Apparatus and method for density separation of plastics
AssigneeHitachi, Ltd.
InventorsMasakatsu Hayashi, Yoshiyuki Takamura, Tsutomu Hasegawa, Hideharu Mori, Tatsuji Katoh
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Abstract
An apparatus for sorting plastic pieces by specific gravity sorting includes a vessel containing water and having an inlet for plastic pieces to be sorted, a device for introducing plastic pieces to be sorted into the vessel through the inlet, a device for removing air bubbles from the plastic pieces within the water, and a device for moving the plastic pieces within the water in the vessel to allow the various plastic pieces to be sorted within the water due to the different specific gravities of the plastic pieces. A method of sorting plastic pieces by specific gravity sorting with the apparatus is also described.
Claims7
An apparatus for sorting plastic pieces by specific gravity sorting, said plastic pieces having sizes suited to the specific gravity sorting and comprising those of at least first, second and third kinds, said first kind of plastic pieces having a specific gravity smaller than that of water, said second kind of plastic pieces having a specific gravity greater than that of water, said third kind of plastic pieces having a specific gravity greater than that of water but smaller than the specific gravity of said second kind of plastic pieces, said apparatus including:
- a vessel containing an amount of water and having an inlet for plastic pieces to be sorted;
- means for introducing plastic pieces to be sorted into said vessel through said inlet;
- air-bubble removing means positioned within the water contained in said vessel for removing air bubbles from the plastic pieces introduced into said vessel;
- and
- means for moving said plastic pieces with said water in said vessel to allow said second kind of plastic pieces to sink in said water at a first stage portion of said vessel and allow said third kind of plastic pieces to sink in said water at a second stage portion of said vessel downstream of said first stage portion, said first kind of said plastic pieces floating on the surface of said water and being moved by the movement of said water to a third stage portion of said vessel downstream of said second stage portion.
A method of sorting plastic pieces by specific gravity sorting, said plastic pieces having sizes suited to the specific gravity sorting and comprising those of at least first, second and third kinds, said first kind of plastic pieces having a specific gravity smaller than that of water, said second kind of plastic pieces having a specific gravity greater than that of water, said third kind of plastic pieces having a specific gravity greater than that of water but smaller than the specific gravity of said second kind of plastic pieces, said method including the steps of:
- preparing a vessel containing an amount of water and having an inlet for plastic pieces to be sorted;
- introducing plastic pieces to be sorted into said vessel through said inlet;
- removing air bubbles from the plastic pieces introduced into the vessel;
- and
- moving said plastic pieces with said water in said vessel to allow said second kind of plastic pieces to sink in said water at a first stage portion of said vessel and allow said third kind of plastic pieces to sink in said water at a second stage portion of said vessel downstream of said first stage portion, said first kind of said plastic pieces floating on the surface of said water and being moved by the movement of said water to a third stage portion of said vessel downstream of said second stage portion.
Dependencies are inferred from the claim text.