Comprehensive Utilization for Neogene Lignite of the Zhaotong Basin, South China, and Its Environment Impacts

Neogene lignite is widely used for enterprise's electric power generation, local residents' warming and cooking, and crops' fertilizer in South China nowadays. But there is still no report about the element variations in Neogene lignite from the Zhaotong Basin, South China. Understanding the elemental concentration in lignite is of great importance to comprehensive utilization and to evaluation of environmental impacts of the Neogene lignite. We studied the variation patterns of 34 elements in lignite samples collected from the Neogene Zhaotong Formation at Zhaotong Basin, Yunnan Province, China. The arithmetic average of Cr, V, Ga, As, Cu, Rb, Co, Mo, and Cd in studied lignite samples is higher than those of China coals, while the content of Li and Bi are lower. Contents of As, Rb, La, Ni, Cd, Mo, Co, Ga, and V in northeastern Yunnan lignite are higher than the corresponding elements in common American Texas lignite, while contents of Li and Bi are lower. Elements are classified into four groups (Si-K-Zn-Rb-Ba-Pb, Co-Cd-Na-Al, Ni-Ti-Bi-Cr-Cu-In-Mn-Mg-Ga-Fe-Tl, and V-U-Cs-Sc-La-Sr-L-Se-Ca-As-Mo-S) based on their correlation coefficient with ash yield. Elements, including Al, K, Na, Si, Ti, Ba, Bi, Cd, Cr, Cu, Cs, Co, Ga, Ni, Sc, Zn, and Pb, decrease from bottom to top of the Neogene Zhaotong Formation, whereas Ca, Mg, As, Se, Mo, Fe, and S increase. In addtion, in M2 and M3 coal-bearing beds, Ga has potential applications after recycling and Se could be reutilized as a kind of Se-containing fertilizer, and their reserves estimations are approximately 98 x 10(4) (Ga) tons and 7.8 x 10(4) tons (Se). Cr and Cd in Neogene lignite have potential risk for local natural environments and the health of human beings.