一、稀土元素的赋存状态及矿物的分类
稀土元素在地壳中的赋存状态有以下三种:(1)参加矿物晶格,构成矿物不可缺少的成份,形成独立的矿物(如独居石、氟碳铈矿),这是稀土元素在地壳中赋存的主要形态;(2)以类质同象置换(钙、锶、钡、锰等)的形态分散于造岩矿物和其他稀有矿物之中,这是次要的赋存形态;(3)呈离子形态吸附在其他矿物表面或颗粒之间,这是比较少见的一种赋存形态。
根据稀土矿物的化学成分,可将已发现的稀土矿物分为九类,各类典型的稀土矿物列于表1。
normal align=center>表1 稀土矿物分类表
normal align=center>类别
normal align=center>主要矿物
normal align=center>氟化物
normal align=center>钇萤石、氟钙钠钇石、氟铈矿等
normal align=center>碳酸盐,氟碳酸盐
normal align=center>氟碳铈矿、黄河矿、碳酸锶铈矿等
normal align=center>磷酸盐
normal align=center>独居石、磷钇矿
normal align=center>硅酸盐
normal align=center>硅铍钇矿、钪钇石
normal align=center>氧化物
normal align=center>褐钇铌矿、易解石、黑稀金矿
normal align=center>砷酸盐
normal align=center>砷钇矿
normal align=center>硼酸盐
normal align=center>水铈钙硼石
normal align=center>硫酸盐
normal align=center>水氟钙钇矾
normal align=center>矾酸盐
normal align=center>钡钇矿
二、主要工业矿物及其物理、化学性质
目前,世界上已发现的含有稀土的矿物大约有250种以上,有研宄和利用价值的稀土矿物大约有50~60种,具有工业开采和实用价值的稀土矿物不过10几种,其重要的稀土矿物的物理、化学性质列于表2。
normal align=center>表2 稀土矿物的物理、化学性质
normal align=center>矿物名称
normal align=center>化学性质
normal align=center>分子式
normal align=center>REO%
normal align=center>可溶性
normal align=center>氟碳铈矿
normal align=center>CeCO3F
normal align=center>74.77
normal align=center>溶于HCl
normal align=center>独居石
normal align=center>CePO4
normal align=center>67.76
normal align=center>H2SO4、HCl、H3PO4微溶于NaOH
normal align=center>磷钇矿
normal align=center>YPO4
normal align=center>63.23
normal align=center>溶于H2SO4、H3PO4微溶于NaOH
normal align=center>氟碳钙铈矿
normal align=center>Ce2Ca(CO3)3F2
normal align=center>60.30
normal align=center>溶于HCl、H2SO4、HNO3
normal align=center>硅铍钇矿
normal align=center>Y2FeBe(SiO4)2O2
normal align=center>51.51
normal align=center>溶于HCl、微溶于NaOH
normal align=center>易解石
normal align=center>(CeThY)(TiNb)2O6
normal align=center>29.36
normal align=center>溶于H2SO4、H3PO4易溶于HF、
normal align=center>H2SO4+(NH4)2SO4
normal align=center>铈铌钙钛矿
normal align=center>(NaCeCa)(TiNb)O3
normal align=center>28.71
normal align=center>不溶于HCl、H2SO4、HNO3溶于HF
normal align=center>复稀金矿
normal align=center>Y(TiNB)2(O·OH)4
normal align=center>29.28~33.43
normal align=center>溶于H2SO4、H3PO4、HF
normal align=center>黑稀金矿
normal align=center>Y(TiNbTi)2(O·OH)6
normal align=center>20.82~29.93
normal align=center>溶于HF、H2SO4、H3PO4
normal align=center>褐钇铌矿
normal align=center>YNbO4
normal align=center>39.94
normal align=center>溶于H2SO4,HNO3
normal align=center>(续表2)
normal align=center>矿物名称
normal align=center>物理性质
normal align=center>密度g∕cm2
normal align=center>硬度
normal align=center>比磁化系数×10-6cm3∕g
normal align=center>介电常数
normal align=center>晶形
normal align=center>2氟碳铈矿
normal align=center>4.72~5.12
normal align=center>4~5.2
normal align=center>12.59~10.19
normal align=center>5.65~6.96
normal align=center>三方晶系
normal align=center>独居石
normal align=center>4.83~5.42
normal align=center>5~5.5
normal align=center>12.75~10.58
normal align=center>4.45~6.69
normal align=center>单斜晶系
normal align=center>磷钇矿
normal align=center>4.4~4.8
normal align=center>4~5
normal align=center>31.28~26.07
normal align=center>8.1
normal align=center>正方晶系
normal align=center>氟碳钙铈矿
normal align=center>4.2~4.5
normal align=center>4.2~4.6
normal align=center>14.37~11.56
normal align=center>三方晶系
normal align=center>硅铍钇矿
normal align=center>4.0~4.65
normal align=center>6.5~7
normal align=center>62.5~49.38
normal align=center>单斜晶系
normal align=center>易解石
normal align=center>5~6.4
normal align=center>4.5~6.5
normal align=center>18.04~12.92
normal align=center>4.4~4.8
normal align=center>斜方晶系
normal align=center>铈铌钙钛矿
normal align=center>4.58~4.89
normal align=center>5.8~6.3
normal align=center>6.54~5.23
normal align=center>5.56~7.8
normal align=center>等轴晶系
normal align=center>复稀金矿
normal align=center>4.28~5.05
normal align=center>4.5~5.5
normal align=center>21.05~18.00
normal align=center>斜方晶系
normal align=center>黑稀金矿
normal align=center>4.2~5.87
normal align=center>5.5~6.5
normal align=center>27.38~18.41
normal align=center>3.7~5.29
normal align=center>斜方晶系
normal align=center>褐钇铌矿
normal align=center>4.89~5.82
normal align=center>5.5~6.5
normal align=center>29.2~21.16
normal align=center>4.5~16
normal align=center>四方晶系
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