Effect of polyaluminum chloride on coal flotation performance with different reagent addition regimes

Abstract

The flotation tests of an artificial mixture of coal (250–125 μm) and kaolinite (−100 μm) were conducted with two different reagent addition regimes to improve understanding of the effect of polyaluminum chloride (PAC) on coal flotation with n-dodecane as collector. The flotation results suggested that improved separation efficiency with reduced kaolinite entrainment could be achieved by addition of PAC at a proper concentration. The kaolinite entrainment mitigation was insensitive to the sequence of addition of PAC and the collector whereas addition of the collector prior to PAC appeared to be conducive to increasing the flotation rate and alleviating the requirement for close management of PAC dosage. A real-time particle characterization tool, Focused Beam Reflectance Measurement (FBRM), was used to measure the particle size distribution of kaolinite and coal in aqueous solution. It was found that the kaolinite particles formed aggregates with PAC at 10–20 mg/L, which matched well with the optimum dosage of PAC for mitigation of kaolinite entrainment in coal flotation. The induction time measurement was conducted for the coal particles, and the results suggested that addition of PAC would decrease the probability of bubble-particle attachment.