Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure
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 formatio...
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MDPI AG
2020-12-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/10/12/1684 |
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| author | Andrei Shoppert Dmitry Valeev Irina Loginova Leonid Chaikin |
| author_facet | Andrei Shoppert Dmitry Valeev Irina Loginova Leonid Chaikin |
| author_sort | Andrei Shoppert |
| collection | DOAJ |
| description | 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—Na<sub>6</sub>[Al<sub>6</sub>Si<sub>6</sub>O<sub>24</sub>]·Na<sub>2</sub><i>X</i> (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 Na<sub>2</sub>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. |
| first_indexed | 2024-03-10T14:01:04Z |
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| id | doaj.art-70752b2528ca41208fc2cce0ea929100 |
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| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T14:01:04Z |
| publishDate | 2020-12-01 |
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| series | Metals |
| spelling | doaj.art-70752b2528ca41208fc2cce0ea9291002023-11-21T01:07:47ZengMDPI AGMetals2075-47012020-12-011012168410.3390/met10121684Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric PressureAndrei Shoppert0Dmitry Valeev1Irina Loginova2Leonid Chaikin3Department of Non-Ferrous Metals Metallurgy, Ural Federal University, 620002 Yekaterinburg, RussiaLaboratory of Sorption Methods, Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences, 119334 Moscow, RussiaDepartment of Non-Ferrous Metals Metallurgy, Ural Federal University, 620002 Yekaterinburg, RussiaDepartment of Non-Ferrous Metals Metallurgy, Ural Federal University, 620002 Yekaterinburg, RussiaOne 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—Na<sub>6</sub>[Al<sub>6</sub>Si<sub>6</sub>O<sub>24</sub>]·Na<sub>2</sub><i>X</i> (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 Na<sub>2</sub>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.https://www.mdpi.com/2075-4701/10/12/1684coal fly ash (CFA)amorphous aluminosilicatedesilicationalkali leachingacicular mulliteneural network |
| spellingShingle | Andrei Shoppert Dmitry Valeev Irina Loginova Leonid Chaikin Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure Metals coal fly ash (CFA) amorphous aluminosilicate desilication alkali leaching acicular mullite neural network |
| title | Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure |
| title_full | Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure |
| title_fullStr | Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure |
| title_full_unstemmed | Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure |
| title_short | Complete Extraction of Amorphous Aluminosilicate from Coal Fly Ash by Alkali Leaching under Atmospheric Pressure |
| title_sort | complete extraction of amorphous aluminosilicate from coal fly ash by alkali leaching under atmospheric pressure |
| topic | coal fly ash (CFA) amorphous aluminosilicate desilication alkali leaching acicular mullite neural network |
| url | https://www.mdpi.com/2075-4701/10/12/1684 |
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