EAF Slag Treatment for Inert Materials’ Production

Abstract

Danieli & C. in collaboration with Politecnico di Milano, designed an innovative, patent pending, treatment plant to solve some issues associated to metals leaching (i.e., Ba, V, and Cr), and high free lime concentration for carbon steel EAF slag, for the production of artificial aggregates featured by mechanical properties suitable for the building purposes. The plant is featured by an innovative pneumatic transport system to convey the stabilizing agent to intercept the molten slag flux during the deslagging operation. The new system promotes stable microstructural phases' formation, able to retain metallic ions leaching, maintaining the same mechanical properties of the as-cast slag. The main advantages of the new implemented stabilization plant are a simple installation and an easy process operation.

The Influence of Slag Tapping Method on the Efficiency of Stabilization Treatment of Electric Arc Furnace Carbon Steel Slag (EAF-C)

“…The pilot plant consisted of a silo stocking the stabilizer and of a metering valve supplying and conveying it through the pneumatic transport to a nozzle that lay close to the EAF door. Dosing of stabilizer was controlled by modifying air pressures and flow (1-3.5 bar; 150-300 Nm 3 /h), stabilizer flow (0-140 kg/min), and silo pressure (2-4 bar) [18]. Several trials were performed to evaluate the impact of the different process parameters on the microstructure transformation.…”

Impact of the solidification path of FeOx–SiO2 slags on the resultant inorganic polymers

“…Although higher amorphous fraction accelerates the reaction kinetics, it cannot totally prevent the leaching of heavy metals that might be present in the slag . Crystalline phases, such as spinel, can irreversibly capture heavy metals (eg, CrAl 2 O 4 captures Cr) and may reduce the extent of leaching of these elements . Previous studies have shown that adaptations to the chemistry (eg, addition of FeO or Al 2 O 3 ) and the cooling rate of the slags could promote the formation of spinel phases and thus the immobilization of heavy metals …”

“…30,31 Crystalline phases, such as spinel, can irreversibly capture heavy metals (eg, CrAl 2 O 4 captures Cr) and may reduce the extent of leaching of these elements. [32][33][34] Previous studies have shown that adaptations to the chemistry (eg, addition of FeO or Al 2 O 3 ) and the cooling rate of the slags could promote the formation of spinel phases and thus the immobilization of heavy metals. 35,36 To summarize the above, small modifications to the chemical composition and cooling rate could cause fundamental changes in the glass formation and chemistry as well as the local structure of the Fe-rich precursor.…”

Ecotoxicity and Genotoxicity of Steel Slags: Preliminary Results

“…Despite that, according to steel production process characteristics (i.e. cooling conditions, blast furnace charges and temperatures), SS can also contain potentially toxic elements, such as chromium, molybdenum, vanadium (Komonweeraket, Cetin, Aydilek, Benson, & Edil, 2015;Primavera, Pontoni, Mombelli, Barella, & Mapelli, 2016;Tossavainen et al, 2007). Moreover, the SS industry remains for a long time in the environment and therefore has a prolonged contact with environmental mixtures such as deep water and soil.…”

“…Moreover, the SS industry remains for a long time in the environment and therefore has a prolonged contact with environmental mixtures such as deep water and soil. It may promote the release (for example through chemical weathering) of substances potentially dangerous both for the environment and for human health (Primavera et al, 2016).…”