Research On The Structure And Flow Field Of The Centrally Driven Thickener Feedwell

Thickeners are a key solid-liquid separation device in many hydrometallurgical processing operations, widely used in the concentrate dewatering and tailing dewatering. The flow field and the flocculation performance in thickener feedwell are affected by the structure of the feedwell and have a great influence on the solid-liquid separation efficiency of the thickener. The design and optimization of the thickener feedwell structure have a theoretical significance and important value of engineering application.Computational fluid dynamics method and experimental research were used in this paper to study the flow field and flocculation performance in thickener feedwell. Splitting up the feed and injecting the flocculant at two points could improve the flocculation performance of the thickener feedwell and make the feedwell achieve great adaptability. This was ascribed to the effective mix of the suspension and the flocculant solution in feedwell. The direction of the flocculant injection and the distance between the feed inlet and the flocculant injection location were two important factors in feedwell flocculation performance. When the flocculant stream was injected in the reverse direction of the feed stream, there was less mixing and dispersion than when it was injected across the stream. The distribution of the path line, solid volume fraction and velocity distribution in the exit plane of the four traditional feedwells were researched. The results indicated that the maximum velocity in the exit plane decreased with the shelf. The maximum velocities in the exit plane of the feedwell with one tangential inlet and two tangential inlets were 48% and 57% of the feed velocities, respectively. The uniformity and symmetry were improved at the same time with one tangential inlet and shelf.The traditional feedwell couldn't dissipate the kinetic energy of the feed stream and provide a uniform discharge pattern at the same time. A novel thickener feedwell with simple structure was designed and the novel thickener feedwell could work without power, saving energy. Numerical simulation was used to research the flow field, solid volume fraction and the velocity distribution in the exit plane of the novel thickener feedwell. The novel thickener feedwell could dissipate the kinetic energy of the feed stream and provide a uniform discharge pattern at different feed velocities. The time increased for the feed to reach the overflow weir, making high solid-liquid separation efficiency. Compared with the traditional feedwell, the novel feedwell had good adaptability to the operation parameters. The research results of this paper could provide reference and basis for the design and optimization of the thickener.