Influence of particle size on the separation performance and flotation kinetics of foundry dust

Abstract

The high-efficiency separation of foundry dust (FD) is imperative for its resource utilization, which contributes to promoting cleaner production and environmental protection in the foundry industry. In order to strengthen the flotation performance of high-quality coal dust in the FD, a systematized investigation was carried out to explore the influence of particle size on the contact angle, separation performance, and flotation kinetics of the FD. The results indicate that the pretreatment process increases the contact angle of the FD, and the liberation degree of coal dust decreases with the decrease of particle size. The fine particles of −53 µm can reduce the separation performance, resulting in a lower coal dust recovery of 60.79%. The coarse particles of −212 + 75 µm and intermediate particles of 75–53 µm possess better flotation results compared to the unclassified FD. The coal dust recovery in the coarse particles can reach up to 84.68%, and the obtained coal dust exhibits a pristine surface and splendid purity. The results of flotation kinetics analysis found that classical first-order model is suitable for characterizing flotation process of the FD with different particle sizes. The flotation rate constant drops as particle size reduces, revealing that the floatability of FD can be significantly improved via a classification method. This may provide a valuable method and scientific guidance for efficient separation and resource utilization of the FD.