中文摘要：

采用高温直接还原熔分工艺处理白云鄂博稀土复合铁矿,在1400℃条件下还原12和15 min,可得到含Fe 94.35%~95.20%的珠铁和含稀土9.71%~10.55%的富稀土渣。直接还原熔分过程未添加CaCO3获得的稀土渣其稀土相以Ce4.667（SiO4）3O析出,当配加5%的CaCO3时,稀土富集相转变为铈磷灰石（Ca3Ce2[（Si,P）O4]3F）,但两种稀土富集相均属于硅酸盐系。将获得富稀土渣磨碎至〈74μm并置于HCl中浸出,实验结果表明：在HCl浓度1 mol·L^-1,浸出时间2 h,固液比为1∶14和环境温度50℃时,稀土浸出率均能达到95%以上,还原熔分过程未添加CaCO3设定还原时间12和15 min或还原熔分过程加入5%CaCO3还原时间12 min,富稀土渣中Th的浸出率从21.92%分别增加到31.43%和51.58%。

英文摘要：

The rare earth composite iron ore was processed by technological process of high-temperature direct reduction melting separation. After reducing for 12 and 15 min at 1400 ℃,the iron nugget containing 94. 35% ~95. 20% Fe and slag containing 9. 71% ~ 10. 55% rare earth were obtained,respectively. Ce4. 667（SiO4）3O precipitated without addition of CaCO3 and britholite（ Ca3Ce2[（ Si,P）O4]3F） was the crystalline phase with addition of 5% CaCO3 in direct reduction process. Both of the two phases were silicate systems. The rare earth sludge,which was smaller than 74 μm,was leached with a hydrochloric acid at different conditions. The optimal technological parameters were suggested as follows： the concentration of hydrochloric acid,the leaching time,the ratio of solid to liquid and the leaching temperature were 1 mol·L^- 1,2 h,1∶ 14 and 50 ℃,respectively. The total recovery rate of thorium was 21. 92%,31. 43% and 51. 58% respectively,when the reduction time was 12 and 15 min and with the addition of 5% CaCO3.