Effect of compound collector and blending frother on froth stability and flotation performance of oxidized coal

Abstract

The beneficiation of oxidized coal is difficult to achieve by conventional flotation with oily collectors. Oxidized coal samples were prepared by the peroxide solution oxidation and a new type of oxygenated polar compound collector (CC) and a powerful blending frother (BF) were used to intensify oxidized coal flotation in the present study. The effects of the CC and BF on the froth stability and flotation performance (i.e., recovery and selectivity) were investigated. The results show that only 44.51% recovery with 9.71s dynamic froth stability index (DFS) was obtained for oxidized coal flotation by using conventional diesel and octanol as the collector and frother, respectively. Lots of oxygen functional groups (−OH and C-O) were introduced after peroxide oxidation indicated by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis, leading to poor hydrophobicity and low flotation recovery. An optimal separation result with 76.24% oxidized coal recovery and 19.43s DFS was obtained using the CC combined with octanol, which was attributed to the hydrogen bonding between the hydrophilic sites on coal surface and polar oxygen functional groups in CC. An identical DFS (19.43s) was obtained using conventional diesel combined with the BF, while with only 21.38% recovery. Diesel did not sufficiently render the coal hydrophobicity and as a result only a small amount of coal particles was collected by attaching to bubble surface in pulp phase. The Fuerstenau upgrading curves show that both the maximum recovery and the best flotation selectivity could be obtained using the CC combined with octanol.