Alkali desilicated coal fly ash as substitute of bauxite in lime-soda sintering process for aluminum production

Bai, Guoliang; Teng, Wei; Wang, Xianggang; Jin-guo, Qin; Xu, Peng; Li, Pengcheng

doi:10.1016/s1003-6326(10)60034-9

Cited by 112 publications

(39 citation statements)

References 9 publications

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“…In another processes by Bai et al [31], fly ash is calcined with soda and lime at 1200 C, and the silica is converted into stable calcium silicate (2CaOÁSiO 2 ), thus separating the silica from the alumina The desilicated coal fly ash could then be used as a substitute for bauxite in the Bayer process, allowing for dissolution using sodium hydroxide. Due to the addition of a large amount of limestone in the sintering process, a considerable amount of calcium silicate residue is generated and this can be used for cement production.…”

Section: Two-step Acid Leachingmentioning

confidence: 99%

Towards the Utilization of Fly Ash as a Feedstock for Smelter Grade Alumina Production: A Review of the Developments

Sibanda

Ndlovu

Dombo

et al. 2016

J. Sustain. Metall.

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The major commercial technology for the production of smelter grade alumina has conventionally been the Bayer process which converts bauxite ore, an aluminum containing ore which typically contains about 50 % Al 2 O 3 , into smelter grade alumina that contains over 99.0 % Al 2 O 3 . Another potential source of aluminum that is receiving renewed attention is coal fly ash (CFA), which is a by-product of coal combustion during electricity generation in power stations. Most coal fly ash found around the world contain typically between 25 and 35 % Al 2 O 3 , which is substantial to make CFA a potential alternative source of alumina. There has been some considerable research effort, in the last two decades, aimed at extracting aluminum from this semi-waste product. Much emphasis from the different workers has been on the leaching of the contained aluminum, while the purification and recovery of alumina from the liquor solution has received less attention. Notwithstanding that several patents on the processes to recover alumina from CFA exist, limited commercialisation of the processes has been reported. This paper seeks to review and discuss the hydrometallurgical extraction processes that have been formulated and tested by different workers and then assesses the available opportunities and the way forward on the prospects of commercially extracting alumina and other valuable components from this abundant resource.

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Section: Two-step Acid Leachingmentioning

confidence: 99%

Towards the Utilization of Fly Ash as a Feedstock for Smelter Grade Alumina Production: A Review of the Developments

Sibanda

Ndlovu

Dombo

et al. 2016

J. Sustain. Metall.

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“…The extraction rate of alumina from the sinter reached as high as 91%. Bai et al [44] recovered alumina from desilicated fly ash by lime-soda sinter process. The recovery rate reached 90% at the optimal conditions.…”

Section: Leaching Of the Sintersmentioning

confidence: 99%

A review of the alumina recovery from coal fly ash, with a focus in China

Yao

Xia

Sarker

et al. 2014

Fuel

318

117

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Coal fly ash, an industrial by-product, is derived from coal combustion in thermal power plants. It is one of the most complex and abundant of anthropogenic materials, and its improper disposal has become an environmental concern and resulted in a waste of recoverable resources. Coal fly ash is rich in alumina, making it a potential substitute for bauxite. With the diminishing reserves of bauxite resources as well as the increasing demand for alumina, recovering alumina from fly ash has attracted extensive attentions. The present review first describes the alumina recovery history and technologies, and then focuses on the recovery status in China. Finally, the current status of fly ash recycling and directions for future research are considered.

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“…The CFA may be pre-processed before leaching using auxiliary reinforcement methods, such as lime stone sintering [6], soda lime sintering [23], and ammonium sulfate sintering [14,24]. combination methods [22].…”

Section: Introductionmentioning

confidence: 99%

An Efficient Approach for Lithium and Aluminum Recovery from Coal Fly Ash by Pre-Desilication and Intensified Acid Leaching Processes

Qin

Kang

et al. 2017

Metals

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A novel technique was developed for the recovery of lithium and aluminum from coal fly ash using a combination of pre-desilication and an intensified acid leaching process. The main components of the high-aluminum fly ash were found to be Al 2 O 3 and SiO 2 , and the Al/Si ratio increased from 1.0 to 1.5 after desiliconization. The lithium content of the coal fly ash met national recycling standards. The optimal acid leaching conditions, under which the leaching efficiencies of lithium and aluminum were 82.23% and 76.72%, respectively, were as follows: 6 mol/L HCl, 1:20 solid to liquid ratio, 120 • C and 4 h. During the hydrochloric acid pressure leaching process, spherical particles of desilicated fly ash were decomposed into flakes. Part of the mullite phase was dissolved, and most of the glass phase leached into the liquor. The generation of the silicates hindered lithium transport, which decreased the leaching rate of lithium. This work suggests that the preprocessing is a promising option for effective recovery of high-aluminum and fly ash-associated lithium.

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Alkali desilicated coal fly ash as substitute of bauxite in lime-soda sintering process for aluminum production

Cited by 112 publications

References 9 publications

Towards the Utilization of Fly Ash as a Feedstock for Smelter Grade Alumina Production: A Review of the Developments

Towards the Utilization of Fly Ash as a Feedstock for Smelter Grade Alumina Production: A Review of the Developments

A review of the alumina recovery from coal fly ash, with a focus in China

An Efficient Approach for Lithium and Aluminum Recovery from Coal Fly Ash by Pre-Desilication and Intensified Acid Leaching Processes

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