US 4,381,916 A · Method and apparatus for roasting fine grained ores

Abstract

A method and apparatus for roasting fine grained ores such as cement raw meal, lime, dolomite, gypsum, phosphate rock and the like. A suspension preheater consisting of a plurality of serially connected cyclone separators is utilized to preheat the raw material. A suspension type roasting furnace follows the suspension preheater which is, depending upon the material being treated, followed by either a rotary kiln for further heat treatment of the material or by a cooler for cooling the product. The apparatus includes an arrangement for recirculating a portion of the material which has passed through the roasting furnace back into the roasting furnace to increase the degree of roasting. An existing preheater, suspension type calciner, rotary kiln cement clinker producing plant can be converted to the method and apparatus by the addition of an appropriately located splash plate.

Claims13

Dependent claims

Apparatus for roasting fine grained material such as cement raw meal, lime or dolomite comprising:

a furnace having an inlet for gas for combustion and raw fine grained material to be roasted, an inlet for fuel for combustion in said furnace and an outlet for spent combustion gas and at least partially roasted fine grained material;
a gas-solids separator having an inlet for spent combustion gas and at least partially roasted fine grained material flow connected to the outlet of said furnace, an outlet for separated at least partially roasted fine grained material and an outlet for separated spent combustion gas;
means defining an independent mixing zone for mixing fine grained material to be roasted and gas for combustion;
means for supplying a portion of the at least partially roasted fine grained roasted fine grained material from the outlet for separated at least partially roasted fine grained material of said gas-solids separator to the means defining an independent mixing zone and the inlet for gas for combustion and raw fine grained material of said furnace and for discharging the remainder of the at least partially roasted fine grained material;
and
means for directly transferring raw fine grained material to be roasted to said means defining an independent mixing zone.

3 more elements

A method of thermal processing fine grained ore comprising the steps of:

providing a furnace for calcining the fine grained ore;
supplying sufficient fuel and gas for combustion to said furnace to maintain within said furnace a temperature at which the ore to be calcined will be substantially calcined;
supplying raw fine grained ore to be processed to an independent mixing zone where the ore to be processed is mixed with hot gases;
supplying the ore to be processed and hot gases to said furnace and maintaining said ore in suspension within the furnace;
discharging in a stream spent combustion gas and suspended at least partially calcined ore from said furnace;
separating the spent combustion gas from the at least partially calcined ore;
and
recirculating a portion of the separated at least partially calcined ore to said independent mixing zone and then to said furnace for further calcination.

5 more elements

Dependencies are inferred from the claim text.

Method and apparatus for roasting fine grained ores

Life of this patent

Method and apparatus for roasting fine grained ores

Life of this patent

Abstract

Claims13