Method and apparatus for preheating and feeding material

Abstract

A casting furnace for preheating and melting solid feed material includes a melting chamber with a melting hearth therein and a feed chamber in fluid communication with the melting chamber for conveying the solid material into the melting chamber. A heat source melts the feed material within the melting hearth and produces surplus heat used to preheat the solid feed material. Preferably, gas is heated by the heat source and moved into the feed chamber to preheat the feed material while it is conveyed toward the melting hearth. The heated gas is recycled back into the melting chamber to be re-heated therein and reused to preheat additional feed material in the feed chamber. Where the heat source in the melting chamber includes a plasma torch, the gas is recycled via the plasma torch, which ionizes the gas to create a plasma plume for melting the solid material.

1 . A method comprising the steps of: 
 preheating solid feed material by moving the solid feed material within a melting chamber in a first direction and moving heated gas within the melting chamber along the feed material in a second direction generally opposite the first direction;    moving the heated solid feed material into a melting cavity of a melting hearth disposed within the melting chamber; and    melting the solid material in the melting cavity of the melting hearth.    
   
   
       2 - 20 . (canceled)  
   
   
       21 . The method of  claim 1  further comprising the step of feeding solid feed material into the melting chamber through a feed entry port formed in a sidewall bounding the melting chamber; and wherein the step of preheating comprises the step of preheating solid feed material by moving the solid feed material in the first direction from the feed entry port toward the melting hearth and moving the heated gas in the second direction from adjacent the melting hearth to adjacent the feed entry port.  
   
   
       22 . The method of  claim 21  wherein the step of preheating comprises the step of preheating solid feed material by moving the solid feed material in the first direction from the feed entry port to the melting hearth atop a conveyor assembly disposed in the melting chamber and having a first end adjacent the feed entry port and a second opposed end adjacent the melting hearth.  
   
   
       23 . The method of  claim 22  wherein the step of preheating comprises the step of preheating solid feed material by moving the solid feed material atop an upper surface of the conveyor assembly onto an upper surface of the melting hearth adjacent the melting cavity and the upper surface of the conveyor assembly.  
   
   
       24 . The method of  claim 23  wherein the step of moving the heated solid feed material comprises the step of sliding the heated solid feed material along the upper surface of the melting hearth to move it into the melting hearth.  
   
   
       25 . The method of  claim 22  wherein the step of moving the solid feed material in the first direction comprises the step of moving the solid feed material in the first direction from the feed entry port to the melting hearth atop one of a conveyor belt assembly and a walking table disposed in the melting chamber.  
   
   
       26 . The method of  claim 22  further comprising the step of pushing solid feed material through the feed entry port onto the first end of the conveyor assembly.  
   
   
       27 . The method of  claim 26  wherein the step of pushing comprises the step of pushing solid feed material through the feed entry port on a platform extending from outside the chamber into the entry port and adjacent the first end of the conveyor assembly.  
   
   
       28 . The method of  claim 21  wherein the step of moving the heated gas comprises the step of moving the heated gas in the second direction from adjacent the melting hearth to a gas exit port formed in the sidewall adjacent the feed entry port; and further comprising the step of moving the gas out of the melting chamber through the gas exit port.  
   
   
       29 . The method of  claim 28  further comprising the step of recycling the gas which exited through the gas exit port back into the melting chamber adjacent the melting hearth and distal the feed entry port.  
   
   
       30 . The method of  claim 29  wherein the step of melting comprises the step of melting the feed material in the melting hearth with a first plasma torch positioned above the melting hearth distal the feed entry port; and wherein the step of recycling comprises the step of recycling the gas back into the melting chamber through the plasma torch.  
   
   
       31 . The method of  claim 28  further comprising the steps of pouring molten material from the melting hearth into a mold disposed in the melting chamber distal the feed entry port; and recycling the gas which exited through the gas exit port back into the melting chamber adjacent the mold.  
   
   
       32 . The method of  claim 31  further comprising the step of heating material in the mold with a plasma torch positioned above the mold distal the feed entry port; and wherein the step of recycling comprises the step of recycling the gas back into the melting chamber through the plasma torch.  
   
