Improved extraction of alumina from coal gangue by surface mechanically grinding modification

Guo, Yanxia; Yan, Kezhou; Cui, Li; Cheng, Fangqin

doi:10.1016/j.powtec.2016.08.034

Cited by 111 publications

(58 citation statements)

References 56 publications

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“…Aluminium leaching rate of calcined products increases with calcination temperature and reaches to the maximal value at 500-600 • C then decreased dramatically when temperature rise to 1000 • C. This was mainly attributed to the formation of meta-kaolinite derived from the dehydration of kaolinite start at 450 • C, which would increase the reactivity of and the aluminium extraction rate of calcined coal gangue [29]. It is noted that aluminium leaching rate from calcined products by fluidized calcination is 25% higher than the leaching rate of static calcination at 500 • C. It implied that the fluidized calcination was more efficient to increase the reactivity of calcined products.…”

Section: Chemical and Physical Characteristicsmentioning

confidence: 97%

Investigation on Calcination Behaviors of Coal Gangue by Fluidized Calcination in Comparison with Static Calcination

Yuan

Han

et al. 2017

Minerals

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Abstract:In order to comprehensively utilize coal gangue, we present fluidized calcination as a new thermal technology for activating coal gangue and systematical study was conducted in comparison with static calcination. The calcined products obtained by different calcination methods under various temperatures were characterized by the means of X-ray diffraction (XRD), thermal gravimetry-differential scanning calorimeter (TG-DSC), Fourier transform-infrared spectroscopy (FT-IR) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). Chemical and physical characteristics such as aluminium leaching rate, chemical oxygen demand and whiteness of calcined products were also investigated. The results show that aluminium leaching rate could reach to the maximal value 74.42% at 500 • C by fluidized calcination, while the maximal value of 66.33% could be reached at 600 • C by static calcination. Products by fluidized calcination obtained higher whiteness and lower chemical oxygen demand (COD) under the same calcination temperature. The well-crystallized kaolinite transform to amorphous meta-kaolinite under 600 • C and mullite presence under 1000 • C according to phase transformation, chemical bond variation and microstructure evolution analysis. Fluidized calcination was more efficiently for combustion of carbon/organic matter and dehydroxylation of kaolinite, which might applied in coal gangue industry in future.

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Section: Chemical and Physical Characteristicsmentioning

confidence: 97%

Investigation on Calcination Behaviors of Coal Gangue by Fluidized Calcination in Comparison with Static Calcination

Yuan

Han

et al. 2017

Minerals

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“…The HA yield increased rapidly from 79.13% to 90.2% in the size range from 0.425-0.250 mm to 0.250-0.180 mm but did not increase thereafter. After the raw coal was ground, its specific surface area and pore structure increased [51], and the organic matter in the coal was mildly oxidized, leading to the breakage and deformation of weak chemical bonds and alkyl structure, the reduction of relative molecular mass, and an increase in the content of oxygen-containing functional groups [52]. Therefore, decreasing the coal sample size contributed not only to the contact between the KOH solution and the coal sample but also to the improvement in the HA yield.…”

Section: Effects Of the Water-to-coal Mass Ratio And Coal Sizementioning

confidence: 99%

Extraction of Humic Acid from Lignite by KOH-Hydrothermal Method

et al. 2019

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Humic acid (HA) was extracted by a hydrothermal method from Huolinhe lignite from Inner Mongolia. The effects of the alkali-to-carbon mass ratio, water-to-coal mass ratio, reaction temperature, and reaction time on the HA yield were investigated. The physicochemical characterization of the products was performed, and the reaction mechanism was explored. Raw coal, HA, and residual coal were characterized using Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–VIS), elemental composition, and X-ray diffraction (XRD) analyses and compared to each other. The maximum HA yield (90.2%) was obtained from the 0.250–0.180 mm size fraction of the coal sample at a reaction temperature and time of 190 °C and 7 h. Proximate analysis proved that the ash and sulfur of lignite can be removed by hydrothermal treatment. Elemental analysis showed that the O/C and H/C ratios were highest for HA, followed by those for residual coal and raw coal, indicating an increase in the oxygen and hydrogen content of HA. FTIR and UV–VIS analyses showed that hydrothermal extraction destroyed the macromolecular structure of lignite. Moreover, the organics were degraded and hydrolyzed during the reaction process.

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“…At present, the major application fields of CG are brick making, concrete production, cement production, roadbed production, power generation, and metal recovery. [11][12][13][14][15][16][17][18][19] However, CG applied as filler into polymer matrix is also a potential means that has received less attention before.…”

Section: Introductionmentioning

confidence: 99%

Impact of titanate coupling agent on properties of high density polyethylene composite filled with coal gangue

Ding

Zhang

et al. 2020

Surface & Interface Analysis

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In this study, surface modification of coal gangue (CG) was performed with titanate coupling agent 201 (isopropyl tri(dioctylpyrophosphate) titanate), and the effects of surface modifier on mechanical properties and thermal stability of high‐density polyethylene filled with CG (HDPE/CG) and high‐density polyethylene filled with modified CG (HDPE/mCG) composites were investigated. The coupling agent was successfully grafted on CG surface through chemical reaction according to the analyses of Fourier transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS), and the coupling agent can effectively enhance the hydrophobicity of surface that was verified by water contact angle beyond 90° of modified CG sample. With the introduction of coupling agent, some enhancements of tensile strength, flexural strength, and impact strength were observed in HDPE/mCG compared with HDPE/CG, due to the improved compatibility between mCG fillers and matrix. The increased storage modulus and decreased loss factor of HDPE/mCG composite further confirm the stronger interface adhesion after modification. Moreover, it is found that titanate coupling agent 201 can improve the thermal stability of HDPE/mCG composite to some extent.

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Improved extraction of alumina from coal gangue by surface mechanically grinding modification

Cited by 111 publications

References 56 publications

Investigation on Calcination Behaviors of Coal Gangue by Fluidized Calcination in Comparison with Static Calcination

Investigation on Calcination Behaviors of Coal Gangue by Fluidized Calcination in Comparison with Static Calcination

Extraction of Humic Acid from Lignite by KOH-Hydrothermal Method

Impact of titanate coupling agent on properties of high density polyethylene composite filled with coal gangue

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