B01F 25/43231

Mixing tubes, e.g. wherein the material is moved in a radial or partly reversed direction with means for dividing the material flow into separate sub-flows and for repositioning and recombining these sub-flows; Cross-mixing, e.g. conducting the outer layer of the material nearer to the axis of the tube or vice-versa {using elements provided with a plurality of channels or using a plurality of tubes which can either be placed between common spaces or collectors the channels or tubes crossing each other several times}