(中南大学 冶金科学与工程学院，长沙 410083)
摘 要: 用于铬盐生产的传统无钙焙烧过程存在铬氧化率低的问题，严重影响铬的生产效率和回收率。为强化铬铁矿氧化焙烧过程，对铬氧化过程的动力学规律及其氧化反应机理进行了研究。结果表明：铬铁矿氧化焙烧过程，铬的氧化反应分为初期和后期两个阶段，初期铬氧化速率快，后期铬氧化速率慢，在优化条件下，铬(Ⅲ)的氧化率可达99%以上；两个阶段铬的氧化反应均符合收缩未反应核动力学模型且受表面化学反应控制，铬氧化反应初期和后期的表观反应活化能分别为68.7和231.8 kJ/mol；反应初期是铬铁矿直接与碳酸钠和氧气发生反应生成铬酸钠，而后期则是铬铁矿与反应初期生成的铁酸钠和氧气发生反应生成铬酸钠。
关键字: 铬铁矿；铬酸钠；氧化焙烧；动力学
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The traditional lime-free roasting process used for manufacturing chromate from chromite ore has low oxidation rate which impact the chromate production efficiency and chromium recovery rate seriously. To intensify the oxidation roasting process of chromite ore, the oxidation kinetics and its mechanism were studied. The results show that there are two stages for the oxidation roasting process of chromite ore. The oxidation reaction is very rapid in the initial stage but quite slow in the later stage. The oxidation rate of chromium(Ⅲ) in chromite ore can reach more than 99% under the optimized conditions. The whole oxidation process of chromite ore follows the shrinking unreacted core model, and the surface chemical reaction is the controlling step. The apparent activation energies of the initial and later stages are 68.7 and 231.8 kJ/mol, respectively. And the sodium chromate is produced by the reaction of chromite with sodium carbonate and oxygen in the initial stage, whereas sodium chromate is formed by the reaction of chromite with sodium ferrite formed in the initial stage and oxygen in the latter stage.
Key words: chromite ore; sodium chromate; oxidation roasting; kinetics
