Method of and plant for producing products from carbon or stainless steel

Abstract

A method of producing products of carbon steel or stainless steel in an electrical arc furnace-converter ( 8 ) with two metallurgical vessels ( 9; 10 ), wherein during melting, an electrode system ( 11 ) pivots above each vessel ( 9; 10 ), and during oxidation with oxygen, in each vessel, a top lance ( 12 ) and one or more side lances ( 13 ) are introduced, and wherein an immediate quality change from carbon melt to stainless melt or vice versa is effected by oxidation with oxygen with top lance ( 12 ) and/or by oxidation with oxygen with at least one side lance ( 13 ) or in reverse order during tapping periods which depend on operation of an immediately adjoining continuous casting machine ( 18 ), makes a time-independent change of the melting sequence possible.

1 . A method of producing products from carbon steel or stainless steel in a electrical arc furnace-converter installation ( 8 ) with two metallurgical vessels ( 9 ;  10 ), wherein during melting, an electrode system ( 11 ) pivots over each metallurgical vessel ( 9 ;  10 ) and during oxidation with oxygen, a copy lance ( 12 ) is introduced in each metallurgical vessel ( 9 ;  10 ) and one or more several side lances ( 13 ) are introduced into a metallurgical vessel ( 9 ;  10 ) for oxidation, wherein an immediate quality change from carbon melt to stainless melt or vice versa is effected by oxidation with oxygen with the top lance ( 12 ) and/or by oxidation with oxygen with at least one side lance ( 13 ) or in reverse order during tapping periods which depend on operation of an immediately adjoining continuous casting machine ( 18 ).  
     
     
         2 . A method according to  claim 1 , 
 characterized in that    the top lance ( 12 ) is set during oxidation above a slag layer ( 29 ), and the side lance ( 13 ) is set during oxidation beneath the slag layer ( 29 ).    
     
     
         3 . A method according to one of claims  1  and  2 , 
 characterized in that  
 tapping period for both metallurgical vessels ( 9 ;  10 ) and charging periods for the continuous casting machine ( 18 ) are planned for less than about 90 minutes.  
 
     
     
         4 . A method according to  claim 1 , 
 characterized in that    during a dephosphorization phase of a phosphorous-reach pig iron, scrap ( 3 ) or other iron carriers, and/or ferrochromium ( 4 ), and/or ferronickel ( 5 ) or other alloying means such as refrigerants and additives (such as slag-forming constituents) are added to a quantity of iron sponge ( 30 ), and the melt is oxidized with a top lance ( 12 ).    
     
     
         5 . A method according to one of claims  1  through  4 , 
 characterized in that  
 oxidization is effected with less than 400 Nm 3 /min of oxygen or oxygen mixture.  
 
     
     
         6 . A method according to  claim 1 , 
 characterized in that    during the oxidation phase of the melt, a quantity of stainless scrap ( 3 ), and or ferrochromium ( 4 ), and/or ferronickel ( 5 ) is supplied, and during finish oxidation with at least one side lance ( 13 ) and, if necessary, with the top lance ( 12 ), less than 100 Nm 3 /min of oxygen or oxygen mixture is fed.    
     
     
         7 . A method according to one of claims  1  through  6 , 
 characterized in that  
 during oxidation with the top lance ( 12 ) and/or at least one side lance ( 13 ), turbulence of the melt and/or the slag layer ( 29 ) is kept low, and that inner wall ( 31 ) of the metallurgical vessel ( 9 ;  10 ) remains free of slag formations.  
 
     
     
         8 . A method according to one of claims  1  through  7 , 
 characterized in that  
 the metallurgical vessel ( 9 ;  10 ) is tilted, during tapping, until a complete discharge of the slag ( 29 ) and the melt.  
 
     
     
         9 . A method according to one of claims  1  through  8 , 
 characterized in that  
 the produced liquid steel after vacuum treatment VD/VOD) in a vacuum installation ( 15 ) and, if necessary, in a crucible furnace station ( 16 ), is cast in a continuous casting machine, with a cast strand being rolled and wound into coils ( 28 ) of carbon steel or stainless steel.  
 
     
     
         10 . A method according to  claim 9 , 
 characterized in that    the continuous casting process and the hot rolling process of carbon steel or stainless still is effected in a compact strip production (CSP) plant.    
     
     
         11 . A method according to  claim 9 , 
 characterized in that    a product of a continuous casting process and of a rolling process of carbon steel or stainless steel is formed in an elongate product in the continuous casting machine ( 18 ).    
     
     
         12 . A plant for producing products from carbon steel or stainless steel in an electrical arc furnace-converter ( 8 ) with two metallurgical vessels ( 9 ;  10 ), with lowerable or rotatable top lances ( 12 ) associated with each metallurgical vessel and with an electrode system ( 11 ) arranged between the metallurgical vessels ( 9 ;  10 ) and pivotable over each metallurgical vessel ( 9 ,  10 ) characterized in that each metallurgical vessel ( 9 ;  10 ) consists of a tiltable or stationary metallurgical vessel ( 9 ;  10 ) and that in addition to the top lances ( 12 ), one or several side lances ( 13 ) are provided, that between the metallurgical vessels ( 9 ;  10 ) an oscillating electrode system ( 11 ) and following installation ( 15 ) (VD/VOD), crucible furnace-station ( 16 ), continuous casbine machine ( 18 ), hot rolling train ( 23 ), continuous rolling mill ( 26 ) or reversing cold rolling mill ( 27 ) for flat or elongated products, and a coiler ( 32 ), all lying on a line ( 24 ), are provided.  
     
     
         13 . A plant according to  claim 12 , 
 characterized in that    a plurality of rolling trains ( 23 ;  26 ) are arranged one after another in the line ( 24 ).    
     
     
         14 . A plant according to  claim 11  or  12 , 
 characterized in that  
 one rolling train ( 23 ) is formed as a continuous cold rolling train ( 26 ) or as a reversing cold rolling train ( 27 ).  
 
     
     
         15 . A plant according to one of claims  11  through  13 , 
 characterized in that  
 a prickling installation ( 25 ) is provided between two, arranged one after another in the line  24 , rolling trains ( 23 ;  26 ).  
 
     
     
         16 . A plant according to one of claims  11  through  14 , 
 characterized in that  
 the continuous casting machine ( 18 ) is designed for production of elongate products, bloom profiles, billet profiles, and thin slab cross-sections, with rolling mill being correspondingly adjusted.