Abstract: The invention relates to a device and to a method for mixing substances, wherein a substance to be treated is pressed with a press piston (3, 4) through a nozzle block (6) arranged between two press cylinders (1, 2). During the mixing, a fixed mixture constituent in the form of a suspension (13) is fed to the substance to be treated. The substance to be treated may be cooled during the mixing process by way of stepwise, controlled evaporation of a process fluid. Preferably, several, differently designed, exchangeable nozzle blocks are used, in order to adapt machine conditions to the changing viscosity of the substance to be mixed. The invention also relates to a mixing reactor and to a method for the continuous discharge of a product. For this, several mixers and an extrusion press are arranged next to one another and connected to one another via a transfer vehicle.