| Title |
Aqueous metal ion leaching processes from high sulfur coal fly ash for carbon mineralization: The importance of pH control on cation extraction, carbonate purity, and silicon Q structure |
| ID_Doc |
7627 |
| Authors |
Zhang, N; Huang, HD; Yang, RX; Zheng, AL; Moment, A |
| Title |
Aqueous metal ion leaching processes from high sulfur coal fly ash for carbon mineralization: The importance of pH control on cation extraction, carbonate purity, and silicon Q structure |
| Year |
2023 |
| Published |
|
| DOI |
10.1016/j.cej.2023.145968 |
| Abstract |
The aim of this study is to characterize potential utilization pathways of high-sulfur fly ash from coal combustion plants for the purpose of fixing CO2 and producing high purity carbonates via carbon mineralization process. Unlike other typical fly ashes, the feedstock in this study contains a mixture of fly ashes and desulfurization residues. We present a multi-step approach for utilizing this industrial waste to provide a sustainable and economical alternative to landfilling or generating low-value products. The solubility of gypsum from the desulfurization residue limits the dissolution behavior of calcium, therefore, developing an efficient process to extract Ca for subsequent carbonation is needed. The dissolution process of different elements (Ca, Si, Fe, Al) was conducted under different pH values ranging from 0 to 13, various reaction temperatures, slurry densities and methods of dosing leaching agents. It was found that the extraction efficiency was significantly influenced by the pH, and the acidic conditions favored calcium release. Progressively adding acid at fixed pH during dissolution can slow down the polymerization of silicon which promotes calcium leaching compared with the rapid addition of acid. Gaseous CO2 can act as a dissolution agent to dissolve calcium and simultaneously produce nanocrystalline calcite on the surface of the fly ash as a direct carbonation approach. Stepwise dissolution and carbonation combined with a pH swing process can produce high purity calcium carbonates and the carbonate polymorphs can be adjusted via controlling operating conditions. The findings presented in this study provide implications for how to sustainably utilize high-sulfur fly ash and design processes for its utilization. |
| Author Keywords |
Carbon mineralization; Acidic dissolution; High sulfur coal fly ash; CO 2 dissolution; Surface chemistry; Metal extraction; Circular economy |
| Index Keywords |
Index Keywords |
| Document Type |
Other |
| Open Access |
Open Access |
| Source |
Science Citation Index Expanded (SCI-EXPANDED) |
| EID |
WOS:001078897200001 |
| WoS Category |
Engineering, Environmental; Engineering, Chemical |
| Research Area |
Engineering |
| PDF |
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