Separation of Cenospheres from Lignite Fly Ash Using Acetone–Water Mixture

Yoriya Yoriya,Intana Intana,Tepsri Tepsri

doi:10.3390/app9183792

Yoriya Yoriya, Intana Intana + Show 1 more

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https://doi.org/10.3390/app9183792

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Abstract

This work reports on the separation of cenospheres from lignite fly ash through a wet separation process-the sink-float method. A better quality of cenospheres could be achieved through a physical–chemical approach using an acetone–water mixture as a medium. This work aimed to elucidate the correlation between the structure, morphology, and composition and medium fraction variables, with data for the freshly prepared and the reused mixtures presented for comparison. The work covers a study of the macrocomponent composition of an Fe2O3–SiO2–Al2O3 system, highlighting the pair dependences of SiO2–Al2O3, Al2O3–Fe2O3, and SiO2/Al2O3–Al2O3 and revealing an interesting result in terms of geochemical characteristics categorizing the collected cenosphere fractions separated from high-calcium class C fly ash produced from a lignite coal power plant in Thailand (as magnetic cenospheres). The CaO and SO3 contents increased monotonically with increased water content, particularly for the CaO composition profile, which was found to be similar to the increased carbonate concentration measured from the mixtures after use. The physicochemical properties in terms of the self-association ability of the acetone–water mixing phase is believed to have played an important role in determining the intermolecular interactions and reactivity of ions in the liquid phase, consequently affecting the separation efficiency, recovery yield, and quality of cenospheres.

Highlights

A byproduct from coal-fired thermal power plants, is a pozzolanic material recognized as a valuable resource that can be added to construction materials to form cementitious compounds when in contact with water [1,2,3]
This work provided a systematic description on the effect of an acetone–water mixture on the recovery of cenospheres from high-calcium class C fly ash using the sink–float method
We presented an investigation of the physical properties, morphology, and chemical composition as a function of the acetone/water ratio

Summary

Introduction

A byproduct from coal-fired thermal power plants, is a pozzolanic material recognized as a valuable resource that can be added to construction materials to form cementitious compounds when in contact with water [1,2,3]. Cenospheres, hollow, spherically shaped particles that are mostly open-pore type in nature, are one of the most important value-added materials or subproducts that mix with fly ash. This is due to the distinctive properties of cenospheres, such as being lightweight, good flowability, chemically inertness, good insulation, high compressive strength, and low thermal conductivity, which enable them to be widely used in many industrial applications. Applications for cenospheres as a construction material have been found, such as in lightweight thermal insulation composite [16], lightweight sound-absorbing structural material with cenosphere-reinforced cement and asphalt concrete [17], and lightweight concrete [18,19]. It has been recently reported that cenospheres are used as an additive or filler in polymer concrete matrix for manufacturing composite beams [20] and composite railway sleepers [21]

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