Patent ID: 7597280

Claim:
An apparatus for separating the organic membrane portion of broken egg shells from the non-organic hard mineral portion of the broken egg shells in a continuous process, wherein said membrane portion has a specific gravity of less than 1.0 and said hard mineral portion has a specific gravity in the range of 2.7 to 3.0, comprising: receiving bin means for receiving and temporarily storing broken egg shells for separation of the membrane portions from the hard mineral portions thereof; a mixing hopper into which water and broken egg shells are introduced; grinding means into which water and broken egg shells from said mixing hopper are introduced, and in which the broken egg shells are ground to a fine particle size so as to form an egg shell slurry, and in which at least partial abrasion and separation of the membrane portion and the hard mineral portion of the broken egg shells is initiated; at least one vertically oriented separating tank into the top of which said egg shell slurry is introduced, and wherein separation of the membrane portion and a hard mineral portion of broken egg shells is effected; at least one protein dewatering means to which the separated membrane portion of egg shells is delivered from said at least one separating tank; protein drying means to which dewatered protein is delivered from said at least one protein dewatering means; mineral drying means to which the separated hard mineral portion of egg shells is delivered from said at least one separating tank; and water feedback means to return water from said at least one protein dewatering means to said at least one separating tank; wherein said at least one separating tank comprises: an output port placed in the side wall of said at least one separating tank, through which water and separated membrane portion of broken egg shells are withdrawn from the at least one separating tank for delivery to said protein dewatering and drying means; a plurality of overlapping vanes placed in the interior of said at least one separating tank in positions below said output port; and an input port near the bottom of said at least one separating tank into which water from said water feedback means is reintroduced into said at least one separating tank with sufficient force so as to cause an upwards, serpentine flow of said reintroduced water past said plurality of vanes; wherein said low specific gravity membrane portion will float or become entrained in the water in said at least one separating tank, and said high specific gravity hard mineral portion will settle to the bottom of said at least one separating tank; and wherein the force of said upward, serpentine flow of said reintroduced water past said vanes is not so great as to preclude the settling action of said high specific gravity hard mineral portion; whereby said membrane portion of broken egg shells and said hard mineral portion of broken egg shells are separated one from the other.