Device and method for enhancing zinc yield from bottom dross

Abstract

A device for removing dross from the bottom of a molten metal bath comprises a perforated basket assembly for receiving said dross, pumping means for pumping said bottom dross and molten metal from the bottom of the molten metal bath into the perforated basket assembly when the perforated basket assembly is in a pumping position, lifting and/or rotating means for moving said perforated basket assembly from its pumping position out of said molten metal bath in a separation position and in a disposal position and separation means for separating said bottom dross from said molten metal, wherein the separation means comprise a paddle assembly capable of contacting said dross inside the perforated basket assembly with a cutting action in a first position followed by a cutting action in at least one adjacent second position, when the perforated basket assembly is in the separation position.

1 . A device for removing dross from the bottom of a molten metal bath, comprising 
 a perforated basket assembly for receiving said dross,    pumping means for pumping said bottom dross and molten metal from the bottom of the molten metal bath into the perforated basket assembly when the perforated basket assembly is in a pumping position,    lifting and/or rotating means for moving said perforated basket assembly from its pumping position out of said molten metal bath in a separation position and in a disposal position and    separation means for separating said bottom dross from said molten metal,    wherein    said separation means comprise a paddle assembly capable of contacting said dross inside the perforated basket assembly with a cutting action in a first position followed by a cutting action in at least one adjacent second position, when the perforated basket assembly is in the separation position.    
   
   
       2 . The device according to  claim 1 , wherein said lifting and/or rotating means for moving the perforated basket assembly comprise a rotary actuator.  
   
   
       3 . The device according to  claim 1 , further comprising an outer non-perforated bucket assembly in which the perforated basket assembly is located when in the pumping position.  
   
   
       4 . The device according to  claim 3 , further comprising lifting and/or rotating means for moving the outer non-perforated bucket assembly in a controlled dumping position above said molten metal bath.  
   
   
       5 . The device according to  claim 4 , wherein said lifting and/or rotating means for moving the outer non-perforated bucket assembly comprise a rotary actuator.  
   
   
       6 . The device according to  claim 3 , wherein said outer non-perforated bucket assembly and/or said perforated basket assembly comprise a stationary and a movable part, wherein the movement of the movable part relative to said respective stationary part effects the emptying of said assembly.  
   
   
       7 . The device according to  claim 6 , wherein the stationary part of said outer bucket assembly and/or perforated basket assembly further comprise a back wall to create a scraping action across the movable part during emptying of the assembly.  
   
   
       8 . The device according to  claim 1 , wherein the paddle assembly consists of a plurality of parallel paddles whose shape, size and number are adapted to fit into the perforated basket assembly when the perforated basket assembly is in the separation position.  
   
   
       9 . The device according to  claim 1 , wherein said disposal position is located outside said molten metal bath above a recycle bin.  
   
   
       10 . The device according to  claim 1 , further comprising a carriage assembly for the pumping means allowing to move the pumping means across the width and the length of the molten metal bath.  
   
   
       11 . The device according to  claim 1 , wherein said pumping means comprise a single stage centrifugal slurry pump with an inlet near the bottom of the molten bath, an outlet located above the perforated basket assembly at least when the latter is in the pumping position and a piping or hose assembly for connecting said pump to said outlet.  
   
   
       12 . The device according to  claim 1 , wherein the molten metal is zinc.  
   
   
       13 . A process for reducing the content of molten metal in a mixture of dross and molten metal comprising the steps of 
 a) providing a perforated basket assembly and a paddle assembly,    b) pouring said mixture of dross and molten metal in the perforated basket assembly,    c) coalescing the molten metal by contacting the paddle assembly with said mixture inside the perforated basket assembly so as to effect a cutting action in a first position followed by a cutting action in at least one adjacent second position and    d) allowing the coalesced molten metal to drain through the perforations in said perforated basket assembly.    
   
   
       14 . The process according to  claim 13 , wherein said mixture of dross and molten metal poured in the perforated basket assembly in step (b) is pumped from the bottom of a molten metal bath into the perforated basket assembly when said perforated basket assembly is in a pumping position.  
   
   
       15 . The process according to  claim 13 , wherein an outer non-perforated bucket assembly is provided in step (b) in which the perforated basket assembly is located when in a pumping position.  
   
   
       16 . The process according to  claim 14 , wherein said perforated basket assembly is lifted and/or rotated from said pumping position in a separation position prior to step (c).  
   
   
       17 . The process according to  claim 13 , further comprising the step of 
 e) disposal of the remaining dross in a recycle bin.    
   
   
       18 . The process according to  claim 13 , wherein the molten metal is zinc.  
   
   
       19 . The process according to  claim 13  using a device according to  claim 1.