Extraction of SiO2 and Al2O3 from coal gangue activated by supercritical water

Han, Lupeng; Ren, Weiguo; Wang, Bing; He, Xingxing; Ma, Lingjun; Huo, Qihuang; Wang, Jiancheng; Wang, Bao; Chang, Liping

doi:10.1016/j.fuel.2019.05.118

Cited by 46 publications

(11 citation statements)

References 51 publications

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“…Recently, we introduced a novel supercritical water treatment method to activate coal gangue for extracting Si species [ 16 ]. Compared to the extensively used high-temperature alkali fusion method (a high temperature (600–900 °C) and a high usage amount of alkali were required), our method involves a much lower activation temperature, a shorter activation time, and a smaller usage amount of alkali; thus, it can effectively reduce the energy consumption.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Coal-Fly-Ash-Based Ordered Mesoporous Materials and Their Adsorption Application

et al. 2023

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A feasible approach was developed for the synthesis of ordered mesoporous SBA-15-type materials using coal fly ash (CFA) as raw material. In the proposed approach, CFA was, firstly, activated by subcritical water with the addition of NaOH, which allowed an efficient extraction of silicon species from CFA under strong acidic conditions at near room temperature. Subsequently, in the synthesis system, using silicon extraction solution as the silicon precursor, the introduction of anhydrous ethanol as a co-solvent effectively inhibited the polymerization of silanol species and promoted their collaborative self-assembly with surfactant molecules by enhancing the hydrogen bond interactions. The resultant SBA-15 material had a high purity, high specific surface area (1014 m2/g) and pore volume (1.08 cm3/g), and a highly ordered mesostructure, and, therefore, exhibited an excellent removal efficiency (90.5%) and adsorption capacity (160.8 mg/g) for methylene blue (MB) from simulated wastewater. Additionally, the generation of surface acid sites from the homogenous incorporation of Al atoms onto the mesoporous walls of SBA-15 combined with the perfect retention of the ordered mesostructure endowed the obtained Al-SBA-15 material with a further boost in the removal performance of MB. The MB removal efficiency can reach ~100%, along with a maximum adsorption capacity of 190.1 mg/g.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Coal-Fly-Ash-Based Ordered Mesoporous Materials and Their Adsorption Application

et al. 2023

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“…However, gangue is a kind of solid waste with low carbon content emitted in the process of coal mining. Its main chemical components are SiO 2 and Al 2 O 3 [3,4]. Raw coal mixed with gangue will not only reduce the quality of coal but also seriously pollute the atmospheric environment when burned.…”

Section: Introductionmentioning

confidence: 99%

A Coal Gangue Identification Method Based on HOG Combined with LBP Features and Improved Support Vector Machine

et al. 2023

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Identification of coal and gangue is one of the important problems in the coal industry. To improve the accuracy of coal gangue identification in the coal mining process, a coal gangue identification method based on histogram of oriented gradient (HOG) combined with local binary pattern (LBP) features and improved support vector machine (SVM) was proposed. First, according to the actual underground working environment of the mine, a machine vision platform for coal gangue identification was built and the coal gangue image acquisition experiment was carried out. Then, the images of coal and gangue were denoised by median filtering, and the coal and gangue features were extracted by using the HOG combined with LBP feature extraction algorithm, and these features were normalized and principal component analysis (PCA) reduced dimension to remove the correlation and redundancy between the features. Finally, SVM, SVM optimized by genetic algorithm (GA-SVM), SVM optimized by particle swarm optimization (PSO-SVM) algorithm, and SVM optimized by grey wolf optimization (GWO-SVM) algorithm were used as classifiers for identification and classification, respectively. The experimental results show that the GWO-SVM classification model has the highest accuracy, and the average classification accuracies were 96.49% and 94.82% of the training set and test set, respectively, which shows that grey wolf algorithm to optimize support vector machine has a good effect on classification of coal gangue images, which proves the feasibility and accuracy of the proposed method.

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“…High-value-added applications of coal gangues include the preparation of molecular sieves [12], the preparation of adsorbents [13], the extraction of elements such as aluminum and silicon [14], and the preparation of products using extracted materials such as Al(OH) 3 [15], Al 2 O 3 [16,17], AlCl 3 [18], A1 2 (SO 4 ) 3 [19], polyaluminium chloride [20], Na 2 SiO 3 , and SiO 2 [21]. Most coal gangues used in these studies have low iron content, so the purity and whiteness of the prepared products are high.…”

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 SiO2 and Al2O3 from coal gangue activated by supercritical water

Cited by 46 publications

References 51 publications

Synthesis of Coal-Fly-Ash-Based Ordered Mesoporous Materials and Their Adsorption Application

Synthesis of Coal-Fly-Ash-Based Ordered Mesoporous Materials and Their Adsorption Application

A Coal Gangue Identification Method Based on HOG Combined with LBP Features and Improved Support Vector Machine

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

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