Patent ID: 7832664

Claim:
A jet mill comprising: a conduit disposed in a substantially vertical loop; an inlet for entry of raw material into the loop; a grinding chamber formed as part of the loop, the grinding chamber being located at the bottom of the loop and having a bottom, a top, and two opposed side walls extending from the bottom to the top of the grinding chamber, the grinding chamber also having plural nozzles, connected to a source of gas outside the loop, for flow of gas from said source, through the nozzles, into the loop, the nozzles being directed obliquely into the grinding chamber to cause a circulating flow of a gas stream in a predetermined direction through the loop; a classifier for centrifugal separation of fine particles in the gas stream from larger particles in the gas stream, the classifier being spaced, along said predetermined direction, downstream from the grinding chamber; and an outlet for delivery of fine particles along with gas from the loop; wherein said nozzles of said grinding chamber are composed of a first set of nozzles constituted by openings in one of said side walls and a second set of nozzles constituted by openings in the other of said side walls, whereby the first and second sets of nozzles are located respectively on opposite sides of the grinding chamber, said opposite sides being respectively left and right sides with reference to the direction of flow of said gas stream through the grinding chamber, each said nozzle being directed obliquely in relation to the direction of flow of the gas stream in the grinding chamber, and each said nozzle on one side of the grinding chamber being directed along a line that intersects obliquely a line along which a nozzle on the opposite side of the grinding chamber is directed.