Effects of SiO2/Al2O3 Ratios on Sintering Characteristics of Synthetic Coal Ash

Hongwei Hu, Kun Zhou, Kesheng Meng, Lanbo Song and Qizhao Lin
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Hongwei Hu: Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
Kun Zhou: Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
Kesheng Meng: Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
Lanbo Song: Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
Qizhao Lin: Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China

Energies, 2017, vol. 10, issue 2, 1-14

Abstract: This article explores the effects of SiO2/Al2O3 ratios (S/A) on sintering characteristics and provides guidance for alleviating ash depositions in a large-scale circulation fluidized bed. Five synthetic coal ash (SCA) samples with different S/As were treated in a muffle furnace for 12 h at different temperatures (from 773 K to 1373 K, in 100 K intervals). The morphological and chemical results of the volume shrinkage ratio (VSR), thermal deformation analysis by dilatometer (DIL), scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), and X-ray diffraction (XRD) were combined to describe the sintering characteristics of different samples. The results showed that the sintering procedure mainly occurred in the third sintering stage when the temperature was over 1273 K, accompanied with significant decreases in the VSR curve. Excess SiO2 (S/A = 4.5) resulted in a porous structure while excess Al2O3 (S/A = 0.5) brought out large aggregations. The other three samples (S/A = 1.5, 2.5, 3.5) are made up of an amorphous compacted structure and are composed of low fusion temperature materials (e.g., augite and wadsleysite.). Sintering temperatures first dramatically decrease to a low level and then gradually rise to a high level as S/A increases, suggesting that Al2O3-enriched additives are more effective than SiO2enriched additives in alleviating depositions.

Keywords: synthetic coal ash (SCA); sintering; dilatometer; eutectics (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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