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<p>Laterite nickel ore contains chromite, a chemically stable but highly abrasive mineral that remains undissolved during high-pressure acid leaching (HPAL). This characteristic causes severe equipment erosion, increasing maintenance costs and operational risks. Therefore, this study aimed to determine the optimal physical separation process for producing chromium concentrate, evaluate conventional methods for recovering, and propose scientific improvement measures to improve the recovery and grade of chromium. The method used was a separation process of a hydrocyclone, a spiral concentrator, a two-stage shaking table, and weak-intensity magnetic separation. The underflow of the hydrocyclone attained only 33.50% Cr<sub>2</sub>O<sub>3</sub> recovery with a chromium grade of 3.69% Cr<sub>2</sub>O<sub>3</sub>. This conventional physical separation obtains chromium concentrate with a Cr<sub>2</sub>O<sub>3</sub> grade of 37.67% and a Cr<sub>2</sub>O<sub>3</sub> recovery rate of 2.28%. These values were achieved, remaining low because a large amount of fine-grained chromium minerals was lost in the hydrocyclone. To solve the problem, the separation process was applied by using a two-stage hydrocyclone, weak-intensity magnetic separation, and high-intensity magnetic separation as the initial pre-concentrate. The underflow of the second-stage hydrocyclone and the high-intensity magnetic separation concentrate are called the first pre-concentrated with 41.02% Cr<sub>2</sub>O<sub>3</sub> recovery and 3.71% Cr<sub>2</sub>O<sub>3</sub> grade. Through the modification for physical separation, chromium concentrate output was significantly increased, while Cr<sub>2</sub>O<sub>3</sub> grade and recovery reached 39.29% and 22.63%, respectively. Chromium concentrate obtained from limonite laterite nickel ore has a Cr/Fe ratio of 1.70. This value meets the standards for chromium concentrate used as a material for electric arc furnace operations, making it possible to sell it to other industries and provide economic value to the company. This study showed the effectiveness of a modified physical separation strategy in significantly improving both the grade and recovery of chromium from limonite laterite nickel ore.</p>

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Integrated Physical Separation Process for Optimizing Chromium Recovery from Limonite Laterite Nickel Ore

  • 期刊论文

  • 发表日期：

    2025年8月8日

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  • Ulfi Rohmawati,
  • Ailiang Chen,
  • Guoquan Jin,
  • Dongdong Yao

摘要

Laterite nickel ore contains chromite, a chemically stable but highly abrasive mineral that remains undissolved during high-pressure acid leaching (HPAL). This characteristic causes severe equipment erosion, increasing maintenance costs and operational risks. Therefore, this study aimed to determine the optimal physical separation process for producing chromium concentrate, evaluate conventional methods for recovering, and propose scientific improvement measures to improve the recovery and grade of chromium. The method used was a separation process of a hydrocyclone, a spiral concentrator, a two-stage shaking table, and weak-intensity magnetic separation. The underflow of the hydrocyclone attained only 33.50% Cr2O3 recovery with a chromium grade of 3.69% Cr2O3. This conventional physical separation obtains chromium concentrate with a Cr2O3 grade of 37.67% and a Cr2O3 recovery rate of 2.28%. These values were achieved, remaining low because a large amount of fine-grained chromium minerals was lost in the hydrocyclone. To solve the problem, the separation process was applied by using a two-stage hydrocyclone, weak-intensity magnetic separation, and high-intensity magnetic separation as the initial pre-concentrate. The underflow of the second-stage hydrocyclone and the high-intensity magnetic separation concentrate are called the first pre-concentrated with 41.02% Cr2O3 recovery and 3.71% Cr2O3 grade. Through the modification for physical separation, chromium concentrate output was significantly increased, while Cr2O3 grade and recovery reached 39.29% and 22.63%, respectively. Chromium concentrate obtained from limonite laterite nickel ore has a Cr/Fe ratio of 1.70. This value meets the standards for chromium concentrate used as a material for electric arc furnace operations, making it possible to sell it to other industries and provide economic value to the company. This study showed the effectiveness of a modified physical separation strategy in significantly improving both the grade and recovery of chromium from limonite laterite nickel ore.