Method for the heat treatment of iron ore lumps in a reduction system

The present invention relates to a method and apparatus for the production of prereduced iron ore, Direct Reduced Iron (DRI), sponge iron, or the like by the gaseous reduction of iron-oxide containing particles (iron oxide lump ore), in a reduction system which comprises a preheating device for said particles, a reduction reactor, a source of natural gas, and a heating device. The natural gas is transformed in the operation of said system by means of a reformer or by the catalytic action of the metallic iron within said reduction reactor, to a reducing gas having carbon monoxide and hydrogen as its main constituents. The heating device heats said reducing gas prior to its introduction into said reduction reactor. More particularly, the invention relates to a method and apparatus which preserves the strength of iron-oxide-containing particles while they are reduced to metallic iron. The pre-reduction strengthening allows for the use of mechanically weak iron-oxide-containing particles as the charge for said reduction reactor while avoiding the sticking and fines problems associated with the use of said particles. The invention provides a method and apparatus for processing iron ore particles which otherwise would not be possible in a moving bed direct reduction process. A method and apparatus for the production of prereduced iron ore, DRI, sponge iron or the like by the gaseous reduction of iron-oxide containing particles in a reduction system which comprises a preheating device for the iron ore particles. The preheating device preserves the strength of the iron ore particles through the reduction system by preheating the particles with non-reducing (or preferably oxidizing) gas, whereby the DRI or like material produced is stronger than if it were processed in a reduction reactor without said preheating device. The invention thereby avoids sticking and fines production problems which some iron ores cause in the reduction reactor. The preheating device also produces other advantages in the reduction system as, for example, that the reducing gas reaches a higher degree of oxidation in the reduction reactor whereby the productivity of the reduction system increases as a result of the decreased amount of reducing gas as well as the decreased residence time required. A further advantage produced by the invention is that the recycled reducing gas can be preheated by heat-exchange with the gas stream effluent from the reduction reactor at a higher temperature as