Abstract: A method and apparatus for improving the grinding result of a pressure chamber grinder includes a feeder for feeding material into a pressurized equalizing tank, then transferring the material into a pre-grinder where the material is fluidized by grinding-gas jets. The fluidized material-gas flow is divided by a bisecting device into two component flows and it is accelerated through two accelerating nozzles which are directed toward a impact point of a main grinding chamber. The grinding chamber has an outlet connected to an acceleration tube inlet which is connected at its discharge to a free-flow grinder provided with tangentially directed grinding-gas nozzles. The material which passes through the nozzles is in a ready ground final product form is removed constantly through a centrally located exhaust pipe.