包头稀土精矿添加25%碳酸钠焙烧反应动力学研究

Study on the Roast Reaction Kinetics of Baotou Rare Earth Concentrate Added by 25% Na_2CO_3

采用XRD、DTATG及化学分析等方法,对包头稀土精矿添加25%碳酸钠焙烧反应进行了研究。分解反应分两个阶段进行,第一阶段:348℃～455℃,稀土氟碳酸盐分解为稀土氟氧化物,铈被氧化得到CeO2;第二阶段:577℃～665℃,稀土磷酸盐分解为稀土氧化物。焙烧反应动力学计算结果为:第一阶段:E=150kJmol,n=087,A=184×1011s-1·mol-1,T=712K时反应速率常数k=0.398;第二阶段:E=229kJmol,n=1.18,A=6.14×109s-1·mol-1,T=921K时反应速率常数k=1.06×10-3。由TG曲线推断其反应机理,两阶段反应机制方程式均为:F1=-ln(1-α),控制反应速率的步骤均为随机成核,每一个粒子有一个核。

The research on the mechanism of roast reaction of Baotou rare earth concentrate added by 25% Na 2CO 3 was carried out by using thermal analysis,X ray diffraction and chemical analysis.RECO 3F was first decomposed into REOF and CeO 2 as roasting at 348～455℃,then REPO 4 was decomposed into RE 2O 3 as roasting at 577～665℃.The kinetics of roast reaction was calculated,at 348～455℃,E=150kJ·mol -1 ,n=0 87,A=1.84×10 11 S -1 ·mol -1 ,k=0.398(T=712k);and at 577～665℃,E=229kJ·mol -1 ,n=1.18,A=6.14×10 9S -1 ·mol -1 ,k=1 06×10 -3 (T=921k).F 1=-ln(1-α) was calculated to be the equation of the mechanism of roast reaction in two stages from thermogravimetric curves.