Concentrations of valuable elements of the coals from the Pingshuo Mining District, Ningwu Coalfield, northern China

A total of 840 coal samples were taken from the Pingshuo (Pinglu-Shuoxian) Mining District, Ningwu Coalfield, northern China. 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 Li, Ga and Al contents of the coals have reached an economically valuable level. Total Li reserves reached 100000, 558400 and 382600 tons in the Nos. 4, 9 and 11 seams, respectively. Total Ga reserves reached 28600, 80700 and 40900 tons in the Nos. 4, 9 and 11 seams, respectively. Total Al reserves reached 206000000 tons in the No. 9 seam. The sequential chemical extraction procedure results indicate that the element concentrations are mainly related to inorganic matter. The minerals are kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. The kaolinite, boehmite and chlorite phase could be the most likely host of the Li, Ga and Al. These elements could be migrated from the Yinshan Oldland or bauxite of the Benxi formation by absorption. The bauxite of the Benxi formation should be the most possible source of Li, Ga and Al of the coal in the Pingshuo district.