Mineral phase transition of desilicated high alumina fly ash with alumina extraction in mixed alkali solution

Sun, Ze; Li, Huiquan; Wang, Bao; Wang, Chenye

doi:10.1016/j.minpro.2016.05.004

Cited by 35 publications

(7 citation statements)

References 16 publications

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“…Besides major elements such as aluminium (Al), calcium (Ca), iron (Fe), etc., FA also includes critical heavy metals/metalloids like antimony (Sb), arsenic [a mettaloid (As)], cadmium (Cd), chromium (Cr), copper (Cd), lead (Pb), mercury (Hg), nickel (Ni) and zinc (Zn). These elements could potentially affect the environment, metabolites, human health and well-being (Paul et al, 2014;Sun et al, 2016). Enhanced Cr (VI) levels are harmful to the circulatory system and may lead to carcinogenicity.…”

Section: Critically Toxic Heavy Metal Elementsmentioning

confidence: 99%

Developing sustainable measures to restore fly‐ash contaminated lands: Current challenges and future prospects

Upadhyay

Edrisi

2021

Land Degrad Dev

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Land degradation is one of the major global environmental issues that need serious attention. The land itself is a complex system regulating myriads of processes. Any perturbation in these processes would undoubtedly lead to the stimulation of land degradation. Among these, fly-ash (FA) dumping is one of the usual practices, which has been adopted to overcome land-use disruption and other health hazards. However, this practice has become a driving factor for FA-induced land degradation.Therefore, in purview to tackle this issue, the present article aimed to identify and suggest sustainable practices to restore and manage FA-contaminated sites. As a preliminarily it deals with the systematic exploration and identification of FA-based and associated contaminated lands via geospatial technology with a brief focus on assessing its different contaminant profiles in the FA and soil systems. Further, this moreover, the article emphasizes the need to identify identifying the potential local plant species in the FA-contaminated regions that can meet the local people's demands. Following this we suggest appropriate sustainable approaches to expedite the restoration of FA-contaminated lands and highlight the critical bottlenecks during ground implementation. Our article aimed to unravel ways to address the aforementioned bottlenecks to develop an efficient restoration enterprise during the UN Decade on Ecosystem Restoration (2021Restoration ( -2030.

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Section: Critically Toxic Heavy Metal Elementsmentioning

confidence: 99%

Developing sustainable measures to restore fly‐ash contaminated lands: Current challenges and future prospects

Upadhyay

Edrisi

2021

Land Degrad Dev

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“…Then, alumina can be separated from silica efficiently in followed sodium carbonate leaching process [26]. However, the sintering method is not suitable for large-scale industrialization due to some problems hard to solve, such as high energy consumption, large-waste residues production and narrow range of sintering reaction temperature [27].…”

Section: Introductionmentioning

confidence: 99%

Extraction of alumina from alumina rich coal gangue by a hydro-chemical process

et al. 2020

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Vast quantities of gangue from coal mining and processing have accumulated over the years and caused significant economic and environmental problems in China. For high added-value utilization of alumina rich coal gangue (ARCG), a mild hydro-chemical process was investigated to extract alumina. The influences of NaOH concentration, mass ratio of alkali to gangue, reaction temperature and reaction time were systematically studied. An alumina extraction rate of 94.68% was achieved at the condition of NaOH concentration 47.5%, alkali to gangue ratio of 6, reaction temperature of 260°C and reaction time of 120 min. The obtained leaching residues were characterized through X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometer. Research confirmed that kaolinite the main alumina-bearing phase of ARCG can be decomposed and transformed to Na 8 Al 6 Si 6 O 24 (OH) 2 (H 2 O) 2 and Ca 2 Al 2 SiO 6 (OH) 2 at relatively low temperature and short reaction time. Additionally, Na 8 Al 6 Si 6 O 24 (OH) 2 (H 2 O) 2 and Ca 2 Al 2 SiO 6 (OH) 2 are unstable and will transform to alumina-free phase NaCaHSiO 4 under the optimal conditions, which is the major reason for high alumina extraction rates.

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“…Specifically, mullite is a major inactive source of Al in CFA [11]. Several processes for extracting alumina from CFA were reported and can be broadly classified into acid [12][13][14][15], alkali [16][17][18][19], and sintering processes [20]. Acid processes can effectively achieve the separation of silica and alumina in CFA [21,22].…”

Section: Introductionmentioning

confidence: 99%

Alumina Extraction from Coal Fly Ash via Low-Temperature Potassium Bisulfate Calcination

Guo

Zou

et al. 2019

Minerals

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Owing to the depletion of bauxite and increasing demand for alumina, calcination methods for extracting alumina from coal fly ash (CFA) were developed. However, these methods have disadvantages such as the need for high temperatures and the emission of toxic gases. Hence, in this study, Al2O3 was extracted from CFA via low-temperature potassium bisulfate calcination technology. Effects of the potassium bisulfate amount, calcination temperature, and calcination time on the alumina extraction efficiency were investigated using X-ray diffraction, thermal gravimetry, scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectroscopy. It was found that this technique could recover alumina efficiently, and potassium bisulfate significantly contributed to the degradation of mullite and corundum phases. Al2O3 in CFA was converted into soluble K3Al(SO4)3. With a KHSO4/Al2O3 molar ratio of 7:1, calcining temperature of 230 °C, and calcining time of 3 h, the alumina extraction efficiency reached a maximum of 92.8%. The Avrami–Erofeev equation showed the best fit with the kinetic data for the low-temperature calcination of CFA with KHSO4. The activation energy was 28.36 kJ/mol.

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Mineral phase transition of desilicated high alumina fly ash with alumina extraction in mixed alkali solution

Cited by 35 publications

References 16 publications

Developing sustainable measures to restore fly‐ash contaminated lands: Current challenges and future prospects

Developing sustainable measures to restore fly‐ash contaminated lands: Current challenges and future prospects

Extraction of alumina from alumina rich coal gangue by a hydro-chemical process

Alumina Extraction from Coal Fly Ash via Low-Temperature Potassium Bisulfate Calcination

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