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Minerals 2018, 8(8), 338; https://doi.org/10.3390/min8080338

Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT)

1
School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China
2
Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
*
Author to whom correspondence should be addressed.
Received: 15 July 2018 / Revised: 21 July 2018 / Accepted: 21 July 2018 / Published: 7 August 2018
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Abstract

As a solid waste, kaolinite-type pyrite flotation tailings (KPFT) are a type of low-quality kaolin that contain impurities, such as iron and titanium. In this study, KPFT were calcined at 800 °C for two hours. The calcined production (CKPFT), which is mainly metakaolin, was used as the silicon and aluminum source to synthesize 4A zeolite (Na12[(AlO2)12(SiO2)12]·27H2O) via hydrothermal synthesis. The optimal hydrothermal synthesis conditions were determined from X-ray diffraction phase analysis, relative crystallinity (RC), and cation ion exchange capacity (CEC). The optimal hydrothermal synthesis conditions were determined to be a ratio of 5 g CKPFT, 6.5 g NaOH, 65 mL H2O, crystallization temperature 110 °C, and crystallization time of three hours. Under the optimal hydrothermal synthesis conditions, the RC and CEC of the synthesized 4A zeolite were 40.77% and 210.32 mg CaCO3·g−1, respectively. Further characterizations including pore size distribution, scanning electron microscopy, energy dispersive X-ray, thermogravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy were performed. The results revealed that impurities in KPFT do not affect the synthesis of 4A zeolite. The surface morphology of the synthesized 4A zeolite was composed of chamfered-edged cubes with a particle size of one to three μm that was thermally stable up to approximately 890 °C. View Full-Text
Keywords: kaolinite-type pyrite flotation tailings; 4A zeolite; hydrothermal synthesis; calcination; relative crystallinity; cation ion exchange capacity kaolinite-type pyrite flotation tailings; 4A zeolite; hydrothermal synthesis; calcination; relative crystallinity; cation ion exchange capacity
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Cui, Y.; Zheng, Y.; Wang, W. Synthesis of 4A Zeolite from Kaolinite-Type Pyrite Flotation Tailings (KPFT). Minerals 2018, 8, 338.

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