More efficient flotation of flocculated coal fines using a modifying agent

Abstract

The flocculation of coal fines using synthetic anionic flocculants based on acrylamide is considered. It is established that acrylamide may compete with water molecules at hydroxyl and carboxyl centers of the coal surface, to form molecular complexes with a hydrogen bond. Thanks to the presence of active polar centers—oxygen and nitrogen atoms—in the copolymer of acrylamide with sodium acrylate, the coal particles that are absorbing the flocculant become more hydrophilic, and consequently the effectiveness of coal flotation is reduced. To improve the flotation of coal fines, a modifying agent is supplied after preliminary flocculation. The modifier employed is Neonol, a product of petroleum processing. HyperChem software is used to confirm that the modifier may be adsorbed on the active centers of the flocculant and coal surface by means of hydrogen bonds. That renders the flocculated coal particles more hydrophobic and thus improves their flotation. This behavior of Neonol modifier is confirmed by gas-chromatographic data regarding the adsorption of chemical compounds on the coal surface and by studying coal flotation in a single-bubble system. If 0.001 kg/t Neonol modifier is used in the flotation of flocculated coal fines, the extraction of the coal’s fuel component in the concentrate is increased by 2.0–4.2%, depending on the conditions.