Enhancement of coal flotation using impact flow conditioning pulp

Large amounts of intergrowth and harmful impurities are present in fine raw coal, and the direct use of these can lead to the serious air pollution and solid waste. On the other hand, these impurities cover the surface of raw coal, resulting in the low hydrophobicity and floatability, which make it difficult to float. In this paper, a new method using impact flow conditioning pulp to enhance coal flotation was proposed, and the impact velocity of the conditioning pulp was optimized, thereby enhancing the flotation and cleaner production of coal. The enhancement mechanism of the impact flow conditioning pulp was investigated via measurements of SEM-EDS, adsorption, contact angle, and induction time. The conditioning-flotation experiments were performed to reveal the effect of the impact flow conditioning pulp with different impact velocities on coal flotation. The SEM-EDS analysis confirmed that the impact flow conditioning pulp could remove the coating covering the coal surface and improve the separation performance of coal from gangue. Furthermore, the impact flow conditioning pulp could significantly enhance the adsorption performance, hydrophobicity, and floatability of coal. The flotation results illustrated that the preconditioning using impact flow conditioning pulp improved the flotation efficiency of the coal, and an optimum ultimate combustible recovery of 92.86% was obtained at an impact velocity of 4 m/s. (C) 2020 Elsevier Ltd. All rights reserved.