US2026043120A1PendingUtilityA1

Carburizer and carburization method using the same

Assignee: NIPPON STEEL CORPPriority: Dec 7, 2018Filed: Oct 23, 2025Published: Feb 12, 2026
Est. expiryDec 7, 2038(~12.3 yrs left)· nominal 20-yr term from priority
C21C 5/52C21C 7/0037C21C 5/527Y02P10/20C23C 8/80C23C 8/66C23C 8/22C21C 7/00C21C 7/0025C23C 8/02
73
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Claims

Abstract

A carburizer, which effects carburization with respect to molten iron accommodated in an electric furnace or a ladle, includes a mixture of quicklime and a carbon material having an ash content of from 5 mass % to 18 mass %, and satisfies the conditions 0.6≤(mc+Mc)/ms≤2.7 and 0.7≤(mc+Mc)/ma≤6.5. A method of carburization uses this carburizer. Here, mc represents the mass of CaO in the carbon material, ms represents the mass of SiO 2 in the carbon material, ma represents the mass of Al 2 O 3 in the carbon material, and Mc represents the mass of the quicklime.

Claims

exact text as granted — not AI-modified
1 . A method of carburization, comprising, in an electric furnace or a ladle, performing carburization by adding a carburizer to a molten iron surface formed by blowing in a gas and agitating the molten iron,
 the carburizer comprising a mixture of quicklime and a carbon material having an ash content of from 5 mass % to 18 mass %, and the carburizer satisfying conditions stipulated in the following Formula (1) and Formula (2):   
       
         
           
             
               
                 
                   
                     
                       0 
                       . 
                       6 
                     
                     ≤ 
                     
                       
                         ( 
                         
                           mc 
                           + 
                           Mc 
                         
                         ) 
                       
                       / 
                       ms 
                     
                     ≤ 
                     2.7 
                   
                 
                 
                   
                     Formula 
                     ⁢ 
                         
                     
                       ( 
                       1 
                       ) 
                     
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     0.7 
                     ≤ 
                     
                       
                         ( 
                         
                           mc 
                           + 
                           Mc 
                         
                         ) 
                       
                       / 
                       ma 
                     
                     ≤ 
                     
                       6 
                       . 
                       5 
                     
                   
                 
                 
                   
                     Formula 
                     ⁢ 
                         
                     
                       ( 
                       2 
                       ) 
                     
                   
                 
               
             
           
         
         wherein, in Formula (1) and Formula (2), mc represents a mass of CaO in the carbon material, ms represents a mass of SiO 2  in the carbon material, ma represents a mass of Al 2 O 3  in the carbon material, and Mc represents a mass of the quicklime. 
       
     
     
         2 . The method of carburization recited in  claim 1 , wherein the mixture satisfies conditions stipulated in the following Formula (1A) and Formula (2A): 
       
         
           
             
               
                 
                   
                     
                       0 
                       . 
                       6 
                     
                     ≤ 
                     
                       
                         ( 
                         
                           mc 
                           + 
                           Mc 
                         
                         ) 
                       
                       / 
                       ms 
                     
                     ≤ 
                     1.9 
                   
                 
                 
                   
                     Formula 
                     ⁢ 
                         
                     
                       ( 
                       
                         1 
                         ⁢ 
                         A 
                       
                       ) 
                     
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     0.7 
                     ≤ 
                     
                       
                         ( 
                         
                           mc 
                           + 
                           Mc 
                         
                         ) 
                       
                       / 
                       ma 
                     
                     ≤ 
                     
                       5. 
                       . 
                     
                   
                 
                 
                   
                     Formula 
                     ⁢ 
                         
                     
                       ( 
                       
                         2 
                         ⁢ 
                         A 
                       
                       ) 
                     
                   
                 
               
             
           
         
       
     
     
         3 . The method of carburization recited in  claim 1 , wherein the carburizer is added by being fed towards the molten iron surface from a lance. 
     
     
         4 . The method of carburization recited in  claim 1 , wherein the carburizer is a briquette. 
     
     
         5 . The method of carburization recited in  claim 1 , wherein a maximum particle size of the carbon material is 20 mm or less. 
     
     
         6 . The method of carburization recited in  claim 1 , wherein the carbon material is coal containing 10% or more of volatile matter and has a maximum particle size of 100 mm or less. 
     
     
         7 . The method of carburization recited in  claim 1 , wherein a maximum particle size of the quicklime is 10 mm or less. 
     
     
         8 . The method of carburization recited in  claim 1 , wherein S concentration in the molten iron is 0.5 mass % or less.

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