中文摘要：

研究了氧化钙对混合稀土精矿焙烧分解过程气相中氟含量的影响，采用气相色谱分析方法对焙烧过程气相中的氟进行测定，结果表明氧化钙在混合稀土精矿的分解过程中起到了固氟的作用，使焙烧过程气相中的氟含量降低60％以上。从加入氧化钙后的混合稀土精矿的焙烧产物XRD实验结果看，焙烧产物中有大量的CaF2和Ca5F（PO4）3生成，说明氧化钙对混合稀土精矿分解过程的固氟机制是CaO与其中的氟碳铈矿的分解产物REOF反应生成了CaF2，同时形成的氟化钙和氧化钙一起在800℃时能够与精矿中的独居石反应，生成Ca5F（PO4）3。

英文摘要：

Effect of CaO on the content of fluorine in gas of decomposition of mixed rare earth concentrate was studied. The content of fluorine was measured by the gas chromatographic analysis method, and the resuits showed that CaO could absorb the fluorine in the decomposition of mixed rare earth concentrate, and 60% fluorine in the gas was absorbed. The result of XRD experiment of roasting production of mixed rare earth concentrate with 15% CaO showed that there is a great deal of CaF2 and CasF （PO4）3 in the roasting production. This showed that the absorbing fluorine mechanism of CaO in the decomposition of mixed rare earth concentrate was that CaF2 was generated by the chemical reaction of CaO and REOF which was the decomposed product of bastinasite in mixed rare earth concentrate, and at the meantime monazite in mixed rare earth concentrate CaO at 800 ℃ to form was decomposed by CaF2 and CasF（PO4）3.