Patent ID: 7258290

Claim:
A jet mill comprising: a jet mill body forming a disk-shaped hollow part and having an annular outer wall; plural air nozzles generating high-speed air flow in said disk-shaped hollow part and being inclined on said annular outer wall with respect to a center of said disk-shaped hollow part; and an exit port being provided in a substantially central area of said disk-shaped hollow part of said jet mill body, wherein said hollow part comprises: an annular grinding zone that is provided inside said annular outer wall and where a material to be ground is milled by means of said high-speed air flow supplied through said plural air nozzles; an annular classifying zone that is provided inside said annular grinding zone and communicates with a space of said exit port and where said milled material is classified by means of air flow that is positioned inward of said annular grinding zone; and a first annular constricted passageway that is provided between said annular grinding zone and said annular classifying zone and that divides said hollow part into said annular grinding zone and said annular classifying zone, wherein said annular grinding zone and said annular classifying zone communicate by means of said first annular constricted passageway.