白云鄂博矿焙烧浸出-萃取沉淀分离稀土及钍的试验研究

采用焙烧浸出-萃取沉淀法从白云鄂博稀土精矿中分离稀土和钍,得到最佳焙烧浸出条件为: 矿酸比1∶1.5、焙烧时间1 h、焙烧温度200 ℃、水浸液固比8∶1、水浸时间4 h、水浸温度50 ℃,最佳条件下CeO₂、La₂O₃、Nd₂O₃、Pr₆O₁₁、Sm₂O₃和ThO₂浸出率分别为80.77%、69.24%、95.71%、76.82%、93.31% 和98.13%。采用羧酸类萃取-沉淀剂从浸液中萃取分离稀土和钍,在萃取-沉淀剂皂化度70%、料液pH=3.1、萃取-沉淀剂和钍的摩尔比4∶1的最佳条件下,稀土和钍萃取-沉淀率分别为19%和90%,实现了稀土和钍的有效分离。

Experimental Study on Separation of Rare Earth and Thorium from Baiyun Obo Ore by Roasting-Leaching and Extraction-Precipitation Process

A processing technique consisting of roasting, leaching, extraction and precipitation was adopted for separating rare earth and thorium from rare earth concentrate in Bayan Obo in the experiment, and the optimal conditions were determined as follows: roasting at 200 ℃ for 1 h with mineral to acid at a ratio of 1∶1.5, immersion at 50 ℃ for 4 h with water to solid at a ratio of 8∶1. Under these conditions, the leaching rates of CeO₂, La₂O₃, Nd₂O₃, Pr₆O₁₁, Sm₂O₃ and ThO₂ reached 80.77%, 69.24%, 95.71%, 76.82%, 93.31% and 98.13%, respectively. Then, the process of carboxylic acid extraction-precipitating agent was used to extract and separate rare earth and thorium from the leaching solution. With the saponification degree of 70% for extraction-precipitating agent, pH of material solution of 3.1, and extraction-precipitating agent to thorium at a molar ratio of 4∶1, the extraction-precipitation rates of rare earth and thorium were 19% and 90%, respectively, indicating the effective separation of rare earth and thorium was actualized.