Influence of the impeller structure and operating parameters of a high intensity conditioning system on the flotation of fine-grained pyrite

Abstract

High intensity conditioning (HIC) is a highly effective strategy for enhancing the recovery of fine coal particles and is increasingly used in mineral processing. The effectiveness of HIC is influenced by several key factors, including equipment design, operational parameters, material properties, and process conditions. Fine materials have unique physical and chemical properties, such as density, surface wettability, and the solubility and diffusion of flotation agents. These properties necessitate customized impeller structures and operational parameters. This study examined pyrite, a typical sulfide mineral with 50 % of particles finer than 22 µm. Using computational fluid dynamics simulations with multiphase flow models, the research revealed that increasing the impeller diameter, pitch angle, and/or agitation speed in a four-baffle tank significantly intensifies the velocity gradient and turbulent kinetic energy of the pulp fluid. These enhancements promote the suspension of solid particles and the dispersion of collectors. Compared with non-HIC scenarios, the optimal 50-mm-diameter impeller with a 60° pitch angle, when operating at 2000  rpm and agitated for 3  min, increased flotation recovery by 54.16 %. This improvement was attributed to an 18 % increase in collector adsorption and a 9.8-fold increase in particle aggregation, as confirmed by adsorption and optical microscopy experiments. This study highlights the critical role of HIC in improving the recovery of fine-grained minerals and provides valuable references for the design and selection of stirred impellers in HIC operations.