Method for producing slag having a desired quality

Abstract

A method is disclosed for generating slag having desired characteristics.

1 . A method for generating slag of desired characteristics in the production of pig iron, with steps as follows:
 a) heating iron oxide in a direct reduction plant, so that with a reducing agent present a majority of the iron oxide is reduced to iron and an iron-containing intermediate is formed;   b) heating the iron-containing intermediate in a reactor arrangement, to give pig iron and the slag;   c) analyzing, via an analysis unit, the iron-containing intermediate and/or the slag which deposits during the further heating of the iron-containing intermediate;   at least one of: d1) determining a property of an additive to be added to the iron-containing intermediate during the heating, depending on the analysis, in order to alter the composition of the slag, and adding the additive during the heating, to give the slag of the desired characteristics; and/or   d2) recognizing that the slag requires a thermal treatment to give the slag having the desired characteristics, and initiating the thermal treatment.   
     
     
         2 . The method as claimed in  claim 1 , wherein the direct reduction plant comprises a feed for hydrogen as reducing agent. 
     
     
         3 . The method as claimed in  claim 2 , wherein the reactor arrangement comprises a smelter having a reducing atmosphere. 
     
     
         4 . The method as claimed in  claim 3 , wherein the direct reduction plant is configured to heat the iron oxide up to a temperature of between 900° C. and 1100° C. 
     
     
         5 . The method as claimed in  claim 4 , wherein an analysis unit is used which is configured during the analysis to determine an actual composition of the iron-containing intermediate and/or of the slag in the reactor unit and to compare it with a desired target composition of the slag and to adjust the properties of the additive depending on the difference between actual composition and target composition. 
     
     
         6 . The method as claimed in  claim 5 , wherein a control unit is used which is configured to determine, as property of the additive, an amount of the additive and a composition of the additive. 
     
     
         7 . The method as claimed in  claim 6 , wherein a control unit is used which is configured to take account, for the target characteristics of the slag, of any selection from the following features in order to alter the actual characteristics of the slag: a desired chemical composition of the granulated slag, a desired physical property of the granulated slag, a mineralogical property of the granulated slag. 
     
     
         8 . The method as claimed in  claim 7 , wherein the smelter has an opening for introducing raw material into the smelter; wherein an analysis unit is used which is configured to analyze the slag after the introduction of the raw material. 
     
     
         9 . The method as claimed in  claim 8 , wherein a control unit is used which is configured to select the amount of the additive such that the slag has a basicity of 1 to 5.5. 
     
     
         10 . The method as claimed in  claim 9 , wherein the reactor arrangement has a first reactor which is configured to receive and to heat the iron-containing intermediate to give the iron and the slag, and wherein the reactor arrangement has a second reactor which is configured to receive the slag from the first reactor; where a control unit is used which is configured to introduce the additive into the second reactor and/or to initiate the thermal treatment of the slag in the second reactor, to give the slag having the desired characteristics. 
     
     
         11 . The method as claimed in  claim 10 , wherein the second reactor is configured to atomize the slag to give atomized slag, the atomized slag having a particle size of 1 to 100 μm. 
     
     
         12 . The method as claimed in  claim 11 , wherein the second reactor is configured a mineral building material, more particularly a binder; wherein the control unit is configured to introduce cement, as part of the additive, into the second reactor; wherein the second reactor is configured to mix the atomized slag and the cement with one another, the atomized slag being mixed with cement in a ratio of 36:64 to 95:5, to give the mineral building material, whose 28-d standard strength is at least 30 N/mm 2 .