Changes in the Composition and Properties of Humic Substances upon the Mechanical Treatment of Coals with Mineral Salts

Abstract—The mechanical treatment (MT) of brown coals in the presence of a complex of oxidizing alkaline reagents and mineral salts increased the yield of water-soluble humic substances (HSs) by 20–30%. The composition of coals and reagents in the MT affected the concentration of acidic functional groups in humic acids. Ion-exchange processes during the MT of coals with mineral salts were accompanied by an increase in the concentrations of macro and trace elements in the composition of HSs. A significant increase in the antioxidant activity of humic acids was found upon MT with ammonium phosphate and ammonium sulfate. Mineral elements in HSs exhibited physiological activity by influencing the development of wheat roots and seedlings.