   
       33 . The method of  claim 1  wherein the step of moving the heated solid feed material comprises the step of sliding the heated solid feed material along an upper surface of the melting hearth adjacent the melting cavity to move it into the melting hearth.  
   
   
       34 . The method of  claim 33  wherein the step of preheating comprises the step of preheating solid feed material by moving the solid feed material with a conveyor assembly disposed in the melting chamber on an upper surface of the conveyor assembly which is adjacent the upper surface of the melting hearth; and 
 further comprising the step of transferring the preheated solid feed material from the upper surface of the conveyor assembly onto the upper surface of the melting hearth.    
   
   
       35 . The method of  claim 34  wherein the step of transferring comprises the step of contacting both upper surfaces simultaneously with a piece of the preheated solid feed material.  
   
   
       36 . The method of  claim 1  further comprising the step of pouring molten material from the melting hearth into a mold disposed in the melting chamber.  
   
   
       37 . The method of  claim 36  further comprising the step of pouring molten material from the melting hearth into a continuous casting mold disposed in the melting chamber.  
   
   
       38 . The method of  claim 36  further comprising the steps of forming a molded body with the mold; and removing the molded body from the melting chamber.  
   
   
       39 . The method of  claim 38  wherein the step of removing comprises the step of lowering the molded body from the melting chamber on a lift.  
   
   
       40 . The method of  claim 36  further comprising the steps of heating material in the mold with a plasma torch positioned above the mold; heating gas within the melting chamber with the plasma torch to produce heated gas used in the step of preheating.  
   
   
       41 . The method of  claim 40  further comprising the steps of recycling the gas back into the melting chamber via the plasma torch; and generating a plasma plume with the gas.  
   
   
       42 . The method of  claim 1  wherein the step of melting comprises the step of melting the feed material in the melting cavity with a first plasma torch positioned above the melting hearth; and further comprising the steps of pouring molten material from the melting hearth into a mold disposed in the melting chamber; heating material in the mold with a second plasma torch positioned above the mold; heating gas within the melting chamber with the first and second plasma torches to produce heated gas used in the step of preheating.  
   
   
       43 . The method of  claim 42  further comprising the steps of recycling the gas back into the melting chamber via the first and second plasma torches; and 
 generating a plasma plume in each torch with the gas.    
   
   
       44 . A method comprising the steps of: 
 preheating solid feed material by moving the solid feed material within a melting chamber from a feed entry port formed in a sidewall bounding the melting chamber toward a melting hearth disposed in the melting chamber and moving heated gas from adjacent the melting hearth out of the melting chamber through a gas exit port formed in the sidewall adjacent the feed entry port;    moving the preheated solid feed material into the melting hearth; and    melting the preheated solid feed material in the melting hearth.    
   
   
       45 . The method of  claim 44  wherein the step of preheating comprises the step of preheating by moving the solid feed material on a conveyor assembly in the melting chamber having a first end adjacent the feed entry port and a second opposed end adjacent the melting hearth and moving heated gas from the second end to the first end.  
   
   
       46 . The method of  claim 44  further comprising the step of pouring molten material from the melting hearth into a mold disposed in the melting chamber; and wherein the step of moving heated gas comprises the step of moving heated gas from adjacent the mold out of the melting chamber through the gas exit port.  
   
   
       47 . A method comprising the steps of: 
 preheating solid feed material within a melting chamber in which a melting hearth is disposed;    sliding the preheated solid feed material along an upper surface of the melting hearth adjacent a melting cavity thereof to move it into the melting cavity; and    melting the preheated solid feed material in the melting cavity.    
   
   
       48 . The method of  claim 47  wherein the step of preheating comprises the step of preheating solid feed material by moving the solid feed material with a conveyor assembly disposed in the melting chamber on an upper surface of the conveyor assembly which is adjacent the upper surface of the melting hearth; and further comprising the step of transferring the preheated solid feed material from the upper surface of the conveyor assembly onto the upper surface of the melting hearth.  
   
   
       49 . The method of  claim 48  wherein the step of transferring comprises the step of contacting both upper surfaces simultaneously with a piece of the preheated solid feed material.