The Importance of Mixing in the Sedimentation of Flocculated Coal Washery Slurries

Abstract

The importance of mixing in the flocculation of kaolin and fine coal slurries was investigated and it was observed that the settling rate was a decreasing function of mixing intensity, whereas the supernatant clarity showed a distinct maximum value. Hence, there is an optimum mixing intensity for flocculation prior to sedimentation. The rate of polymer addition was also shown to affect the settling rate, but the addition of a clarity aid had little effect. Experiments designed to test the keeping qualities of flocculant solutions are reported together with an examination of the period of time required for the dispersion and dissolution of flocculant in water.