Concentration and Distribution of Cr, Pb and Zn in the Jurassic Coals from Northern Shaanxi and Ningxia, China

The concentration and distribution of Cr, Pb and Zn in 22 Jurassic coals from northern Shaanxi,and Ningxi, China were studied. The samples were collected from eight coal mines of five different region, including Yuyang Region, Hengshan, Shenmu, Huangling and Lingwu. Comparing with Chinese coals, American coals and coal Clarke value: Pb showed different degree enrichment in the study region except Ningxia ; Cr was enriched in Shenmu coals, Huangling coals and Hengshan coals; whereas the content of Zn in the study region coals was lower than in American coals. Horizontal variation of the three elements in the study region indicated that different elements showed different variation trend. Based on statistical analyses, Pb showed a moderate relationship with ash yield, whereas Cr had a high correlation coefficients with total sulfur.