Notes on the occurrence of phosphate mineral relics and spheres (phosphospheres) in coal and biomass fly ash

Valentim, Bruno; Flores, Deolinda; Guedes, Alexandra; Guimarães, Renato; Shreya, Neha; Paul, Biswajit; Ward, Colin R.

doi:10.1016/j.coal.2015.12.009

Cited by 20 publications

(13 citation statements)

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“…The composition of these morphotypes can vary, as they can contain different elements, such as P, Si, Ca, K and Mg. Indeed, their composition depends on the composition of the thermally processed feed and on the processes that take place during thermal processing of waste, such as transformations of the substances present in the feed, interactions between melting particles and later vitrification during cooling [41]. Table 1 summarizes the physical properties, the chemical composition and the content of organic and inorganic pollutants in the poultry ash.…”

Section: Ash Characterizationmentioning

confidence: 99%

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A Mineral By-Product from Gasification of Poultry Feathers for Removing Cd from Highly Contaminated Synthetic Wastewater

Gusiatin

Kumpienė

Janiszewska³

et al. 2020

Minerals

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Ash from poultry feather gasification was investigated as an adsorbent for Cd removal from synthetic wastewater under a range of operational conditions: initial pH (2–8) and salinity (8–38 mS/cm) of wastewater, ash dosage (2.5–50 g/L), Cd concentration (25–800 mg/L) and contact time (5–720 min). The ash was highly alkaline and had low surface area and micropores averaging 1.12 nm in diameter. Chemical/mineralogical analysis revealed a high content of P2O5 (39.9 wt %) and CaO (35.5 wt %), and the presence of calcium phosphate, hydroxyapatite and calcium. It contained only trace amounts of heavy metals, BTEX, PAHs and PCBs, making it a safe mineral by-product. Cd adsorption was described best with Langmuir and pseudo-second order models. At pH 5, an ash dosage of 5 g/L, 40 min contact time and 100 mg Cd/L, 99% of Cd was removed from wastewater. The salinity did not affect Cd sorption. The maximum adsorption capacity of Cd was very high (126.6 mg/g). Surface precipitation was the main mechanism of Cd removal, possibly accompanied by ion exchange between Cd and Ca, coprecipitation of Cd with Ca-mineral components and Cd complexation with phosphate surface sites. Poultry ash effectively removes high concentrations of toxic Cd from wastewater.

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Section: Ash Characterizationmentioning

confidence: 99%

“…In addition, gaseous phosphorus oxides can be released from organic-P compounds at c.a. 500 • C, and these substances may condense on the ash surface, and thus contribute to the content of P 2 O 5 in ash [41].…”

Section: Ash Characterizationmentioning

confidence: 99%

A Mineral By-Product from Gasification of Poultry Feathers for Removing Cd from Highly Contaminated Synthetic Wastewater

Gusiatin

Kumpienė

Janiszewska³

et al. 2020

Minerals

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“…The SEM/EDS BSE mode of pulverized fuel FA and BA samples from Romania and Poland shows residual volumes of sub-rounded to rounded morphotypes with a brightness between the aluminosilicate glass and the ferrospheres, and primarily with P, Ca, and Mg EDS peaks. While P-bearing morphotypes (Figure 1A,B) were named "phosphospheres" by Valentim et al [28] since P is capable of forming a network of its own and forming a morphotype with a distinctive "pomegranate" structure composed of P-bearing microglobules in the Al-Si matrix [27,28], no petrographic nomenclature exists for Ca and Mg morphotypes. They may be included in a category together with "others" or they may be named "undifferentiated inorganics"; consequently, they will not be differentiated.…”

Section: Nomenclature and Systematizationmentioning

confidence: 99%

“…The utilization of an SEM-backscattered electron mode (BSE), however, highlights many morphotypes that are "weird and unique of their kind" from a grey aluminosilicate background due to their average atomic composition, which makes it easier to characterize them, including their chemical composition by EDS (e.g., Ca-rich sphere in Dai et al [24]; vide figure 5 in [24]). Using these methods, O'Connor, and O'Connor and Meeker [25][26][27] described the abundant occurrence of P, and of Mg-Ca, morphotypes in Wyodak-Anderson coal FA, while Valentim et al [28] classified P-rich morphotypes in a specific class due to their distinctive petrographic characteristics, and due to the occurrence of a major or secondary P-peak in the EDS spectra.…”

