Decomposition and phase transformation mechanism of kaolinite calcined with sodium carbonate

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

doi:10.1016/j.clay.2017.07.010

Cited by 57 publications

(21 citation statements)

References 46 publications

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“…The evident endothermic peak at 528 • C, the weak exothermic peak at 894 • C and a strong exothermic peak at 1001 • C, representing the dehydroxylation of kaolinite, the transformation of γ-Al 2 O 3 to θ-Al 2 O 3 and the formation of Al-Si spinel, respectively [13,21,[43][44][45]. Of note, the similar thermal decomposition behavior of RCG relative to kaolinite in previous research [42,46] also indicated that the main mineralogical component of RCG was kaolinite. As shown in Figure 3, RCG was mainly in the plate-like structure, with small sheets attached to large layers of well-crystallized kaolinite.…”

Section: Composition and Structure Of Starting Samplessupporting

confidence: 55%

Dispersibility of Kaolinite-Rich Coal Gangue in Rubber Matrix and the Mechanical Properties and Thermal Stability of the Composites

Zhang

Liu

et al. 2021

Minerals

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The aim of this work was to investigate the dispersibility of kaolinite-rich coal gangue in rubber matrix, the mechanical properties and thermal stability of coal gangue/styrene butadiene rubber (SBR) composites, and to compare these properties to those of the same coal gangue but had undergone thermal activation and modification. Several experimental techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric-differential scanning calorimetry (TG-DSC), laser-scattering particle analyzer were adopted to characterize the coal gangue particles and then the obtained composites. The results demonstrated the raw coal gangue (RCG) was mainly composed of kaolinite. Calcination led to amorphization of thermal activated coal gangue (ACG), increased hydrophilicity and void volume, and decreased pH. The grain size of ACG became coarser than RCG, but ACG turned loose confirmed by higher degree of refinement after grinding. Modification enhanced the hydrophobicity of the coal gangue and improved its dispersibility than fillers without modification. Calcined samples had better dispersibility than uncalcined fillers. Additionally, the coal gangue treated by calcinating, grinding and modifying (MGA) had the best dispersion in rubber matrix. Either calcination or modification could improve the mechanical properties and thermal stability of coal gangue filled rubber, while the performance of MGA reinforced SBR (MGA-SBR) was the best. The enhanced performance of the MGA-SBR was owed to better dispersion of particles as well as stronger interactions between particles and rubber macromolecules.

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Section: Composition and Structure Of Starting Samplessupporting

confidence: 55%

Dispersibility of Kaolinite-Rich Coal Gangue in Rubber Matrix and the Mechanical Properties and Thermal Stability of the Composites

Zhang

Liu

et al. 2021

Minerals

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“…Therefore, the chemical compatibility of composites before and after acid modification is investigated by XRD analysis (Figure b). The SA/Kaol displays a simple recombination of diffraction peaks between SA (at 2θ=21.5 ° and 23.9 °) and Kaol (at 2θ=12.3 °, 21.4 ° and 24.9 °) . It reveals that SA is successfully loaded into the Kaol and the crystal structure of SA does not be devastated during hot blending process, demonstrating the excellent compatibility between SA and Kaol.…”

Section: Resultsmentioning

confidence: 99%

Thermal Performance and Interfacial Aspects of Kaolinite‐Based Stearic Acid Composite in the Presence of Nitric Acid

Yang

Zuo

et al. 2019

ChemistrySelect

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The effect of nitric acid on the thermal performance of stearic acid/kaolinite (SA/Kaol) composite phase change materials (PCMs) was studied. SA/Kaol was subjected to HNO3 manipulations at different acidity conditions. The results indicated that inferior thermal properties were detected at the acid‐treated composites with pH < 2. The latent heat value of SA/Kaol‐0.5 demonstrated an obvious reduction of about 30% compared with that of SA/Kaol, and its supercooling extent could reach as many as 11.2 °C while that of SA/Kaol was only 1.4 °C. Based on interfacial reaction analysis, the reduced crystallinity of SA should be attributed to the confinement effect originated from acid molecular clusters, while the supercooling behavior was caused by external ions. These ions could hinder SA molecules from adsorbing to the surface of crystal nucleus and thus delay the solidification process. As a result of segregation effect, the latent heat value of acid‐treated samples was deteriorated but the supercooling extent was relieved during thermal cycles. This work was the first that reported the effect of nitrogen oxides on PCMs. We believe that the results could play an enlightening role in the stability study of thermal property during PCMs practical applications.

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“…The addition of soda ash Na 2 CO 3 (in the case of soda-lime sinter method) leads to producing of the sodium aluminate phase (Na 2 O.Al 2 O 3 ) which prevents the selfdisintegration process and hence an additional cost is necessarily required for the pre-leaching grinding process (Bai et al, 2010;Guo et al, 2014;Tian et al, 2016b;Toama et al, 2018;Yan et al, 2017). Moreover, the resulting white sludge usually contains a low soda content, when compared with a resultant sludge by the sodalime sinter and Bayer methods, and therefore the sludge obtained by the lime-sinter method does not require intensive washing (Smith 2009;Kaußen & Friedrich, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the charcoal, previous researches indicated that the common other additive of inorganic fluxing agents were MgO, A1 2 O 3 , Fe 2 O 3 , BaO, B 2 O 3 , Na 2 O, K 2 O, P 2 O 5 , MnO 2 and Cr 2 O 3 . The small amounts of these components either as chemical impurities or fluxing additives to kaolin showed undesirable effect, because these oxide materials stabilized the C 2 S β phase and hence led to preventing of the self-disintegration process (Wang et al, 2011;Yu et al, 2012;Guo et al, 2014;Yu et al, 2014;Yan et al, 2017;Yu et al, 2019;Bazhirov et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

et al. 2021

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Decomposition and phase transformation mechanism of kaolinite calcined with sodium carbonate

Cited by 57 publications

References 46 publications

Dispersibility of Kaolinite-Rich Coal Gangue in Rubber Matrix and the Mechanical Properties and Thermal Stability of the Composites

Dispersibility of Kaolinite-Rich Coal Gangue in Rubber Matrix and the Mechanical Properties and Thermal Stability of the Composites

Thermal Performance and Interfacial Aspects of Kaolinite‐Based Stearic Acid Composite in the Presence of Nitric Acid

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

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