Method and apparatus for separating a protein membrane and shell material in waste egg shells

Abstract

A method and apparatus for separating the membrane portion of waste egg shells from the hard mineral portion thereof, so that each can be used or further processed as desired, thereby addressing the environmental and economic issues associated with disposing of waste egg shells. The membrane and shell are separated by first processing waste egg shells so as to yield small waste egg shell particles. During this processing, the waste egg shell particles are at least slightly abraded, whereby the linking structure between the membrane and shell is at least partially disrupted. Thereafter, the waste egg shell particles are conveyed to a tank containing, preferably, water, and allowed to settle therethrough. As the waste egg shell particles settle, the particles experience turbulent forces in the liquid which cause the membrane and shell portions to fully separate. Since the membrane particles are very light, they tend to remain entrained in the liquid, where they are, for example, siphoned off and dewatered. The “clean” egg shell particles settle to the bottom of the tank where they too are collected and/or dried.

What is claimed is:  
     
         1 . A separating apparatus for separating egg shells from a membrane attached thereto, the apparatus comprising: 
 a reducing device constructed and arranged to output the egg shells having the membrane attached thereto in a particulate form and to at least partially abrade the membrane from the egg shells;    a tank constructed and arranged to contain a liquid, said reducing device being constructed and arranged to output the egg shell particles having the membrane attached thereto into said tank, the egg shell particles having the membrane attached thereto separating into membrane particles and clean egg shell particles;    an agitator constructed and arranged to agitate clean egg shell particles and membrane particles settled on a bottom of said tank so as to entrain the membrane particles in the liquid;    a membrane recovery device communicating with said tank; and    a clean egg shell particle recovery device communicating with said tank.    
     
     
         2 . The apparatus according to    claim 1   , wherein said reducing device is constructed and arranged to yield egg shell particles sized between 0.5 and 4.0 mm with respect to the largest linear edge-to-edge dimension thereof.  
     
     
         3 . The apparatus according to    claim 1   , wherein said reducing device is constructed and arranged to yield egg shell particles sized less than 1.0 mm with respect to the largest linear edge-to-edge dimension thereof.  
     
     
         4 . The apparatus according to    claim 1   , wherein said agitator is a movable arm provided at the bottom of said tank.  
     
     
         5 . The apparatus according to    claim 4   , wherein said movable arm is a sweep arm constructed and arranged to rotatingly sweep over the bottom of said tank.  
     
     
         6 . The apparatus according to    claim 4   , wherein said movable arm is a sweep arm constructed and arranged to move linearly over the bottom of said tank in a direction perpendicular to said sweep arm.  
     
     
         7 . The apparatus according to    claim 1   , wherein said agitator comprises an aerator.  
     
     
         8 . The apparatus of    claim 1   , wherein said membrane recovery device comprises: 
 a membrane extractor constructed and arranged to extract the membrane from said tank;    a suction system for suctioning and conveying the content of said tank to said membrane extractor; and    a return communicating said membrane extractor and said tank.    
     
     
         9 . The apparatus of    claim 8   , wherein said membrane extractor comprises a screening device.  
     
     
         10 . The apparatus of    claim 9   , wherein said screening device includes at least two screens having different mesh sizes, respectively.  
     
     
         11 . The apparatus of    claim 9   , wherein said screening device comprises a mesh conveyor belt.  
     
     
         12 . The apparatus of    claim 8   , wherein said agitator is said return.  
     
     
         13 . The apparatus of    claim 1   , wherein said tank includes a clean egg shell particle transport mechanism for transporting the clean egg shell particles from said tank to said clean egg shell particle recovery device.  
     
     
         14 . The apparatus of    claim 13   , wherein said clean egg shell particle recovery device comprises a drying unit for drying the clean egg shell particles transported to said clean egg shell particle recovery device by said clean egg shell particle transport mechanism.  
     
     
         15 . The apparatus of    claim 14   , wherein said clean egg shell particle transport mechanism comprises an auger device disposed in an elongate groove at a bottom of said tank.  
     
     
         16 . The apparatus of    claim 8   , wherein said tank includes a clean egg shell particle transport mechanism for transporting the clean egg shell particles from said tank to said clean egg shell particle recovery device.  
     
     
         17 . The apparatus of    claim 16   , wherein said clean egg shell particle recovery device comprises a drying unit for drying the clean egg shell particles transported to said clean egg shell particle recovery device by said clean egg shell particle transport mechanism.  
     
     
         18 . The apparatus of    claim 17   , wherein said clean egg shell particle transport mechanism comprises an auger device disposed in an elongate groove at a bottom of said tank.  
     
     
         19 . A method for separating a membrane attached to egg shells comprising the steps of: 
 processing a size of egg shells so as to yield egg shell particles having the membrane attached thereto and at least partially abrading the membrane from the egg shell particles;    directing the egg shell particles having the at least partially abraded membrane attached thereto into a tank containing a liquid, whereby the egg shell particles having the membrane attached thereto is separated by turbulent forces in the liquid into membrane particles and clean egg shell particles free from the membrane, the membrane particles primarily remaining entrained in the liquid and the clean egg shell particles settling to the bottom of the tank;    agitating clean egg shell particles and any membrane particles settled on the bottom of the tank whereby the settled membrane particles are substantially entrained in the liquid;    collecting the membrane particles entrained in the liquid; and    collecting the clean egg shell particles.    
     
     
         20 . The method of    claim 19   , wherein said processing step yields egg shell particles having the membrane attached thereto sized between 0.3 mm and 4.0 mm with respect to the longest linear edge-to-edge dimension thereof.  
     
     
         21 . The method of    claim 20   , wherein said processing step yields egg shell particles having the membrane attached thereto sized less than 1.0 mm with respect to the longest linear edge-to-edge dimension thereof.  
     
     
         22 . The method of    claim 19   , wherein said agitating step comprises agitating the settled clean egg shell particles and membrane particles with a movable arm.  
     
     
         23 . The method of    claim 19   , wherein said agitating step comprises aerating the liquid.  
     
     
         24 . The method of    claim 19   , wherein said step of collecting the membrane comprises passing the liquid in which the membrane is entrained through a screen and returning the resultant clean liquid to the tank.  
     
     
         25 . The method of    claim 24   , wherein said agitating step comprises said step of returning the resultant clean liquid to the tank.  
     
     
         26 . The method of    claim 19   , wherein the liquid comprises water.  
     
     
         27 . The method of    claim 19   , wherein the liquid is water.