How do you you separate four recycled materials that have been ground into a fine powder?

To separate four recycled materials ground into a fine powder, you can use a combination of physical and chemical methods. Techniques like air classification can help separate materials based on their density and particle size, while sieving can further refine the separation. Additionally, magnetic separation can be employed if one of the materials is ferromagnetic. Lastly, flotation could be used to exploit differences in surface properties among the materials.