B01F 25/4321

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 {the subflows consisting of at least two flat layers which are recombined, e.g. using means having restriction or expansion zones}