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A jet mill includes plural nozzle devices for discharging a composite stream of high velocity fluid. Each nozzle device includes a plural odd number of nozzle openings for discharging an individual stream of high velocity fluid. Each nozzle opening comprises (i) a converging region for converging an

A jet mill includes plural nozzle devices for discharging a composite stream of high velocity fluid. Each nozzle device includes a plural odd number of nozzle openings for discharging an individual stream of high velocity fluid. Each nozzle opening comprises (i) a converging region for converging and accelerating a volume of high pressure fluid; (ii) a throat region defining a narrowest diameter region of the nozzle opening; (iii) a first expansion region for producing a linear expansion of the volume of high pressure fluid, and (iv) a second expansion region for producing a turning expansion as well as a parallel flow of the volume of high pressure fluid. The first expansion region has a radius “r1” and a length “s1” with radius r1 and length s1 determined such that (dr1/ds1) is a constant. The second expansion region has a radius “r2” and a length “s2” with radius r2 and length s2 determined such that (dr2/ds2) is non-linear and a function of s2.

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1. A nozzle device for mounting through side walls of a fluidized bed jet mill to discharge a composite stream of high velocity fluid for receiving, entraining and delivering particles of material into a grinding chamber of the fluidized bed jet mill for particle to particle collision, said nozzle d

