Using a slag conditioner to beneficiate bag house dust from a steel making furnace

Abstract

A slag conditioner containing MgO, up to 50% slag-making carbon, 10 to 60% particulates of bag house dust and dropout box particles and 2% to 25% binder is mixed and formed under pressure to produce aggregates which can have the form of a briquette. The MgO content of the mixture comprising: 20% to 90% burned aggregates comprised of particles less than 8 mm of which at least 30% is 0.2 mm or greater and containing between 35% and 94% MgO; and up to 50% light burned magnesite.

1 . A slag conditioner comprising by weight a mixture and 2% to 25% binder for bonded agglomerates or larger particles of said mixture, said mixture comprising: 10% to 60% particulates comprised of bag house dust essentially containing oxides of iron, calcium, silicon, magnesium, zinc, lead and cadmium; 20% to 90% burned aggregates comprised of particles less than 8 mm of which at least 30% is 0.2 mm or greater and containing between 35% and 94% MgO; up to 50% slag-making carbonaceous additive; and up to 50% light burned magnesite. 
   
   
       2 . The slag conditioner according to  claim 1  wherein said particulates comprised comprise between 10% and 30% of bag house. 
   
   
       3 . The slag conditioner according to  claim 1  wherein said particulates comprised comprise between 10% and 25% of bag house. 
   
   
       4 . The slag conditioner according to  claim 1  wherein said particulates comprised of bag house dust comprise particles in the range of 0.1 and 1000 microns. 
   
   
       5 . The slag conditioner according to  claim 1  wherein said particulates comprised of bag house dust include particulates of drop out boxes essentially including oxides of iron, calcium, silicon, magnesium, zinc, lead and cadmium. 
   
   
       6 . The slag conditioner according to  claim 1  wherein said burned aggregate is selected from the group consisting of: dead burned MgO; light burned MgO; burned dolomite; crushed magnesite carbon brick; fines of a bonded mixture containing MgO and carbon and fines of said mixture. 
   
   
       7 . The slag conditioner according to  claim 6  wherein said carbonaceous additive is selected from the group consisting of: coal; coke; petroleum coke; crushed magnesite carbon brick; ladle slag line brick, steel making furnace brick; fines of a bonded mixture containing MgO and carbon and fines of said mixture. 
   
   
       8 . The slag conditioner according to  claim 1  wherein said carbonaceous additive is selected from the group consisting of: coal; coke; petroleum coke; crushed magnesite carbon brick; ladle slag line brick, steel making furnace brick; and fines of said mixture. 
   
   
       9 . The slag conditioner according to  claim 1  wherein said burned aggregate comprises particle less than 8 mm of dead burned magnesite containing between 80% and 94% MgO. 
   
   
       10 . The slag conditioner according to  claim 1  wherein said burned aggregate comprise particles in a size range of 6×0 mm. 
   
   
       11 . The slag conditioner according to  claim 1  wherein said burned aggregate comprise particles 3×0 mm. 
   
   
       12 . The slag conditioner according to  claim 1  wherein said burned aggregate comprise particles 1×0 mm including fines. 
   
   
       13 . A method of making steel including the steps of:
 recovering particulate emissions containing oxides of iron, calcium, silicon, magnesium, zinc, lead and cadmium from a particulate containment system including bag house of a electric steel making furnace;   producing a slag conditioning by forming agglomerates comprised of a mixture of aggregates and 15% to 60% of said particulate emissions obtained by said step of recovering and 2% to 30% binder to agglomerate said mixture, said mixture comprising: by weight 15% to 80% dead burned magnesite comprised of particles less than 8 mm of which at least 30% is 0.2 mm or greater and containing between 35% and 94% MgO; up to 40% light burned magnesite; and 5% to 50% carbon selected from the group consisting of: coal; coke; graphite and petroleum coke and iron oxide;   introducing an iron bearing charge into said electric steel making furnace;   melting and refining an iron bearing charge in said electric furnace while forming an overlying layer of slag;   introducing said slag conditioner to said electric steelmaking furnace in an amount needed to raise the MgO level in said overlying layer of slag to between 5% to 14% and thereby impart a creamy slag texture, non leaching for soluble MgO, foam producing to increase slag volume, and protectively coat refractory sidewalls of said electric steelmaking furnace.   
   
   
       14 . The method of making steel according to  claim 13  wherein said step of introducing a slag conditioner includes introducing briquettes, produced by said step of forming, to said electric steel making furnace during said step of introducing an iron bearing charge. 
   
   
       15 . The method of making steel according to  claim 13  wherein said step of introducing a slag conditioner includes introducing briquettes produced by said step of forming to said electric steel making furnace during said step of melting and refining an iron bearing charge. 
   
   
       16 . The method of making steel according to  claim 13  including the step of crushing said agglomerates to form slag conditioner particulates for said step of introducing a slag conditioner, and wherein said step of introducing a slag conditioner includes injecting said slag conditioner particulates into said overlying layer of slag. 
   
   
       17 . The method of making steel according to  claim 13  wherein said particulates comprise between 10% and 30% . 
   
   
       18 . The method of making steel according to  claim 13  wherein said particulates comprise between 10% and 25%. 
   
   
       19 . The method of making steel according to  claim 13  wherein said particulates comprise particles in the range of 0.1 and 1000 microns. 
   
   
       20 . The method of making steel according to  claim 13  wherein said particulates include particulates of drop out boxes essentially including oxides of iron, calcium, silicon, magnesium, zinc, lead and cadmium.