Classifying – separating – and assorting solids – Electrostatic – Attracting
Reexamination Certificate
2000-05-16
2004-01-20
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Electrostatic
Attracting
Reexamination Certificate
active
06680451
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention pertains to a particle separation method and apparatus.
More particularly, the invention relates to an apparatus and method for separating dielectric particles.
In a further respect, the invention relates to a particle separation apparatus and method which reduce the risk that a fire or explosion will occur during the separation of particulate.
In another respect, the invention relates to a particle separation apparatus and method which facilitates the separation of elongate fiber strands from a plurality of small substantially round particles.
2. Description of the Related Art including information disclosed under 37 C.F.R. 1.97 and 1.98.
A wide variety of particle separation apparatus is apparently known in the art. One such particle separation apparatus is illustrated in FIG.
1
and includes a cylindrical steel roller
10
which rotates in the direction of arrow E about axle
42
. A hopper
11
feeds a mixture of electrically non-conductive
12
and electrically conductive particles
13
onto the cylindrical outer surface or roller
10
. The size of the particles is greatly exaggerated for purposes of clarity. The positive side of the power supply is connected to the roller
10
. The roller
10
is grounded. An elongate wire
14
is spaced apart from and parallel to the cylindrical surface of roller
10
. The wire
14
serves as the negative electrode. A large voltage is directed through wire
14
to produce a corona around the wire. Negative ions move through the field produced by the wire to roller
10
. The conductive particles
13
conduct negative ions to roller
10
. Consequently, the conductive particles
13
fall off the surface or roller
10
or are thrown off roller
10
into bin
16
. In contrast to the conductive particles
13
, negative ions are believed to accumulate on the outer surface of each non-conductive particle
12
to cause each particle
12
to be attracted to the positively charged roller
10
. The negatively charged non-conductive particles are scrapped off by scraper
43
into bin
15
. Several disadvantages are associated with the apparatus of FIG.
1
. First, the high voltage required to form a corona around wire
14
increases the risk of explosion or fire during the separation of particulate. Seconded, while the apparatus of
FIG. 1
is well suited for the separation of conductive and non-conductive particles, it ordinarily is not believed well suited for separation of two types of conductive particles (for instance copper and silver particles) or for separation of two types of non-conductive particles (for instance rubber and paper particles).
Accordingly, it would be highly desirable to provide an improved particle separation apparatus and method which would significantly minimize the risk of fire or explosion and which could be utilized to separate dielectric particulate.
Therefore, it is a principal object of the invention to provide an improved method and apparatus for separating particles.
A further object of the invention is to provide an improved method and apparatus for separating dielectric particles.
Another object of the invention is to provide an improved particle separation method and apparatus which minimizes the utilization of energy at levels which increase the risk of fire.
Still a further object of the invention is to provide an improved particle separation method and apparatus which can distinguish between particles of differing size and tribolelectric propensity.
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patent: 2187637 (1940-01-01), Sutton et al.
patent: 2328577 (1943-09-01), Oglesby
patent: 2889042 (1959-06-01), Baron
patent: 4174030 (1979-11-01), Philibert
patent: 4247390 (1981-01-01), Knoll
patent: 4282303 (1981-08-01), Bergen
patent: 4289837 (1981-09-01), Gundlach
patent: 5735402 (1998-04-01), Pezzoli et al.
patent: 6467628 (2002-10-01), Maehata et al.
patent: 1297913 (1987-03-01), None
patent: 1472128 (1989-04-01), None
Nissle P.C. Tod R.
Schlak Daniel
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