Analysis Of Flow Field Form And Its Influencing Factor In The Process Of Mixing Pulp

Agitation machine is essential for flotation, for the flotation effect is associated with its performance. With mine exploitation going further, it is urgent to improve the utilization of mineral resources. Therefore, it is an inevitable trend to develop large-scale agitation machines.Currently, the design of large-scale agitation machines and the study of its inner fluid field are in preliminary stage, and relative theories and technology are incomplete. With the development of computer technology, Computational Fluid Mechanics(CFD) is gradually becoming a pivotal method in analyzing internal flowing and mixing characteristics. The application of CFD technology can shorten the development cycles, reduce costs and will play a more important role in related areas of fluid mechanics.Generally, mixing pulp is classified as particles suspension. Internal flowing characteristics of mixing tanks were studied under the Euler multiphase flow theory through CFD software. The mixing tank model was simplified and by Multiple Reference Frame method, internal flowing characteristics of mixing tanks were obtained through numerical calculation. The relation between concentration distributions and stirring speed as well as the impeller position in the mixing tank was settled by controlling single variable.As the numerical simulation manifested, in vertical direction, there are two vertical cycles above and below the impeller region; in horizontal direction, there is a circumferential cycle in the mixing tank. Flow velocity is high in impeller region while low in other regions. Stirring speed has a significant impact on concentration distributions. The higher the stirring speed, the better off-bottom suspension and the more uniform. At one stirring speed, pulp concentration keeps similar at the same height and goes down with the increase of height. Impeller height also contributes a lot to fluid field. If impeller height is too low, there is sediment of mixture,which is the stirring dead zone; while too high, the fluid cycle effect is inconspicuous. In this dissertation, under current experimental environment the stirring speed and impeller height of approximate optimum are 70r/min and 4.77 m.