of various parameters including temperature, acid type, acid concentration, liquid-to-solid ratio and residence time were studied. A response surface model was calculated for the selected case of citric acid leaching of Hungarian bauxite residue. The investigations showed that the type of bauxite residue has a strong influence. The easily leachable fraction of Sc can vary considerably between the types, reaching ~20–25% in German Bauxite residue and ~50% in Russian bauxite residue. Mineralogical investigations revealed that a major part of this fraction was released from secondary phases such as cancrinite and katoite formed during Bayer processing of the bauxite. The effect of temperature on Sc and Fe recovery is strong especially when citric acid is used. Based on the exponential relationship between temperature and Fe-recovery it was found to be particularly important for the selectivity of Sc over Fe. Optimization of the model for a maximum Sc recovery combined with a minimum Fe recovery yielded results of ~28% Sc recovery at <2% Fe recovery at a temperature of 60 ◦C, a citric acid normality of 1.8, and a liquid-to-solid ratio of 16 ml/g. Our study has shown that detailed knowledge about the Sc association and distribution in bauxite and bauxite residue is key to an efficient and selective leaching of Sc from bauxite residues. KW - Bauxite residue KW - Scandium KW - Leaching KW - Design of experiments KW - Red mud PY - 2022 DO - https://doi.org/10.1016/j.gexplo.2022.107041 SN - 0375-6742 VL - 2022 IS - 240 SP - 1 EP - 13 PB - Elsevier Science CY - Amsterdam AN - OPUS4-55531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Severin, M. A1 - Breuer, J. A1 - Rex, M. A1 - Stemann, Jan A1 - Adam, Christian A1 - Van den Weghe, H. A1 - Kücke, M. T1 - Phosphate fertilizer value of heat treated sewage sludge ash N2 - This study focuses on the question whether heat treated sewage sludge ashes are more favourable as fertilizers than untreated sewage sludge ashes (USSA) and whether their fertilization effects are comparable with commercial triple superphosphate (TSP). In a pot experiment, maize was fertilized either with one of three heat treated and Na-, Ca- and Si-compounds amended sewage sludge ashes (two glown phosphates, steel mill slag + sewage sludge ash) or USSA or TSP as control. Fertilization with USSA did not increase the biomass yield and the P uptake of maize in comparison to the P0 treatment (7.25 resp. 8.35 g dry matter/pot). Fertilization with heat treated sewage sludge ashes and TSP resulted in significantly higher yields and plant P uptakes which are on average eight times higher than treatment with USSA and P0 control. Biomass yields and P uptake of maize after fertilization with heat treated sewage sludge ashes are not significantly different from those after TSP fertilization. The main P compound in USSA is Ca3(PO4)2. By heat treatment and amendment with different sodium, calcium, sulphur and silicon containing additives or steel mill converter slag, Ca3(PO4)2 is converted to Ca- and Na-silico-phosphates, which have a higher water solubility than Ca3(PO4)2. This increased solubility is responsible for the high plant availability of this phosphates. KW - P recycling KW - Sustainability KW - P solubility PY - 2014 UR - http://www.agriculturejournals.cz/publicFiles/138177.pdf SN - 1214-1178 SN - 1805-9368 VL - 60 IS - 12 SP - 555 EP - 561 PB - Inst. CY - Prague AN - OPUS4-32147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Adam, Christian A1 - Schick, J. A1 - Kratz, S. T1 - Düngemittel aus Klärschlammasche - Die Ergebnisse aus dem EU-Projekt SUSAN legen die großtechnische Umsetzung eines neuen thermochemischen Verfahrens für die Phosphor-Rückgewinnung nahe KW - Klärschlamm KW - Phosphor KW - Ressource KW - Klärschlammasche KW - P-Düngemittel KW - Pilotanlage PY - 2008 SN - 0934-3482 VL - 3 SP - 16 EP - 20 PB - Rhombos-Verl. CY - Berlin AN - OPUS4-17847 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Adam, Christian A1 - Peplinski, Burkhard A1 - Kley, Gerd A1 - Kratz, S. A1 - Schick, J. A1 - Schnug, E. T1 - Phosphorrückgewinnung aus Klärschlammaschen - Ergebnisse aus dem EU-Projekt SUSAN N2 - Phosphor ist ein für alle Lebewesen essenzielles Element und kann in seinen Funktionen z. B. als Bestandteil der DNS und RNS sowie als Schlüsselelement beim Energiestoffwechsel (ADP/ATP) nicht ersetzt werden. Klärschlammaschen sind aufgrund