Recovery of alumina and alkali in Bayer red mud by the formation of andradite-grossular hydrogarnet in hydrothermal process

Zhang, Ran; Zheng, Shili; Ma, Shuhua; Zhang, Yi

doi:10.1016/j.jhazmat.2011.03.004

Cited by 188 publications

(80 citation statements)

References 20 publications

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“…Quantification of andradite (Table 1) reveals that this phase was transformed by hydrochloric, sulfuric and citric acids and also in combination with gypsum, to form a stable residue due to its persistent chemical characteristics in acid solutions [52]. Calcite existed in BR (2.1 %), however it was not identified in all TBRs.…”

Section: Mineral Chemistrymentioning

confidence: 99%

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

Kong

Xue

et al. 2017

Journal of Hazardous Materials

150

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Graphical abstractHighlights  Speciation and transformation of solid and soluble alkalinities were investigated. SEM, NEXAFS, and STXM were used to observe particle morphology and alkaline Na speciation and distribution. Gypsum combination promoted leaching of Na-bearing solids and the replacement of exchangeable Na. The use of organic citric acid to transform bauxite residue alkalinity.ABSTRACT: Bauxite residue (BR) is a highly alkaline solid hazardous waste produced from bauxite processing for alumina production. Alkaline transformation appears to reduce the environmental risk of bauxite residue disposal areas (BRDAs) whilst potentially providing opportunities for the sustainable reuse and on-going management of BR. Mineral acids, a novel citric acid and a hybrid combination of acid-gypsum treatments were investigated for their potential to reduce residue pH and total alkalinity and transform the alkaline mineral phase. XRD results revealed that with the exception of andradite, the primary alkaline solid phases of cancrinite, grossular and calcite were transformed into discriminative products based on the transformation used. Supernatants separated from BR and transformed bauxite residue (TBR) displayed distinct changes in soluble Na, Ca and Al, and a reduction in pH and total alkalinity. SEM images suggest that mineral acid transformations promote macro-aggregate formation, and the positive promotion of citric acid, confirming the removal or reduction in soluble and exchangeable Na. NEXAFS analysis of Na K-edge revealed that the chemical speciation of Na in TBRs was consistent with BR.Three acid treatments and gypsum combination had no effect on Na speciation, which affects the distribution of Na revealed by sodium STXM imaging.

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Section: Mineral Chemistrymentioning

confidence: 99%

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

Kong

Xue

et al. 2017

Journal of Hazardous Materials

150

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“…Previously, aluminum has been recovered from CFA using hydrometallurgy techniques such as solvent extraction [13], acid leaching [14][15][16][17][18], alkaline leaching [19][20][21], and acid/alkali combination methods [22]. 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].…”

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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“…The production of 1 tons alumina generates 1-1.5 tons red mud [1]. The generation of red mud is estimated to be 4 billion tons by 2015 based upon its current rate of production [2].…”

Section: Introductionmentioning

confidence: 99%

Extraction of Alumina from Red Mud for Synthesis of Mesoporous Alumina by Adding CTABr as Mesoporous Directing Agent

et al. 2018

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Recovery of alumina and alkali in Bayer red mud by the formation of andradite-grossular hydrogarnet in hydrothermal process

Cited by 188 publications

References 20 publications

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

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

Extraction of Alumina from Red Mud for Synthesis of Mesoporous Alumina by Adding CTABr as Mesoporous Directing Agent

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