Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/103207
Title: Complete extraction of amorphous aluminosilicate from coal fly ash by alkali leaching under atmospheric pressure
Authors: Shoppert, A.
Valeev, D.
Loginova, I.
Chaikin, L.
Issue Date: 2020
Publisher: MDPI AG
Citation: Complete extraction of amorphous aluminosilicate from coal fly ash by alkali leaching under atmospheric pressure / A. Shoppert, D. Valeev, I. Loginova, et al. — DOI 10.3390/met10121684 // Metals. — 2020. — Vol. 10. — Iss. 12. — P. 1-17. — 1684.
Abstract: One of the potential sources of alumina and mesoporous silica is the coal-fired thermal plants waste known as the coal fly ash (CFA). The studies of the alumina extraction from CFA are often focused on the preliminary desilication, but the efficiency of the alkali desilication is low due to formation of the desilication product—Na6 [Al6 Si6 O24 ]·Na2 X (DSP). This research is focused on the possibility of CFA desilication without formation of DSP using a leaching process with higher liquid to solid ratios (L/S) and alkali concentrations. The experimental data were analyzed using an artificial neural network (ANN) machine learning method and a shrinking core model (SCM). The investigation of the CFA morphology, chemical and phase composition before and after leaching were carried out by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The present work shows that it is possible to avoid formation of DSP if using the L/S ratio >20 and concentration of Na2 O—400 g/L during CFA leaching. The kinetics analysis by SCM showed that the process is limited by the surface chemical reaction at T <100◦ C, and by diffusion through the product layer at T >100◦ C, respectively. The SEM images of the solid residue after NaOH leaching under conditions that prevent the DSP formation show mullite particles with an acicular structure. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Keywords: ACICULAR MULLITE
ALKALI LEACHING
AMORPHOUS ALUMINOSILICATE
COAL FLY ASH (CFA)
DESILICATION
KINETICS
NEURAL NETWORK
SHRINKING CORE MODEL
URI: http://hdl.handle.net/10995/103207
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85098135871
PURE ID: 20413258
3120e641-c886-42e5-b907-692c5e73955e
ISSN: 20754701
DOI: 10.3390/met10121684
metadata.dc.description.sponsorship: This research was funded by Russian State Assignment, grant number 0836-2020-0020.
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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