Effect of slag composition on the dissolution of phosphorus from steelmaking slag by selective leaching

Chuanming Du, Xu Gao, Shigeru Ueda, Shinya Kitamura

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Steelmaking slag is considered a potential source of P because of its huge production. In steelmaking slag, P is mainly distributed in the C2S-C3P solid solution which is more water-soluble than other phases. In order to recover P and recycle steelmaking slag, we have proposed the selective leaching of the P-concentrated solid solution. To clarify the applicability of this process to steelmaking slags with various compositions, the effects of P2O5 content, Fe2O3 content, and slag basicity on the dissolution behavior of the slag modified with the addition of Na2O were investigated in this study. It was determined that the dissolution ratio of P reached approximately 76% regardless of the P2O5 content in slag, while the dissolution of Fe and Mg was poor. In the case of high P2O5 content, a leachate with higher P concentration and lower Ca and Si concentrations was obtained, exhibiting excellent selective leaching of P. Increasing the Fe2O3 content in slag not only promoted the dissolution of P but also decreased the dissolution ratios of other elements. With the increase in slag basicity, the dissolution ratios of Ca, Si, and P all increased. Most of the solid solution was dissolved from each slag without a large dissolution of other phases at pH 6, indicating that selective leaching of the solid solution was achieved over a wide range of slag compositions. After leaching, a residue with low P2O5 content and high Fe2O3 content was obtained.

Original languageEnglish
Pages (from-to)1659-1668
Number of pages10
JournalIsij International
Issue number9
Publication statusPublished - 2018 Sept 15


  • Dephosphorization
  • P recovery
  • Selective leaching
  • Slag composition
  • Steelmaking slag

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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