Two-chamber furnace for the melt- contact smelting of contaminated aluminum scrap

Abstract

A two-chamber furnace for smelting scrap aluminum which is contaminated, has a distillation chamber above the first furnace chamber functioning as a charging stack and separated from the first chamber by a slider or flap arrangement. Flue gas from the first chamber is forced through the distillation chamber to destructively distill off the contaminants. The hood of the distillation chamber is equipped with a pressing body to compact the charge.

I claim:  
     
         1 . A furnace for the smelting of contaminated aluminum scrap, comprising: 
 a first furnace chamber adapted to receive a contaminated aluminum scrap for contacting said contaminated aluminum scrap with an aluminum melt, thereby dissolving aluminum from said scrap in said melt;    a second chamber connected to said first chamber for receiving said aluminum melt;    gas-fired burners in said chamber for heating same while producing flue gases in said chambers;    a flue-gas recirculation system connected to as least one of said chambers for withdrawing flue gas therefrom and recirculating withdrawn flue gas to the furnace;    a destructive-distillation chamber receiving a charge of said contaminated scrap for decontaminating said charge and connectable to said first chamber; and    means connected with said flue-gas recirculation system for forcing hot flue gas through said destructive-distillation chamber to destroy contaminants on said charge.    
     
     
         2 . The furnace defined in    claim 1    wherein said means connected with said flue gas recirculation system comprises at least one inlet into said destructive-distillation chamber for hot flue gas and at least one outlet opposite said inlet for discharging said hot flue gas.  
     
     
         3 . The furnace defined in    claim 2    wherein said destructive-distillation chamber is formed as a filling shaft for said first furnace chamber and is separated from said first furnace chamber by a closure element.  
     
     
         4 . The furnace defined in    claim 3    wherein said shaft is generally upright and said closure element is comprised of a pair of bottom flaps or a slider which opens over the entire cross section of said destructive-distortion chamber.  
     
     
         5 . The furnace defined in    claim 4    wherein said destructive-distillation chamber has a rectangular cross section, said furnace further comprising a pressing body displaceable with play in said destructive-distillation chamber and adapted to compact a charge therein.  
     
     
         6 . The furnace defined in    claim 5   , further comprising a hood adapted to cover said destructive-distillation chamber and removable therefrom to enable filling of said charge into said destructive-distillation chamber, said hood being provided with a guide for said pressing body.  
     
     
         7 . The furnace defined in    claim 6    wherein each of said furnace chambers comprises a respective gas burner system, each of said gas burner systems having an O 2  sensor for controlling conbustion in the respective chamber to maintain a constant air excess therein.  
     
     
         8 . The furnace defined in    claim 7    wherein the gas burner system of said first furnace chamber maintains a flue gas temperature of substantially 600° C. therein and the gas pressing system of said second chamber maintains a flue gas temperature of about 1000° C. therein.  
     
     
         9 . The furnace defined in    claim 8   , further comprising means for controlling inensity of distortion gas formation in the destructive-distillation chamber by controlling temperature and velocity of flue gas through said destructive-distillation chamber.  
     
     
         10 . The furnace defined in    claim 9   , further comprising means for controlling fuel gas flow to said burner system in inverse proportion to generation of distillation gases in said dstructive-distillation chamber.  
     
     
         11 . The furnace defined in    claim 10   , further comprising a flue gas outlet in said second chamber connected with a combustion air preheater.  
     
     
         12 . The furnace defined in    claim 11   , further comprising a flue gas passage connecting said first and second chambers.  
     
     
         13 . The furnace defined in    claim 12    wherein said first chamber is provided with an elevated smelting platform above a level of melt in said first and second chambers when said level of said melt in said first and second chambers is equal.  
     
     
         14 . The furnace defined in    claim 12   , further comprising a melt pump for pumping molten metal from said second chamber into said first chamber and a throttled return passage connecting said first chamber to said second chamber, said pump having at least two speed settings.  
     
     
         15 . The furnace defined in    claim 14   , further comprising a level measuring device for establishing a maximum liquid level in said first chamber.