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<p>High-pressure acid leaching (HPAL) of laterite ores produces vast quantities of iron-rich residues typically containing more than 42-wt% Fe. This paper develops a sustainable route to transform ultralow-grade laterite HPAL residues into secondary iron resources through reduction roasting followed by magnetic separation. A systematic evaluation was conducted to investigate the influence of roasting temperature (700–1100°C), reductant dosage (5–25 wt% coal), roasting time (20–100 min), particle size (50–325 mesh), additive type (CaO, Na<sub>2</sub>CO<sub>3</sub>, a CaO–Na<sub>2</sub>CO<sub>3</sub> mixture, Na<sub>2</sub>SO<sub>4</sub>, MgO), and magnetic field strength (1000–2400 Gauss). Phase transformations and reduction mechanisms were examined using XRD, SEM–EDS, and XPS. The results show that Na<sub>2</sub>CO<sub>3</sub> provided the most significant improvement, achieving an Fe grade of 70.23% and a recovery of 95.77% under optimal conditions (1000°C, 20 wt.% coal, 20-wt% Na<sub>2</sub>CO<sub>3</sub>, 40 min, 200 mesh, 1600 Gauss), with minimizing Fe losses in tailings to 13.63%. These findings demonstrate a practical and efficient pathway to convert HPAL residues into valuable iron concentrates, contributing to waste reduction, sustainable resource utilization, and enhanced feedstock availability for the steel industry.</p> Graphical Abstract <p></p>

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Enhancing Iron Recovery from Ultralow-grade Laterite HPAL Residues via Reduction Roasting and Magnetic Separation

  • 期刊论文

  • 发表日期：

    2026年1月26日

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  • Irwan Syah Bana,
  • Leiting Shen,
  • Yaguang Peng,
  • Wei Liu,
  • Donny Marihot Siburian,
  • Akhsan Fakhrurozi,
  • Mohammad Wahyu Andriyan,
  • Kaihua Xu

摘要

High-pressure acid leaching (HPAL) of laterite ores produces vast quantities of iron-rich residues typically containing more than 42-wt% Fe. This paper develops a sustainable route to transform ultralow-grade laterite HPAL residues into secondary iron resources through reduction roasting followed by magnetic separation. A systematic evaluation was conducted to investigate the influence of roasting temperature (700–1100°C), reductant dosage (5–25 wt% coal), roasting time (20–100 min), particle size (50–325 mesh), additive type (CaO, Na2CO3, a CaO–Na2CO3 mixture, Na2SO4, MgO), and magnetic field strength (1000–2400 Gauss). Phase transformations and reduction mechanisms were examined using XRD, SEM–EDS, and XPS. The results show that Na2CO3 provided the most significant improvement, achieving an Fe grade of 70.23% and a recovery of 95.77% under optimal conditions (1000°C, 20 wt.% coal, 20-wt% Na2CO3, 40 min, 200 mesh, 1600 Gauss), with minimizing Fe losses in tailings to 13.63%. These findings demonstrate a practical and efficient pathway to convert HPAL residues into valuable iron concentrates, contributing to waste reduction, sustainable resource utilization, and enhanced feedstock availability for the steel industry.

Graphical Abstract