Influence of Aluminum-Carbon Composite Pellets on FeO Reduction and Iron Recovery from Electric Arc Furnace Slag
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ELECTRIC arc furnace (EAF) slag is an inevitable by-product in steelmaking when utilizing the EAF process. Globally, the amount of EAF slag is expected to increase steadily in proportion to the amount of steel produced via the EAF process.[1–3] Unfortunately, EAF slag has faced difficulties in post-mortem treatment (disposal and/or reuse) because it contains relatively large amounts of FeO, unlike blast furnace slag. Additionally, the treatment required to landfill EAF slag is costly and has adverse environmental effects. Thus, a novel idea for recycling EAF slag is required. The recovery of iron from EAF slag represents a practical goal; EAF slag, which contains 20 to 30 mass pct iron depending on the operating parameters, has the potential to be a large alternative iron resource. In many steel shops, magnetic separation has been applied to physically separate iron particles due to its convenient
JUNG HO HEO and JOO HYUN PARK are with the Department of Materials Engineering, Hanyang University, Ansan, 426-791, Korea. Contact e-mail: [email protected] JUN SOO YOO and YONGSUG CHUNG are with the Department of Advanced Materials Engineering, Korea Polytechnic University, Siheung, 429-793, Korea. Contact e-mail: [email protected] Manuscript submitted July 11, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
treatment after EAF slag has cooled.[4] However, iron recovery is not fully satisfied because the amount of metallic iron in EAF slag is relatively low, and it is difficult to separate just iron due to the presence of small amounts of magnetite in the slag. Smelting reduction of FeO in slags with carbonaceous materials has been investigated by employing various methods, such as the cylinder rotating method,[5–8] direct reaction between carbon and FeO in molten slag,[9–15] and slag–metal reactions,[16,17] in order to determine the reaction kinetics and feasibility of iron recovery. Additionally, we recently investigated iron recovery from FeO-rich (fayalite-based) waste copper smelting slag by using a carbonaceous reductant.[15] Furthermore, an aluminothermic reduction process has been investigated by several authors because this process has advantageous reaction kinetics.[18–22] Thus, we also attempted to comprehensively understand the reduction behavior of FeO and to quantify the iron recovery from FeO-rich copper smelting slag and steel EAF slag by using the aluminothermic smelting reduction (ASR) process.[23–25] Al dross was used to reduce FeO in EAF slag because it contains 20 to 40 mass pct metallic Al with several oxides.[26–30] Both the reaction mechanisms of FeO reduction and a novel triangular iron balance diagram were proposed.[23–25] It was also confirmed that high-fluidity slags should be maintained for higher iron recovery.[15,23–25]
Basically, in previous studies, a single carbonaceous material or aluminum (dross) was used as a reductant for FeO reduction in ferrous- and non-ferrous slags.[15,23–25] Because there are advantages and disadvantages for each material, investigating the effects of using
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