I would suspect if the sand particles would be calculated for their mass per particle and activitated charcoal was sieved to get a particle of the same mass the exertion of a force such as wind in a fluidized bed would create a mixture of particles which would show a randomized distribution pattern and not necessarily segregate out.

Paul Reed Hepperly are you able to elaborate on that a bit more?

i am mainly looking at how to mix them in a mixture (using liquid) but without segregation.

In a liquidized bed the force of moving air can suspend solids so they flow like a liquid and maintain their dry state. Fluidized beds have been used to improve coal combustion as the exposition of the material is maintained in the combustion process.