Process for the production of liquid pig iron or liquid steel pre-products

Abstract

In the process for the production of liquid pig iron ) or liquid steel pre-products from charging substances comprising iron ore ( ) and fluxes and at least partially containing a portion of fines, the iron ore is directly reduced to sponge iron in at least two reduction stages ( ) by the fluidized bed method, the sponge iron is melted in a melt-down gasifying zone ( ) under the supply of carbon carriers and an oxygen-containing gas, and a CO- and H -containing reducing gas is produced which is injected into reduction zones of the reduction stages ( ), is reacted there, is withdrawn as a top gas and optionally is supplied to a consumer. To achieve uniform reduction of the iron ore at optimum exploitation of the reducing gas, the iron ore ( ) in a first reduction stage ( ) by aid of the reducing gas is fractionated into at least two fractions having different grain size distributions each, each fraction is reduced by the reducing gas in a separate fluidized bed ( ), wherein the reducing gas maintains a first fluidized bed ( ) containing the coarse-grain fraction and separates the fine-grain fraction from the same, and wherein, further, reducing gas is additionally introduced into the further fluidized bed ( ) directly reduced iron ore ( ) is discharged both from the first and from the further fluidized bed ( ) and the fine- and the coarse-grain fraction reduced in the first reduction stage ( ) are further reduced in at least one further reduction stage ( ) operating in the same manner as the first reduction stage ( ) and from the last reduction stage ( ) the fine-grain fraction is introduced into the melt-down gasifying zone ( ) while being agglomerated by provision of oxygen, and the coarse-grain fraction is fed directly into the melt-down gasifying zone ( ) gravitationally (FIG. 1).