氟碳铈矿-(La)的水热合成实验

Experimental Study on the Hydrothermal Synthesis of Bastnasite-(La)

氟碳铈矿是稀土矿床最主要的矿石矿物,开展氟碳铈矿的水热合成实验对于揭示稀土元素的热液成矿作用具有重要意义。本文采用La（NO3）3·6H2O、NaF和NaHCO3/Na2CO3作为实验初始物,分别在不同温度、pH、氟离子浓度,碳酸氢钠/碳酸钠条件下,运用水热法合成了氟碳铈矿,并对合成产物进行了XRD和SEM分析。实验结果显示,碳酸氢钠、碳酸钠和低氟离子浓度条件下均可形成氟碳铈矿-（La）纯相,但高氟离子浓度条件下还生成有氟铈矿-（La）杂相。鉴于自然界氟碳铈矿的普遍出现以及氟铈矿的极少产出,稀土矿床中氟碳铈矿结晶沉淀于氟离子浓度不太高的环境。

Bastnasite is one of the most important minerals in rare earth deposits. Therefore, research on the hydrothermal synthesis of bastnasite is significantly important for revealing the hydrothermal mineralization of rare earth elements. In this paper, La（NO3）3·6 H2O, NaF and NaHCO3/Na2CO3 were used to synthesize bastnasite by using hydrothermal method at various temperatures, pH values, fluoride ion concentrations, and sodium bicarbonate/sodium carbonate. Then the synthesized products have been analyzed by using XRD and SEM. The results show that the pure bastnasite-（La） phase can be formed in hydrothermal fluid with sodium bicarbonate/sodium carbonate and low fluoride ion concentration, while the complex of bastnasite-（La） and fluocerite-（La） phases was formed in the fluid of high fluoride ion concentration. Due to the common appearance of bastnasite and the occasional present of fluocerite in the nature, it is believed that the bastnasite of REE deposites could be crystalized and precipitated in the fluid with low fluoride ion concentration.