Production of ferro-alloys

Abstract

A method for producing a ferro-alloy, such as steel, in an electric arc furnace or other suitable metallurgical furnace is disclosed. The method comprises supplying a mixture of (a) a carbon-containing polymer that is capable of acting as a slag foaming agent and (b) another source of carbon into the furnace during at least a part of a power-on phase of the method. A metallurgical furnace is also disclosed.

1 . A method for producing a ferro-alloy, such as steel, in an electric arc furnace or other suitable metallurgical furnace that comprises supplying a mixture of (a) a carbon-containing polymer that is capable of acting as a slag foaming agent and (b) another source of carbon into the furnace during at least a part of a power-on phase of the method. 
     
     
         2 .- 3 . (canceled) 
     
     
         4 . The method defined in  claim 1  wherein the carbon-containing polymer comprises any one or more of rubber (synthetic or natural) and other polymers such as polypropylene, polystyrene, polybutadiene styrene, and APS. 
     
     
         5 . The method defined in Claim  1  wherein the other source of carbon comprises any one or more of coke, carbon char, charcoal and graphite. 
     
     
         6 . The method defined in  claim 1  comprises assessing the time to commence supply of the mixture of the carbon-containing polymer and the other carbon source during the power-on phase or phases based on any one or more of the power consumption of the furnace, the composition of the melt in the furnace, and the melt temperature. 
     
     
         7 . The method defined in  claim 6  comprises varying the ratio of the carbon-containing source and the other carbon source in the mixture of these materials during the time period or periods of supply of the mixture to the furnace. 
     
     
         8 . The method defined in  claim 7  comprises maintaining the flowrate of the mixture of the carbon-containing source and the other carbon source constant during the time period or periods of supply of the mixture to the furnace. 
     
     
         9 . The method defined in  claim 7  comprises varying the flowrate of the mixture of the carbon-containing source and the other carbon source during the time period or periods of supply of the mixture to the furnace. 
     
     
         10 . The method defined in  claim 1  comprises maintaining a continuous supply of the mixture of the carbon-containing source and the other carbon source during the power-on phase or phases. 
     
     
         11 . The method defined in  claim 1  wherein the carbon-containing polymer comprises 20-60 wt. % of the total weight of the mixture. 
     
     
         12 . The method defined in  claim 11  wherein the carbon-containing polymer comprises 25-35 wt. % of the total weight of the mixture. 
     
     
         13 . The method defined in  claim 1  wherein the mixture of the carbon-containing source and the other carbon source supplied to the furnace during the first power-on phase is the same as the mixture supplied during the second power-on phase. 
     
     
         14 . The method defined in  claim 1  comprises injecting an oxygen-containing gas, such as oxygen, into the furnace during the power-on phase or phases. 
     
     
         15 . A metallurgical furnace such as an electric arc furnace that comprises a materials handling system for supplying a mixture of (i) a carbon-containing polymer that is capable of acting as a slag foaming agent and (ii) another source of carbon to the furnace during a method of producing a ferro-alloy in the furnace. 
     
     
         16 . The furnace defined in  claim 15  wherein the materials handling system comprises separate hoppers for storing the carbon-containing polymer and the other carbon source, a pipeline for transporting the carbon-containing polymer and the other carbon source to the furnace, and control valves for controlling the flow of each of the carbon-containing polymer and the other carbon source into the supply line so that the mixture of these materials forms in the pipeline and is transported to and supplied to the furnace. 
     
     
         17 . A method for producing a ferro-alloy, such as steel, in an electric arc furnace or other suitable metallurgical furnace that comprises supplying a mixture of (a) a carbon-containing polymer that is capable of acting as a slag foaming agent and (b) another source of carbon into the furnace during at least a part of a first power-on phase of the method and supplying a further mixture of the carbon-containing polymer and another source of carbon into the electric arc furnace during a second power-on phase of the method.) 
     
     
         18 . A method of producing a ferro-alloy in an electric arc furnace or other suitable metallurgical furnace which comprises:
 (a) supplying an initial charge of a feedstock for the ferro-alloy to the furnace;   (b) operating in a first power-on phase and establishing an arc between an electrode or electrodes of the furnace and the solid feedstock charge and generating heat in the furnace and melting the solid feedstock charge;   (c) after a first period of time into the first power-on phase, commencing supply of a mixture of (i) a carbon-containing polymer that is capable of acting as a slag foaming agent and (ii) an another source of carbon into the furnace;   (d) at the end of the first power-on phase, supplying a further charge of the ferro-alloy feedstock to the furnace;   (e) operating in a second power-on phase by re-establishing the arc;   (f) after a first period of time into the second power-on phase, commencing injection of a mixture of (i) a carbon-containing polymer that is capable of acting as a slag foaming agent and (ii) an another source of carbon into the furnace; and   (g) at the end of the second power-on phase, tapping molten ferro-alloy from the furnace.