Abstract

This study investigated the effects of temperature, pH, and stirring speed of multistage precipitation processes. The purification process consists of uranium and thorium precipitation, oxalate precipitation, calcination, HNO₃ leaching, and oxidation; finally, multistage precipitation is performed using Na₂CO₃ and NH₄OH. The precipitation efficiencies of light rare earth elements (LREEs) and heavy rare earth elements (HREEs) reached 88% and 74%, respectively, during precipitation with 15% Na₂CO₃ at a temperature of 50 °C, pH of 4.5, and 200 rpm. The precipitation process was continued by adding 10% NH₄OH to the first precipitation raffinate. A total of 45% of the LREEs were recovered at a temperature of 30 °C, pH of 8, and 300 rpm. Meanwhile, 72% of the HREEs were recovered at a temperature of 30 °C, pH of 7, and 200 rpm. It was observed that Na₂CO₃ was effective in precipitating rare earth elements (REEs) at higher temperatures, whereas NH₄OH was better at precipitating the HREEs from an REE-nitrate solution under the same processing conditions.

Graphical Abstract

中文翻译：

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印尼锆石尾矿中稀土元素纯化多级沉淀工艺的优化

摘要

这项研究调查了温度，pH值和多阶段沉淀过程的搅拌速度的影响。提纯过程包括铀和precipitation沉淀，草酸盐沉淀，煅烧，HNO ₃浸出和氧化。最后，使用Na ₂ CO ₃和NH ₄ OH进行多阶段沉淀。在温度为50°C，pH为4.5和pH为15的条件下用15％Na ₂ CO ₃沉淀期间，轻稀土元素（LREEs）和重稀土元素（HREEs）的沉淀效率分别达到88％和74％。200 rpm。通过添加10％NH ₄继续沉淀过程OH至第一个沉淀萃余液。在30°C，pH 8和300 rpm的温度下，总共回收了45％的L​​REE。同时，在30°C，pH 7和200 rpm的条件下回收了72％的HREE。观察到，在相同的处理条件下，Na ₂ CO ₃在较高温度下可有效沉淀稀土元素（REE），而NH ₄ OH在从REE-硝酸盐溶液中沉淀HREE方面更好。

图形概要