In Japan, 15 million tons of steelmaking slag as a by-product of the steelmaking process is produced annually, and more than 60% of it is used in civil construction. Steelmaking slag has high FeO(x) and CaO content compared with genuine stone, which may introduce unique undiscovered properties. In this paper, we focus on the possibility of effective use as an environmental restoration material from two aspects, application for seaweed-bed construction and dissolved sulfide reduction. Marine algae and seaweeds are known to absorb CO2 in seawater by photosynthesis, which is effective for prevention of global warming. For the growth of kelp (a kind of seaweed), supply of Fe ions is considered to be effective. The construction of seaweed bed in actual coastal area using dredged soil for organic acid resource and steelmaking slag for Fe ion supply source is demonstrated. The average strength of the bed made of a mixture of dredged soil and steelmaking slag was 110 kN/m2 and the Fe content of the water above the bed was around 5 ppb higher than that above natural stones. The average dry weight of the soft seaweed and brown seaweed taken from beds were respectively 1.1 times and 2.1 times as much as that from mounds of natural sand. About dissolved sulfide reduction, it is shown that that steelmaking slag removed the hydrogen sulfide from seawater and reduced the concentration of hydrogen sulfide in sediment. Fine particles are generated in artificial seawater with sulfide after addition of steelmaking slag and these have corresponding peaks of FeS, FeS2, sulfur and sulfate on X ray absorption fine structure (XAFS) measurements. These results imply that effective utilization of steelmaking slag in coastal area restoration can significantly improve the surrounding marine environment.
Environmental restoration of coastal sea area using steelmaking slag - applications for seaweed-bed construction and dissolved sulphide reduction
Rekultivierung von küstennahen Meeresbereichen mit Stahlwerksschlacken - Anwendungen zur Anlegung von Seegrasfeldern und zur Verringerung des gelösten Sulfidgehalts
2012
10 Seiten, 11 Bilder, 4 Tabellen, 8 Quellen
Conference paper
Storage medium
English
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