Study Of Solid-liquid Two-phase Flow Of Centrifugal Slurry Pump For Mineral Processing

Large centrifugal slurry pumps are widely used in mining and dredging industries.This kind of slurry pump has several characteristic,such as low speed,high flow rate and transport high concentration slurry.So the wear is very serious.Universal life of slurry pumps used in mining industry is only 20-30 days.The disassembly and installation of large centrifugal pumps need much time.Frequent replacement of overflow parts will bring huge economic losses.Therefore,improving the service life of slurry pump is one of the important research direction for scholar at home and abroad.Local wear is one of the main reason of wear failure.Local severe wear of overflow parts lead to performance decrease.The study of flow characteristics in large centrifugal pump and analysis of the causes about local wear can provide some suggestions for its optimal design.In this paper,the heavy slurry pump used in grinding circuit of concentrator is taken as the research object.Analyze the flow law of slurry in the whole flow channel under different working conditions and particle concentration.The research work is as follows:(1)Summarize the current numerical simulation methods of solid-liquid twophase flow,select the appropriate calculation model for this paper and verify the independence of the calculation model.The results show that the Euler method is selected to calculate the internal flow field of two-phase flow according to the characteristics of high concentration and fine particles for slurry conveying,different number of grids have little effect on pump performance;with the increase of grids,the influence of grids on the internal flow field is gradually reduced.(2)CFX software was used to simulate the two-phase flow field in slurry pump.The effects of different flow conditions and particle concentration on the internal flow field were analyzed,with emphasis on the solid volume fraction and solid slip velocity distribution.The results show that the flow in the pump is very unstable and the reflux increases,it is obvious under the condition of small flow rate;the particle concentration increases from 10% to 50%,the solid phase velocity near the tongue increases and the solid phase volume fraction of the front guard plate increases,resulting in local wear.(3)Field test of slurry pump was carried out in SABC grinding circuit.Observe and record the location of severe local wear to verify the rationality of simulation analysis.The results show that the location of local wear is located at the impeller inlet,the position on guard plate and the sheath which near the tongue,and inside the front guard plate.(4)Change the structure of slurry pump and analyze the influence of different structures on the internal flow field.Compare with the actual wear situation,to provide some reference for wear optimization.The results show that reducing the impeller inlet diameter and outlet width can effectively improve the flow at the impeller inlet and reduce the solid volume fraction of the front guard plate;removing the back blade can effectively reduce the solid velocity near the tongue wall,but the removal of the front blade will cause the increase of the solid volume fraction of the front guard plate;appropriately increasing the clearance of the front chamber can reduce the wall wear.