Physicochemical Properties of Fe-Bearing Phases from Commercial Colombian Coal Ash

Author:

Santos Ana Cláudia1ORCID,Cruz Cláudia1ORCID,Font Eric23ORCID,French David4,Guedes Alexandra1ORCID,Moreira Karen1,Sant’Ovaia Helena1ORCID,Vieira Bruno J. C.5ORCID,Waerenborgh João C.5ORCID,Valentim Bruno1ORCID

Affiliation:

1. Earth Science Institute—Porto Pole, Department of Geosciences, Environment and Spatial Plannings, Faculty of Sciences, University of Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal

2. Department of Earth Sciences, University of Coimbra, 3030-790 Coimbra, Portugal

3. Instituto Dom Luís (IDL), Faculdade de Ciências, Universidade de Lisboa, 1749-026 Lisboa, Portugal

4. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia

5. Centro de Ciências e Tecnologias Nucleares, DECN, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal

Abstract

High amounts of coal combustion products, such as fly ash and bottom ash, are generated every year; however, only 64% are used, which means that a significant part is landfilled despite containing valuable materials such as ferrospheres, which may be used as catalysts, substituting critical raw materials (e.g., platinoids). In commercial coals, pyrite contents are reduced as a pre-combustion S-emissions control measure, so low amounts of ferrospheres are expected in the respective ashes. However, given the large amounts of ash being generated from these coals, it may provide a reliable source of catalysts, with ferrospheres being easily recovered via magnetic separation. Several studies have been conducted regarding these morphotypes; however, there is a lack of investigation considering the ash derived from highly beneficiated coals and the variations with location and time. In this study, bottom ash, economizer grits, and fly ash samples from a Portuguese power plant burning Colombian commercial coal were fractionated using ferrite (Fe-MC fraction) and Nd (Nd-MC fraction) magnets, and a multi-technique approach was used to assess their properties (magnetic parameters, particle size distribution, mineralogy, particle morphology, microtexture, and chemical composition). The Fe-MC presented higher Fe concentrations (up to 44 wt.% Fe2O4) than the Nd-MC (up to 7 wt.% Fe2O4). Once it was a sequential process, Nd magnets essentially collected Fe-bearing aluminosilicate glass, and Fe-bearing minerals were residual when compared to the Fe-MC, where magnetite, magnesioferrite, hematite, and maghemite accounted for up to 30 wt.%. Among the Fe-MC, the sample collected from electrostatic precipitator fly ash (ESP FA), despite having a lower yield, presented higher Fe concentrations than the ones from bottom ash and economizer grits, which was related to the mode of occurrence of Fe-bearing phases: in the Fe-MC from ESP FA, discrete ferrospheres predominated, while in the remaining Fe-bearing phases, they were often embedded in aluminosilicate glass. All Fe-MC samples showed an increase of Fe-substituting elements (e.g., Mn and Ni) and their concentration tended to increase with decreasing particle size along with Fe. The integrated study of cross-sections enabled the identification of oxidation rims, martitization aspects, and the co-existence of hematite and magnesioferrite.

Funder

Fundação para a Ciência e Tecnologia (FCT) and Ministério da Ciência, Tecnologia, e Ensino Superior

CHARPHITE of the 3rd ERA-MIN Program 2015

INSUB

PhD scholarship

FCT support

Publisher

MDPI AG

Subject

Geology,Geotechnical Engineering and Engineering Geology

Reference107 articles.

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3