Method for producing granular metallic iron

Abstract

A method for producing granular metallic iron of the present invention includes: an agglomeration step of obtaining agglomerates through agglomeration of a mixture that contains an iron oxide-containing material and a carbonaceous reducing agent; and a granulation step of obtaining granular metallic iron by heating the agglomerates, reducing iron oxides in the agglomerates, aggregating generated metallic iron to be granular while separating the metallic iron from slag generated as a by-product, and thereafter cooling and solidifying the metallic iron, wherein agglomerates satisfying all the conditions given by formulas (1) to (3) below are used as the agglomerates: (1) [(total CaO amount+total SiO 2 amount+total Al 2 O 3 amount)/total Fe amount]≧0.250; (2) (total CaO amount/total SiO 2 amount)≧0.9; (3) [total Al 2 O 3 amount/(total CaO amount+total SiO 2 amount+total Al 2 O 3 amount)]×100≧9.7. In the formulas, the total CaO amount, the total SiO 2 amount, the total Al 2 O 3 amount and the total Fe amount respectively represent the mass percentage of CaO, the mass percentage of SiO 2 , the mass percentage of Al 2 O 3 and the mass percentage of Fe contained in the agglomerates.

1 . A method for producing granular metallic iron, comprising:
 an agglomeration step of obtaining agglomerates through agglomeration of a mixture that contains an iron oxide-containing material and a carbonaceous reducing agent; and   a granulation step of obtaining granular metallic iron by heating the agglomerates, reducing iron oxides in the agglomerates, aggregating generated metallic iron to be granular while separating the metallic iron from slag generated as a by-product, and thereafter cooling and solidifying the metallic iron;   wherein agglomerates satisfying all the conditions given by formulas (1) to (3) below are used as the agglomerates:
   [(total CaO amount+total SiO 2  amount+total Al 2 O 3  amount)/total Fe amount]≧0.250   (1);
 
   (total Cat) amount/total SiO 2  amount)≧0.9   (2);
 
   [total Al 2 O 3  amount/(total CaO amount+total SiO 2  amount+total Al 2 O 3  amount)]×100≧9.7   (3),
 
   wherein the total CaO amount, the total SiO 2  amount, the total Al 2 O 3  amount and the total Fe amount in the formulas (1) to (3) respectively represent the mass percentage of CaO, the mass percentage of SiO 2 , the mass percentage of Al 2 O 3  and the mass percentage of Fe comprised in the agglomerates.   
     
     
         2 . The method for producing granular metallic iron of  claim 1 , wherein in the agglomeration step an Al 2 O 3 -containing material is added to the mixture, before the agglomeration of the mixture.