Interpretation of induction time and particle recovery in a microstructured counter-current flow column

Abstract

Low-grade coal is in abundance, which is used in most thermal power plants, cement units, metallurgical plants, etc., and creates environmental pollution because of the generation of large amounts of fine solid particles and gaseous pollutants. Therefore, it is of utmost importance to clean coal before use. The present work reports the particle recovery and bubble-particle induction times based on the demineralization of coal particles using the column flotation beneficiation technique in a microstructured flotation column. The effect of operating variables on particle recovery, flotation rate constant, efficiency index, ash content, combustible recovery, and induction time is studied. Induction time is enunciated using the phenomenological kinetic model, which is based on the consecutive sub-processes comprising bubble-particle collision, attachment, and detachment. The results showed a shorter induction time and a higher rate constant at higher particle recovery. The flotation system was optimized by varying the collector as well as surfactant doses, and the maximum efficiency index was found to be 47.70%, with 91.88% combustible recovery and 12.53% ash content in the concentrate at 0.020 m/s feed and 0.082 m/s gas velocity. The induction time was observed to vary from 8.68 to 16.6 ms.