To explore the flotation mechanism of oxidized coal slimes within low-rank metamorphic, coal slimes from Shuilian coal mine were chosen and their characteristics were analyzed by proximate analysis and grain size composition analysis. Results showed these coal slimes were of high ash content, fine particle size, and serious sliming. To understand the effects of oxidation on flotation, BET adsorption and Fourier transform infrared spectroscopy (FTIR) were used to analyze the pores, specific surface area, and surface functional groups of coal slimes before and after oxidation. The results indicated increase in the number of pores on the surface of coal slimes after oxidization. Furthermore, the specific surface area increased by 79% and the number of oxygen-containing functional groups also increased on the surface. Coal slimes of different oxidation degree were chosen for the flotation experiments. With the increase of oxidation days, clean coal yield and combustible matter recovery reduced to a great extent; however, by contrast, the ash content of clean coal improved. Our results are helpful to understand the flotation mechanism of oxidized coal slimes within low-rank metamorphic. (C) 2018 Elsevier B.V. All rights reserved.