Apparatus and method for discharging molten metal

Abstract

The invention provides apparatus and methods for discharging molten metal from a vessel based upon increasing the amount of molten metal moved into the vessel per unit time by a molten metal mover, such as a pump. This causes the level for at least part of the vessel to increase and so discharge through a discharge location. More reliable, safer to operate discharge of molten metal is provided as result.

1 . A method of discharging molten metal from a vessel to a further vessel, the method comprising 
 providing a vessel, the vessel having a discharge location;    providing a molten metal mover connected to the vessel by an inlet;    introducing molten metal to the vessel through the inlet using the molten metal mover;    the molten metal having an operating level in the vessel, the operating level being at or below the level of a discharge level;    increasing the amount of molten metal moved by the molten metal mover per unit of time, the increase in the amount of molten metal moved causing the molten metal to have a discharge level in the vessel, the discharge level being higher than the level of the discharge location and/or operating level around at least a part of the internal perimeter of the vessel;    molten metal discharging through the discharge location to the further vessel.    
   
   
       2 . A method according to  claim 1  in which the discharge level is higher around the full internal perimeter of the vessel.  
   
   
       3 . A method according to  claim 1  in which the vessel is used for one or more additional purposes to discharge, for instance to introduce material to the molten metal.  
   
   
       4 . A method according to  claim 1  in which the molten metal flows within the further vessel to a location within that vessel or to a still further vessel.  
   
   
       5 . A method according to  claim 1  in which the operating level is not consistent across the entire top surface and/or the width of the molten metals top surface.  
   
   
       6 . A method according to  claim 1  in which the surface at the operating level is highest around the internal perimeter of the vessel.  
   
   
       7 . A method according to  claim 1  in which the operating level is between 40% and 60% of the distance up the side wall from the internal base of the vessel particularly when the metal in the vessel has a level below the level of the discharge location for the majority of its operating time.  
   
   
       8 . A method according to  claim 1  in which the operating level is between 2% and 25% of the distance up the side wall from the internal base of the vessel, particularly when the metal in the vessel has a level above the level of the discharge location for the majority of its operating time, the increase in molten metal moved occurring at a time when the level of molten metal has dropped below the discharge level.  
   
   
       9 . A method according to  claim 8  in which the operating level is the level after a period of gravity drainage from the vessel.  
   
   
       10 . A method according to  claim 1  in which the amount of molten metal moved is increased by increasing the speed of the pump.  
   
   
       11 . A method according to  claim 1  in which the discharge level is higher than the operating level due to an increase in the total amount of metal within the vessel and/or due to the redistribution of metal within the vessel.  
   
   
       12 . A method according to  claim 1  in which amount of metal discharged through the discharge location is controlled by the time at which the metal moving means operates at the higher throughput.  
   
   
       13 . A method according to  claim 1  in which the amount of molten metal moved by the molten metal mover per unit of time is decreased to cease discharge and/or return the level in the vessel to a level lower than the discharge level.  
   
   
       14 . A method according to  claim 1  in which the operating level is a level at which gravity drainage stops or is diminished, a level monitor is used to trigger a transition from operating throughput to discharge throughput and the discharge throughput is used to restart or increase gravity drainage and/or to empty substantially all the remaining metal from the vessel and/or larger vessel.  
   
   
       15 . A method according to  claim 14  in which at a level, for instance the operating level or a lower level, a removeable stopper is introduced to seal the outlet from the vessel to prevent metal returning to the larger vessel and assists in maintaining a discharge level in the vessel.  
   
   
       16 . Apparatus for discharging molten metal from a vessel, the apparatus comprising 
 a vessel, the vessel having a discharge location;    a molten metal mover connected to the vessel by an inlet, the molten metal mover having a first throughput which provides molten metal at an operating level in the vessel and having a second, higher, throughput which provides molten metal moved at a discharge level, the discharge level being higher than the operating level around the full internal perimeter of the vessel and being higher than the discharge location.    
   
   
       17 . Apparatus according to  claim 16  in which the vessel is connected to a furnace.  
   
   
       18 . Apparatus according to  claim 16  in which a further vessel is permanently positioned or removably positioned relative to the discharge location.  
   
   
       19 . Apparatus according to  claim 16  in which the lower part of the internal shape of the vessel is a truncated cone, the outlet from the vessel is provided in the base of the vessel and a removable stopper is provided for the outlet.  
   
   
       20 . Apparatus according to  claim 16  in which the discharge location is provided at between 60% to 80% of the distance between the bottom and top of the vessel particularly when the metal in the vessel has a level below the level of the discharge location for the majority of its operating time.  
   
   
       21 . Apparatus according to  claim 16  in which the discharge location is provided between 5 and 25% of the distance between the internal bottom and top of the vessel particularly when the metal in the vessel has a level above the level of the discharge location for the majority of its operating time, the increase in molten metal moved occurring at a time when the level of molten metal has dropped below the discharge level.  
   
   
       22 . Apparatus according to  claim 16  in which the molten metal mover is a pump, particularly an electromagnetic pump.  
   
   
       23 . Apparatus according to  claim 16  in which the discharge level is at least 25 cm higher than the operating level at the same position.