Abstract: In the separation process, the distribution rules of tangential velocity, radial velocity and axial velocity and the hydrodynamics mechanism could make the decisive effect on the particle cut size and the efficiency, which would also be impacted by the factors, such as structure, operating parameters of hydrocyclone and properties of treated object. The wear and corrosion-resistance material, polyurethane, has been used to manufacture the different specification liquid-solid hydrocyclone. Synthetically regarding with the particle cut size, the treatment capacity, and grit deposit efficiency, the optimization parameters of hydrocyclone separating calcium clay are diameter 50 mm, du=10 mm, do=8 mm, through the multi objective orthogonal experiment. Meanwhile, the particle cut size could be under 1.78μm at the pressure 0.30 mPa. And the processing capacity would reach 2.39 m3/h. According to the optimization parameters of hydrocyclone and the Reynolds stress model, which is suitable for rapids flow field in hydrocyclonee, the velocity field of pellet water affinity solid with different diameter is calculated by the FLUENT software. It is indicated that retention time of the separation medium is 1.8×10−2 s, the reverse axis speed may reach 3.08 m/s most greatly, and the radius of the most greatly tangential velocity is 0.046 m, so that the separation efficiency could reach 78.6%. Based on the numerical simulation result of pressure field, the pressure gradient of radial direction increases from 762.5 kPa/m to 6 822.2 kPa/m, in order to realize the particle cut size 1.78 μm. According to the numerical simulation results of distribution characters of the pressure field, speed field as well as separation medium path, it was proposed that the extending the retention time of separation medium, enhancing the feeding pressure, reducing the velocity gradient of the central accurate forced vortex, slowing down the forward axis speed gradient in the radial direction would be the main way to improve the separation effect. Therefore, through the comparison of the experiment and the theoretical calculation, it is revealed the dynamics mechanism of the hydrocyclone optimized to achieve the best separation efficiency by experiment.

Key words: Calcium clay, Hydrocyclone, Model analysis, Multi objective orthogonal test, Separation efficiency