Method and device for producing molten material

Abstract

A method for producing molten material, wherein oxygen, reducing agents and iron that has been reduced in a reduction reactor are introduced into a melter gasifier. The reducing agent is gasified with the oxygen and the heat thereby produced melts the reduced iron. Cupola gas from the melter gasifier is used at least as a portion of the reduction gas, and reacted top gas is withdrawn from the reduction reactor. The aim of the invention is to increase energy efficiency and raw material efficiency as well as productivity while at the same time obtaining metallurgically improved properties of the product. For this purpose, at least a portion of the top gas is branched off from the line for the withdrawal of the top gas from the reduction reactor and is returned via at least one return line leading to the melter gasifier and is introduced into the melter gasifier.

1 . A method for production of molten metal, comprising
 reducing oxygen, reducing agent and iron in a reduction reactor and introducing them into a melt gasifier, wherein the reducing agent is gasified with the oxygen, and the reduced iron is melted by the heat which in this case occurs,   using cupola gas present in the melt gasifier as at least a fraction of the reduction gas, and   drawing off reacted top gas from the reduction reactor, introducing at least part of the drawn-off top gas into the melt gasifier and compressing the gas recirculated to the melt gasifier,   at least one of cooling the recirculated gas between its compression and its introduction into the melt gasifier, reducing the carbon dioxide content of the recirculated gas, reforming at least one part stream of the recirculated gas with higher hydrocarbons, using a further part stream of the recirculated gas as fuel gas, and controlling the theoretical adiabatic flame temperature in a swirl zone by at least one of quantity, temperature and CO 2  fraction of the recirculated gas.   
     
     
         2 . The method as claimed in  claim 1 , wherein at least a first part of the recirculated gas is only compressed, at least a second part of the recirculated gas is only cooled and the carbon dioxide content thereof is reduced, and mixing the compressed gas and the carbon dioxide-reduced gas before their introduction into the melt gasifier. 
     
     
         3 . The method as claimed in  claim 1 , further comprising heating the recirculated and at most cooled and carbon dioxide-reduced gas before introducing them into the melt gasifier, and using a part stream of the recirculated gas as fuel gas. 
     
     
         4 . The method as claimed in  claim 1 , further comprising mixing the reformed recirculated gas with at least one of the only compressed and the cooled and carbon dioxide-reduced gas and then introducing the mixed gas into the melt gasifier. 
     
     
         5 . The method as claimed in  claim 1 , further comprising separating particles cotransported in the cupola gas and recirculating the particles into the melt gasifier, and admixing a part stream of at least one of the only compressed and of the cooled and carbon dioxide-reduced gas for transporting the recirculated particles. 
     
     
         6 . The method as claimed in  claim 1 , further comprising cooling the recirculated gas, between its compression and introduction into the melt gasifier, to 30 to 50° C. 
     
     
         7 . The method as claimed in  claim 1 , wherein the carbon dioxide content is reduced to 2 to 3% by volume. 
     
     
         8 . A plant for the production of molten metal, comprising
 a reduction reactor, a melt gasifier having an oxygen supply and a supply system for reducing agent, at least one line for supplying cupola gas present in the melt gasifier into the reduction reactor, and at least one first line for drawing off the top gas from the reduction reactor, at least one return line branching off from the first line for the top gas and leading into the melt gasifier; a compressor inserted into the return line;   a cooling device and a carbon dioxide reduction stage inserted between the compressor and the oxygen supply, a reformer inserted between the compressor and the oxygen supply, the cooling device, the carbon dioxide reduction stage and the reformer are provided in parallel branches of the return line; and   a common supply line to the oxygen supply to the melt gasifier, and the parallel branches leading into the common supply line.   
     
     
         9 . The plant as claimed in  claim 8 , wherein the return line for the gas runs parallel to the oxygen supply as far as the issue of the latter. 
     
     
         10 . The plant as claimed in  claim 8 , wherein the compressor has an outlet and the carbon dioxide reduction stage has an outlet and those outlets lead into a common supply line to the oxygen supply to the melt gasifier. 
     
     
         11 . The plant as claimed in  claim 10 , further comprising a heating device downstream of the convergence of the outlet of the compressor and of the outlet of the carbon dioxide reduction stage. 
     
     
         12 . The plant as claimed in  claim 11 , wherein the heating device operates with;
 a branch emanating from the return line upstream or downstream of the compressor and leading to the fuel gas connection of the heating device.   
     
     
         13 . The plant as claimed in  claim 8 , further comprising a branch emanating from the return line and leading to a fuel gas connection of the reformer. 
     
     
         14 . The plant as claimed in  claim 8 , further comprising at least one line for the cupola gas, a particle separator having a particle discharge with a particle recirculation leading to the melt gasifier, and a branch from the return line issuing into the particle recirculation.