Numerical Simulation Of Centrifugal Field Disc Separation Process

With the development and utilization of mineral resources, a large number of low grade resource development and utilization will become focus, Fine grinding is the main method to realize low grade minerals monomer dissociation. And then the problem of fine particle separation will appear. Derive from gravity separation technology, the centrifugal separation technology is one of the ways to solve the problem of fine particle separation, which can enhance the gravity acceleration by using centrifugal acceleration and effectively improve the settling velocity of solid particles. Disc separator is one of centrifugal separators, there are lots of discs in the separation chamber, the separation process in the thin film layer of discs. The separation efficiency can be improved by shortening the distance of centrifugal sedimentation. In order to investigate separation performance of disc separator and conduct structure optimization, mainly use computational fluid dynamics method in this paper.Firstly, under the rotating coordinate system, the single phase simulation and DPM particle trajectory are carried out to ensure calculation mesh and the calculation model reasonable. The flow pattern in disc zone is measured according to cant flow film theory. Then combined with the Eulerian multiphase flow model, studies the effect of particle size on flow field. Three drag coefficient models: Wen-Yu, Gidaspow and Huilin-Gidaspow are compared, and the results show that predicted values of Huilin-Gidaspow model relatively close to the experimental values. Therefore, will Huilin-Gidaspow drag coefficient model will be selected in this study. Based on above study, the three key parameters including the operation speed, inlet velocity and feed concentration on flow field was investigated. Mainly focus on the effect of operating parameters on axial velocity and tangential velocity and phase volume fraction in the disc separation zone. Yield and power selected as indexes, to design the L25 (5 6)orthogonal test table to synthetically evaluate the effect of operating parameters on the indexes. Sequential order on yield is A (Rotational Speed)>C (Solid Phase Concentration)>B (Inlet Velocity), on power is A (Rotational Speed)>B (Inlet Velocity)>C (Solid Phase Concentration).Secondly, five kinds of disc space (1.5 mm, 2.5 mm, 3.5 mm, 5 mm, 5.5 mm)and five kinds of nozzle diameter (2.2 mm, 2.6 mm, 3 mm, 3.3 mm, 3.9 mm) are studied by numerical simulation, in which operating parameters based on orthogonal test results. To optimize structure,Eulerian model coupling PBM Method to calculate and evaluate the recovery of two particles( 15 ?m and 30 ?m) . The results show that the small spacing and big nozzle was beneficial to the improvement of the separation efficiency.Finally, the structures obtained by numerical simulation were processed to carry out separation test. Newton separation efficiency of four kinds of disc space and four kinds of nozzle structure were obtained by experimental test. Results of test show that the disc space decreases from 5.5 mm to 1.5 mm, separation efficiency can be increased 1.2 times. The nozzle diameter increase from 2.2 mm to 3.9 mm, separation efficiency can be increased by 5%. Therefore, the experimental results confirmed the conclusion of numerical simulation.The research in this paper laid a foundation for fine mineral separation as well as structure optimization of disc separator.