Tempering and modification of basic oxygen furnace slag with blast furnace slag: Mineral phase transformations and cementitious material enrichment mechanisms

Shuai Hao; Guoping Luo; Lin Wang; Shengli An; Yifan Chai; Wei Song

Case Studies in Construction Materials (Dec 2024)

Tempering and modification of basic oxygen furnace slag with blast furnace slag: Mineral phase transformations and cementitious material enrichment mechanisms

Shuai Hao,
Guoping Luo,
Lin Wang,
Shengli An,
Yifan Chai,
Wei Song

Affiliations

Shuai Hao: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China
Guoping Luo: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China; Corresponding authors at: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China
Lin Wang: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China
Shengli An: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China
Yifan Chai: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China; Corresponding authors at: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China
Wei Song: School of Rare Earth Industry (School of Rare Earth Engineering and Technology), Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources (Inner Mongolia University of Science and Technology), Ministry of Education, Baotou, Inner Mongolia 014010, China

Journal volume & issue: Vol. 21
p. e03803

Abstract

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This study investigates the phase evolution and enrichment mechanism of the cementitious materials in a blend of blast furnace (BF) and basic oxygen furnace (BOF) slags. Theoretical calculations reveal that there is an optimal modification temperature range of 1400–1550 °C, which is crucial for the transformation of the slag constituents. At lower temperatures (500–850 °C), the addition of BF slag reduces the proportion of calcium iron oxide (Ca2Fe2O5, C2F) and promotes the formation of merwinite (Ca3MgSi2O8, C3MS2). At higher temperatures (850–1450 °C), the addition of BF slag decreases the free CaO content, enhancing the stability of the modified slag. The presence of the dicalcium silicate and tricalcium phosphate complex (α-Ca2SiO4–Ca3(PO4)2, α-C2S-C3P), dicalcium ferrite (C2F), and magnesioferrite (MgFe2O4) in the modified slag facilitates the creation of dicalcium silicate (Ca2SiO4, C2S) and C3MS2 phases, which improve the stability of the slag and increase the amount of cementitious active materials, indirectly reducing crushing costs. Experimental results indicate that excessive BF slag content results in the over formation of gehlenite (Ca2Al2SiO7, C2AS) and C3MS2, potentially affecting the cementitious active material proportion. Insufficient BF slag does not fully utilize its CaO, SiO2, and Al2O3 for enhancing the BOF slag stability and increasing the cementitious material content. A BF slag content of approximately 30 % optimally consumes free CaO, promotes C2S formation, and enhances the stability of the modified slag. This research highlights the crucial role of the temperature and BF slag content in the phase evolution and cementitious potential of BF-modified BOF slags, providing guidelines for optimized utilization in construction materials.

Published in Case Studies in Construction Materials

ISSN: 2214-5095 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/case-studies-in-construction-materials

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