Nucleation and growth control for iron- and phosphorus-rich phases from a modified steelmaking waste slag

Juncheng Li, Guoxuan Li, Feng Qiu, Rong Wang, Jinshan Liang, Yi Zhong, Dong Guan, Jingwei Li, Seetharaman Sridhar, Zushu Li

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Recovering the iron (Fe) and phosphorus (P) contained in steelmaking slags not only reduces the environmental burden caused by the accumulated slag, but also is the way to develop a circular economy and achieve sustainable development in the steel industry. We had previously found the possibility of recovering Fe and P resources, i.e., magnetite (Fe3O4) and calcium phosphate (Ca10P6O25), contained in steelmaking slags by adjusting oxygen partial pressure and adding modifier B2O3. As a fundamental study for efficiently recovering Fe and P from steelmaking slag, in this study, the crystallization behavior of the CaO—SiO2—FeO—P2O5—B2O3 melt has been observed in situ, using a confocal scanning laser microscope (CLSM). The kinetics of nucleation and growth of Fe- and P-rich phases have been calculated using a classical crystallization kinetic theory. During cooling, a Fe3O4 phase with faceted morphology was observed as the 1st precipitated phase in the isothermal interval of 1300–1150°C, while Ca10P6O25, with rod-shaped morphology, was found to be the 2nd phase to precipitate in the interval of 1150—1000°C. The crystallization abilities of Fe3O4 and Ca10P6O25 phases in the CaO—SiO2—FeO—P2O5—B2O3 melt were quantified with the index of (TU − TI)/TI (where TI represents the peak temperature of the nucleation rate and TU stands for that of growth rate), and the crystallization ability of Fe3O4 was found to be larger than that of Ca10P6O25 phase. The range of crystallization temperature for Fe3O4 and Ca10P6O25 phases was optimized subsequently. The Fe3O4 and Ca10P6O25 phases are the potential sources for ferrous feedstock and phosphate fertilizer, respectively.

Original languageEnglish (US)
Pages (from-to)378-387
Number of pages10
JournalInternational Journal of Minerals, Metallurgy and Materials
Issue number2
StatePublished - Feb 2023


  • calcium phosphate
  • growth
  • kinetics
  • magnetite
  • nucleation
  • steelmaking slag

ASJC Scopus subject areas

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


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