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Leaching kinetics of iron from coal-series kaolin by oxalic acid solutions

Shao Hui, Ji Mengjiao, Yu Mingming

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 1

134--146

Removal of iron from coal-series kaolinite and its kinetics by chemical leaching were investigated in this paper. The optimal removal rate of iron reaches 29.09% (the content of Fe2O3 decreased from 0.55 to 0.39%) under the conditions of 100 °C, 0.4 M C2H2O4, and liquid-to-solid ratio of 4 cm3/g for 120 min. The leaching process was successfully described by the Avrami model and mainly controlled by internal diffusion control of shrinking core model, the apparent activation energy is 18.46 kJ/mol. The experimental results were consistent with the internal diffusion control of shrinking core model, improving acid concentration and leaching temperature could promotes the removal of iron from coal-series kaolin.

Effect of calcination temperature on activation behaviors of coal-series kaolin by fluidized bed calcination

Yuan S., Han Y., Li Y., Gao P., Yu J.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 2

590--600

This paper is aimed at investigating activation behaviors for coal-series kaolin using fluidized bed calcination as a novel method. The properties of calcined products at different temperature by fluidized bed calcination were evaluated by determination of weight loss rate, whiteness, chemical oxygen demand (COD), aluminum dissolution degree. The thermal behaviors and reaction mechanism were characterized by thermo gravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), particle size distribution (PSD) and scanning electron microscopy (SEM). The results showed that calcination temperature was essential factor determining the properties and crystallinity of calcined products using fluidized bed calcination. Coal-series kaolin transformed into irregular and amorphous metakaolin with excellent properties as calcined at 600-900 °C, which attributed to the dehydroxylation of kaolinite and combustion of carbon/organic matter. Calcined kaolin eliminated activity ascribed to the recrystallization into mullite when calcination temperature was over 1000 °C. It was believed that fluidized bed calcination was an efficient thermal activation technology for coal-series kaolin and the calcination temperature should be controlled accurately.

Preparation of TiO2/Al-MCM-41 mesoporous materials from coal-series kaolin and photodegradation of methyl orange

Li S., Wu Q., Cui C., Lu G., Zhang C., Zhiye Y.

Materials Science Poland

2013

Vol. 31, No. 3

372--377

TiO2/Al–MCM-41 mesoporous materials were prepared via sol-gel method by loading titania onto Al–MCM-41 mesoporous molecular sieve by hydrothermal treatment from coal-series kaolin as raw material. The TiO2/Al–MCM-41 mesoporous materials were characterized by XRD, FT-IR, HRTEM, N2 adsorption-desorption and the photocatalytic degradation of methyl orange solution under visible light irradiation. The results showed that the TiO2/Al–MCM-41 mesoporous materials possessed a high surface area of 369.9 – 751.3 m2/g and a homogeneous pore diameters of 2.3 – 2.8 nm. The titania crystalline phase was anatase, and the particles size of TiO2 increased with TiO2 content. The Al–MCM-41 mesoporous materials exhibited excellent photodegradation activity under visible-light irradiation for methyl orange.