ihrer hohen Gehalte an Phosphor (15–25 % P2O5) geeignete Sekundärrohstoffe für die Herstellung von P-Düngemitteln. Aufgrund der schlechten Pflanzenverfügbarkeit des Phosphors und der Gehalte an umweltrelevanten Schwermetallen sollten diese allerdings nicht direkt in der Landwirtschaft eingesetzt werden. Im Mittelpunkt des EU-Projekts SUSAN steht die Entwicklung und Optimierung einer thermochemischen Behandlung von Klärschlammaschen, mit der die Düngewirkung der Aschen auf das Niveau konventioneller Mineraldünger (Thomaskali und Superphosphat SSP) angehoben wird und die Schwermetallkonzentrationen unter die Grenzwerte nach Düngemittelverordnungen europäischer Länder abgesenkt werden. Die sehr positiven Ergebnisse, die bisher im SUSAN-Projekt erzielt wurden, und die darauf basierenden ökonomischen Betrachtungen legen eine großtechnische Umsetzung des Verfahrens nahe. KW - Klärschlamm KW - Phosphor KW - Ressource KW - Klärschlammasche KW - P-Düngemittel KW - Mineralische Phasen PY - 2008 DO - https://doi.org/10.1007/s00506-008-0152-3 SN - 0945-358X SN - 1613-7566 VL - 60 IS - 3-4 SP - 55 EP - 64 PB - Springer CY - Wien AN - OPUS4-17449 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peplinski, Burkhard A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Müller, Ralf A1 - Schadrack, Reinhard A1 - Michaelis, Matthias A1 - Emmerling, Franziska A1 - Reuther, H. A1 - Menzel, Michael T1 - Evidence of formation of the tridymite form of AlPO4 in some municipal sewage sludge ashes N2 - Evidence is provided that the tridymite component observed in the X-ray diffraction patterns of some sewage sludge ashes (SSAs) should not be interpreted as the tridymite modification of SiO2 but as the tridymite form of AlPO4. This proof is based on a combined X-ray Powder Diffraction (XRD), X-ray fluorescence (XRF) and Mossbauer spectroscopy investigation of two SSAs produced at two fluidized bed incineration facilities, located in different municipalities and operated differently. The structural and chemical characterization was carried out on the 'as received' SSA samples as well as on the residues of these two SSAs pretreated by leaching in citric acid. In addition, direct proof is presented that the tridymite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850 °C) typical for fluidized bed incinerators. KW - Aluminium phosphate KW - Ash KW - Fly ash KW - Incinerator ash KW - Sewage sludge ash KW - Tridymite form PY - 2013 DO - https://doi.org/10.1017/S0885715613000869 SN - 0885-7156 VL - 28 IS - S2 SP - S425 EP - S435 PB - JCPDS CY - Swarthmore, Pa. AN - OPUS4-29703 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Oliver A1 - Adam, Christian T1 - Recovery potential of German sewage sludge ash N2 - Incineration of sewage sludge is expected to increase in the future due to growing concerns about the direct use of sludge in agriculture. Sewage sludge is the pollutant sink of wastewater treatment and thus loaded with contaminants that might pose environmental hazards. Incineration degrades organic pollutants efficiently, but since the ash is currently mostly disposed of, all valuable component like phosphorus (P) and technologically relevant metals present in the sewage sludge ash (SSA) are removed from the economic cycle entirely. We conducted a complete survey of SSA from German mono-incineration facilities and determined the theoretical recovery potential of 57 elements. German SSA contains up to 19,000 t/a P which equals approximately 13% of phosphorus applied in the German agriculture in form of phosphate rock based mineral fertilizers. Thus, SSA is an important secondary resource of P. However, its P-solubility in ammonium citrate solution, an indicator for the bioavailability, is only about 26%. Treatment of SSA is recommended to enhance P bioavailability and remove heavy metals before it is applied as fertilizer. The recovery potential for technologically relevant metals is generally low, but some of these elements might be recovered efficiently in the course of P recovery exploiting synergies. KW - Sewage sludge ash KW - Recovery potential KW - Phosphorus KW - Critical raw materials KW - Bioavailability KW - Phosphorus recovery KW - Monitoring PY - 2015 DO - https://doi.org/10.1016/j.wasman.2015.01.025 SN - 0956-053X VL - 45 SP - 400 EP - 406 PB - Pergamon Press CY - New York, NY AN - OPUS4-34157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -