Foundry bond and sand, apparatus and methods, with accumulator

Abstract

Apparatus and methods for preparing foundry sand mixes, using a pre-mix tank to pre-mix water and particulate bond material to make a water/bond slurry, then delivering the slurry into the foundry sand recovery stream. The slurry is mixed with return sand, and then discharged for use in making foundry molds. Delivery of the slurry to the sand stream can take the place of all particulate addition of bond to the sand stream. The slurry optionally is worked through a recycle stream, an accumulator tank, or both. A invention contemplates mixing, recycling, holding, and delivering the slurry to the sand system. The slurry can be delivered to multiple sand system entry loci at the mixer/mullor and/or the sand cooler. Slurry can be made up in batches or on a continuous basis. Slurry delivery can be batch, or continuous, with optional variability in rate of slurry delivery.

1 . Apparatus for use in preparing sand mixes in a sand system in a foundry, said apparatus comprising: 
 (a) a pre-mix tank adapted and configured to receive thereinto particulate bond material and a liquid carrier therefore, and to make and discharge a slurry of such bond material and such liquid carrier from said pre-mix tank;    (b) an accumulator tank adapted and configured to receive such slurry from said pre-mix tank, and to hold such slurry in condition ready for use in such foundry sand system;    (c) a first slurry discharge line connecting said pre-mix tank to said accumulator tank, said first slurry discharge line being adapted to receive such slurry from said pre-mix tank and to feed such slurry to said accumulator tank; and    (d) a second slurry discharge line connecting said accumulator tank to said foundry sand system and adapted to receive such slurry from said accumulator tank and to feed such slurry to such foundry sand system.    
   
   
       2 . Apparatus as in  claim 1 , further comprising a pre-mix tank discharge pump in said first slurry discharge line, and a recycle line connected to said first slurry discharge line downstream of said pre-mix tank discharge pump and connected to said pre-mix tank so as to convey a recycle stream back to said pre-mix tank.  
   
   
       3 . Apparatus as in  claim 1 , further comprising an accumulator tank discharge pump in said second slurry discharge line, and a recycle line connected to said second slurry discharge line downstream of said accumulator tank discharge pump and connected to said accumulator tank so as to convey a recycle stream back to said accumulator tank.  
   
   
       4 . Apparatus as in  claim 2 , further comprising a mixer in said foundry sand system, adapted to receive thereinto sand and such slurry, and to produce therefrom a foundry sand mix operable for making foundry sand molds, said first slurry discharge line being connected to said mixer, and feeding such slurry into said mixer.  
   
   
       5 . Apparatus as in  claim 3 , further comprising a mixer in said foundry sand system, adapted to receive thereinto sand and such slurry, and to produce therefrom a foundry sand mix which can be bonded together so as to be operable for making foundry sand molds, said second slurry discharge line being connected to said mixer, and feeding such slurry to said mixer at a feed port in said mixer.  
   
   
       6 . Apparatus as in  claim 1 , including water spray apparatus in said pre-mix tank, said water spray apparatus being designed, configured, and positioned to apply a disperse spray of water onto a stream of bond material particles traversing an open space in said pre-mix tank.  
   
   
       7 . Apparatus as in  claim 1 , including a pre-mix controller which controls quantities and timing of addition of carrier liquid and bond material to said pre-mix tank.  
   
   
       8 . Apparatus as in  claim 1 , including a control system which controls quantities and timing of addition of carrier liquid and bond material to said pre-mix tank, transfer of slurry to said accumulator tank, and transfer of slurry from said accumulator tank to such foundry sand system.  
   
   
       9 . Apparatus as in  claim 1 , including a bond material hopper, and a bond conveyor which conveys particulate bond material from said hopper to said pre-mix tank.  
   
   
       10 . Apparatus as in  claim 6 , including a water line feeding said water spray apparatus in said pre-mix tank, further comprising a water meter in said water feed line which meters desired quantities of water to said water spray apparatus.  
   
   
       11 . Apparatus as in  claim 1 , said pre-mix tank further comprising driven mixing apparatus adapted to mix such particulate bond material and such liquid carrier to thus form such slurry.  
   
   
       12 . Apparatus as in  claim 1 , further comprising a level sensor in said pre-mix tank, adapted to sense a top surface of such slurry in said pre-mix tank.  
   
   
       13 . Apparatus as in  claim 12 , said level sensor comprising a radar sensor.  
   
   
       14 . Apparatus as in  claim 1 , further comprising a level sensor in said accumulator tank, adapted to sense a top surface of such slurry in said accumulator tank.  
   
   
       15 . Apparatus as in  claim 14 , said level sensor comprising a radar sensor.  
   
   
       16 . Apparatus as in  claim 1 , said foundry sand system comprising a mixer, adapted to receive thereinto sand and such slurry, and to produce therefrom a foundry sand mix which can be bonded together so as to be operable for making foundry sand molds, said second slurry discharge line being connected to said mixer, and feeding such slurry to said mixer.  
   
   
       17 . Apparatus as in  claim 1 , said sand system comprising a sand cooler, said second slurry discharge line being connected to said sand cooler, and feeding such slurry to said sand cooler.  
   
