Method for refining non-ferrous metal

Abstract

A method for refining non-ferrous metal wherein a stream of oxygen containing gas is provided from a lance into the headspace of a refining vessel for passage to the molten metal bath within the refining vessel, and a flame envelope is provided around and along the oxygen containing gas stream for a portion of its length, wherein the flame envelope simultaneously serves to keep accretions from forming on the lance face and serves to maintain the oxygen-containing gas stream coherent.

1 . A method for refining non-ferrous metal comprising: 
 (A) providing a refining vessel containing a bath of non-ferrous metal and having a headspace above the bath of non-ferrous metal;    (B) passing a stream of oxygen containing gas from a lance at a velocity of not more than 3 Mach into the headspace, and passing the oxygen containing gas stream through the headspace from the lance to the non-ferrous metal bath;    (C) providing a flame envelope around the oxygen containing gas stream for a portion of the distance from the lance to the bath; and    (D) reacting oxygen from the oxygen containing gas stream with material in the bath to oxidize said material.    
     
     
         2 . The method of  claim 1  wherein the non-ferrous metal comprises copper.  
     
     
         3 . The method of  claim 1  wherein the non-ferrous metal comprises nickel.  
     
     
         4 . The method of  claim 1  wherein the material in the bath comprises sulfur and the oxygen oxidizes the sulfur to form sulfur dioxide.  
     
     
         5 . The method of  claim 1  wherein the stream of oxygen containing gas is passed from the lance at a velocity within the range of from 0.835 to 1.13 Mach into the headspace.  
     
     
         6 . The method of  claim 1  wherein the flame envelope is formed by passing fuel and oxidant into the headspace from the lance around the oxygen containing gas stream and combusting the fuel and oxidant.  
     
     
         7 . The method of  claim 1  further comprising agitating the bath by injecting a mixing gas into the non-ferrous metal bath from below the surface of the bath, and bubbling said mixing gas up through the non-ferrous metal bath.  
     
     
         8 . The method of  claim 7  wherein said mixing gas comprises one or more of nitrogen, oxygen, argon and steam.  
     
     
         9 . The method of  claim 7  further comprising forming a well agitated region of the non-ferrous metal bath above the area where the mixing gas passes up through the non-ferrous metal bath.  
     
     
         10 . The method of  claim 9  wherein the oxygen containing gas stream impacts the well agitated region of the bath.