US 6,811,765 B1Granted

Thermal treatment of fine grain materials in a coarse-grain fluidized bed

AssigneeEpion Corporation

InventorsRolf Maiwald, Hans Zeiringer

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Abstract

The invention relates to a method for heat-treating fine-grained materials which tend to agglomerate at high temperatures and which have an average grain size of preferably 0 to 1000 μm within temperature ranges around and above the agglomeration temperature, in a fluidized bed of another, coarse-grained material. The temperature range in which the coarse-grained material tends to agglomerate and sinter to the reactor walls is higher than that of the fine-grained material. The coarse-grained material used is a material of the same type, a similar type or a different type with an average grain size of 1 to 10 mm. The fine-grained material is fed in directly over the tuyere bottom of a closed furnace chamber containing the fluidized bed, performs a circulating movement in said fluidized bed and once the heat treatment has been carried out, is pneumatically withdrawn from the fluidized bed into the top section of the furnace, and cooled immediately.

Claims10

Dependent claims

Process for the thermal treatment in a reactor of a fine-grain material with an average grain size under 1000 μm comprising the steps of:

(a) establishing and maintaining, in a walled reactor space, a fluidized bed of suspended coarse grain material of 1 to 10 mm grain size and imparting a high temperature to the atmosphere of such space and the coarse grain material;
(b) inserting the fine grain material to be treated immediately above the bottom of the fluidized bed and imparting a circulating motion to the fine grain material in the reactor space;
(c) subjecting the fine grain material to thermal treatment for a chemical or physical reaction;
and
(d) transporting the fine grain material pneumatically through a diffuser neck having an opening ratio of fluidized-bed area to diffuser neck area within a range of 6 to 9 and a linear ratio of diffuser neck length to diffuser neck diameter within an 0.5 to 1 range from the fluidized bed into an upper oven segment above the reactor where the fine grain material is cooled to below its softening or agglomeration temperature.

2 more elements

Dependencies are inferred from the claim text.