Synthesis of zeolitic materials from natural clinker: A new alternative for recycling coal combustion by-products

School of Applied Sciences, The University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1LY, UK
Fuel (Impact Factor: 3.52). 09/2008; 87(12):2482-2492. DOI: 10.1016/j.fuel.2008.03.014
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In this study, we report an innovative process of zeolite synthesis through transforming of natural raw clinker (NRC) via (1) conventional hydrothermal alkaline activation and (2) alkaline fusion prior to hydrothermal reaction. Both methods were evaluated at 100 °C as a function of the alkaline agent, although in the first method other variables such as concentration of the activation solution and reaction time were selected, whereas in the second method similar ratios of alkaline activator/NRC and H2O/alkali fused product during different reaction times were used. Experimental results indicate that the method, alkali activator, concentration and time have a strong effect on the type and degree of crystallinity of the synthesized zeolite. Low-silica sodium or potassium zeolitic materials were synthesized, which include Na-phillipsite, hydroxysodalite and hydroxycancrinite, K-chabazite, zeolite K-F, faujasite and zeolite Linde Type A. The use of a recycling process of NRC in zeolite synthesis could become an area of important interest and research, playing an active role in encouraging and promoting technological advances, research and technology transfer related to the use and disposal of mining wastes, remaining after the natural and spontaneous combustion of coal seams. NRC-based zeolites (NRCZs) synthesized under well-optimized experimental conditions could be used in applications for environmental waste treatment.

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    • "Se han desarrollados otros métodos de síntesis para disminuir los tiempos del procesos hidrotermal, la técnica de sembrado fue usada por Mignoni et al [8] para la obtención de zeolita tipo mordenita de altas relaciones Si/Al ~20 y ZSM-5 por medio de la introducción de fuentes de Si y Al adicionales al metacaolín. La técnica de ultrasonido fue usada por Park y Kim [9] para reducir los tiempos de síntesis y la temperatura de reacción obteniendo productos como zeolita A con mayor grado de cristalinidad al obtenido por medio del método de síntesis hidrotermal; la síntesis por microondas, en el cual se aprovecha la energía del microondas para la etapa inicial de calentamiento durante la síntesis y a diferencia del método hidrotermal en la cual se elimina el gradiente de temperatura en la mezcla [10] y el método denominado hidrotermal con previa fusión, en el cual el caolín es calcinado en soluciones alcalinas en presencia de NaOH o de KOH alrededor de los 600ºC y posteriormente se sigue con la síntesis hidrotermal, este método ha sido aplicado igualmente a otros materiales de partida [11]. "
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    ABSTRACT: The utilization of Exhausted Fluid Catalytic Cracking Catalysts, (FCC), as raw materials for the low-silica zeolite synthesis was analyzed. The FCC, is mainly composed aluminosilicates orders of up to 90%, and has a chemical composition similar to that metakaolin. Therefore, the same synthesis parameters (Na2O/SiO2 and H2O/Al2O3 molar ratios, temperature and time), obtained in previous studies for obtaining zeolites from the thermal activation of a natural kaolin are used in the process. The zeolites obtained were characterized by scanning electron microscopy and X-ray diffraction. The Cation Exchange Capacity was also determined. The results indicate that is possible to recover the FCC for obtaining zeolites type A, with Cation Exchange Capacity 341,47 mequiv/100g. The results obtained in this study provide an important perspective for the reusing of FCC in the production of zeolitic materials considering that in Colombia the zeolites are imported and are of high demand in the industrial sector. It should be noted that the exchange capacity of the zeolites obtained from kaolin by the same process parameters is 442 mequiv/100g, and zeolites imported for use in the domestic industry is 408 mequiv/100g.
    Revista Latinoamericana de Metalurgia y Materiales 04/2015; 35(2).
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    • "The glassy amorphous material was identified as the broad hump in the XRD spectra which was observed to occur between 20° and 40° 2h. This hump was also identified by other researchers (Inada et al., 2005; Ríos and Williams, 2008). The main mineral phases in the fused fly ash were Na-aluminate (Na 2 AlO 3 ) and Na-silicate (Na 2 SiO 3 ) and no presence of Quartz, Hematite and Mullite remained. "
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    ABSTRACT: a b s t r a c t In this study mine waters obtained from coal mining operations in South Africa were used as a substitute for pure water during the synthesis of zeolites from South African coal fly ash. Procedures that had been optimized to produce single phase zeolite Na-P1 and X using pure water were employed independently. The use of circumneutral mine water resulted in similar quality zeolite Na-P1 and X whereas the use of acidic mine drainage led to the formation of a single phase hydroxysodalite zeolite. Since these two wastes (fly ash and mine waters) are found in close proximity to each other, this study demonstrates that they can be used to ameliorate each other and at the same time produce saleable zeolitic products that can be used to offset their costs of disposal and treatment.
    Minerals Engineering 06/2013; 53(53):9-15. DOI:10.1016/j.mineng.2013.06.019 · 1.60 Impact Factor
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    • "Optimal conditions for the synthesis of zeolites from coal by-products with a maximum value of cation exchange capacity are a coal by-product/ alkaline activator ratio of 1:1.2 [17] [18]. Therefore, alkali hydroxide powder was dry mixed with the coal by-product with this ratio for 30 min and the resultant mixture was calcined at 600 °C for 1 h [18]. The alkaline reagent added to the starting material acts as an activator agent during fusion. "
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    ABSTRACT: Colombian industrial coal by-products were evaluated as raw materials in laboratory-scale synthesis of faujasite-type low-SiO2 zeolite of using an alkaline fusion step followed by hydrothermal treatment under various experimental conditions. By fusion with NaOH followed by hydrothermal reaction, coal by-products were converted into faujasite-type zeolite. The process of faujasite formation is discussed.
    Dyna (Medellin, Colombia) 12/2012; 79(176):105-114. · 0.22 Impact Factor
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