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<p>Enhancing chromium dissolution from chromite, a mineral with a complex and refractory structure, remains a critical challenge for efficient recovery. Targeted mechanical activation has emerged as a promising strategy to overcome these limitations. This study systematically investigates the effects of mechanical activation on chromite’s structure and dissolution behavior. Initial alkaline and acidic leaching experiments revealed that chromite responds more favorably to acidic leaching. Optimal acidic extraction conditions were determined as 300&#xa0;°C, 300&#xa0;kg/t acid, L/S = 15, 400&#xa0;rpm, and 4&#xa0;h, achieving 53.3% chromium extraction. Mechanical activation was then applied prior to leaching, varying rotation speed, ball-to-powder ratio (BPR), and activation time, resulting in chromium recovery up to 80% under optimal activation conditions (BPR = 2, 15&#xa0;min, 440&#xa0;rpm). Structural analyses [Brunauer–Emmett–Teller (BET), Fourier-transform infrared (FTIR), and field-emission scanning electron microscopy (FESEM)] confirmed reduced particle size, increased surface area, and formation of lattice defects. Kinetic analysis using the shrinking core model indicated diffusion-controlled leaching through the product layer, while mixed-control modeling revealed a combined surface-reaction and diffusion mechanism, with mechanical activation increasing the apparent reaction rate constant four-fold. The apparent activation energy of the mechanically activated sample, based on the mixed-control model, was 18.78&#xa0;kJ&#xa0;mol<sup>−1</sup>, further supporting the predominance of diffusion-controlled kinetics. These results demonstrate that structural changes induced by mechanical activation significantly enhance chromite reactivity, providing mechanistic insight and practical guidance for more efficient chromium recovery.</p> Graphical Abstract <p></p>

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Mechanical Activation of Chromite for Enhanced Chromium Dissolution: Structural, Kinetic, and Recovery Insights

  • 期刊论文

  • 发表日期：

    2026年4月13日

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  • Alireza Razavi,
  • Asghar Azizi

摘要

Enhancing chromium dissolution from chromite, a mineral with a complex and refractory structure, remains a critical challenge for efficient recovery. Targeted mechanical activation has emerged as a promising strategy to overcome these limitations. This study systematically investigates the effects of mechanical activation on chromite’s structure and dissolution behavior. Initial alkaline and acidic leaching experiments revealed that chromite responds more favorably to acidic leaching. Optimal acidic extraction conditions were determined as 300 °C, 300 kg/t acid, L/S = 15, 400 rpm, and 4 h, achieving 53.3% chromium extraction. Mechanical activation was then applied prior to leaching, varying rotation speed, ball-to-powder ratio (BPR), and activation time, resulting in chromium recovery up to 80% under optimal activation conditions (BPR = 2, 15 min, 440 rpm). Structural analyses [Brunauer–Emmett–Teller (BET), Fourier-transform infrared (FTIR), and field-emission scanning electron microscopy (FESEM)] confirmed reduced particle size, increased surface area, and formation of lattice defects. Kinetic analysis using the shrinking core model indicated diffusion-controlled leaching through the product layer, while mixed-control modeling revealed a combined surface-reaction and diffusion mechanism, with mechanical activation increasing the apparent reaction rate constant four-fold. The apparent activation energy of the mechanically activated sample, based on the mixed-control model, was 18.78 kJ mol−1, further supporting the predominance of diffusion-controlled kinetics. These results demonstrate that structural changes induced by mechanical activation significantly enhance chromite reactivity, providing mechanistic insight and practical guidance for more efficient chromium recovery.

Graphical Abstract