A process for the micronisation of a powdered material or product by means of a micronising mill of the spiral jet-mill type with high-energy jets of a gaseous fluid, in which micronizing spiral jet-mill the powdered material or product is micronised, said micronizing spiral jet-mill in turn comprising an annular outer pressure chamber and a circular inner micronisation chamber, separated from on another by an annular intermediate wall which is provided with a plurality of channels or through holes, suitably inclined relatively to the radius of the micronisation chamber, which place the two chambers in communication,
- the process comprising a feeding step of feeding the powdered product to said inner micronisation chamber of the spiral jet-mill, in which chamber a plurality of high-energy fluid jets cause the micronisation of the powdered material,
- the process being wherein said feeding step is carried out by a volumetric microdispenser device that is designed to dispense and feed volumetrically the powdered material in a dense state directly to said inner micronising chamber of the spiral jet-mill, where the powdered material is micronised, so as to measure the precise amount or quantity of the same powdered material, namely to control precisely its flow rate, fed to the said inner micronisation chamber of the spiral jet-mill
- wherein said microdispenser device comprises one or more dispensing units associated with a suction line in which vacuum is created and a pressure line in which pressure is generated,
- wherein a plurality of control valves are fitted to place each dispensing unit selectively in communication with the suction line and the pressure line respectively, and
- wherein a plurality of control valves are fitted to place each dispensing unit selectively in communication with an inlet line, for transporting powered material from said container to said microdispenser device, and the outlet line respectively.