Improvement of the production of Rhenania phosphate fertilizer by means of investigations in a laboratory rotary kiln reactor

Jantzen, H.; Schügerl, K.; Helmrich, Harald

doi:10.1016/0032-5910(79)85020-2

Cited by 3 publications

(5 citation statements)

References 6 publications

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“…The results presented here show that P in SS ashes can be converted from mainly Ca orthophosphates into mixed K, Ca, and Mg phosphates, such as CaKPO 4 , KMgPO 4 , or CaK 2 P 2 O 7 , by co-combustion with K-rich biomass if the process temperature enables the formation of an ash melt. Considering the high plant availability of similar phosphate phases, such as CaNaPO 4 or CaK 2 P 2 O 7 , ,− this transition may improve the P-plant availability of co-combusted SS ashes in comparison to mono-incinerated SS ashes. If post-processing of the ash is still required, the higher solubility of mixed phosphates compared to Ca phosphates may decrease the amount of acid required in ash treatment with wet chemical methods.…”

Section: Discussionmentioning

confidence: 99%

“…The process is temperature-dependent, with fluorapatite (Ca 5 (PO 4 )F) requiring temperatures in the 1000− 1250 °C range to improve the plant availability. 28 While these studies only investigated already formed ash particles, they may suggest that co-combusting sewage sludge with alkali-rich biomass in technologies using high process temperatures could benefit the plant availability of P in the resulting ash.…”

Section: Introductionmentioning

confidence: 99%

“…Information regarding the plant availability of mineral phosphate phases is relatively scarce but seems to indicate that alkali-containing ortho- and pyrophosphates are suitable compounds to target. For instance, phases such as CaNaPO 4 and CaK 2 P 2 O 7 indicate high fertilizer quality. ,− The concentration of alkali in most sewage sludges is quite low . Therefore, it is unlikely that a significant share of alkali-containing phosphates would form during mono-combustion of sewage sludge.…”

Section: Introductionmentioning

confidence: 99%

“…The method bears some resemblance to the Rhenania process, which historically has been used to produce phosphate fertilizers (Rhenania phosphate) from phosphate minerals, soda (Na 2 CO 3 ), and silica (SiO 2 ). The process is temperature-dependent, with fluorapatite (Ca 5 (PO 4 )F) requiring temperatures in the 1000–1250 °C range to improve the plant availability . While these studies only investigated already formed ash particles, they may suggest that co-combusting sewage sludge with alkali-rich biomass in technologies using high process temperatures could benefit the plant availability of P in the resulting ash.…”

Section: Introductionmentioning

confidence: 99%

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Fate of Phosphorus in Fixed Bed Combustion of Biomass and Sewage Sludge

et al. 2020

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The recovery of phosphorus (P) from societal waste streams, such as sewage sludge, could make a significant contribution to alleviating the global dependency upon non-renewable phosphate sources, such as phosphate rock. This study aims to determine the effect of fuel ash composition, chemical association, and combustion technology on the fate of P in ashes from the combustion of sewage sludge and biomass blends to enable more efficient P recovery from combustion ashes. Experiments were performed in a fixed bed pellet burner (20 kW), combusting two sewage sludge blends and three biomass blends of similar fuel ash composition but with different P source (sewage sludge, dried distiller's grain with solubles, or phosphoric acid). Slag, bottom ash, and particulate matter samples were collected and analyzed by scanning electron microscopy−energy-dispersive X-ray spectroscopy and X-ray diffraction for morphology and elemental and crystalline phase composition and compared to results from experiments in fluidized bed combustion using the same fuel blends reported separately. The distribution and elemental composition of ash fractions indicated that sub-micrometer particles contained a minor share of fuel P, with the significant share of fuel P found in the slag and bottom ash fractions. No apparent difference in phosphate speciation could be observed between the slag and bottom ash from sewage sludge blends and biomass blends, with a range of crystalline Ca, Mg, and K phosphates detected in the ash. By comparison, only Ca-rich phosphates were detected in the ashes from the combustion of the sewage sludge blends in the bench-scale fluidized bed. The difference in P speciation between the technologies was attributed to a difference in the process temperature between the two technologies. In comparison to fluidized bed combustion, fixed bed combustion favored the formation of (Ca, Mg)−K phosphates rather than Ca phosphates for similar fuel blends.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fate of Phosphorus in Fixed Bed Combustion of Biomass and Sewage Sludge

et al. 2020

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“…However, the formation of K-containing phosphates may be restricted because of the immiscibility gap in the system, as the partitioning of Si and P may limit the interaction between the two systems. On the basis of the Rhenania process, 55 substitution reactions between the Ca-rich phosphates and K silicates are likely necessary to facilitate the formation of phosphates with a higher share of alkali.…”

Section: Resultsmentioning

confidence: 99%

Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus

et al. 2023

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This work investigates the ash transformation during fixed-bed co-combustion of sewage sludge mixtures with the agricultural residues wheat straw and sunflower husks, focusing on the fate of phosphorus (P) in the resulting ash fractions. The study aims to determine suitable process parameters for fixed-bed combustion of fuels previously investigated in single-pellet experiments. The pure fuels and fuel mixtures were combusted in a 20 kWth residential pellet burner while monitoring the flue gas composition, temperature, and particulate matter formation. Subsequently, the different ash fractions were collected and characterized by CHN, SEM/EDS, and XRD analysis. The results showed that co-combustion of sewage sludge and agricultural residues reduced the formation of particulate matter as well as the formation of slag. Co-combustion of sewage sludge with either agricultural residue resulted in a change in phosphate speciation, displaying higher shares of Ca and lower shares of Fe and Al in the formed orthophosphates as well as amorphous phases containing higher shares of K. The formation of K-bearing phosphates was hindered by the spatial association of P with Ca and Fe in the sewage sludge, the incorporation of available K in K-Al silicates, and the depletion of K in the P-rich melt phase. Compared to mono-combustion, co-combustion experiments showed the potential for improving the combustion performance and reducing the risk of slag formation. The outcome suggests that co-combustion is a feasible path to integrate waste streams in fixed-bed energy conversion with simultaneous formation of phosphates enabling P recovery.

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Drehrohrreaktoren in der Chemietechnik

Helmrich

Schügerl

1979

Chemie Ingenieur Technik

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Die Rolle von Drehrohrreaktoren in der Chemietechnik wird dargelegt . Nach einer apparativen Beschreibung dieser Anlagen werden folgende Vorgange behandelt : Kornbewegung, Gutwanderung, axialer und radialer Feststofftransport, Stoff-und Warmeubergang sowie chemische Reaktionen. Die gebrauchlichsten Modelle werden vorgestellt .Drehrohrreaktor-Herstellungsverfahren werden exemplarisch dargestellt. Derzeitiger Stand der Regelung und Automatisierung dieser Anlagen wird diskutiert.Rotary kiln in chemical engineering. This review stresses the importance ofrotary kilns in industry. After a briefaccount of design considerations, the following processes are treated : particle and product motion, longitudinal and transverse transfer of solids, mass-and heat transfer, as well as chemical reactions. Common models used for rotary kilns are discussed. Typical industrial processes employing rotary kilns are presented. The present status of control and automation of these plants are discussed.

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Improvement of the production of Rhenania phosphate fertilizer by means of investigations in a laboratory rotary kiln reactor

Cited by 3 publications

References 6 publications

Fate of Phosphorus in Fixed Bed Combustion of Biomass and Sewage Sludge

Fate of Phosphorus in Fixed Bed Combustion of Biomass and Sewage Sludge

Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus

Drehrohrreaktoren in der Chemietechnik

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