1. A nozzle device for mounting through side walls of a fluidized bed jet mill to discharge a composite stream of high velocity fluid for receiving, entraining and delivering particles of material into a grinding chamber of the fluidized bed jet mill for particle to particle collision, said nozzle device having a first end, and a second end pointing towards a central axis of the grinding chamber when mounted through said side walls, and said nozzle device including a plural odd number of nozzle openings for each discharging an individual stream of high velocity fluid that together form said composite stream, each said nozzle opening having a nozzle axis and including:(i) a converging region defined by a first nozzle wall section located towards said first end for converging and accelerating a volume of high pressure fluid into said individual stream of high velocity fluid; (ii) a throat region defined by a second nozzle wall section comprising a point of narrowest diameter of said nozzle opening; (iii) a first expansion region for producing a linear expansion of said volume of high pressure fluid passing through said throat region, said first expansion region including a third nozzle wall section having an increasing radius “r1”, and an increasing length “s1” running from said throat region towards said second end, and said radius r1 and said length s1 being determined such that (dr1/ds1) is a constant; and (iv) a second expansion region for producing a turning expansion and a parallel flow of said volume of high pressure fluid from said first expansion region, said second expansion region including a fourth nozzle wall section having an increasing radius “r2” and an increasing length “s2” significantly greater than the length s1 of the first expansion region and running from said first expansion region towards said second end, and said radius r2 and said length s2 being determined such that (dr2/ds2) is equal to a non-linear function of s2. 2. The nozzle device of claim 1 wherein said nozzle device is cylindrical and includes a longitudinal axis and said plural odd number of nozzle openings is three.3. The nozzle device of claim 2 wherein each nozzle opening of said plural odd number of nozzle openings is located a distance DS from said longitudinal axis.4. The nozzle device of claim 2 wherein each nozzle opening of said plural odd number of nozzle openings has a nozzle axis slanted at 3 degree towards a longitudinal axis of the nozzle device such that each said nozzle axis thereof intersects said longitudinal axis of said nozzle device.5. The nozzle device of claim 2 wherein adjacent nozzle openings of said plural odd number of nozzle openings border a space between them for receiving particles during operation of the nozzle device.6. The nozzle device of claim 3 wherein each nozzle opening of said plural odd number of nozzle openings has a diameter DM and said distance DS is within a range of 0.4 through 0.7 times DM and most preferably half DM.7. The nozzle device of claim 4 wherein when said nozzle device is mounted through said side walls, each said nozzle axis thereof intersects said longitudinal axis of said nozzle device at a point between said central axis of said grinding chamber and said second end of said nozzle device.8. The nozzle device of claim 5 wherein each said space between adjacent said nozzle openings is located opposite to, and on a common diameter with, one of said plural odd number of said nozzle openings.9. The nozzle device of claim 5 including a plural odd number of said spaces for receiving particles during operation of the nozzle device.10. A fluidized bed jet mill for grinding particles of material comprising:(a) a base, a top and side walls defining a grinding chamber having a central axis; and (b) plural nozzle devices mounted through said side walls into said grinding chamber for discharging a composite stream of high velocity fluid to receive and deliver, for particle to particle collision, entrained particles of material to be ground within said grinding chamber, each said nozzle device including a plural odd number of bell-like nozzle openings for each discharging an individual stream of high velocity fluid for together forming said composite stream of high velocity fluid, each said bell-like nozzle opening including: (i) a converging region for converging and accelerating a volume of high pressure fluid being moved from a first end to a second end thereof; (ii) a throat region defining a narrowest diameter region of said bell-like nozzle opening; (iii) a first expansion region for producing a linear expansion of said volume of high pressure fluid passing through said throat region, said first expansion region has a radius “r1” and a length “s1” running from said throat region towards said second end, and said radius r1 and length s1 are determined such that (dr1/ds1) is a constant; and (iv) a second expansion region for producing a turning expansion as well as a parallel flow of said volume of high pressure fluid coming from said first expansion region, said second expansion region has a radius “r2”, and a length “s2” significantly greater than the length s1 of the first expansion region and running from said first expansion region towards said second end, and said radius r2 and length s2 are determined such that (dr2/ds2) is non-linear and is equal to a function of s2. 11. A fluidized bed jet mill for grinding particles of material, the fluidized bed jet mill comprising:(a) a base, a top and side walls defining a grinding chamber having a central axis; and (b) plural nozzle devices mounted through said side walls into said grinding chamber to discharge a composite stream of high velocity fluid, each said nozzle device having a first end, and a second end pointing towards said central axis of said grinding chamber, and each said nozzle device including at least one nozzle opening for discharging an individual stream of high velocity fluid through said second end for entraining the particles of material, each said at least one nozzle opening having a nozzle axis and nozzle wall sections defining: (i) a converging region having a first nozzle wall section located towards said first end for converging and accelerating a volume of high pressure fluid being moved from said first end for discharge through said second end; (ii) a throat region having a second nozzle wall section defining a narrowest diameter of said nozzle opening; (iii) a first expansion region for producing a linear expansion of said volume of high pressure fluid passing through said throat region, said first expansion region including a third nozzle wall section having a radius “r1” and a length “s1” running from said throat region towards said second end, and said radius r1 and length s1 being such that (dr1/ds1) is a constant; and (iv) a second expansion region for producing a turning expansion and parallel flow of said volume of high pressure fluid from said first expansion region, said second expansion region including a fourth nozzle wall section having a radius “r2”, and a length “s2” significantly greater than the length s1 of the first expansion region and running from said first expansion region towards said second end, and said radius r2 and length s2 being such that (dr2/ds2) is equal to a function of s2. 12. The fluidized bed jet mill of claim 11, wherein said volume of high pressure fluid comprises a volume of high pressure air.13. The fluidized bed jet mill of claim 11, wherein each said nozzle device is cylindrical and includes a longitudinal axis and said plural number of nozzle openings is from three to five.14. The fluidized bed jet mill of claim 13 wherein each nozzle opening of said plural number of nozzle openings is located a distance DS from said longitudinal axis.15. The fluidized bed jet mill of claim 13 wherein each nozzle opening of said plural number of nozzle openings has a nozzle axis slanted inwardly such that each said nozzle axis thereof intersects said longitudinal axis of said nozzle device at a point downstream of said second end of said nozzle device.16. The fluidized bed jet mill of claim 13 wherein adjacent nozzle openings of said plural number of said nozzle openings border a space between them for receiving particles during operation of the nozzle device.17. The fluidized bed jet mill of claim 15 wherein said composite stream of high velocity fluid has a low velocity region downstream of said second end of said nozzle device and upstream of said point of intersection of said individual streams of high velocity fluid.18. The fluidized bed jet mill of claim 15 wherein when said nozzle device is mounted through said side walls, each said nozzle axis thereof intersects said longitudinal axis of said nozzle device at a point between said central axis of said grinding chamber and said second end of said nozzle device.19. The fluidized bed jet mill of claim 16 wherein each said space between adjacent said nozzle openings is located opposite to, and on a common diameter with, one of said plural odd number of said nozzle openings.20. The fluidized bed jet mill of claim 16 including a plural odd number of said spaces for receiving particles during operation of the nozzle device.