   
       18 . Apparatus as in  claim 1 , said foundry sand system comprising a mixer, adapted to receive thereinto sand and such slurry, and to produce therefrom a foundry sand mix which can be bonded together so as to be operable for making foundry sand molds, said first slurry discharge line being connected to said mixer, through a by-pass line, and feeding such slurry to said mixer.  
   
   
       19 . Apparatus as in  claim 1 , said sand system comprising a sand cooler, said first slurry discharge line being connected to said sand cooler, through a by-pass line, and feeding such slurry to said sand cooler.  
   
   
       20 . A method of preparing a foundry sand mix, using return sand, a determined amount of fresh sand, a determined amount of fresh bond, and a determined amount of water, for use in a foundry sand system, the method comprising: 
 (a) pre-mixing fresh bond material in a pre-mix tank, with enough water to make a pumpable slurry of the bond material and water; and    (b) discharging the slurry from the pre-mix tank into a first discharge line capable of delivering the slurry to an accumulator tank adapted and configured to receive such slurry from said pre-mix tank, to hold such slurry in condition ready for use in such foundry sand system, and subsequently to discharge the slurry from the accumulator tank into a second discharge line, and thence to the foundry sand system, thereby adding at least a portion of the determined amounts of bond and water to the sand system.    
   
   
       21 . A method as in  claim 20 , further comprising recycling at least a portion of the slurry from the first discharge line, back into the pre-mix tank.  
   
   
       22 . A method as in  claim 20 , further comprising recycling at least a portion of the slurry from the second discharge line, back into the accumulator tank.  
   
   
       23 . A method as in  claim 20 , further comprising conveying the slurry from the discharge line into a by-pass line effective to by-pass the accumulator tank in delivering the slurry to the sand system.  
   
   
       24 . A method as in  claim 20 , further comprising monitoring the level of slurry in the pre-mix tank using a surface level sensor inside the pre-mix tank.  
   
   
       25 . A method as in  claim 20 , further comprising monitoring the level of slurry in the accumulator tank using a surface level sensor inside the accumulator tank.  
   
   
       26 . A method of satisfying a changed demand for fresh bond addition in a foundry sand system which typically operates on an ongoing basis with a generally stable baseline composition demand for fresh bond, the method comprising: 
 (a) using a control system to establish the baseline composition demand for draws of fresh bond to the foundry sand system;    (b) making a slurry in a pre-mix tank, capable of satisfying the baseline demand for fresh bond;    (c) transferring the slurry capable of satisfying the baseline demand for fresh bond to an accumulator tank and holding, in the accumulator tank, a quantity of the slurry capable of satisfying multiple routine draws of slurry to the sand system, as requested by the control system;    (d) discharging multiple draws of the slurry, in requested quantities, to the foundry sand system; and    (e) upon perceiving a need for a slurry composition which cannot be satisfied from the slurry in the accumulator tank, making up a supply of slurry in the pre-mix tank, corresponding to the requested slurry composition, and delivering the requested composition and amount of slurry to the foundry sand system through a by-pass line which by-passes the accumulator tank.    
   
   
       27 . A method as in  claim 26 , further comprising monitoring subsequent needs for slurry, and continuing to satisfy slurry requests through the by-pass line until a need can be satisfied with the base-line composition, and then satisfying the baseline composition need from the slurry which is being held in the accumulator tank.  
   
   
       28 . A method as in  claim 26 , further comprising at least periodically discharging slurry from the accumulator tank, passing such slurry through a pump, thereby continuing to work the slurry, and returning the slurry to the accumulatortank through a recycle line.  
   
   
       29 . A foundry sand mix, comprising sand, particulate bond material, and water, said foundry sand mix including a return sand fraction having a first set of material specifications and a fresh sand fraction having a second set of material specifications, the return sand fraction comprising return sand particles and return bond material particles, the fresh sand fraction comprising fresh sand particles and fresh bond material particles, 
 the combination of the return sand fraction and the fresh sand fraction, when mixed together in a process at a given ratio of fresh sand to return sand, in an environment wherein the fresh sand particles and the fresh bond particles, in combination, comprise no more than 5 percent by weight water when introduced to the mix process, and wherein the fraction of fresh bond material to fresh sand particles is a base quantity by weight, and wherein the fresh bond particles are added directly to a sand composition containing no more than 3 percent by weight water, having potential to develop a first level of green sand strength when used to make a sand mold for use in foundry operations,    said foundry sand mix, using a return sand fraction having substantially the first set of material specifications and a fresh sand fraction having substantially the second set of material specifications, having a capacity, when mixed together at the given ratio, to develop the first level of green sand strength with no more than 85 percent by weight of the base quantity of fresh bond material particles in the fresh sand fraction.    
   
   
       30 . A foundry sand mix as in  claim 29 , said sand mix having capacity to develop the first level of green sand strength with no more than 80 percent by weight of the base quantity of fresh bond material particles in the fresh sand fraction.  
   
   
       31 . A foundry sand mix as in  claim 29 , said sand mix having capacity to develop the first level of green sand strength with no more than 75 percent by weight of the base quantity of fresh bond material particles in the fresh sand fraction.  
   
   
       32 . A foundry sand mix as in  claim 29 , said sand mix having capacity to develop the first level of green sand strength with no more than 70 percent by weight of the base quantity of fresh bond material particles in the fresh sand fraction.