Isothermal reduction and nitridation kinetics of ilmenite concentrate in ammonia gas
Isothermal reduction and nitridation kinetics of ilmenite concentrate in ammonia gas
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DOI：
10.1016/j.mineng.2023.108319
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发表时间：
2023-11
影响因子：
4.8
通讯作者：
Yongjie Liu;F. He;Qingqing Hu;Qing-yun Huang;Zhixiong You;G. Qiu;X. Lv
中科院分区：
文献类型：
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作者：
Yongjie Liu;F. He;Qingqing Hu;Qing-yun Huang;Zhixiong You;G. Qiu;X. Lv
低温氯化工艺适用于高含量氧化镁和氧化钙的钛铁矿。然而，还原碳化或氮化是将氧化钛转化为碳化物或氮化物的关键，而磁选可以使碳化物或氮化物富集化。研究了攀枝花钛精矿在氨气气氛中的等温还原氮化动力学。用无模型法和模型拟合法比较了等温动力学。反应过程可分为两个连续的阶段：还原反应和氮化反应。用无模型法求出还原反应的平均表观活化能为139.63 kJ/m o l。用模型拟合法也可以将还原过程细分为两个阶段。化学反应(G(α)n=1-(1-α)1/3=kt)和三维扩散(G(α)n=0[1-(1-α)1/3]2=kt)是还原过程的机理函数。这两个阶段的活化能分别为121.73和141.40。函数G(α)n=1-(1-α)1/3=kt也符合化学反应机理(R3)，最适合于氮化阶段。相应的活化能为32.10kJ/mol。还原阶段生成金属铁和Ti3O5，氮化阶段生成Ti3O5。
Low-temperature chlorination is considered a suitable process for ilmenite containing high contents of MgO and CaO. However, reduction carbonization or nitridation is essential to convert titanium oxide to carbide or nitride, which can be enriched by magnetic separation. In this paper, the isothermal reduction–nitridation kinetics of Panzhihua ilmenite concentrate in an ammonia atmosphere was investigated. Both model–free and model–fitting methods were used to compare the isothermal kinetics. The reaction process can be divided into two successive stages: the reduction reaction and the nitridation reaction. The average apparent activation energy for the reduction reaction was 139.63 kJ/mol, obtained by the model–free method. The reduction process can also be subdivided into two stages by the model–fitting method. The chemical reaction (G(α) = 1–(1–α)1/3=kt) and three–dimensional diffusion (G(α) = [1–(1–α)1/3]2=kt) were identified as the mechanism function for the reduction process. The activation energies of these two stages were 121.73 kJ/mol and 141.40 kJ/mol, respectively. The function G(α) = 1–(1–α)1/3=kt, which also corresponds to the chemical reaction mechanism (R3), exhibited the best fit for the nitridation stage. The corresponding activation energy was 32.10 kJ/mol. Metallic iron and Ti3O5were formed in the reduction stage, while Ti3O5was then transformed to Ti(N,O) in the nitridation stage.