Q: We use a tumble blender. I’ve heard that if you mix too long, you can undo the mixing results. What is this “de-mixing” and what causes it?

A: Unlike most liquid blends, in which mutually soluble liquids form a stable blend that doesn’t degrade over time, dry mixtures have a tendency to segregate. This is because particles have different sizes, shapes, and densities. When the particles are in motion (as in mixing), the differences cause the particles to segregate.

In a tumble blender, the ingredients are loaded in batches, often forming stratified layers in the vessel. Then the unit begins tumbling, and its symmetrical rotation creates a nonrandom mixing pattern. This pattern, when combined with the various particles’ different trajectories, can demix or segregate the particles in a pattern different from that formed by the layers during loading. To avoid this segregation in the later mixing stages, it’s best to use a tumble blender for relatively short mixing times. A tumble blender can also be designed to provide asymmetrical rotation to minimize demixing caused by trajectory segregation. For instance, a V-blender can have one extended leg and a double cone mixer can have offset cones; by using such designs, you can shorten mixing times, improve mixing quality, and limit further segregation.

Vortex is a leading powder mixer manufacturer in China. Our products contain ribbon blender, plough shear mixer, twin shaft paddle mixer, double cone blender, conical screw mixer, and other auxiliary equipment.

Vortex  not only focus on quality, but also pay attention to customer’s process. Our competitive edge has come from generating added value for customers worldwide. We design the mixers for multiple functions such as mixing, drying, coating, cooling and reaction in food, chemicals, pharmaceutical, feed, building material and dyestuff industry.