Combined effect of chemical composition and spreading velocity of collector on flotation performance of oxidized coal

In this study, the combined effect of chemical composition and spreading velocity of collector on flotation performance of oxidized coal was investigated. Oxidized coal samples were prepared using the H2O2 solution oxidation method. The contents of oxygen-containing groups on the coal surface increased with the oxidation degree by X-ray photoelectron spectroscopy (XPS) analysis and the coal surface became more hydrophilic by water contact angle measurement. The chemical composition and the spreading velocity of three oily collectors, including diesel collector, novel collector a (NCA), and novel collector b (NCB), were compared. The content of oxygen-containing groups was the order of NCB > NCA > diesel by FTIR analysis. The spreading velocity determined from the interfacial tension, viscosity and coal-oil-water contact angle measurement results showed the order of diesel> NCA> NCB. With more oxygen-containing groups to induce adsorption and higher spreading velocity to achieve spreading rapidly on the coal surface, NCA kept the fastest flotation rate all along by flotation kinetics experiment, while the flotation rates of diesel and NCB depend a lot on the oxidation degree of coal surface. This can be explained by a combined interaction mechanism from chemical composition and spreading velocity of collector. During the oxidized coal flotation, oxygen-containing groups of collector played a leading role in the collector-particle adhesion process which determined whether the collector can adsorb on the oxidized surface, while the spreading velocity acted as a dominant part in the spreading process which affected the final flotation rate. (C) 2017 Published by Elsevier B.V.