宁武煤田平朔矿区9号煤中锂的富集机理

Enrichment Mechanism of Lithium in Coal Seam No. 9 of the Pingshuo Mining District,Ningwu Coalfield

从宁武煤田平朔矿区的9号煤中共采了58个煤样,通过光学显微镜、逐级化学提取、SEM-EDX分析、X射线粉末衍射和ICP-MS技术对这些样品进行分析。结果表明9号煤中Li的平均含量达到152 mg/kg,9号煤的点储量为36.7亿吨,Li O2的量达119.5万吨,也就是说煤层中锂的储量约为55.8万吨;逐级化学提取过程的结果表明,Li的富集主要与无机物有关,只有约5.5%的锂具有有机亲和力,这些无机矿物是高岭石、勃姆石、绿泥石族矿物、石英、方解石、黄铁矿以及无定形粘土状矿物等,在含锂煤层中,锂可能被粘土矿物吸附;根据古地理研究,9号煤中锂的最初来源可能是阴山古陆,盆地北部本溪组中的铝土矿可能是锂的直接来源。

A total of 58 coal samples of seam No. 9 were collected from the Pingshuo mining district,Ningwu coalfield,Shanxi Province. The samples were analysed by optical microscopy,sequential chemical extraction procedure,SEM- EDX analysis,X-ray powder diffraction,and ICP- MS techniques. The results indicate that the average Li content of seam 9 reaches 152 mg / kg. The coal reserves of seam 9 are 3. 67 Gt,implying Li reserves of the seam amount to 558 kt,i. e. 1. 195 mt Li2 O. The sequential chemical extraction results suggest that the Li concentration is mainly related to inorganic materials,and only about 5. 5% lithium has an organic affinity. These minerals are kaolinite,boehmite,chlorite-group minerals,quartz,calcite,pyrite,and amorphous clay-like material. Lithium could be absorbed by clay minerals in the Li-bearing coal seam. According to the paleogeography,the Yin Shan ancient land could be the most possible source of Li in the coal. The bauxite of the Benxi Formation,originally derived from the Yin Shan in the north part of the basin,could be the direct Li's source of the coal.