Characterization of MSWI fly ashes along the flue gas cooling path and implications on heavy metal recovery through acid leaching

Wolffers, Mirjam; Eggenberger, Urs; Schlumberger, Stefan; Churakov, Sergey V.

doi:10.1016/j.wasman.2021.08.022

Cited by 14 publications

(11 citation statements)

References 25 publications

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“…Comparison of predicted ash mineralogy with field observations. Figure 5(a, left) and (b) shows the predicted mineralogy of the different ash fractions for the reference scenario and the mineralogy from previously performed ash characterization summarized in Wolffers et al (2021), respectively. The predicted mineralogy of precipitates in the box-flux model is in reasonable agreement with the observations.…”

Section: System Evolution In Dynamic Box-flux Modelmentioning

confidence: 99%

“…Another difference is the amount of predicted alkali sulphates. In previous investigations (Wolffers et al, 2021), it was observed that the alkali sulphates forming while passing the boiler are often captured or preferentially accumulate in the heat exchanger deposits and are therefore only periodically released to the hoppers where the BOA is collected. Their produced amounts can therefore be difficult to estimate, and the measured concentration represents only a share of what is released to the BOA.…”

Section: System Evolution In Dynamic Box-flux Modelmentioning

confidence: 99%

“…It was shown that MSWI FA is a material difficult to characterize due to its complex mineralogy and the presence of only about 50% crystalline phases, associated with the short residence time in the combustion chamber. When investigating HM binding forms, conventional methods such as powder X-ray diffraction (XRD) or scanning electron microscopy (SEM) reach their limits due to low HM concentrations present at ppm range and low grain size (<200 μm to submicron scale) (Wolffers et al, 2021). Furthermore, wet chemical methods for characterization of HM binding forms in FA may be error prone due to matrix interferences (Funatsuki et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic model of MSWI flue gas cooling path: Effect of flue gas composition on heavy metal binding forms

et al. 2023

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In the context of circular economy and heavy metal (HM) recovery from municipal solid waste incineration (MSWI) fly ash (FA), detailed knowledge of HM binding forms is required for achieving higher extraction rates. The FA mineralogy is still poorly understood due to its low grain size and low metal concentration. To investigate the HM binding forms, a sophisticated thermodynamic reactive transport model was developed to simulate ash-forming processes. The stability of different binding forms was investigated at different flue gas conditions (varying ratios of HCl, SO2, O2) by simulating the gas cooling path in closed system and dynamic open system, where the gas composition is changing upon cooling due to precipitation of solids. The simulations predict that at flue gas conditions of molar ratio S/Cl < 1, Cu and Zn precipitate as oxides (and Zn silicates) at approximately 650°C. At temperatures <300°C, Zn, Cu, Pb and Cd are predicted to precipitate as easily soluble chlorides. In flue gas with molar ratio S/Cl > 1, the HM precipitate as less soluble sulphates. The results indicate that the less soluble HM fraction in the electrostatic precipitator ash represent oxides and silicates that formed in the boiler section but were transported to the electrostatic precipitator. The model provides insight into the physical–chemical processes controlling the metal accumulation in the flue gas and FA during the cooling of the flue gas. The obtained data serve as valuable basis for improving metal recovery from MSWI FA.

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Section: System Evolution In Dynamic Box-flux Modelmentioning

confidence: 99%

Section: System Evolution In Dynamic Box-flux Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamic model of MSWI flue gas cooling path: Effect of flue gas composition on heavy metal binding forms

et al. 2023

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“…Fly is a mixture of empty pass ashes (EA), boiler ashes (BOA) and the electrostatic precipitator ashes (ESPA). It is found that 70-75% of FA is made up of ESPA [30]. It is mainly composed of several toxic substances, such as metal salts, and its composition varies depending on the composition of the waste [20].…”

Section: Fly Ash Characteristicsmentioning

confidence: 99%

Heavy metals removal/stabilization from municipal solid waste incineration fly ash: a review and recent trends

Ajorloo

Ghodrat

Scott

et al. 2022

J Mater Cycles Waste Manag

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Waste treatment using thermal technologies, such as incineration, leads to the production of pollutants and wastes, including fly ash (FA). Fly ash contains heavy metals (HMs) and other contaminants and can potentially pose high risks to the environment and negatively impact health and safety. Consequently, stabilizing fly ash prior to either use or landfilling is crucial. The toxicity of fly ash through heavy metal leaching can be assessed using leaching tests. The leaching rates of heavy metals primarily depend on the surrounding conditions as well as fly ash properties and metal speciation. Physical separation, leaching or extraction, thermal treatment and solidification/chemical stabilization are proposed as suitable approaches for fly ash treatment. Economic considerations, environmental concerns, energy consumption and processing times can define the efficiency and selection of the treatment approach. This review considers the latest findings and compares the advantages and shortcomings of different fly ash treatment methods with the aim of highlighting the recent advances in the field. The review concludes that the simultaneous implementation of various methods can lead to highly efficient heavy metals removal/stabilization while simultaneously taking economic and environmental considerations into account.

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“…This study proves that printed paper electronics can be safe for the environment by design, thanks to the intricate intertwining of the silver wires and cellulose fibers, stemming from their geometrical and chemical affinity. This conservation of the metal inside the pristine and recycled material thus avoids to dispose of the printed paper electronics by burning, for example, in which case the recovery of the metal in the flue gas of the incinerator requires complex chemical and heat treatments [37].…”

Section: Right)mentioning

confidence: 99%

Multiscale investigation of the fate of silver during printed paper electronics recycling

Zareeipolgardani

Piednoir

Joyard-Pitiot

et al. 2022

Composite Interfaces

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The use of printed paper electronics in consumer goods is expected to experience a mass development in the next future. The ink used in these devices contains silver nanomaterials that may be released in the environment at the product end-of-life.We report here the first evaluation of the fate of silver during a pilot-scale recycling of printed paper electronics, made of paper printed with a cellulose nanofibrils-silver nanowire ink. We show that the released effluents are mainly free from silver, which is retained in the pulp conserved for recycling. We use atomic force microscopy experiments to show that this strong pulp-silver bond is due to the embedding of the silver nanowires in the pulp by coils of cellulose nanofibrils. We propose an estimate of the resulting adhesion stress of the nanowires to the ink, high enough to keep the silver inside the pulp during the recycling procedure.

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Characterization of MSWI fly ashes along the flue gas cooling path and implications on heavy metal recovery through acid leaching

Cited by 14 publications

References 25 publications

Thermodynamic model of MSWI flue gas cooling path: Effect of flue gas composition on heavy metal binding forms

Thermodynamic model of MSWI flue gas cooling path: Effect of flue gas composition on heavy metal binding forms

Heavy metals removal/stabilization from municipal solid waste incineration fly ash: a review and recent trends

Multiscale investigation of the fate of silver during printed paper electronics recycling

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