Flotation Optimization of Ultrafine Microcrystalline Graphite Using a Box-Behnken Design

In this investigation, emulsified kerosene and high-shear agitation were used to improve flotation performance of microcrystalline graphite. The flotation conditions were determined first and then optimized through a Box-Behnken design to minimize the concentrate ash content and to maximize the concentrate yield. Two quadratic models were developed to correlate the flotation variables, including agitation speed, agitation time, and collector dosage. As a result, both responses and the predicted optimal results were obtained. The lowest ash content of 7.81% and the highest yield of 91.00% were achieved by using an agitation speed of 27,173 rpm, an agitation time of 20 min, and a collector dosage of 79 kg/t. The analysis of variance indicated that the models of concentrate ash content and concentrate yield were significant terms to both responses.