Mild leaching with HNO acid can be suggested as a potential pre-treatment technique for removing most impurities found in ilmenite which has not been properly investigated yet. This study examines the mild HNO leaching behavior of ball-milled ilmenite as a novel pre-treatment method to produce high-purity synthetic rutile. Ilmenite was mechanically activated for 1 h at 500 rpm which was then reacted with 1 M HNO acid solution in the solid-to-liquid ratio (S/L) of 1:5 (/) at 90 °C, 300 rpm, for 2 h to obtain pretreated (ball-milled and ball-milled-mild-leached) ilmenite. The ball-milled ilmenite and ball-milled-mild-leached ilmenite were then reacted with varying concentrations of HSO, HCl, and KOH solutions at predetermined conditions. Titanium and iron extraction, TiO purity, phase transformations, surface morphologies, and relative elemental abundances were determined by atomic absorption spectroscopy (AAS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscope equipped with an energy-dispersive X-ray spectroscopy (SEM/EDX), respectively. The initial mild leaching process removed VO, MgO, MnO, CaO, and AlO impurities. The crystallinity indices of ball-milled ilmenite (39.7%) and ball-milled-mild-leached ilmenite (56.7%) indicate the effect of ball milling and mild leaching, respectively. The maximum Ti extraction of ball-milled-mild-leached ilmenite obtained from the sulfate method, chloride method, and alkaline method were 62.1%, 13.2%, and 41.8%, respectively. However, the Ti extraction of ball-milled-mild-leached ilmenite is relatively low compared to ball-milled ilmenite based on percentage extractions. Therefore, the HNO mild leaching process is important to remove impurities, and mechanical activation is more suitable for efficient Ti extraction than a combined step with leaching.

中文翻译：

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机械活化和 HNO3 预处理 Pulmoddai 钛铁矿对 H2SO4、HCl 和 KOH 辅助浸出提取 Ti 和 TiO2 的影响


建议使用硝酸进行温和浸出作为一种潜在的预处理技术，用于去除钛铁矿中发现的大多数杂质，但尚未得到适当的研究。本研究研究了球磨钛铁矿的温和 HNO 浸出行为，作为生产高纯度合成金红石的新型预处理方法。将钛铁矿以 500 rpm 机械活化 1 小时，然后与固液比 (S/L) 为 1:5 (/) 的 1 M HNO 酸溶液在 90 °C、300 rpm 下反应 2 h 获得预处理（球磨和球磨轻度浸出）钛铁矿。然后，球磨钛铁矿和球磨轻度浸出钛铁矿在预定条件下与不同浓度的 HSO、HCl 和 KOH 溶液反应。钛和铁的提取、TiO 纯度、相变、表面形貌和相对元素丰度通过原子吸收光谱 (AAS)、X 射线荧光 (XRF)、X 射线衍射 (XRD) 和配备有分别是能量色散 X 射线光谱 (SEM/EDX)。最初的温和浸出过程去除了 VO、MgO、MnO、CaO 和 Al2O 杂质。球磨钛铁矿（39.7%）和球磨轻度浸出钛铁矿（56.7%）的结晶度指数分别表明了球磨和轻度浸出的效果。硫酸盐法、氯化法和碱法得到的球磨轻浸钛铁矿的最大Ti提取率分别为62.1%、13.2%和41.8%。然而，与基于提取百分比的球磨钛铁矿相比，球磨轻度浸出钛铁矿的 Ti 提取率相对较低。 因此，HNO温和浸出工艺对于去除杂质非常重要，而机械活化比与浸出相结合的步骤更适合有效地提取Ti。