Quantitative study on correlations of chemical properties and trace elements of coals based on real database

The chemical properties and trace elements of coal affect its reactivity, slagging, fouling, corrosion, and conversion performance, which are crucial for its application in combustion for power generation and environmental protection. Based on approximately 1700 coal samples collected over the last 20 years, the correlations of chemical properties and trace elements, topics that have been insufficiently researched to date, were quantitatively investigated in this paper. Correlations between various chemical property indices were noted. The moisture (M_ar), ash (A_ar), and oxygen (O_ar) contents tend to decrease with increasing carbon content (C_ar), while volatile matter (V_ar), fixed carbon (FC_ar), hydrogen (H_ar), nitrogen (N_ar), and low heat value (Q_net,_ar) tend to increase. The FC_ar, C_ar, and Q_net,_ar are negatively correlated with volatile matter content (V_daf), wherea O_ar is positively correlated with V_daf. While chromium (Cd) is significantly enriched, the concentration of chlorine (Cl) varies over a much wider range of 0-8000 µg·g⁻¹ and exhibits a negative correlation with ash content (A_ar). Furthermore, mercury (Hg) and V_daf present a negative correlation, while Cl and nickel (Ni) show positive correlations with V_daf. Approximately 47.5% of the coal samples collected tend to be seriously slagging. There is a negative correlation between Cl and softening temperature (ST), implying that Cl tends to exacerbate slagging. This study assists in further comprehending the quantitative correlations among chemical properties, trace elements, environmental issues, slagging behaviors, and reactivity of coals.