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

Yang, Quancheng; Zhang, Fan; Deng, Xingjian; Guo, Hongchen; Zhang, Chao; Shi, Changsheng; Zeng, Ming

doi:10.1098/rsos.192132

Cited by 21 publications

(4 citation statements)

References 34 publications

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“…It is a resource that can be used, but the traditional ways of utilization are relatively simple, and the added value is not as high as when it is used to make brick, to pave roads, or make cement [ 8 ]. Coal gangue mainly contains aluminum, silicon, iron, and other components [ 9 , 10 , 11 ], which can be used to prepare new products after being extracted by certain methods [ 12 ]. Most of the gangue contains about 40–60% silica, more than 15–35% alumina, and 1–15% iron oxide [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF2 Assistance and Process Optimization

et al. 2023

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To reveal how CaF2 improves the dissolution ratios of aluminum and iron ions in coal gangue, CaF2 and hydrochloric acid are used to extract Al3+ and Fe3+ from the coal gangue calcined powder. The leaching ratios of Al3+ and Fe3+ are measured, and the filter residues are analyzed by BET, XRD, and SEM. The results show that adding 3% CaF2 could increase the extraction ratio of Al3+ from 62.96% to 92.10% under optimized conditions, and that of Fe3+ is increased from 85.12% to 95.73%. The mechanism of CaF2 as an auxiliary to improve the leaching ratio of Fe3+ is that HF reacts with the thin layers of gangue calcined powder containing silica to form soluble SiF4, thus forming pores that promote the diffusion of H+ and inner ions, improving the leaching ratios of Al3+ and Fe3+. Finally, the CaF2-assisted acid leaching process is optimized. The results showed that it is efficient and feasible to extract Al3+ and Fe3+ with the assistance of CaF2 and that HF has a catalytic effect in the reaction system. This work provides a reference for the next step of actual production.

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Section: Introductionmentioning

confidence: 99%

Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF2 Assistance and Process Optimization

et al. 2023

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Section: Introductionmentioning

confidence: 99%

“…Currently, the main methods regarding the extraction of aluminum from coal gangue (CG) and coal gasification slag (CGS) are alkali and acid methods [ 15 , 16 ]. Alkali methods, including sintering and leaching [ 16 ], have been extensively studied for the extraction of alumina from CG and CGS. However, the sintering method requires high temperatures (around 1100 °C to 1200 °C), resulting in increased energy consumption and significant emission of dicalcium silicate residue [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Study on Extraction Valuable Metal Elements by Co-Roasting Coal Gangue with Coal Gasification Coarse Slag

Zhao,

Yu,

Zhang

et al. 2023

Molecules

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Coal gangue (CG) and coal gasification coarse slag (CGCS) possess both hazardous and resourceful attributes. The present study employed co-roasting followed by H2SO4 leaching to extract Al and Fe from CG and CGCS. The activation behavior and phase transformation mechanism during the co-roasting process were investigated through TG, XRD, FTIR, and XPS characterization analysis as well as Gibbs free energy calculation. The results demonstrate that the leaching rate of total iron (TFe) reached 79.93%, and Al3+ achieved 43.78% under the optimized experimental conditions (co-roasting process: CG/CGCS mass ratio of 8/2, 600 °C, 1 h; H2SO4 leaching process: 30 wt% H2SO4, 90 °C, 5 h, liquid to solid ratio of 5:1 mL/g). Co-roasting induced the conversion of inert kaolinite to active metakaolinite, subsequently leading to the formation of sillimanite (Al2SiO5) and hercynite (FeAl2O4). The iron phases underwent a selective transformation in the following sequence: hematite (Fe2O3) → magnetite (Fe3O4) → wustite (FeO) → ferrosilite (FeSiO3), hercynite (FeAl2O4), and fayalite (Fe2SiO4). Furthermore, we found that acid solution and leached residue both have broad application prospects. This study highlights the significant potential of co-roasting CG and CGCS for high-value utilization.

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“…Generally, aluminum and iron elements from coal gangue can be extracted to prepare Al(OH) 3 , Al 2 O 3 , Fe 2 O 3 , and composite coagulant [23,24]. There are various methods for the extraction of aluminum and iron ions, such as acid leaching and alkali leaching [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Extraction of Aluminum and Iron Ions from Coal Gangue by Acid Leaching and Kinetic Analyses

et al. 2022

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Extracting valuable elements from coal gangue is an important method for the utilization of coal gangue. In order to obtain the suitable technological conditions and the acid leaching kinetic model of leaching aluminum and iron ions from high-iron and low-aluminum coal gangue, the effects of calcination temperature, calcination time, and acid types on the leaching results of aluminum and iron ions are studied. The results show that when the gangue is calcined at 675 °C for 1 h, then the calcined gangue powder is leached by 6 mol/L hydrochloric acid at 93 °C for 4 h, the leaching ratio of iron ions is more than 90%, and that of aluminum ions is more than 60%. Furthermore, the acid leaching kinetic equations at 30 °C, 50 °C, 70 °C, and 90 °C are studied by three kinetic models, and the apparent activation energies of the reactions are calculated by the Arrhenius formula. The results show that the leaching behavior of aluminum and iron ions conformed to the “mixing control” model equation: “(1 − x)−1/3 − 1 + 1/3ln(1 − x) = kt + b”. The apparent activation energies of aluminum and iron ions are 55.5 kJ/mol and 55.8 kJ/mol, respectively. All these indicate that the acid leaching process is controlled by the “mixing control”.

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

Cited by 21 publications

References 34 publications

Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF2 Assistance and Process Optimization

Acid Leaching Extraction Mechanism of Aluminum and Iron Ions from Coal Gangue Based on CaF2 Assistance and Process Optimization

Study on Extraction Valuable Metal Elements by Co-Roasting Coal Gangue with Coal Gasification Coarse Slag

Extraction of Aluminum and Iron Ions from Coal Gangue by Acid Leaching and Kinetic Analyses

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