Apparatus for pulverizing solid materials

Claim 1

Apparatus for the pulverization of solid material into finely divided form comprising a generally circular grinding chamber for the particles to be pulverized formed between a pair of top and bottom heads, means for injecting a pressurized gaseous fluid into said chamber to establish therein a high velocity inwardly spiralling vortex of the gaseous fluid, means for injecting the material to be pulverized into said grinding chamber for entrainment of said particles of material into the outer reaches of said vortex for movement inwardly thereof toward a discharge outlet coaxial with the center of the vortex, and baffle means including a fixed member disposed centrally within the grinding chamber in axial alinement with said discharge outlet and extending vertically from the floor of said grinding chamber substantially beyond the horizontal median plane of said chamber to a level short of and in relatively closely spaced relation to the top head of said chamber, said baffle member having an external surface defining the inner wall of an annular zone within said grinding chamber which is closed at its bottom end and open at its top end, the top end of said baffle member having an outline defining a cross-sectional area which is at least substantially as great as that of the bottom end of said member and said inner wall of said annular zone being radially unobstructed across the top thereof and of a cross-sectional area at least equal to that of the inlet end of said discharge outlet to provide an unobstructed free space of vertically limited depth located between said topmost end of said baffle member and the top head of said grinding chamber, said space extending across said topmost end of said annular zone inner wall for unrestricted direct communication with said zone about the full peripheral extent of said wall, whereby those heavier and coarser particles of material which have traversed said vortex and are gravitationally held in said zone are centrifugally thrown back into said vortex and subjected thereby to its grinding energy until the same have been reduced in size by attrition in said zone and so are sufficiently lightened in weight to be lifted out of said zone against the force of gravity for discharge solely from the upper region of the grinding chamber together with the exhausting stream of said gaseous vortex radially inward across the top end of said baffle member into said discharge outlet.