Industrial powder mixers mixing mechanisms
Do you have a question, a remark ? Please contact the author at firstname.lastname@example.org
Powder Mixing (main
Types of mixers
Coefficient of Variation
Segregation / demixing
Mixer Bearing seals
Mixer discharge valve
There are 3 types of mixing identified for bulk solids : diffusive mixing, convective mixing and shear mixing. Many design of industrial mixers are available and one can select a mixer based on any of these mechanisms or even a combination of those mechanisms. This page aims at detailing the mixing mechanisms and defining what kind of mixer fits in each category.
2. Diffusive (or dispersion) mixing
In diffusive mixing, the particles of solids move randomly, typically rolling down when their container is rotated. There is no forced pattern in the mixer, as such than the one that could be done by an agitator, but particles are moving locally one by one.
Tumbler mixers, drum blenders, IBC blenders typically fall in this category, although their design can be complicated by the addition of an agitator that gives some convective mixing
3. Convective mixing
For convective mixing, the movement of solids is forced thanks to a mixing tool ("agitator") that is defining a pattern within the convective mixer. The mixing tool is moving large groups of particles, splitting the bulk of particles and thereby achieving mixing.
Mixing will be typically shorter than for diffusive mixers, although the actual mixing time will depend largely in the design of the agitator, process parameters and nature of the solids to be mixed.
Ribbon blenders, a very widespread dry mixer is working according to convective mixing, as well as paddle mixers, although paddle mixers are fluidizing the mixture, which constitute a kind of sub-type of convective mixing.
4. Shear mixing
In shear mixing, a mixing tool at high speed is used to make groups of particles slip in between each others. Such shearing force can be particularly efficient when the mixture has some agglomerates that should be broken down to achieve a good mix.
Ploughshare mixers, when operated at sufficiently high speed rely on convective AND shear mixing. To be noted that some deagglomerators can be fitted in other types of mixer to give them some shearing capabilities.
5. Classification of mixers
|Do you want to
know more ?
www.powderprocess.net is covering all aspects of solids and powder processing and handling
The pages below will probably interest you !
Answers ALL your questions on pneumatic transport
of MIX / MEASURING DEGREE OF MIXING
All you need to know about measuring the degree of mixing (Coefficient of Variation) of a dry mix
OF POWDERS / DEMIXING
All on the physical phenomena causing segregation of particles and how to avoid them
All on main size reduction processes, key equipement, design consideration..etc..
All on powder key physical characteristics, among others : flowability, density...etc..
All equipment found in bulk solids handling industries, explained, with design tips...
|You can find much more through the menus at the top of the page !|