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Title: Upcycling Basic Oxygen Furnace (BOF) Slag into a Carbon Negative Supplementary Cementitious Material (SCM) through Mineral Carbonation

Author(s): Hadi Kazemi Kamy, Peter Nielsen, Bert Riems, and Liesbeth Horckmans

Publication: Symposium Paper

Volume: 362

Issue:

Appears on pages(s): 558-569

Keywords: BOF slag, Concurrent grinding/milling and carbonation, dynamic carbonation, mineral carbonation, reactive silica, SCM

DOI: 10.14359/51741011

Date: 6/14/2024

Abstract:
Lowering the direct CO₂ emissions of cement production is a prime objective of the cement industry. Substitution of clinker, for instance with by-products from other industries, is a widely adopted means to reduce direct emissions. A bottleneck in lowering clinker content is the availability of known clinker-replacement materials, as beneficiation processes are often required to condition the materials for such use. This may range from grinding and purification operations to calcination treatments. A novel approach is to use mineral carbonation as a beneficiation step for the conversion of by-products, such as steel slag, into SCMs. The reaction with CO₂ activates Ca-silicates by the formation of calcium carbonates and reactive silica, and more importantly, it enables sequestering of CO₂ in stable mineral products. It also provides a recycling strategy for steel producers. The ERA-MIN3 project CO₂ TREAT aims at transforming BOF slag into valuable SCMs for cement production. In this paper, the results of an experimental campaign to better understand the effect of process conditions for carbonating BOF slag, to obtain the highest degree of carbonation and reactivity, are presented.