US2026028688A1PendingUtilityA1

Fired pellets for reduction and method for producing same

Assignee: JFE STEEL CORPPriority: Aug 1, 2022Filed: Aug 1, 2022Published: Jan 29, 2026
Est. expiryAug 1, 2042(~16 yrs left)· nominal 20-yr term from priority
C21B 13/0086C21B 13/105C21B 13/008C21B 13/0046C22B 1/2406C22B 1/243
53
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Claims

Abstract

Fired pellets for use in a solid reduction furnace that are effective in preventing clustering by reducing the possibility of contact between low-melting-temperature slags and thus preventing the fusion therebetween, and a method for producing such fired pellets. Fired pellets for reduction, wherein the proportion of high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) to the total Fe (T.Fe) satisfies an expression: (Al 2 O 3 +MgO+SiO 2 )/T.Fe≥0.09, and a method for producing the same. In the expression, Al 2 O 3 represents the concentration (mass %) of Al 2 O 3 in the fired pellets, MgO represents the concentration (mass %) of MgO in the fired pellets, SiO 2 represents the concentration (mass %) of SiO 2 in the fired pellets, and T.Fe represents the concentration (mass %) of T.Fe in the fired pellets.

Claims

exact text as granted — not AI-modified
1 . Fired pellets for reduction,
 wherein   a proportion of high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) to total Fe (T.Fe) satisfies the following Expression (1):   
       
         
           
             
               
                 
                   
                     
                       
                         
                           ( 
                           
                             
                               
                                 Al 
                                 2 
                               
                               ⁢ 
                               
                                 O 
                                 3 
                               
                             
                             + 
                             MgO 
                             + 
                             
                               SiO 
                               2 
                             
                           
                           ) 
                         
                         / 
                         
                           T 
                           . 
                           Fe 
                         
                       
                       ≥ 
                       0.09 
                     
                     , 
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         where Al 2 O 3  represents a concentration (mass %) of Al 2 O 3  in the fired pellets, 
         MgO represents a concentration (mass %) of MgO in the fired pellets, 
         SiO 2  represents a concentration (mass %) of SiO 2  in the fired pellets, and 
         T.Fe represents a concentration (mass %) of T.Fe in the fired pellets. 
       
     
     
         2 . Fired pellets for reduction,
 wherein   a proportion of high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) to total Fe (T.Fe) satisfies the following Expression (2):   
       
         
           
             
               
                 
                   
                     
                       
                         
                           ( 
                           
                             
                               
                                 Al 
                                 2 
                               
                               ⁢ 
                               
                                 O 
                                 3 
                               
                             
                             + 
                             MgO 
                             + 
                             
                               SiO 
                               2 
                             
                           
                           ) 
                         
                         / 
                         
                           T 
                           . 
                           Fe 
                         
                       
                       ≥ 
                       0.12 
                     
                     , 
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
         where Al 2 O 3  represents a concentration (mass %) of Al 2 O 3  in the fired pellets, 
         MgO represents a concentration (mass %) of MgO in the fired pellets, 
         SiO 2  represents a concentration (mass %) of SiO 2  in the fired pellets, and 
         T.Fe represents a concentration (mass %) of T.Fe in the fired pellets. 
       
     
     
         3 . The fired pellets for reduction according to  claim 1 ,
 wherein a porosity is 20% or more.   
     
     
         4 . The fired pellets for reduction according to  claim 1 ,
 wherein a porosity is 30% or more.   
     
     
         5 . A method for producing the fired pellets for reduction according to  claim 1 , wherein
 reduction and firing are performed by using an iron-containing raw material formulated to achieve an average LOI (Loss on Ignition) of 5% or more.   
     
     
         6 . The method for producing the fired pellets for reduction according to  claim 5 , wherein
 the iron-containing raw material has been subjected to a crystal water removal pretreatment in advance so as to achieve an average LOI (Loss on Ignition) of 2% or less.   
     
     
         7 . The method for producing the fired pellets for reduction according to  claim 6 , wherein
 the crystal water removal pretreatment comprises heating and drying using a rotary kiln and using a measurement value of a sample at the exit side of the kiln as the average LOI (Loss on Ignition) of the iron-containing raw material.   
     
     
         8 . The method for producing the fired pellets for reduction according to  claim 5 , wherein
 a mixed raw material containing 4 mass % to 24 mass % M.Fe is prepared by mixing a raw material containing M.Fe, and the mixed raw material is granulated and fired.   
     
     
         9 . The method for producing t fired pellets for reduction according to  claim 8 , wherein
 the raw material is reduced iron having a particle size of 3 mm or less that has been reduced in a solid reduction furnace.   
     
     
         10 . The method for producing the fired pellets for reduction according to  claim 9 , wherein
 the reduced iron contains 78 mass % or more M.Fe.

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