Abstract Titanium production by a direct TiO2 reduction route which is highly energy-efficient and environment-friendly compared to commercial Kroll's process, known as HAMR (Hydrogen Assisted Magnesiothermic Reduction) process has been developed in recent times to meet the growing global demands of low-cost pure Ti. Removal of the Mg compounds after each reduction and de-oxygenation step in the HAMR process by leaching, is essential to ensure good purity and mechanical properties of the final Ti powder. In this study, we investigate the effects of temperature, particle size, and pH on the dissolution kinetics of Mg from Mg-bearing compounds such as MgO and MgCl2 that remain after the HAMR Process. We also report the underlying mechanism and rate-controlling steps of Mg removal using HCl in connection with the HAMR process. The dissolution kinetics followed a logarithmic rate kinetic model for diffusion through a porous medium that is commonly used for battery research. Kinetics of leaching were significantly improved using finer particles with 99.96 wt.% Mg removal and corresponding Ti loss of only 1.8 wt. %. The rate of dissolution exhibited a weak dependence with the pH and did not abide by the rate-controlling steps of dissolution of ionic oxides like MgO proposed by previous kinetic models.

中文翻译：

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影响TiO2氢辅助磁热还原(HAMR)中含Mg氧化物杂质浸出机理的因素

摘要 通过直接 TiO2 还原路线生产钛，与商业 Kroll 工艺相比，它具有高能效和环境友好性，称为 HAMR（氢辅助磁热还原）工艺，以满足全球日益增长的低-成本纯钛。通过浸出在 HAMR 工艺中的每个还原和脱氧步骤之后去除 Mg 化合物对于确保最终 Ti 粉末的良好纯度和机械性能至关重要。在本研究中，我们研究了温度、粒径和 pH 值对 HAMR 工艺后残留的含镁化合物（如 MgO 和 MgCl2）中 Mg 溶解动力学的影响。我们还报告了与 HAMR 过程相关的使用 HCl 去除 Mg 的潜在机制和速率控制步骤。溶解动力学遵循对数速率动力学模型，用于通过多孔介质扩散，这通常用于电池研究。使用更细的颗粒显着改善了浸出动力学，镁去除率为 99.96 重量％，相应的钛损失仅为 1.8 重量％。%。溶解速率表现出与 pH 值的弱相关性，并且不遵守先前动力学模型提出的离子氧化物（如 MgO）溶解速率控制步骤。