An expedient experimental method has been proposed to characterise the mixing process and performance of powder mixers based on the measurement of changes in the color of the mixture with operating time. To evaluate the mixing and dispersing characteristics among the different types mixing equipment, adhesive fine calcium-carbonate (white) and iron-oxide (dark red) powders were applied as a bulk and a tracer, respectively. The influence of the mixing procedures on the calibration curves of the relationship between the lightness value of the mixture and the tracer concentration has been discussed based on the agglomerate size of the tracer powder. The degree of attainment to the final dispersing state, η_I was defined as an index of the intensity of mixing or dispersing process of the powder.
It has been shown that the characteristics of mixers are classified into three groups according to the dispersing process by using the index η_I.