Modes of occurrence of elements in high-germanium coals using correlation analysis algorithm

Abstract

Modes of occurrence of elements in Ge-rich coals are important because they provide an understanding of Ge mineralization and insight into Ge behavior during coal combustion and the modes of occurrence for Ge in the resulting combustion products. Previous researchers showed that the leaching of granite by N2 – CO2 mixed hydrothermal solutions in the Lincang coal in southwest China led to the enrichment of Ge. Elevated Ge concentrations from leaching of granite by hydrothermal solutions have been established in the nearby Lincang Ge ore deposit; however, the influence of hydrothermal solutions, especially mixed hydrothermal solutions, on the modes of occurrence of elements in coal have not been quantitatively analyzed. In this paper, we focus on the quantitative analysis of the influence of mixed hydrothermal solutions on the modes of occurrence of elements in coal. Samples used in this study were collected from the Dazhai Mine, located in the Lincang Ge ore deposit, Yunnan Province, southwestern China. The correlation coefficients between pyrite, ash yield, Al2O3, and SiO2 versus elemental concentrations in coal are processed with the correlation analysis algorithm. The results show that a distinct break in pyrite content of ∼16.8 wt% as a threshold for different elemental modes of occurrence of elements as a result of hydrothermal fluids. The modes of occurrence of As and Hg changes from an organic-inorganic mixed affinity to predominantly in pyrite by the influence of volcanic hydrothermal fluids when the content of pyrite is higher than 16.8 wt%.