Abstract: In a method of and apparatus for accelerating and pressurizing a fluidized stream of particulate material, e.g. for blast cleaning by ice particles, the stream flows through a constriction in a flow passage. A flow of blast medium is discharged from a blast nozzle at supersonic speed into the fluidized stream so as to form within the fluidized stream a flow front which is impenetrable by the fluidized stream and which co-operates with the constriction to form an effective nozzle for accelerating the fluidized stream. Grounding is provided controlling electrostatic charges for either better work effect or neutralization in unwanted or hazardous conditions, and safety pressure relief, blast intensity control, articulation and changement of final nozzles for effective operation are also provided.