Even if mixing same kind of granular matter, it is not so easy as you can see here. As you may imagine, it is much, much more difficult. For example, spontaneous band structure and radial structure appear in rotating drums filled with binary mixture. It is also related to segregation. You can also find here or here how to mix granular matter in industry by animations.
Granular matter flows like fluid, but do so in remarkably different way from fluid.
You can see that it flows very intermittently. After here V ibrating bed is recently the most attracting topics for physicists. Especially, standing surface wave is popular topics. After here Other interesting feature of vibrating bed is convection and segregation . Under strong vibration, the bed is fluidized and comes to have flow, which usually results in convection.