Abstract: Micrometric separator (1) for biomasses (100) in particles, of the type including a first crushing stage (2) wherein particles are introduced dispersed in a conveying fluid bed, and a first conveyor for conveying the particles in the fluid bed. The first crushing stage (2) has a first crushing chamber (5) for reciprocal collisions of particles, that has a first revolving disc (7) provided with first members (9) for generating a turbulent flow in the fluid bed, and a first contrast body (8), in front of the first revolving disc (7), as well as one or more outlets (22) of the fluid bed, the first contrast body (8) being provided with an inlet (6) having an inflow section with the axis substantially incident to the first revolving disc (7).