抑制混合型稀土精矿焙烧过程中氟逸出的研究

利用气相色谱技术研究含混合稀土精矿焙烧过程中氟逸出的问题,分别对混合稀土精矿和加入一定量CaO-NaCl-CaCl2助剂的混合稀土精矿在400～750℃下焙烧30～120min的各个条件进行实验,测出不同条件下焙烧气体中的氟总量、逸出率、分解率以及焙烧产物的物相组成。结果表明:70%的环境湿度下,焙烧混合稀土精矿过程中氟的逸出率随焙烧温度和时间的增加而增大,其中焙烧温度的影响较大,750℃下焙烧2h时可达29.952%;添加CaO-NaCl-CaCl2助剂不仅降低了混合稀土精矿的分解温度,使混合稀土精矿在700℃下焙烧2h的分解率在90%以上,更重要的是抑制了焙烧过程中氟的逸出,使氟的逸出率由19.296%下降为0.315%,相对抑制作用为98.37%。

Inhibition of Fluorine Escape in Calcination Process of Rare Earth Concentrate

Gas chromatography (GC) technology was used to study the problem of fluorine escape in calcination process of rare earth concentrate. The rare earth concentrate and its assistant of CaO-NaCl-CaCl_2 were calcined at 400～750 ℃ for 30 ～ 120 min, and then the total amount of fluorine, emission ratio of fluorine, decomposition ratio and the components were determined. The results showed that the emission ratio of fluorine increased with the increase of temperature and time when the humidity was 70% in the calcination process of the rare earth concentrate, and the effect of temperature was obvious, the emission ratio of fluorine was 29.925% at 750 ℃ for 2 h. The decomposition ratio was up to 90% at 700 ℃ in 2 h calcination process of rare earth concentrate calcined with CaO-NaCl-CaCl_2, the emission ratio of fluorine decreased from 19. 296% to 0.315%, and the relative inhibition effect of fluorine was 98.37%.