Study On The Froth Transportation And Distribution Of Self-Suction And Closed Type For Flotation Column

Mineral flotation froth is a gas-liquid-solid three-phase system, and the type of froth featuring high gas holdup, poor fluidity and too high stability usually causes processing problems. By now, the steady flotation froth is mainly generated and transported using slurry pump during the column separation process. However, it is still very difficult to transport three-phase froth using slurry pump because the pump efficiency can be greatly reduced by cavitation and aerial binding, resulting in lower processing stability and lower column separation efficiency. In addition, this froth-pump-transporting manner has other drawbacks, such as complicated configuration system, high investment cost and large area occupation. To solve this froth-transporting problem, the research subject of the development of froth transporting and self-sucking device for the flotation column was proposed and received research funding. And this thesis originates from it. As one of the projects of the study on common problems and key technology of shortened process for column separation, this thesis focuses on the study of the technology of flotation froth transmission and distribution under the condition of closed type and undisturbed, which could develop the high efficient shortened process for column separation.After reviewing literature, this paper summarized and analyzed the rheological properties of foam. Based on the reserach of flotation froth stability, a new research idea of self-sucking and transporting manner for column flotation froth was presented. The preliminary structure of froth transporting and self-sucking device was constructed.Applying the research results of fluid transporting machinery with blades, the theory of flow for froth transporting and self-sucking device was analyzed. And the new device was tested under lab-scale to study the influence of relevant parameters on its performance curve. And the energy equation for self-sucking device was established under lab-scale.By using the computational fluid dynamics software, the numerical simulation was carried out for the gas-liquid two-phase flow in impeller of froth transporting and self-sucking device. The influence mechanism of the gas holdup and bubble diameter on the flow in impeller was disclosed. Meanwhile, the flow characteristics of compund impeller with propulsive impeller and centrifugal impeller were explained.Based on the pattern form analysis of flow passage components of self-sucking device, the numerical simulation of the liquid-solid two-phase flow in self-sucking device was carried out. It simulated the relative velocity, pressure and concentration distribution in self-sucking device. The influence of the flow field characteristics on wearing for the flow passage components of self-sucking device was discussed. And the wear effect of particle diameter and solid concentration on the flow passage components of self-sucking device was explained.Based on the working principle, structural characteristics and transporting manner of self-sucking device, the structure of self-sucking device were determined. By referring to the design methods of vane pump and the studies on two-phase flow characteristics in self-sucking device, the hydraulic design method and optimization measures for self-sucking device were preliminarily confirmed.Two self-sucking devices with diameters of 400 mm and 450 mm had been developed on the basis of laboratory tests, numerical simulation and structure design of self-sucking device. The industrial application of this system for froth transporation in column separation process was established, and the column separation froth transported in the same operating platform was realized. The system configuration for this column separation had been simplified, and the separation condition and the separation indexes for column were improved.