Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
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Basic Study on the Recycling of a Waste MgO-C Refractory Material as a Flux for EAF Steelmaking

전기로 폐 MgO-C계 내화재의 제강원료 활용 가능성 연구

  • Wang, Jei-Pil (Department of Metallurgical Engineering, Department of Marine Convergence Design Engineering (Advanced Materials Engineering), Pukyong National University) ;
  • Kim, Hang-Goo (Major of Energy & Resources Engineering, Korea Maritime&Ocean University) ;
  • Go, Min-Seok (Department of Marine Convergence Design Engineering(Advanced Materials Engineering), Pukyong National University) ;
  • Lee, Dong-Hun (Department of Marine Convergence Design Engineering(Advanced Materials Engineering), Pukyong National University)
  • 왕제필 (국립부경대학교 금속공학과, 마린융합디자인공학과(첨단소재공학)) ;
  • 김행구 (한국해양대학교 에너지자원공학과) ;
  • 고민석 (국립부경대학교 마린융합디자인공학과(첨단소재공학)) ;
  • 이동헌 (국립부경대학교 마린융합디자인공학과(첨단소재공학))
  • Received : 2021.11.26
  • Accepted : 2021.12.20
  • Published : 2021.12.31
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Abstract

In EAF steelmaking industries, MgO content in slag increases due to the addition of dolomite flux to protect refractory lines of furnaces and improve the desulfurization capability of slag. In addition, coal powder is injected in the molten steel bath to increase the energy efficiency of the process. In this regard, the utilization of waste MgO-C refractory material as a flux was examined because it has high amounts of MgO (>70%) and graphite carbon (>10%). A series of experiments were carried out using industrial EAF slag with added light burnt dolomite and waste MgO refractory material from a Korean steel company. The results for the addition of the two fluxes were similar in terms of slag basicity; therefore, it is expected that waste MgO-C refractory material can successfully replace dolomite flux. In addition, when the waste MgO-C refractory material was added as flux, slag foaming phenomenon was demonstrated because of the reaction between the graphite from the refractory material and iron oxides in the slag.

현재 EAF 전기로 제강공정에서는 슬래그 중의 MgO 함량을 증가시켜 탈황능과 내화재 수명을 개선시키고자 돌로마이트(백운석) 용제(Flux)를 첨가하고 있으며, 또한 에너지효율을 증가시키기 위해 용강 중에 가탄재를 취입하고 있다. 이러한 견지에서 폐 MgO-C계 내화재를 재활용하는 연구를 진행하였다. 폐 MgO-C계 내화재는 MgO(>70%)과 탄소(>10%)를 대량 함유하고 있기 때문이다. 이런 목적으로 제강 슬래그를 대상으로 해서 폐 MgO-C계 내화재를 첨가하는 효과를 실험하였고 그 결과를 경소 돌로마이트를 첨가한 결과와 비교하여 폐 MgO-C계 내화재 재활용 효과를 평가하였다. 폐 MgO-C계 내화재를 사용해서 얻은 결과가 슬래그 염기도 측면에서 경소 돌로마이트를 사용한 결과와 유사하게 나타남으로써 기존 경소 돌로마이트 대체 가능성을 확인하였다. 특히 폐 MgO-C계 내화재를 사용한 경우에는, 폐 내화재에 다량 함유된 흑연 성분에 의한 슬래그 중의 철산화물과의 환원반응으로 CO가스가 발생하여 생긴 크고 작은 기포들이 관찰되었으며 이로써 슬래그 Foaming 효과를 기대할 수 있는 것으로 확인하였다.

Keywords

Acknowledgement

이 연구는 2021년도 산업통상자원부 및 산업기술평가관리원(KEIT) 연구비 지원에 의한 연구임(20016138).

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