Coating processes – Particles – flakes – or granules coated or encapsulated
Reexamination Certificate
2001-03-02
2003-04-22
Drodge, Joseph W. (Department: 1723)
Coating processes
Particles, flakes, or granules coated or encapsulated
C118S303000, C366S172100, C366S293000, C366S317000, C366S325200, C366S326100, C366S348000
Reexamination Certificate
active
06551655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to the application of liquid additives to materials.
2. Description of Related Art
Generally, it is known to chip, chop, cut, or grind various woods and/or herbaceous materials into small pieces, generally referred to as “wood chips”. These wood chips are often used as a decorative bedding material around shrubbery, trees, and other plants to enhance the appearance of yards and gardens. In addition to their esthetic qualities, wood chips can also be used as a ground cover to limit the growth of unwanted plants and weeds and help retain moisture within the ground.
However, exposure to the ultraviolet ray of the sun and the natural process of decay quickly turns natural wood chips to a dull and unattractive, gray color. Furthermore, untreated wood chips generally tend to rot quickly, particularly in areas with a high moisture concentration.
Therefore, it is generally known to treat wood chips with various chemicals, colorants, dies, and/or paints to ensure that the wood chips maintain a desired color and resist rotting.
One of the known methods for applying chemicals, colorants, dies, and/or paints to wood chips involves the application of a liquid, such as, for example, a liquid colorant, to wood chips as the wood chips travel within an auger-screw conveyor. The auger-screw conveyors typically comprise one or two elongated screw(s) that are contained within a cylindrical or trough-like housing. These auger-screw conveyors are similar to those commonly used in industry and on farms for moving relatively fine particulate materials, such as, for example grains, along horizontal or upwardly angled paths.
The liquid colorant is generally applied to the wood chips by one of two methods. The first method involves immersing the wood chips in a pool of the liquid colorant and then allowing the wood chips to be drawn out of the colorant pool and moved to another location by the auger-screw conveyor. The second method involves the positioning of spray nozzles within the auger-screw conveyor such that, as the wood chips travel along the conveyor, the liquid colorant is sprayed onto the wood chips.
In both methods, it is important to allow the wood chips to be sufficiently coated with the liquid colorant and substantially dried before they are discharged from the auger-screw conveyor.
Because the various chemicals, colorants, dies, and/or paints that are applied to the wood chips are relatively expensive, the primary goal of these known methods is to allow a sufficient amount of liquid to saturate the wood chips so that a desired color and/or preservative quality is achieved without allowing excess liquid to be used during the process. For example, any amount of liquid that is used, which exceeds the amount necessary to color and/or chemically treat each wood chip, is an amount of liquid that is wasted.
SUMMARY OF THE INVENTION
Unfortunately, known methods fail to apply a uniform coating of liquid additives, such as, for example, chemicals, colorants, dies, and/or paints, to wood chips. In any given batch of treated wood chips, some of the wood chips are overly saturated with the liquid solution while other of the wood chips have surfaces that are not completely covered with colorant or treated sufficiently to provide adequate preservation of the wood chips.
Additionally, the use of known auger-screw conveyors to mix the additives into the wood chips is relatively inefficient. For example, the wood chips are typically fed into the auger-screw conveyors by means of a hopper structure mounted directly above the auger-screw conveyor. This method has several drawbacks. First, the size and speed of the auger-screw conveyor requires a relatively high amount of horsepower in order to function, thus resulting in elevated operational costs.
Second, batches of pre-processed wood chips often include varying size particles, larger than normal particles, stringing material, or foreign objects, which can cause the auger-screw conveyor to jam or stall. Each time the auger-screw conveyor jams or stalls, valuable production time is lost until the auger-screw conveyor can be cleared. Clearing an auger-screw conveyor is usually a manual process, which is dangerous and labor intensive.
Third, since auger-screw conveyors operate at low rotational speeds, they do not provide much agitation for the wood chip and additive mixture. Thus, in order to provide a consistent finished product, the wood chips must be immersed in the additive over a relatively long length of the auger-screw conveyor. This, in turn, adds time to the known processes of applying the additive to the wood chips and ultimately reduces productivity levels. Furthermore, auger-screw conveyors require the use of large volumes of additive to ensure the proper coverage. This leads to higher costs and longer drying times and or higher transportation cost due to the weight of an overly saturated finished product.
Fourth, auger-screw conveyors tend to tear or break down the wood chips as they are conveyed. This creates “fines” or undersized particles that are not desired in the finished product. When adding liquid additives these “fines” are very absorbent and increase the amount of additive needed for the finished product.
Last, when the auger-screw conveyor is fed by a fixed hopper above the conveyor, the wood chips tend to “bridge” or become non-flowing. This, like the presence of varying size particles, can cause the auger-screw conveyor to jam or stall, requiring that the auger-screw conveyor be stopped and manually cleared. Additionally, “bridging” can cause the auger-screw conveyor to be fed in an erratic manner, which creates a finished product that is not uniformly coated.
Accordingly, this invention provides systems, methods and apparatuses, which apply additives to a materials, such as, for example, wood chips, more evenly and more thoroughly mix the materials to ensure a consistent finished product.
In accordance with the apparatuses, systems and methods of this invention, one exemplary embodiment of the system for applying liquid additives to materials, such as, for example wood chips, uses a mixing chamber for applying the liquid additives to the materials. Unlike prior mixing chambers, the mixing chamber of this invention does not include an auger-screw conveyor, which suffers from at least the problems described above. Instead, the mixing chamber of this invention utilizes several tined cylinders to convey the wood chips through the mixing chamber.
Each of the tined cylinders includes a number of spring biased tines extending from the surface of the cylinder. The tined cylinders are arranged within the mixing chamber such that, as the tined cylinders rotate about an axis, the spring biased tines engage wood chips (which have been input into the mixing chamber via a mixing chamber input opening) within the mixing chamber and “sweep” the wood chips along towards a discharge opening of the mixing chamber.
The tined cylinders are further arranged within the mixing chamber such that, as the wood chips are swept along by, for example, a first rotating tined cylinder, the wood chips are sequentially engaged and swept along by successive rotating tined cylinders until the wood chips are discharged from the discharge opening of the mixing chamber.
The use of spring biased tines provide a flexible method of propelling wood chips through the mixing chamber. Thus, materials can be conveyed through the mixing chamber without being crushed, ground, or damaged.
As the wood chips are conveyed through the mixing chamber, an additive liquid, typically containing various chemicals, colorants, dies, and/or paints, is sprayed onto the wood chips.
In various exemplary embodiments of this invention, the system for applying liquid additives to materials includes an infeed hopper. Unlike most known systems, the infeed hopper of this invention is an independent portion of the system.
During operation, the infeed hopper supplies wood chips to the mixing chamber. An adjustable flow control gat
Brantley, Jr. Stanley A.
White Junius W.
Amadas Industries, Inc.
Drodge Joseph W.
Kaufman & Canoles
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