Characterization of mixing of binary particles in a continuous colliding static mixer

•The mixing of binary particles was studied in a continuous colliding static mixer.•Mixing homogeneity stabilized at certain deviations after mixing with four internals.•Binary particles with salient difference in particle sizes were easier to be mixed.•The predicted model described the mixing characteristics of the mixer quantitatively.

The mixing of particulate solids in a continuous colliding static mixer was studied by using binary particles with different colors and properties. A method of image analysis was used to measure the contrasting colors in a sample picture in order to quantify the component concentration, thus to evaluate the mixing homogeneity of different particles. Experiments were conducted to investigate the effect of the number of mixing internals, feeding mass ratio, particle size and falling height on mixing performance of the mixer. The results showed that mixing homogeneity seemed to stabilize at certain standard deviations after colliding with four mixing internals. Large size particles were easier to be mixed than that of small particles, which indicated that a continuous colliding static mixer was suitable for mixing binary inhomogeneous particles in millimeter scale with salient difference in particle sizes. There was an optimal mixture surface position in the falling height. For large particles, the optimal mixture surface position was only a small distance in the falling height. The predicted model proposed in our study was able to describe the mixing characteristics in the continuous colliding static mixer quantitatively.

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