加碳氯化-氧化反应方法从氟碳铈矿-独居石混合精矿中提取稀土

Rare Earth Extraction from Mixed BastnaesiteMonazite Concentrate by Carbochlorination-Oxidation

以活性炭为还原剂、氯气为氯化剂、SiCl4为除氟剂、O2和H2O混合气体为氧化剂,采用氯化-氧化反应方法从氟碳铈-独居石混合精矿中提取稀土元素.在脱氟剂SiCl4作用下,随着反应温度由500℃增至800℃,氟碳铈-独居石混合精矿稀土氯化率由92%增至99%,而无SiCl4时同样温度范围内,稀土氯化率为56%～88%,500℃氯化反应2h时主要产物为稀土氯化物、氯化钙;当氯化反应温度小于500℃时,与原料比钍的氯化产物挥发量小于1.0%.水洗氟碳铈-独居石混合精矿的焙砂,过滤并在空气中固化得到氯化产物,在550℃,O2+H2O气氛下氧化反应90min,实现稀土元素和非稀土元素、铈和非铈稀土元素的分离.

A stepwise carbochlorination-oxidation process was developed for the rare earth extraction from mixed bastnaesite-monazite concentrate using carbon as reductant, chlorine gas as chlorination agent, SiCl4 gas as defluorination agent, and O2＋H2O mixed gas as oxidant. Under the temperatures from 500℃to 800 ℃, the rare earth chlorinated conversion rate for 2 h was 56% to 88% in the absence of SiCl4, but 92% to 99% in the presence of SiCl4. The residue of carbochlorination of the mixed concentrate at 500℃ for 2 h mainly contained LnCI3 and CaCl2. When the temperature of carbochlorination was below 500 ℃, the portion of evaporated thorium to the thorium in the raw material was less 1.0%. The product of carbochlorination was leached with water and solidified in air. The subsequent oxidation of the solid chloride mixture in the wet air at 550℃ for 90 rain may result in the separation of rare earth elements and non-rare earth elements, and the separation of Ce and non-Ce elements.