Large volumes of slags are formed as by-products during the refinement of pig iron by basic oxygen steelmaking or electric arc furnace steelmaking. In order to lower the environmental impact of the steel industry and ensure its economic sustainability, there have been significant studies finding the ways to recycle by-products. The formation, composition and physical properties of steel making slag are discussed with regard to the problems associated with its reuse. The volume instability caused by free lime exposure to moisture means that the reuse of steelmaking slag is often limited as many potential applications, and the leaching behavior of steelmaking slag is important for environmental considerations. Land-based applications that have been demonstrated include replacing natural sand as aggregate in cement, which may be combined with the CO2 sequestration properties. Steel slag shows use as a liming material (when spread over acidic soils to help to raise the pH to a more neutral level) and to enhance the physical properties of soft soils. Potential benefits to the marine environment is due to high porosity and large surface area, making slags ideal for coral reef repair (e.g., overcoming coral bleaching) and replacement (e.g., artificial reef to promote growth of green marine plants and seagrass), as well as a growth promoter for seaweed and phytoplankton that are microscopic organisms that are an essential component of ecosystems in oceans around the world. The chemistry of steelmaking slag also makes it a contender for adsorption of H2S and metalloids from marine environments.

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The recycling and reuse of steelmaking slags — A review

Wettability and interfacial reactions in the systems NiYSZ and Ni/Ti-TiO2/YSZ

The influence of superficially applied CeO2 coatings on the isothermal-oxidation behavior, preceded by nonisothermal heating, as well as cyclic-oxidation behavior of three grades of austenitic stainless steel (AISI-316, −321, and −304), in dry air is reported. The superficial coating had a thickness of 2.1 μm. The linear heating rate employed was 6 K min−1 up to a maximum temperature of 1423 K, and the isothermal holding temperature was 1273 K. The results clearly depict that CeO2 coatings not only reduced the rates of scale growth for all three varieties of steel but also imparted improved scale adhesion to the respective alloy substrates, as evident from the fact that the coated steels could withstand a number of thermal cycles without scale rupture. In the bare condition, 321-grade steel exhibited the best performance. However, in the presence of the coating, the improved performances of 316 and 321 grades were almost identical, whereas the 304 variety showed improvement only in the first cycle of exposure. The kinetics results have been substantiated by postoxidation analyses of the alloy/scale combinations by SEM, EDS, EPMA, and XRD techniques to reveal the role of rare-earthoxide coatings on the observed behavior.

Lucien Coudurier

Papers

Fundamentals of Metallurgical Processes

Iron and steelmaking

Chapter 6 – SLAGS

Experimental and bibliographical methods

Heterogeneous reactions in metallurgy, kinetics and catalysis