Decomposition process of bastnaesite concentrate in NaOH-CaO-H2O system
来源期刊：JOURNAL OF RARE EARTHS2019年第7期
论文作者：Jiang Liu Ting’an Zhang Zhihe Dou Yan Liu Guozhi Lv
文章页码：760 - 766
摘 要：A novel process of calcification-leaching for bastnaesite concentrate（REFCO3） was proposed. The prior calcification was carried out in the system of NaOH-CaO-H2O and the lgC-pH pattern for Ce-F-Ca-C-H2O system was drawn. The thermodynamics result indicates that decomposition for bastnaesite requires certain alkaline condition, but excessive alkalinity also causes decomposition of CaF2. XRD and SEM-EDS analyses on the calcification-leaching process reveal that bastnaesite first decomposes into RE（OH）3 and CaF2. Then, by HCl leaching rare earths were extracted,while CaF2 was left in the leaching residue. In addition, effects of temperature, time, NaOH and CaO on the calcification were investigated. The results show that the leaching rate of rare earths（REs）reaches 72.5 wt%, at the same time 99.2 wt% of F is left in leaching residue with 20 wt% NaOH and 38 wt% CaO at 493 K for 180 min.
Jiang Liu，Ting’an Zhang，Zhihe Dou，Yan Liu，Guozhi Lv
摘 要：A novel process of calcification-leaching for bastnaesite concentrate（REFCO3） was proposed. The prior calcification was carried out in the system of NaOH-CaO-H2O and the lgC-pH pattern for Ce-F-Ca-C-H2O system was drawn. The thermodynamics result indicates that decomposition for bastnaesite requires certain alkaline condition, but excessive alkalinity also causes decomposition of CaF2. XRD and SEM-EDS analyses on the calcification-leaching process reveal that bastnaesite first decomposes into RE（OH）3 and CaF2. Then, by HCl leaching rare earths were extracted,while CaF2 was left in the leaching residue. In addition, effects of temperature, time, NaOH and CaO on the calcification were investigated. The results show that the leaching rate of rare earths（REs）reaches 72.5 wt%, at the same time 99.2 wt% of F is left in leaching residue with 20 wt% NaOH and 38 wt% CaO at 493 K for 180 min.
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