Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications

Merwe, Elizabet M. van der; Prinsloo, Linda C.; Mathebula, Confidence Lethabo; Swart, H.C.; Coetsee, E.; Doucet, Frédéric J.

doi:10.1016/j.apsusc.2014.08.080

Cited by 67 publications

(40 citation statements)

References 30 publications

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“…The FA was found to be fine powder particles and predominantly spherical in shape, either solid or hollow (Fig. 3), which were similar to the results of previous studies (Ahmaruzzaman, 2010;Van der Merwe et al, 2014). The FA in > 150 µm size grade exhibited irregular spherical shape with rough edges [ Fig.…”

Section: Residual Carbon Content and Surface Morphologysupporting

confidence: 86%

Emission and Species Distribution of Mercury during Thermal Treatment of Coal Fly Ash

Wang

Shi

Chiang

et al. 2016

Aerosol Air Qual. Res.

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The thermal treatment of coal fly ash (FA) utilized by industries will inevitably lead to the emission of mercury, potentially causing atmospheric pollution. The present study is aimed at understanding the emission amount and species distribution of mercury during FA thermal treatment, and attempts were made to further provide basic data of mercury emission for environmental utilization of the FA by industries as raw materials. The physio-chemical properties of FA were analyzed and FA samples were heated at 200-1200°C in a tubular furnace in an oxidizing atmosphere. Thermogravimetric analysis (TGA) was carried out to determine the content of residual carbon in FA. The mercury species distribution was determined using United States EPA method 3200. The results indicated that semi-mobile mercury was the main mercury species in FA. Owing to the adsorption of residual carbon on Hg 0 , more residual carbon which lead to higher proportion of semi-mobile obtained in coarser size grades. 20% of total mercury emitted at 206°C, followed by a rapid growth of the emission rate of mercury at above 206°C, and the emission of total mercury achieved to be 50% and 90% corresponding to 291°C and 515°C, respectively. A distinct transformation from semi-mobile mercury to extractable mercury occurred at 200°C due to catalytic oxidation of Hg 0 and enhance the mobility and potential toxicity of mercury. Both extractable and semi-mobile mercury decreased sharply at 300-400°C. Finally, the non-mobile mercury was emitted with combustion of residual carbon in FA at 600-800°C. It was thus concluded that measures would be taken to control emission of mercury for environmentally friendly utilization of coal FA by industries when the FA was heated higher than 300°C.

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Section: Residual Carbon Content and Surface Morphologysupporting

confidence: 86%

Emission and Species Distribution of Mercury during Thermal Treatment of Coal Fly Ash

Wang

Shi

Chiang

et al. 2016

Aerosol Air Qual. Res.

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“…%). Detailed surface and bulk characterization of the sample, which included XRF, XRD, PSD, FE-SEM, Raman, FTIR and XPS analyses, was reported elsewhere (van der Merwe et al, 2014). Briefly, the sample consisted of an amorphous glass phase (64.3%), which co-existed with two primary crystalline phases, mullite (Al 6 Si 2 O 13 ; 30.2%) and quartz (SiO 2 ; 5.5%).…”

Section: Materials Description and Characterisationmentioning

confidence: 99%

“…The occurrence of new mineral phases during one-hour thermochemical treatment of CFA with (NH 4 ) 2 SO 4 was examined previously using XRD (Doucet et al, 2016). The amorphous silica alumina glass phase content of untreated and thermochemically-treated CFA was determined by addition of silicon as internal standard and the relative phase amounts were estimated using the Rietveld method, as described before (van der Merwe et al, 2014). The current results, which were obtained after 2h thermochemical treatment, confirmed that Al was extracted from CFA primary phases to form either millosevichite (Al 2 (SO 4 ) 3 ) only (at 600°C), or co-existing millosevichite and godovikovite (NH 4 Al(SO 4 ) 2 ) (at both 400 and 500°C) (Fig.…”

