Critical review of applications of iron and steel slags for carbon sequestration and environmental remediation

One of the major concerns faced by the iron and steel industry, other than the abundant emission of carbon dioxide into the atmosphere, is the huge quantity of slag that is generated during the manufacturing of iron and steel. A comprehensive understanding of the iron and steel slag properties has diverted them away from stockpiling or landfilling to useful engineering applications. The similarity of these slags to natural minerals used in geologic carbon dioxide sequestration has made them sustainable alternative for industrial-scale carbon capture and storage. Further, they possess properties that are conducive for remediation of soil and groundwater contaminated with heavy metals and other toxic chemicals. This paper reviews the iron and steel slag characteristics suitable for engineering applications, describes several engineering application examples, and discusses challenges and opportunities to develop practical applications using iron and steel slags. This paper also discusses the on-going research which explores the use of steel slag along with the biochar-amended soil to develop a biogeochemical landfill cover to sequester fugitive gas emissions such as CH4, CO2 and H2S from MSW landfills and attain zero-emissions landfill.