Mineral phase transformation in coal gangue by high temperature calcination and high-efficiency separation of alumina and silica minerals

Xie, Mingzhuang; Liu, Fengqin; Zhao, Hongliang; Ke, Chaoyang; Xu, Zhiyuan

doi:10.1016/j.jmrt.2021.07.129

Cited by 57 publications

(14 citation statements)

References 9 publications

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“…Kaolinite (Al 2 O 3 ·2SiO 2 ·2H 2 O) is a silicate with a 1:1 type structure consisting of [SiO 4 ] tetrahedral layers joined with [AlO 2 (OH) 4 ] octahedral layers [ 32 ]. The substances of this crystal structure are chemically inactive and must be activated [ 33 ]. Activation methods include mechanical activation, thermal activation [ 34 ], microwave irradiation activation [ 35 ], and composite activation, among which, high-temperature calcination is one of the most common activation methods [ 36 , 37 ] and is suitable for industrial production.…”

Section: Resultsmentioning

confidence: 99%

Preparation of Poly Aluminum-Ferric Chloride (PAFC) Coagulant by Extracting Aluminum and Iron Ions from High Iron Content Coal Gangue

et al. 2022

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Poly aluminum-ferric Chloride (PAFC) is a new type of high efficiency coagulant. In this study, high iron type gangue is used as a main raw material. It is calcined at 675 °C for 1 h and 3% CaF2 is added to the calcined powder and reacted with 20% hydrochloric acid at 93 °C for 4 h. The leaching ratio of aluminum ions is 90% and that of iron ions is 91%. After Fe2+ ions are oxidized in the filtrate, CaCO3 is used to adjust the pH of the filtrate to 0.7. The microwave power is adjusted to 80 W and the filtrate is radiated for 5 min. After being aged for 24 h, PAFC product is obtained. The prepared PAFC is used to treat mine water and compared with the results of PAC and PAF, the turbidity removal ratio of PAFC is 99.6%, which is greater than 96.4% of PAC and 93.7% of PAF. PAFC is a mixture with different degrees of polymerization. It demonstrates that extracting aluminum and iron ions from high iron content gangue to prepare PAFC by microwave is efficient and feasible.

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Section: Resultsmentioning

confidence: 99%

Preparation of Poly Aluminum-Ferric Chloride (PAFC) Coagulant by Extracting Aluminum and Iron Ions from High Iron Content Coal Gangue

et al. 2022

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“…When the temperature exceeds 650 • C, kaolin, pyrite, siderite, and other substances have basically produced decomposition, so the quantity is almost unchanged. The low exothermic peak near 800 • C is formed by the continuous combustion and heat release of the residual coal in the coal gangue [34]. The endothermic valley between 900 and 1000 • C is attributed to metakaolin, which is endothermically decomposed into spinel and amorphous silica [35,36].…”

Section: Tg-dsc Analyses Of the Coal Ganguementioning

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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“…The XRD pattern indicates an effective removal of impurities from coal gangue and most of silicon phases were still retained, the acid-leached residue from coal gangue pretreated by this new route is amorphous without any diffraction peaks for crystalline silica. Amorphous silica is more easily dissolved in NaOH solution to form sodium silicate (Na 2 SiO 3 ), the usual and cheap precursor for silica aerogels [22,23]. pattern indicates an effective removal of impurities from coal gangue and most o phases were still retained, the acid-leached residue from coal gangue pretreated new route is amorphous without any diffraction peaks for crystalline silica.…”

Section: The Sio 2 Extraction From Coal Ganguementioning

confidence: 99%

“…pattern indicates an effective removal of impurities from coal gangue and most o phases were still retained, the acid-leached residue from coal gangue pretreated new route is amorphous without any diffraction peaks for crystalline silica. Amo silica is more easily dissolved in NaOH solution to form sodium silicate (Na2Si usual and cheap precursor for silica aerogels [22,23].…”

Section: The Sio 2 Extraction From Coal Ganguementioning

confidence: 99%

Ambient-Dried Silica Aerogel Powders Derived from Coal Gangue by Using One-Pot Method

2022

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In this paper, we report a new and convenient method for the synthesis of insulating aerogel by recycling solid waste coal gangue, which can reduce the industrial production cost of silica aerogels and realize high value-added utilization of solid waste. Sodium silicate was prepared from a cheap industrial waste coal gangue as the precursor for silica aerogels, which was used for silica wet gel preparation by a one pot method; this method of solvent exchange/surface modification was carried out quickly by mechanical stirring process, and the wet gels derived from coal gangue were dried under ambient pressure condition. A high surface area (~748 m2/g) nanostructured aerogel with a 3D open porous microstructure was synthesized, which exhibits a low density (~0.18 g/cm3) and a superior thermal insulation performance (~0.033 W·m−1·K−1). More significantly, the synthetic yield of silica aerogel powder by recycling coal gangue can reach 92%.

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Mineral phase transformation in coal gangue by high temperature calcination and high-efficiency separation of alumina and silica minerals

Cited by 57 publications

References 9 publications

Preparation of Poly Aluminum-Ferric Chloride (PAFC) Coagulant by Extracting Aluminum and Iron Ions from High Iron Content Coal Gangue

Preparation of Poly Aluminum-Ferric Chloride (PAFC) Coagulant by Extracting Aluminum and Iron Ions from High Iron Content Coal Gangue

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

Ambient-Dried Silica Aerogel Powders Derived from Coal Gangue by Using One-Pot Method

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