Abstract: Green pellets are sintered by drying, pre-heating, firing and cooling steps, at least the drying and pre-heating steps being carried out with said pellets resting, in the form of a bed, on an endless gas-permeable conveyor and at least the first part of the drying operation being carried out with a gas which passes upwardly through said conveyor and the pellet bed, while subsequent temperature-increasing treatment steps carried out on the conveyor are effected with a hot gas flowing downwardly through the pellet bed and the conveyor. At least the first part of the drying operation is effected with heat stored in the conveyor and/or in a hearth layer for the pellet bed arranged on said conveyor by using a drying gas which comprises substantially cool air and which is heated during its passage through the conveyor and/or the hearth layer by the heat stored therein.

Abstract: In a plant for heating or heat-treating a bed of material carried by an upper part of an endless, perforated belt-type conveyor, said upper part extending through at least one heating or heat-treatment zone in which heating or heat-treatment gas passes through said upper part and the bed being conveyed thereon, the conveyor includes a plurality of mutually adjacent endless, imperforate belt parts. These belt parts are separated by perforated regions. The upper conveyor part is slidably supported, preferably by means of gas-cushion bearings, along at least substantially the whole of its material-carrying length in the region of said belt parts.

Abstract: Agglomerates are fired in a sintering apparatus of the type, in which the agglomerates during transport on a travelling grate in zones along said grate are pre-dried with substantially pure warm air passing upwardly through the grate and finally dried and heated with hot process gas passing downwardly through the grate, and in which the hot process gas is generated by combusting fuel while using, as secondary air of combustion, air previously used to cool fired agglomerates. In order to reduce the quantity of gas contaminated during the firing process there is maintained in a sealing zone located between the pre-drying and final-drying zones and mechanically shielded thereagainst, by supplying air above the grate and removing air by suction from beneath the grate, pressures which are substantially equal to the pressure above the grate and the pressure beneath the grate respectively in the adjacent final-drying zone.

Abstract: Pellets having uniform size and excellent strength properties are manufactured without fluctuations in production from finely-divided moist material by rolling nuclei of substantially mutually identical size in at least one pellet-rolling circuit in the presence of the finely-divided moist material, to form pellets having at least one layer of said material surrounding respective nuclei.

Abstract: In a method of operating a shaft furnace for the production of sintered iron ore pellets, in which the pellets are fired by introducing hot gas at the level of the furnace adjacent the opening for introducing the pellets to be fired and located at the top of the furnace and cooling air for cooling the pellets after having been heated by the hot gas is introduced into the shaft at the bottom thereof to pass upwardly through the shaft while cooling the pellets, the improvement of applying a substantial portion of the coolant air through air inlet channels distributed around the circumference of the shaft at a level of the shaft located between the bottom opening of the shaft and the burner openings at a substantial distance from both said openings as compared with the distance between the openings, to provide a temperature distribution of the coolant air flowing through the shaft such that the temperature of the coolant air flowing along and in the vicinity of the shaft adopts a value which is substantially low