Section: Introductionmentioning

confidence: 99%

Undifferentiated Inorganics in Coal Fly Ash and Bottom Ash: Calcispheres, Magnesiacalcispheres, and Magnesiaspheres

et al. 2018

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During a study aiming to recover strategic elements and minerals from coal fly ash and bottom ash (RAREASH and CHARPHITE projects funded, respectively, by the 2nd ERA-MIN and 3rd ERA-MIN Programs of the European Union Commission), it was found that in coal fly ash and bottom ash from Romania and Poland, several morphotypes did not fit into the general fly ash classifications, unless grouped together as "undifferentiated inorganics". However, the combination of reflected light optical microscopy under oil immersion, scanning electron microscopy, and X-ray microanalysis (SEM/EDS) showed that many of these morphotypes not only have distinctive petrographic patterns but are also characterized by a chemical assemblage dominated by Ca, Mg, and P. In this paper, a survey of the literature is presented together with several detailed studies of samples from the RAREASH and CHARPHITE projects from which the following nomenclature are proposed: "calcispheres" for spongy Ca-rich morphotypes, "calcimagnesiaspheres" for (Ca + Mg)-rich morphotypes with visible MgO nodules and/or periclase (MgO) exsolved from Ca aluminate-silicate glass, and "magnesiaspheres" divided into "magnesiaferrospheres" for (Mg + Fe)-rich morphotypes with magnesioferrite, and "magnesiaoxyspheres" for magnesiaspheres mainly composed of (Mg + Fe)-rich amorphous material with visible MgO nodules and/or periclase.

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“…To quantify the minerals present in the Ib and Umaria coal samples, X-ray powder diffraction (XRD) was carried out. XRD is the most extended tool to investigate the mineralogy of coal and their crystallisation phases and also to understand the exact nature of their structure and the progressive stages of coalification (Zhou et al 2010;Mishra and Das 2010;Saikia et al 2014;Singh et al 2015b;Valentim et al 2016;Mishra et al 2016a, b).…”

Section: Introductionmentioning

confidence: 99%

Microstructural relation of macerals with mineral matter in coals from Ib valley and Umaria, Son-Mahanadi basin, India

Mishra

Singh

2017

Int J Coal Sci Technol

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Coal petrology provides significant inputs for the industrial utilisation of coal and for broad understanding the coal formation and diagenesis. The present paper entails the results of the investigations carried out on the selected coal samples, from Ib valley and Umaria coalfield, using scanning electron microscope (SEM) and X-ray diffraction (XRD) to study the surface microstructures and minerals present in them and the relationship of the finely dispersed mineral matter with the organic constituents. This would further help in evaluating the distribution and chemical character of the mineral matter occurring within the maceral types. Ib valley and Umaria coals are typical Indian (Lower Gondwana) non-coking coals and only scanty data is available on SEM study of these coals. Under SEM examination, it manifests that, the mineral matters of these coal occur as deep intergrowth, massive impregnation, superficial mounting, filling and depletion of micropores, mechanical cavity filling and fusinitic cavity filling.

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Notes on the occurrence of phosphate mineral relics and spheres (phosphospheres) in coal and biomass fly ash

Cited by 20 publications

References 54 publications

A Mineral By-Product from Gasification of Poultry Feathers for Removing Cd from Highly Contaminated Synthetic Wastewater

A Mineral By-Product from Gasification of Poultry Feathers for Removing Cd from Highly Contaminated Synthetic Wastewater

Undifferentiated Inorganics in Coal Fly Ash and Bottom Ash: Calcispheres, Magnesiacalcispheres, and Magnesiaspheres

Microstructural relation of macerals with mineral matter in coals from Ib valley and Umaria, Son-Mahanadi basin, India

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