Method and apparatus for heating and grinding materials
AssigneeBPB Industries Public Limited Company
InventorsArthur G. T. Ward, David J. Ball, Philip Curtis, Edward Varney
Life of this patent
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Abstract
Hot gas is introduced into a fluidised bed of granular material, for example gypsum, contained in a vessel 10 having a grinding device or mill 11 in its lower region, which may comprise grinding rollers 15 cooperating with a table 17 on the base of the vessel. The gas may be supplied through a tube 20 passing down through the vessel, while raw material is fed into the bed, preferably by a feed screw 34. The ground product is discharged from the bed by an overflow 28 which determines the level of the bed.
Claims15
A method of heating and grinding a material which comprises and steps of:
- establishing a bed of said material having a lower region and a top level;
- introducing hot gas into said bed to heat and fluidize the bed, the material being reacted by the heat supplied by said hot gas;
- grinding the material in said lower region of the bed;
- introducing fresh raw material into the bed;
- and withdrawing ground and heated material from the bed, at least a significant proportion of said withdrawn material being discharged by gravity flow from said bed.
The method according to any of claims 1-4 and 6 wherein the significant proportion of material withdrawn is a major proportion of the material withdrawn.
Apparatus for heating and grinding material comprising:
- a vessel adapted to contain a fluidized bed of the material, said vessel having a base, a lower region and an upper region, said base being imperforate;
- a grinding or milling device, said device being disposed in the lower region of said vessel;
- a raw material feed for said bed disposed to supply raw material into said bed;
- a hot gas feed for said bed said hot gas feed comprising one or more tubes extending through said vessel and terminating in an opening or openings in said lower region;
- and
- means for withdrawing heated and ground material from the bed, said withdrawing means using gravity flow of material from said bed.
Dependencies are inferred from the claim text.