How can a centrifuge partially separate large particles from smaller particles?

A centrifuge separates particles by applying a sustained centrifugal force, which acts as a stronger substitute for gravity. When a mixture is spun, particles denser than the surrounding liquid migrate toward the periphery of the rotor.1

The rate of this migration depends on several factors, including the intensity of the centrifugal field, the viscosity of the liquid, and the size and shape of the particles. Because larger particles experience a greater net motivating force, they move through the liquid more rapidly than smaller ones.1

To achieve a partial separation of two groups of particles of different sizes, you can limit the duration of the centrifugation. By stopping the process once the larger particles have been completely packed into the sediment, many of the smaller particles will remain suspended in the fluid. If further purification is required, the surface fluid can be drawn off and the sediment can be resuspended and centrifuged again.1