PURPOSE: A rotor with projections provided with inclined front edges, a nozzle for separating fibers and an outlet for chuting substances to be mixed are mounted at specific positions respectively to open fibers of high cohesion fully and mix them with cement or the like.

CONSTITUTION: A rotor 3 provided with projections 2 with the front edge 4 inclined so that the top end goes more forward in the rotation direction of the rotor 8 than the ground edge is fitted in the front of the conveyor 1 for feeding fiber lumps to ensure the take-up of fibers from fiber lumps 16. A nozzle for separating 5 that jets the air in the direction reverse to the rotation of the rotor 3 is mounted to open fibers fully. An outlet 6 for chuting materials to be mixed on to the fibers 14 sticking to projections 2 is fitted to remove the fibers 14 easily by utilizing the gravity of the materials to be mixed and they are uniformly mixed and piled up on the conveyor 15.