US 5,305,888 AGranted

Fruit/vegetable floatation grading

OwnerDonald M. Meylor, Patrick J. Finninventors

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Abstract

A floatation separation method is described for separating pieces of fruit or vegetable of the same type, but wherein desirable pieces have a slightly different specific gravity from the undesirable ones, and all have a specific gravity about the same as that of water. The pieces (12, FIG. 3 ) are placed near the surface of a body of water, and a cloud (40) of tiny air bubbles is maintained in the water. As the bubbles float to the surface they encounter the articles and slightly increase their buoyancy. The increase in buoyancy is slight and uniform, so those articles having a density slightly greater than that of the water will remain at the water surface, while those of a slightly greater density cannot be floated by the air bubbles and will sink to the bottom. The cloud of air bubbles is created by allowing air at about atmospheric pressure, to emerge from apertures in a rapidly spinning rotor that open in a direction primarily opposite to the spin direction.

Claims9

Dependent claims

A method for separating first and second groups of articles of fruit or vegetable, wherein almost all articles of said first group have a slightly lower density than the articles of said second group, comprising:

feeding the articles of said first and second group, wherein substantially every article of said groups has a volume of a plurality of cubic millimeters, to the surface of a pool of liquid having a specific gravity slightly less than some of said articles of said first group, and moving said articles along a path in said pool, so some of said placed articles of said first group and almost all of said placed articles of said second groups tend to sink in said liquid from a location near the surface of the liquid as said articles move along said path;
continually maintaining a cloud of gas bubbles of an average volume of less than one cubic millimeter in said body of liquid below substantially all of said path of articles in said pool, which includes bubbles that continually rise in substantially the entire surface region of said body which contains said articles, including creating new gas bubbles at a rate sufficient to float substantially all of said first articles including those having a slightly greater density than the density of said liquid in the absence of gas bubbles, but not said second articles;
the articles of said first and second group remaining on said path and being exposed to said cloud of gas bubbles for at least 30 seconds.

Dependencies are inferred from the claim text.