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The Process of the Intensification of Coal Fly Ash Flotation Using a Stirred Tank

Chinese National Engineering Research Center for Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China
School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
Author to whom correspondence should be addressed.
Minerals 2018, 8(12), 597;
Received: 14 November 2018 / Revised: 13 December 2018 / Accepted: 14 December 2018 / Published: 17 December 2018
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Pulp preconditioning using a stirred tank as a pretreatment process is vital to the flotation system, which can be used to improve the flotation efficiency of mineral particles. The kinetic energy that is dissipated in the stirred tank could strengthen the interaction process between mineral particles and flotation reagents to improve the flotation efficiency in the presence of the preconditioning. In this paper, the effect of the conditioning speed on the coal fly ash flotation was investigated using numerical simulations and conditioning-flotation tests. The large eddy simulation coupled with the Smagorinsky-Lilly subgrid model was employed to simulate the turbulence flow field in the stirred tank, which was equipped with a six blade Rushton turbine. The impeller rotation was modelled using the sliding mesh. The simulation results showed that the large eddy simulation (LES) well matched the previous experimental data. The turbulence characteristics, such as the mean velocity, turbulent kinetic energy, power consumption and instantaneous structures of trailing vortices were analysed in detail. The turbulent length scale (η) decreased as the rotation speed increased, and the minimum value of η was almost unchanged when the rotation speed was more than 1200 rpm. The conditioning-flotation tests of coal fly ash were conducted using different conditioning speeds. The results showed that the removal of unburned carbon was greatly improved due to the strengthened turbulence in the stirred tank, and the optimal results were obtained with an LOI of 3.32%, a yield of 78.69% and an RUC of 80.89% when the conditioning speed was 1200 rpm. View Full-Text
Keywords: intensification; coal fly ash; flotation; preconditioning; stirred tank intensification; coal fly ash; flotation; preconditioning; stirred tank

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Yang, L.; Zhu, Z.; Qi, X.; Yan, X.; Zhang, H. The Process of the Intensification of Coal Fly Ash Flotation Using a Stirred Tank. Minerals 2018, 8, 597.

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