Ilmenite ore is an important Ti-bearing raw material for titania pigment and titanium metal production. Traditional fluidizing chlorination is not suitable to ilmenite containing high contents of MgO and CaO. In this study, a new process for reduction and nitridation of ilmenite using NH₃ gas was proposed to prepare titanium oxynitride, which can be used for low-temperature selective chlorination. The thermodynamic calculation indicated that reduction and nitridation of FeTiO₃ by NH₃ was feasible at a relatively low temperature. Metallic iron and titanium nitride were the ultimate products. The experimental results showed that titanium oxynitride Ti(N,O) can be formed at 900–1000 ℃. After reacting at 1000 ℃ for 8 h, the main phases were Fe and Ti(N,O). Increasing the reduction temperature and prolonging the duration time were beneficial to the reduction and nitridation process. Density functional theory study was also conducted to reveal the reaction mechanism. Theoretical and experimental results indicated that the reaction process can be divided into two stages: the initial deoxidation to form Fe and TiO₂, deep deoxidation and nitridation of TiO₂ to generate Ti(N,O).

Graphical Abstract

中文翻译：

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洁净氨能对钛铁矿的还原氮化行为

钛铁矿是二氧化钛颜料和钛金属生产的重要含钛原料。传统的流化氯化法不适用于MgO和CaO含量高的钛铁矿。本研究提出了一种利用NH ₃气对钛铁矿进行还原氮化制备氧氮化钛的新工艺，该工艺可用于低温选择性氯化。热力学计算表明，NH _{3对FeTiO 3的还原和氮化作用}在相对较低的温度下是可行的。金属铁和氮化钛是最终产品。实验结果表明，氮氧化钛Ti(N,O)可在900~1000 ℃形成。1000 ℃反应8 h后，主要相为Fe和Ti(N,O)。提高还原温度和延长反应时间有利于还原和氮化过程。还进行了密度泛函理论研究以揭示反应机理。理论和实验结果表明，该反应过程可分为两个阶段：初始脱氧生成Fe和TiO _{2 ，​​TiO 2}深度脱氧和氮化生成Ti(N,O)。

图形概要