Estimation of a possibility to use the quantumchemical approach while selecting reagents for coals flotation intensification

Decrease of mined coal quality results in deterioration of main quality characteristics of coal concentrates: ash content, moisture, calorific efficiency and sintering ability. Application of selective reagent modes of coals flotation is an effective method of solving the problem. Elaboration of the reagent modes should be based on a study of mechanism of reagents action on the coal surface. Study of the aromatic esters effect on the physicochemical and flotation properties of gas coals from the Komsomolets mine of the Kuznetsk coal basin accomplished. It was shown that the low natural floatability of gas coals is due to the significant energy unsaturation of their surface, in particular, the presence of large pores, oxygen-containing groups and mineral impurities. The results of quantum chemical calculations demonstrate that the electrophilic centres of the coal are formed due to the electron density shift to the oxygen atoms. It was determined that the hydrophobization of the coal surface can be achieved using reagents that have more rigid nucleophilic nature compared to water molecules. The study of the quantum-chemical characteristics of aromatic esters suggests that they can interact with electrophilic areas of the organic mass of coal through a charge-controlled mechanism with the formation of charge transfer complexes. Results of the study of the aromatic esters effect on the physicochemical properties of coals surface and calculation of quantum-chemical characteristics of compositions, simulating the organic coals mass and studied reagents, allow to make a conclusion about possibility to intensify the coals flotation process based on application the quantum-chemical approach at the reagents selection.