Classifying – separating – and assorting solids – Plural – diverse separating operations – Gaseous suspension and sifting
Reexamination Certificate
1999-04-07
2001-12-04
Nguyen, Tuan N. (Department: 3653)
Classifying, separating, and assorting solids
Plural, diverse separating operations
Gaseous suspension and sifting
C209S029000, C209S283000, C209S389000, C209S393000
Reexamination Certificate
active
06325215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved method and apparatus for separating non-fibrous particulates from fibers. More particularly, the present invention provides an improved method and apparatus for separating entrained and/or adherent elastomeric particulates, such as crumb rubber, from fibers such as nylon or polyester.
2. Description of the Prior Art
The disposal of discarded rubber vehicle tires, especially for cities, states and industries throughout the United States, has been a problem ever since transportation first began to use tires. Billions of discarded tires occupy landfills and stockpiles, which as they have grown, governmental and corporate bodies have worked to reduce. Some states charge disposal fees and/or sales surcharges of $1.00 to $2.00 per tire.
Indiscriminate discarding of rubber vehicle tires poses environmental and health problems. Waste tires provide breeding grounds for insects and rodents, and are not biodegradable. Further, their geometry being that of a noncompactable hollow toroid shape is voluminous and brings about the premature filling of dump sites.
The difficulty of discarding worn out rubber tires has led to investment in disposal technologies related to either volumetric reduction or material recycling. Recycling of rubber tires is difficult because of problems associated with their multi-component non-homogenous construction. A tire typically comprises rubber tread and sidewalls reinforced with enmeshed layers of steel wire and reinforcing fabric. Further, the rubber is usually vulcanized resulting in a toughness for the tire that contributes to its associated indestructibility.
The majority of the techniques used to recover recyclable components from waste tires requires initial physical processing, such as shredding or cryogenic pulverization, followed by further refining by some secondary process, such as converting the materials into a reusable form by chemical digestion, mechanical reclamation, destructive distillation, etc. In cryogenic crushing or pulverizing, liquid nitrogen is used to lower the temperature of the tire to about −300 degrees Fahrenheit. At such low temperatures, rubber hardens and is easily fractured into tiny granules or particulates, leaving steel wire and reinforcing fibers relatively unaffected. The steel wire is removed by electromagnetics and the reinforcing fibers are removed by sieving. The cost of cryogenic processing is relatively high, and typically suffers from inadequate recovery of rubber. The remaining rubber granules and fibers are usually disposed of in landfills.
In a related co-pending patent application Ser. No. 09/107,760, filed on Jun. 30, 1998 and entitled “A Method for Separating Elastomeric Particulates from Fiber”, a method is disclosed for separating non-fibrous particulates from fibers by contacting a pulverized mixture with a plurality of revolving mixture-engaging structures to cause the revolving mixture-engaging structures to engage the fibers and separate the fibers from the non-fibrous particulates. The produced non-fibrous particulates typically contain residual fibers which are removed in a reclaiming zone containing a saw cylinder, a doffing brush cylinder, and a cylinder with protruding rods. The method disclosed in patent application Ser. No. 09/107,760 has limited capabilities of recovering both non-fibrous particulates and fibers.
Therefore, what is needed and what has been invented is an improved method for separating and recovering a higher percentage of both non-fibrous particulates and fibers from a pulverized mixture without the deficiencies associated with the prior art in recovering recyclable components from waste tires. What is further needed and what has been invented is an improved, inexpensive and effective method for recovering rubber particulates from a pulverized tire mixture. What is also further needed and what has been invented is an improved method for separating particulate rubber (e.g., crumb rubber) from fibers (e.g., polyester or nylon fibers).
SUMMARY OF THE INVENTION
The present invention accomplishes its desired objects by broadly providing a method for separating non-fibrous particulates from fibers comprising:
(a) providing a pulverized mixture or composition comprising non-fibrous particulates (e.g., crumb rubber or the like) adhered and/or mixed with fibers (e.g., polyester or nylon fibers, or the like);
(b) introducing the pulverized composition into a first separation zone containing a plurality of revolving mixture-engaging structures so as to separate the fibers from the non-fibrous particulates and thereby produce a flowstream of partially cleaned non-fibrous particulates and a flowstream of residual fibers; and
(c) introducing the flowstream of partially cleaned non-fibrous particulates into a second separation zone containing at least two contiguous revolving cylinder assemblies comprising centrifugally releasable fiber-engaging structures to further separate the remaining fibers therefrom. The partially cleaned non-fibrous particulates produced in the first separation zone represent over about 90% by weight of the non-fibrous particulates from the pulverized mixture. The partially cleaned non-fibrous particulates produced in the second separation zone after the residual fibers have been separated therefrom by the fiber-engaging structures represent over about 95% by weight of the non-fibrous particulates from the pulverized mixture. Typically, at least some of the fibers are adhered to the non-fibrous particulates. “Centrifugally releasable fiber-engaging structures” broadly means, and not by way of any limitation, any structure that is capable of engaging any substance, mixture, component(s), or any of the like, and releasing, propelling, or impelling the same because of or due to centrifugal force caused by the revolving or rotating cylinder assemblies. As the cylinder assemblies rotate, a centrifugal force is outwardly exerted on any substance, mixture, component(s), or any of the like, from the center of rotation of the cylinder assemblies, and the “centrifugally releasable fiber-engaging structures” are possessed with a structure having a geometric shape or configuration that allows, or is capable of allowing, any substance, mixture, component(s), or any of the like, to be outwardly released, propelled, or impelled off of or from the “centrifugally releasable fiber-engaging structures”.
The immediate foregoing method preferably additionally comprises scrubbing the residual fibers in the second separation zone. At least one of the contiguous revolving cylinder assemblies comprises a wiping member. The centrifugally releasable fiber-engaging structures preferably comprise a plurality of generally identical fiber-engaging structures, such as a plurality of projections that may be spikes, rods or the like. Scrubbing of the residual fibers preferably comprises moving the residual fibers against a generally concave structure while the projections engage the residual fibers. The generally concave structure includes a plurality of openings, preferably having an average diameter ranging from about ⅛ inch to about ⅜ inch. In the alternative, the pulverized mixture, including the non-fibrous particulates and fibers, may also be scrubbed in the first separation zone by moving the same against a generally concave structure having grid rods spaced less than about ½ inch (e.g., from about ⅛ inch to about ⅜ inch) apart while the mixture-engaging structures engage the same. Over about 90% by weight of the non-fibrous particulates present in the original pulverized mixture are preferentially segregated into products containing <5% by weight residual fiber upon passage through the present invention. The concomitantly segregated fiber flowstreams are of sufficient quality as to represent saleable products.
The present invention also accomplishes its desired objects by broadly providing a method of separating non-fibrous particulates from fibers co
Fado John D.
Lipovsky Joseph A.
Nguyen Tuan N.
Silverstein M. Howard
The United States of America as represented by the Secretary of
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