Development of a Selective Separation and Recovery Method for Phosphorus in Steelmaking Slag

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H04367
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 64030:Environmental materials and recycle technology-related
• Research Institution: Hokkaido University
• Principal Investigator: TSUBOUCHI Naoto 北海道大学, 工学研究院, 准教授 (90333898)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 有価物回収 / 分離精製高純度化 / リサイクル化学 / 資源循環

Outline of Final Research Achievements

The objective of this study was to develop a technique to selectively separate and recover only P from steelmaking slag (C-slag) by carbon reduction of de-Fe C-slag after pre-separation of Fe, which interferes with P recovery from C-slag by the carbon reduction method, by converting chloride to oxide by H2O reforming, and then by carbon reduction of de-Fe C-slag in Cl2. After heating to 1000℃ and holding for 60 min, Fe and Ti were almost completely released, and the volatilization rate of Mg was 35%. In other words, this method enabled selective volatilization separation of Fe, Ti, and a part of Mg. Next, when the chlorinated residue was heated to 1000℃ in a 50%H2O stream, the Cl ions were almost completely removed and the chlorides were converted to oxides. Furthermore, when the residue after 60 min reforming was mixed with carbon materials and heated in N2, P was released and the volatilization rate reached 95% at 1500℃.

Free Research Field

有機資源化学、触媒化学、環境化学

Academic Significance and Societal Importance of the Research Achievements

学術上の最大の成果は、①製鋼スラグをＣｌ２ガス中で１０００℃まで加熱するとＦｅ、ＴｉならびにＭｇの一部を選択的に揮発分離できること、②その塩素化後の残渣を５０％Ｈ２Ｏガス中で１０００℃に加熱すると、Ｃｌイオンがほぼ完全に除去されること、③その改質残渣と炭素物質を混合しＮ２中で加熱するとＡｌとＳｉも揮発するが、その程度は小さい一方、Ｐ放出は顕著に進み、揮発率は１５００℃で９５％に上ることを見出した点にある。本成果は、新しいＰ回収技術として大いに期待され、また、海外からのＰ鉱石輸入依存からの脱却が可能な希少資源確保の戦略的効果が期待され、非資源保有国である我が国にとってその意義は非常に大きい。