Study of loss-on-ignition anomalies found in ashes from combustion of iron-rich coal

Vandenberghe, R. E.; Resende, Valdirene Gonzaga de; Costa, Giulia; Grave, E. De

doi:10.1016/j.fuel.2010.01.022

Cited by 38 publications

(24 citation statements)

References 14 publications

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“…2 shows that a small weight gain was observed in both types of ashes, from 700-800°C up to 1000°C. This weight gain might be related to the oxidation of metals and/or iron-bearing minerals occurring in the ash materials as suggested by Vandenberghe et al (2010). This observation is consistent with the presence of hematite (Fe 2 O 3 ) but also of iron oxide (FeO) especially in the coarse fractions of both types of BA, as detected by XRD (Rocca et al, 2009(Rocca et al, , 2012.…”

Section: Tg-ms Analysissupporting

confidence: 75%

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Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

et al. 2013

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a b s t r a c tThe focus of this study was to identify the main compounds affecting the weight changes of bottom ash (BA) in conventional loss on ignition (LOI) tests and to obtain a better understanding of the individual processes in heterogeneous (waste) materials such as BA. Evaluations were performed on BA samples from a refuse derived fuel incineration (RDF-I) plant and a hospital waste incineration (HW-I) plant using thermogravimetric analysis and subsequent mass spectrometry (TG-MS) analysis of the gaseous thermal decomposition products. Results of TG-MS analysis on RDF-I BA indicated that the LOI measured at 550°C was due to moisture evaporation and dehydration of Ca(OH) 2 and hydrocalumite. Results for the HW-I BA showed that LOI at 550°C was predominantly related to the elemental carbon (EC) content of the sample. Decomposition of CaCO 3 around 700°C was identified in both materials. In addition, we have identified reaction mechanisms that underestimate the EC and overestimate the CaCO 3 contents of the HW-I BA during TG-MS analyses. These types of artefacts are expected to occur also when conventional LOI methods are adopted, in particular for materials that contain CaO/Ca(OH) 2 in combination with EC and/or organic carbon, such as e.g. municipal solid waste incineration (MSWI) bottom and fly ashes. We suggest that the same mechanisms that we have found (i.e. in situ carbonation) can also occur during combustion of the waste in the incinerator (between 450 and 650°C) demonstrating that the presence of carbonate in bottom ash is not necessarily indicative for weathering. These results may also give direction to further optimization of waste incineration technologies with regard to stimulating in situ carbonation during incineration and subsequent potential improvement of the leaching behavior of bottom ash.

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Section: Tg-ms Analysissupporting

confidence: 75%

“…On the other hand, Vandenberghe et al (2010) showed that oxidation of iron minerals in coal BA and FA samples led to a weight gain at temperatures of about 960°C. This weight gain may partially compensate the weight loss due to the burning of the residual organic carbon (combustion at around 350°C) of the sample.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

et al. 2013

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“…The dominating G04 paramagnetic component (46.0 %) is a doublet of the values of IS and QS pointing to Fe 3+ origin-characteristic of iron-bearing paramagnetic aluminosilicate glass [8] identified as mullite (porcelanite, Al 6 Si 2 O 13 ) with Fe 3+ ions [9,10]. The last component G05 (doublet of 18.4 % abundance) parameters correspond to fly ash paramagnetic phase with Fe 2+ ions recognized in [9,10] as hercynite (Fe 2+ Al 2 O 4 spinel). The widths of IS distributions both for paramagnetic components are almost as huge as mean values, which is a sign of possible structural distortions, surface effects or chemical disorder.…”

Section: Resultsmentioning

confidence: 96%

Iron speciation in coal fly ashes—chemical and Mössbauer analysis

et al. 2013

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Iron speciation analysis of fly coal ashes was performed using transmision Mössbauer spectrometry as well as chemical methods. The investigated samples of ashes came from stoker-fired boiler and pulverized-fuel boiler (of significantly higher combustion temperature). The Mössbauer spectra show noticeable differences in iron-bearing phases content. In the first case aluminosilicate glass dominates, whereas in the second one-a spinel-type phase.

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“…Typically for Swedish bottom ashes LOI (550°C) vary from 2.3% to 7.7% depending on combustion system and its effectiveness [25]. In the current study this range is from 0% to 6.6%, including some negative values of LOI (likely due to oxidation) [45,47]. Table 8 shows that in this study, LOI (550°C) values are higher for bottom ash from grate facilities than any of the ashes from fluidized boilers.…”

Section: Loss On Ignitionmentioning

confidence: 55%

Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes

Saqib

Bäckström

2016

Fuel

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h i g h l i g h t sBottom ashes from 13 Swedish waste incineration facilities were collected. Trace elements contents followed the sequence as Cu > Zn > Pb > Cr > Ni > Sb > As. Standard leaching indicates Cr had strongest mobility followed by Pb, Sb and Cu. Large amount of Cu is found in organic bound phase in 31% of samples. Amounts of unstable trace elements in biofuel bottom ashes are comparatively lower. a b s t r a c tThe release of trace elements from waste incineration bottom ash is problematic during utilization/ landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550°C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000°C) in few samples ...

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Study of loss-on-ignition anomalies found in ashes from combustion of iron-rich coal

Cited by 38 publications

References 14 publications

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

Iron speciation in coal fly ashes—chemical and Mössbauer analysis

Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes

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