Section: Structural Changes Following Thermochemical Treatment and Sumentioning

confidence: 99%

Ammonium sulphate and/or ammonium bisulphate as extracting agents for the recovery of aluminium from ultrafine coal fly ash

et al. 2017

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Highlights Aluminium was extracted from an ultrafine coal fly ash  Ammonium sulphate and ammonium bisulphate were used as extracting agents  A process of thermochemical treatment followed by aqueous leaching was employed  A maximum non-selective recovery of 46.6% aluminium was obtained  Selective extraction of aluminium (37.3%) over silicon and iron was achieved AbstractWe recently showed that the selective extraction of aluminium from the amorphous phase of a South African ultrafine coal fly ash can be achieved via thermochemical treatment with ammonium sulphate for 1h followed by aqueous dissolution, as an alternative to conventional hydrometallurgical processes. In this study, insight gained from the previous work was applied to investigate and compare total vs selective aluminium extraction efficiencies using ammonium sulphate or ammonium bisulphate either on its own, or as a mixture of the two salts as extracting agents during a 2h thermal treatment process. The effects of (i) ash-to-extractant mass ratio and (ii) temperature during thermal treatment on extraction efficiency was investigated. While a maximum, but non-selective, recovery of 46.6% total aluminium was achieved using ammonium bisulphate at 400 °C, the most technically appropriate results for selective recovery yielded 37.3% aluminium, with only 0.3% silicon, 0.1% titanium and 3.9% iron having been co-extracted when using ammonium sulphate at a processing temperature of 600°C. Extraction of most of the calcium and magnesium could not be prevented. Using mixtures of ammonium salts as extracting agents during 2 thermochemical treatment may however introduce technical difficulties on large scale. Our results indicate that any of the two ammonium salts could be used on their own during thermochemical treatment.Thermochemical treatment of coal fly ash using ammonium salts may therefore represent a promising technology for extracting aluminium from South African coal fly ash.

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“…Some research focused on how to manage and recycle the waste effectively . Except of traditional utilization such as addition in concrete and cement manufacturing , more attention moved to develop multifunctional material from FA and its usage in polymer .…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Fly Ash‐Based Mesoporous Aluminosilicate Oxides Loaded with Zinc and its Synergistic Fire Resistancy in Polypropylene

Zhang

Tang

et al. 2019

Vinyl Additive Technology

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A kind of mesoporous aluminosilicate oxides (MAOs) were fabricated from industrial waste, coal fly ash. After loaded with zinc on MAO, the product MAO-Zn was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy (SEM). MAO-Zn was incorporated with intumescent flame retardant (IFR) together and used in polypropylene (PP). Basic characterization including limiting oxygen index (LOI), vertical burning test (UL-94), and cone calorimeter test (CCT) were finished. The result showed the LOI value of PP was only 17.7 and cannot pass UL-94 grade; however, 25 wt% IFR in PP help the composite obtained LOI value of 27.6 and passed UL-94V-1 grade. Surprisingly, with only 2 wt% MAO-Zn substitution of IFR, the LOI of PP/IFR composite sharply went up to 37.2 and passed V-0 grade. CCT results documented that heat, smoke, and fatal gas release were obviously suppressed by IFR/MAO-Zn combination. By SEM observation and quantitative analysis of TGA results, the contribution of MAO-Zn was summarized as adsorption of heat/smoke and promotion on charring. It was worth mentioning that the low dose of MAO-Zn (≤ 3 wt%) did not bring further deterioration on mechanical properties. J. VINYL ADDIT. TECHNOL., 26:135-143, 2020.

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Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications

Cited by 67 publications

References 30 publications

Emission and Species Distribution of Mercury during Thermal Treatment of Coal Fly Ash

Emission and Species Distribution of Mercury during Thermal Treatment of Coal Fly Ash

Ammonium sulphate and/or ammonium bisulphate as extracting agents for the recovery of aluminium from ultrafine coal fly ash

Fabrication of Fly Ash‐Based Mesoporous Aluminosilicate Oxides Loaded with Zinc and its Synergistic Fire Resistancy in Polypropylene

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