Method of producing cast iron

Abstract

A method of producing a silicon-and-carbon-enriched cast iron melt. The method can include melting an initial cupola charge in a cupola, conducting the molten metal to a mixing vessel, increasing the silicon and carbon content of the molten metal by a substantially continuous addition of granular silicon carbide having a purity of greater than 94% and a size of less than ⅜″ to the mixing vessel while simultaneously agitating the molten metal to an extent sufficient to bring the silicon carbide into solution with the molten metal, and conducting the silicon-and-carbon-enriched molten metal away from the mixing vessel.

What is claimed is:  
     
         1 . A method of producing a silicon-and-carbon-enriched cast iron melt, the method comprising: 
 melting an initial cupola charge in a cupola to produce a molten metal; and    increasing the silicon and carbon content of the molten metal by a substantially continuous addition of granular silicon carbide having a purity of greater than 94% and a size of less than ⅜″ to the molten metal.    
     
     
         2 . The method of  claim 1 , wherein the addition of granular silicon carbide increases the silicon content of the melt by an amount between about 0.50-2.50 percent by weight.  
     
     
         3 . The method of  claim 1 , wherein the granular silicon carbide has a purity of approximately 97%.  
     
     
         4 . The method of  claim 1 , wherein the granular silicon carbide has a size of 10-100 mesh.  
     
     
         5 . The method of  claim 1 , further comprising providing a mixing vessel, wherein the molten metal is sent from the cupola to the mixing vessel and wherein the silicon carbide is added to the mixing vessel while simultaneously agitating the molten metal to an extent sufficient to bring the silicon carbide into solution with the molten metal.  
     
     
         6 . The method of  claim 5 , wherein agitating the melt includes providing vibratory means.  
     
     
         7 . The method of  claim 6 , wherein providing vibratory means includes providing acoustic vibratory means.  
     
     
         8 . The method of  claim 5 , wherein agitating the melt includes providing electric stirring.  
     
     
         9 . The method of  claim 5 , wherein agitating the melt includes introducing gas under pressure through multiple porous plugs located in the bottom of the mixing vessel.  
     
     
         10 . The method of  claim 1 , wherein the granular silicon carbide has a purity of greater than 95%.  
     
     
         11 . The method of  claim 1 , wherein the granular silicon carbide has a purity of greater than 97%.  
     
     
         12 . The method of  claim 1 , wherein the granular silicon carbide has a size of 10-100 mesh.  
     
     
         13 . The method of  claim 1 , wherein the granular silicon carbide has a size of 6 mesh and smaller.  
     
     
         14 . The method of  claim 1 , wherein the granular silicon carbide has a size of 8 mesh by 50 mesh.  
     
     
         15 . A method of producing a silicon-and-carbon-enriched cast iron melt, the method comprising: 
 melting an initial cupola charge in a cupola;    conducting the molten metal to a mixing vessel;    increasing the silicon and carbon content of the molten metal by a substantially continuous addition of granular silicon carbide to the mixing vessel, the granular silicon carbide added sufficiently to increase the silicon and carbon content of the molten metal by at least  1 . 0 % by weight when having a retention time of 1.5 minutes within the mixing vessel; and    conducting the silicon-and-carbon-enriched molten metal away from the mixing vessel.    
     
     
         16 . A method of producing a silicon-and-carbon-enriched cast iron melt, the method comprising: 
 melting an initial cupola charge in a cupola;    conducting the molten metal to a mixing vessel;    increasing the silicon and carbon content of the molten metal by a substantially continuous addition of granular silicon carbide to the mixing vessel while agitating the molten metal using a vibratory mechanism to an extent sufficient to bring the silicon carbide into solution with the molten metal; and    conducting the silicon-and-carbon-enriched molten metal away from the mixing vessel.    
     
     
         17 . The method of  claim 16 , wherein the vibratory mechanism includes a mechanical vibratory mechanism.  
     
     
         18 . The method of  claim 16 , wherein the vibratory mechanism includes an acoustic vibratory mechanism.  
     
     
         19 . The method of  claim 16 , wherein the vibratory mechanism includes an electrical vibratory mechanism.  
     
     
         20 . A method of producing a silicon-and-carbon-enriched cast iron melt, the method comprising: 
 melting an initial cupola charge in a cupola;    introducing a granular silicon carbide at a substantially continuous rate to the cupola proximate a melt zone of the cupola; and    conducting the silicon-and-carbon-enriched molten metal away from the mixing vessel.    
     
     
         21 . The method of  claim 20 , wherein the silicon carbide is introduced through a tuyere of the cupola.  
     
     
         22 . The method of  claim 20 , wherein the silicon carbide has a purity of greater than 95%.  
     
     
         23 . The method of  claim 20 , wherein the silicon carbide has a purity of greater than 94% and a size of less than ⅜″.  
     
     
         24 . The method of  claim 20 , wherein the silicon carbide is introduced to a lower portion of the melt zone.  
     
     
         25 . A system comprising: 
 a cupola having one or more tuyeres;    a granular silicon carbide delivery system communication with at least one tuyere to deliver granular silicon carbide into the cupola through the tuyere.    
     
     
         26 . The system of  claim 25 , wherein the delivery system is a pneumatic system.