Complex utilisation of ekibastuz brown coal fly ash: Iron &amp; carbon separation and aluminum extraction

Valeev, Dmitry; Кунилова, И. В.; Алпатов, А. В.; Михайлова, А. Б.; Goldberg, M. A.; Kondratiev, A.

doi:10.1016/j.jclepro.2019.01.342

Cited by 75 publications

(19 citation statements)

References 50 publications

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“…In addition, recycling and improper disposal of by-products generated from coal industry may exacerbate health hazards of Ga and In. For example, the utilization of CFA in China included subgrade construction, soil modifier and production of cement, concrete and brick [134,147], while a considerable quantity of CFA was stored in ponds, landfills and dumps [148]. All of these can result in releasing of HTEs, which contaminates the soil and water on account of the leachability of HTEs in CFA.…”

Section: Discussion On Potential Health Risks Of Enriched Ga and In Imentioning

confidence: 99%

Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

Zhang

Hao

Tian³

et al. 2021

Minerals

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To provide a comprehensive insight into the enrichment mechanism of gallium and indium in No. 9 coals, eighteen samples were collected from Anjialing mine, Ningwu Coalfield, Shanxi Province for coal petrological, mineralogical and geochemical analyses. The results suggested that Ga and In enrichment mainly hosted in the top horizons, with average concentration coefficients of 8.99 and 2.73 respectively, compared with the rest of horizons (2.46 for Ga and 1.69 for In). Source apportionment indicated that Ga and In were mainly derived from bauxite of Benxi Formation in Yinshan Oldland, while In could originate from felsic magmatic rocks in Yinshan Oldland as well. In addition, weak oxidation condition, medium to intensive weathering, transgression and input of terrestrial higher plants had positive effects on Ga and In enrichment. With the rapid expansion of emerging electronics manufacturing, Ga and In, of which potential risks on human health were neglected previously, were recently considered as hazardous elements. Therefore, this paper also discussed the potential pathways that these elements threatened human health. We suggested that potential risks on environment and human health caused by Ga and In enrichment in coals and coal-related products should be taken into account besides their economic value.

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Section: Discussion On Potential Health Risks Of Enriched Ga and In Imentioning

confidence: 99%

Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

Zhang

Hao

Tian³

et al. 2021

Minerals

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“…Magnetite concentrate and unburned carbon were separated from CFA by wet magnetic separation and by foam flotation with kerosene as a collector, respectively [30]. The non-magnetic fraction, after the enrichment process, was subjected to high-pressure HCl leaching to maximize the aluminum extraction from the liquor (T = 210 • C, C HCl = 30%, τ = 3 h, and the solid liquid ratio = 1:5) [29]. The chemical composition of the liquor is presented in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina

Valeev

Shoppert

Михайлова

2020

Metals

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Sandy grade alumina is a valuable intermediate material that is mainly produced by the Bayer process and used for manufacturing primary metallic aluminum. Coal fly ash is generated in coal-fired power plants as a by-product of coal combustion that consists of submicron ash particles and is considered to be a potentially hazardous technogenic waste. The present paper demonstrates that the Al-chloride solution obtained by leaching coal fly ash can be further processed to obtain sandy grade alumina, which is essentially suitable for metallic aluminum production. The novel process developed in the present study involves the production of amorphous alumina via the calcination of aluminium chloride hexahydrate obtained by salting-out from acid Al-Cl liquor. Following this, alkaline treatment with further Al2O3 dissolution and recrystallization as Al(OH)3 particles is applied, and a final calcination step is employed to obtain sandy grade alumina with minimum impurities. The process does not require high-pressure equipment and reutilizes the alkaline liquor and gibbsite particles from the Bayer process, which allows the sandy grade alumina production costs to be to significantly reduced. The present article also discusses the main technological parameters of the acid treatment and the amounts of major impurities in the sandy grade alumina obtained by the different (acid and acid-alkali) methods.

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“…It is believed that exothermic effects mainly result from the dissolution of solid fly ash components in a strongly alkaline aqueous solution and the disintegration of fly ash particles together with the formation of oligomeric compounds in the aqueous phase in combination with the formation of alumina / silica-hydroxy type. Polymerisation / condensation reactions can be attributed to a small share of heat evolution, which means that the process of network consolidation is a rather thermally stable state [3,29,35]. Fig.…”

Section: Apparent Activation Energymentioning

confidence: 99%

“…Carbon fly ash (CFA) is an unavoidable by-product of thermal energy production from coal combustion [1][2][3][4][5]. Of the total amount of ash produced, CFA constitutes 85-95% wt.…”

Section: Introductionmentioning

confidence: 99%

The influence of alkaline activator concentration on the apparent activation energy of alkali-activated materials

Mierzwiński

Walter

Olkiewicz³

2020

MATEC Web Conf.

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The aim of this article is to analyse the changes of apparent activation energy (Ea) of alkali-activated materials (AAM) at temperatures up to 100°C. Apparent activation energy (Ea) refers to the minimum amount of energy is required for the occurrence of reaction. The existing AAM research is based on assumptions about Portland cement (OPC). A number of studies have been conducted on the development of concrete strength depending on, inter alia, the duration of seasoning and the liquid to solid ratio (L/S). Based on the apparent activation energy and taking into account the effect of time and temperature at the same time, the physical and mechanical properties of OPC can also be predicted. The influence of the activator on the solidification process should also be taken into account for alkali-activated materials. This article shows the effect of changes in the concentration of the alkaline solution used in the AAM process on activation energy. The synthesized AAM material uses a solution based on water glass, sodium hydroxide, sand and volatile ash from the ‘Skawina’ coal-fired power plant (located in Skawina, Lesser Poland). The chemical composition of the material used is classified as class F ash. The concentration of the alkaline solution was 8M, 10M, 12M and 14M. The described research method was based on the use of thermistors with a negative temperature factor. It enabled prediction of the physical and mechanical properties of the materials tested. The results clearly indicate that this method can be used to determine the activation energy of the AAM. However, when determining apparent activation energy (Ea), the time and activation temperature of the binding processes of these types of materials should be taken into consideration.

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Complex utilisation of ekibastuz brown coal fly ash: Iron & carbon separation and aluminum extraction

Cited by 75 publications

References 50 publications

Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina

The influence of alkaline activator concentration on the apparent activation energy of alkali-activated materials

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