Method for producing steel

Abstract

A method for producing steel in which iron ore is reduced with hydrogen and the resulting intermediate product of reduced iron ore is subjected to further metallurgical processing; the hydrogen is produced through electrolysis of water; the electrical energy required for the electrolysis is regenerative energy from hydroelectric, wind, and/or photovoltaic sources and the hydrogen and/or the intermediate product is produced regardless of demand, whenever enough regeneratively produced electrical energy is available; and unneeded intermediate product is stored until there is demand or it is used so that the regenerative energy that is stored therein is also stored; and using a calculation model to calculate a required discharge rate in a reduction shaft to achieve a desired metallization grade of the steel by tracing batches of the iron ore in the reduction shaft, and using the calculation model to calculate the amount of carbon-containing gas or hydrogen-containing gas to add to the hydrogen for the reduction.

What is claimed is: 
     
         1 . A method for producing steel, comprising:
 reducing iron ore with hydrogen and subjecting a resulting intermediate product of reduced iron ore to further metallurgical processing, wherein the hydrogen is produced through electrolysis of water, and electrical energy required for the electrolysis is regenerative energy selected from the group consisting of hydroelectric sources, wind sources, and photovoltaic sources; and   the hydrogen and/or the intermediate product is produced regardless of demand for energy, whenever enough regeneratively produced electrical energy is available, where unneeded intermediate product is stored until there is demand or it is used so that the regenerative energy that is stored therein is also stored, and in reducing the iron ore to produce the intermediate product, a carbon-containing or hydrogen-containing gas is added to the hydrogen in order to incorporate carbon into the intermediate product; and the hydrogen for the reduction has at least enough carbon-containing gas or hydrogen-containing gas added to it to make a carbon content in the intermediate product 0.0005 mass % to 6.3 mass %;   using a calculation model to calculate a required discharge rate in a reduction shaft to achieve a desired metallization grade of the steel by tracing batches of the iron ore in the reduction shaft; and   using the calculation model to calculate the amount of carbon-containing gas or hydrogen-containing gas to add to the hydrogen for the reduction;   wherein the calculation model is Fe 2 O 3 +6CO→2Fe+3CO+3CO 2  for carbon-containing gas flows and Fe 2 O 3 +6H 2 →2Fe+3H 2 +3H 2 O for hydrogen-containing gas flows.   
     
     
         2 . The method according to  claim 1 , wherein the carbon-containing or hydrogen-containing gas is obtained from a source selected from the group consisting of industrial processes, biogas production, pyrolysis, and synthesis gas from biomass. 
     
     
         3 . The method according to  claim 1 , wherein the hydrogen for the reduction has at least enough carbon-containing-or hydrogen-containing gas added to it to make the carbon content in the intermediate product 1 mass % to 3 mass %. 
     
     
         4 . The method according to  claim 1 , wherein the reduction gas composed of hydrogen and possibly a carbon-containing gas is introduced into the reduction process at a temperature of 450° C. to 1200° C. 
     
     
         5 . The method according to  claim 1 , wherein excess pressure in the reduction is between 0 bar and 15 bar. 
     
     
         6 . The method according to  claim 1 , wherein a ratio between hydrogen from regenerative production and carbon-containing or hydrogen-containing gas flows is varied continuously as a function of availability; when there is sufficient regenerative energy, hydrogen from the production with regenerative energy is used and in the absence of regenerative energy, then the system switches to purely carbon-containing or hydrogen-containing gas flows. 
     
     
         7 . The method according to  claim 1 , wherein an adjustment of the content of hydrogen and, or carbon-containing or hydrogen-containing vas flows in the overall gas flow is carried out using a predictive control; the predictive control is used to measure at least one of the group consisting of a predicted yield/production quantity of hydrogen, regenerative energy, carbon-containing or hydrogen-containing gas flows from biogas production or from pyrolysis of renewable resources, and forecasts flow into an estimation of regenerative energy; and demand predictions of other external consumers also flow into the process, thus permitting the electrical energy from regenerative sources to be distributed optimally and in a most economical fashion. 
     
     
         8 . The method according to  claim 1 , wherein gas flow that is emitted as exhaust by a direct reduction system is conveyed into the process as a carbon-containing or hydrogen-containing gas flow.