Briquette for producing a foamed slag effect in eaf technology in stainless steel production

Abstract

Briquette for producing a foamed slag on stainless steel melts in an electric arc furnace, made up of mixtures of individual or multiple substances of following basic components: O 2 carrier Dust, sludge or slag with ≧10% FeO/Fe 2 O 3 , Dust, sludge or slag with ≧1% Cr 2 O 3 , Dust, sludge or slag with ≧1% MnO, Dust, sludge or slag with ≧1% NiO, Scale with ≧10% FeO/Fe 2 O 3 , Gas carrier Dust with ≧40% CaCO 3 , Density adjuster Dust with FeCr, Dust with Fe/low alloy fine scrap, Dust with Cr/ferritic fine scrap, Dust with Ni/austenitic fine scrap, grinding dust, Dust with Mn/ferritic or low alloy fine scrap, Reducing agent Carbon-containing substances ≧90% C, Dust or fine granulate of coke, coal or graphite, Binder Molasses, cement, Ca(OH) 2 , in each case ≦5% by weight.

What is claimed is: 
     
         1 . Briquette for producing a foamed slag on stainless steel melts in an electric arc furnace, containing a mixture of metal oxides, limestone, carbon and a binder, which is introduced into the furnace and arranged there such that below the slag at a metal-slag interface, the metal oxides are reduced by the carbon, and the limestone is thermally dissociated, and gases produced in a process cause foaming of the slag by forming bubbles, characterized in that the briquette for use in a melt of stainless steel, low alloy steel or high alloy steel is made up of substances selected from a group of following basic components and consisting of:
 O 2  carrier selected from a group consisting of:
 Dust, sludge or slag with ≧10% FeO and/or Fe 2 O 3 , by weight, 
 Dust, sludge or slag with ≧1% Cr 2 O 3 , by weight, 
 Dust, sludge or slag with ≧1% MnO, by weight, 
 Dust, sludge or slag with ≧1% NiO, by weight, 
 Scale with ≧10% FeO and/or Fe 2 O 3  by weight, 
   Gas carrier Dust with ≧40% CaCO 3 , by weight,   Density adjuster 10%-16% by weight and selected from a group consisting of:
 Dust with FeCr, 
 Dust with Fe/low alloy fine scrap, 
 Dust with Cr/ferritic fine scrap, 
 Dust with Ni/austenitic fine scrap, grinding dust, 
 Dust with Mn/ferritic or low alloy fine scrap, 
   Reducing agent selected from a group consisting of:
 Carbon-containing substances ≧90% C, by weight, 
 Dust or fine granulate of coke, coal or graphite, 
   Binder Molasses, cement, Ca(OH) 2 , in each case ≦5% by weight.   
     
     
         2 . Briquette according to  claim 1 , characterized in that the briquette for use in foamed slag production for stainless steel is made up from all substances of the basic components. 
     
     
         3 . Briquette according to  claim 1 , characterized in that a CO/CO 2  gas evolution in the standard state (20° C., 1 bar) is ≧0.15 Nm 3 /kg briquette. 
     
     
         4 . Briquette according to claim  10 , characterized in that the briquette density is between 2.5 and 7.0 g/cm 3 . 
     
     
         5 . Briquette according to  claim 1 , characterized in that after drying for 24 hr and at ≦4% humidity, compressive strength of the briquette is ≧0.5 N/mm 2  and disintegration strength from 2 m on a 120 mm thick plate is ≧97%. 
     
     
         6 . Briquette according to  claim 1 , characterized in that the briquette, a diagonal size of which is between 20 and 100 mm and a height of which is between 15 and 40 mm with a briquette volume of ≦800 cm 3 , has a form selected from a group consisting of ellipsoid, a hexagonal cuboid, a cuboid, and a cylinder.