Method and apparatus for melting metal in a shaft furnace

Abstract

A system wherein oxygen is provided to a shaft furnace in addition to the blast air, and a flame shroud is formed around the oxygen stream enabling deep penetration of the oxygen into the furnace for not only combusting carbonaceous material for generating heat but also for cutting and oxidizing metal within the furnace.

1 . A method for melting metal in a shaft furnace comprising: 
 (A) passing blast air into a shaft furnace containing a charge comprising metal, carbonaceous material, and flux material;    (B) providing a stream of oxygen from a lance, and surrounding the stream of oxygen with combusting fuel and oxidant forming a flame shroud around the stream of oxygen;    (C) passing the stream of oxygen into the shaft furnace; and    (D) combusting carbonaceous material and cutting and oxidizing metal with the stream of oxygen within the shaft furnace and generating heat for melting metal within the shaft furnace.    
     
     
         2 . The method of  claim 1  wherein the stream of oxygen is passed into the cupola furnace with the blast air.  
     
     
         3 . The method of  claim 1  wherein the stream of oxygen has a supersonic velocity.  
     
     
         4 . The method of  claim 1  wherein the carbonaceous material comprises coke.  
     
     
         5 . A shaft furnace for melting metal comprising a refractory lined furnace wall, a blast air tuyere positioned in the furnace wall for passing blast air into the cupola furnace, and an oxygen lance positioned within the blast air tuyere, said oxygen lance having a tip which is recessed from the end of the blast air tuyere, having means for passing oxygen in an oxygen stream out from the lance at the tip, and having means for providing fuel and oxidant out from the lance to form a flame shroud around the oxygen stream.  
     
     
         6 . The shaft furnace of  claim 5  wherein the means for passing oxygen from the lance includes a central passage which communicates with an opening at the lance tip.  
     
     
         7 . The shaft furnace of  claim 6  further comprising a converging/diverging nozzle positioned in the central passage.  
     
     
         8 . The shaft furnace of  claim 5  wherein the means for providing fuel out from the lance includes an inner ring of holes at the lance tip and the means for providing oxidant out from the lance includes an outer ring of holes at the lance tip.  
     
     
         9 . The shaft furnace of  claim 5  wherein the oxygen lance tip is recessed from 2 to 6 inches from the end of the blast air tuyere.  
     
     
         10 . The shaft furnace of  claim 5  having a plurality of blast air tuyeres with at least two of said tuyeres having an oxygen lance positioned therein, said oxygen lance having a tip which is recessed from the end of the blast air tuyere, having means for passing oxygen in an oxygen stream out from the lance at the tip, and having means for providing fuel and oxidant out from the lance to form a flame shroud around the oxygen stream.