Classifying – separating – and assorting solids – Stratifiers – With liquid treatment
Reexamination Certificate
2000-02-01
2002-04-30
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Stratifiers
With liquid treatment
C209S451000, C209S481000, C209S482000, C209S500000
Reexamination Certificate
active
06378704
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates generally to a system for the separation of lower density debris from higher density debris, and more particularly to such a system, method and apparatus which is particularly adapted to separate construction debris where the low density fraction in general has a density lower than the density of water, and the high density fraction has a density substantially greater than water. More particularly, this would be particularly adapted for use where a large percentage of the low density fraction comprises wood, and also a large portion of the high density fraction comprises rock, cement, metal and other materials commonly found in building structure or other structures.
b) Background Art
It is common practice that when a building structure is being demolished, the debris is simply gathered somewhat indiscriminately into piles and then carried to the dumpsite. Particularly in more recent years, it has been found to be more economical to simply use bulldozers, back hoes, demolition balls, explosives, etc. Depending upon the building or other structure being demolished, there may be a very high percentage of wood or other low density material, or a relatively small amount of the same.
One of the challenges regarding disposal of construction debris is how to recycle or process this material so that it could be used for some useful purpose, instead of just being accumulated in the dumpsite as waste material. Such debris, if properly sorted and/or processed, could be used for land fill, or road beds and this may be accomplished by crushing the rock or rock like material into smaller particles. However, organic material such as wood, is not desirable for a land fill. First, the organic material would decay over time and thus have its load bearing capability degraded. Second, quite often wood pieces come in sections of a two by four, etc., and when placed in a land fill these could protrude upwardly from the surface, etc.
With regard to the wood component of the construction debris, if properly separated, this could be recycled into a variety of useful products, such as ground cover, fuel, etc.
The practical problems in the existing separating processes are often too expensive relative to the economic return that might be realized by productive use of the separated and/or processed materials. The sheer mass and volume of construction debris generally makes manual separation uneconomical. Attempted separation by machinery, (e.g. back hoes and/or bull dozers) involves not only the expense of operating the machinery, but the separation process itself is difficult to be accomplished effectively.
It has been known for many decades, if not centuries, that the separation of material in accordance with its density could be achieved by flotation techniques, where the liquid medium has a specific gravity between that of the two fractions which are to be separated (i.e. where one of the fractions to be separated has a density greater than the liquid medium and the other density less than this liquid medium). Such flotation techniques have been employed in a wide variety of commercial applications.
Accordingly, it is understandable that there have been attempts to use flotation techniques to separate the low density fraction (which would generally comprise in large part wood and possibly other material having a specific gravity less than water) and the high density fraction (comprising stone, concrete, metal pieces, etc.). To the best knowledge of the applicant, the efforts to effectively accomplish such separation by flotation have only marginal success. One method is to provide an upwardly open tank which is filled with water. The construction debris is deposited into the tank, and two back hoes are operated to remove the separated fractions. One back hoe is used to skim the top of the water to remove the wood particles, while the other back hoe is used to remove the denser particles which fall to the bottom of the tank.
Another method and apparatus is disclosed in two U.S. patents (U.S. Pat. Nos. 5,240,114 and 5,110,454). In both of these patents, there is shown a system where a mixture of rock, soil particles and wood is introduced into a water tank. Near the upper water level, a plurality of jet nozzles direct streams of water through the mixture to remove the lower density particles so that these flow toward a slanted baffle
66
, thence over the baffle into an area where some of the wood particles float, and some descend downwardly onto a wood piece conveyor
150
. This conveyor removes the wood pieces from the water. The rocks from the mixture drop down onto a rock receiving portion
82
where there is a rock conveyor that removes these from the water tank.
A search of the patent literature has disclosed a number of other patents which relate generally to flotation/separation techniques for variety of industrial environements. These are described below.
U.S. Pat. No. 5,373,946 (Olivier) discloses a separating apparatus which utilizes what is termed a “scrolled” barrel. It is pointed out that these are classified as mono- or bi-directional. In the mono-directional barrels both of the floats and sinks move in the same direction and exit in the same end of the barrel. The bi-direction barrels have the floats and sinks move in opposite directions. It is pointed out that in the bi-directional barrel the raw feed is introduced near the place where the sinks are evacuated and the only practical way of evacuating the sinks is by means of a scrolled cone. However, there is a very annoying problem which the patent points out as up to the time of this patent never been solved in a satisfactory way, namely, how to prevent a small percentage of the floats from working their way toward the sink side of the barrel and eventually reporting with the sinks being screwed up to the sinks evacuation cone. This is solved by having the discharge end of the rotating drum formed having a fursto-conical configuration, and the larger diameter input end has a diameter greater than that of the main central barrel. Also, there is a barrier positioned at the front side of the main central portion to prevent the floats from proceeding toward the high density end. Further, the high density discharge portion has its large diameter end of a diameter greater than that of the central portion.
U.S. Pat. No. 5,169,005 (Beane) shows a separator in which material passes into a chamber that is provided with paddle drum
20
. The material enters through chute
32
, and the lighter material is impelled across the surface of the fluid by additional fluid supplied under pressure through nozzle
16
. The lighter material passes out through chute
40
. The paddles drum
20
, brings up the heavy material that exits through
78
.
U.S. Pat. No. 5,104,047 (Simmons) shows a waste treating system in which material entered through hopper
36
, and the floating material is driven into a chopping or milling means
34
, by fluid injected through jets
62
. The heavier accumulates on the bottom and is removed by conveyor
70
.
U.S. Pat. No. 4,944,869 (Lyakov et al.) shows a system in which a mix of crushed storage battery material is separated into constituent material by a series of flotation units as shown on sheet
5
. The separator unites are formed of rotating flotation unites in which the lighter weight materials pass through, and the heavier materials separate out as them material moves through the system.
U.S. Pat. No. 3,392,828 (Muller) shows a separator in which a mix of materials enters the system via
2
, and pass into a fluid fill chamber. There is a rotating mesh drum with vanes
12
, operating in the fluid body. The drum is slanted relative the surface of the fluid so that at the input end the fluid is below the entrance, but at the output end the fluid flow out. Small heavy, particles
7
fall through the mesh, while large heavy bodies
9
, are lifted by the vanes so as to drop on chute
10
, and roll out of the separator. The light material which fl
Hughes Robert B.
Hughes Law Firm PLLC
Schlak Daniel K
Walsh Donald P.
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