Abstrict A biodegradable, clumpable cat litter made from corncob and biomass
components. The animal litter is a mixture of heavy density particles
and light density particles. The heavy density particles are formed
of corncob grit and the light density particles are formed of sized
pellets of light weight corncob components. Heavy density and light
density particles are coated with mineral oil to which is adhered
guar gum. The heavy density particles compose 30%-70% of the mixture
and the remainder is composed of light density particles.
Claims We claim:
1. An animal litter comprising:
a mixture of a plurality of biomass heavy density particles and
a plurality of biomass light density particles, at least 70% of
said light density particles being pelletized corncob chaff and
pith and having a screen size to pass through 10 mesh, said mixture
being between 30 to 70% by weight of said heavy density particles
and a remainder of said mixture being said plurality of light density
particles.
2. The animal litter of claim 1 wherein at least 60% by weight
of said heavy density particles are sized between 10 mesh and 20
mesh.
3. The animal litter of claim 1 wherein said heavy density particles
have a density generally in the range of 27 to 33 lb/cu ft.
4. The animal litter of claim 1 wherein light density particles
have a density generally in the range of 20 to 26 lb/cu ft.
5. The animal litter of claim 1 wherein at least 60% of light
density particles are sized between 14 mesh and 40 mesh.
6. The animal litter of claim 1 wherein said heavy density particles
comprise generally 60% of said mixture by weight.
7. The animal litter of claim 1 wherein each of said plurality
of heavy density particles and each of said plurality of light density
particles have a coating of oil.
8. The animal litter of claim 7 wherein particles of guar gum
are adhered to each of said pluralities of heavy density and light
density particles.
9. The animal litter of claim 8 wherein at least 90% of said particles
of guar gum have a screen size less than 20 mesh.
10. An animal litter comprising:
a plurality of corncob particles, each of said plurality of particles
having an outer surface having a coating of mineral oil and guar
gum.
11. The animal litter of claim 10 wherein said plurality of corncob
particles is comprised of a plurality of heavy density particles
and a plurality of light density particles, said light density particles
being formed from chaff and pith.
12. The animal litter of claim 10 wherein at least 80% of said
plurality of particles have a size between 10 mesh and 40 mesh.
13. The animal litter of claim 10 wherein said guar gum is in
the range of 3% to 7% of the total weight of said litter.
14. The animal litter of claim 10 wherein said oil coating is
0% to 6% by weight of the total weight of the animal litter.
15. A method of producing animal litter comprising the steps of:
reducing corncob grit to heavy density particles;
forming pellets of light weight natural materials and reducing
said pellets to a predetermined size;
forming a mixture which is at least 30% by weight of heavy density
particles and the remainder of said light density particles;
adding coating oil to said mixture to coat said particles and said
sized pellets;
mixing a clumping agent to said mixture after said step of adding
oil.
16. The method of claim 15 further comprising the step of screening
at least 60% of said light density particles to have a size between
14 mesh and 40 mesh.
17. An animal litter comprising:
a mixture of a plurality of biomass heavy density particles and
a plurality of biomass light density particles, at least 70% of
said heavy density particles being corncob grit, at least 70% of
said light density particles being pelletized corncob chaff and
pith, said mixture being between 30 to 70% by weight of said heavy
density particles and a remainder of said mixture being said plurality
of light density particles, at least 87% of said mixture being sized
between 10 and 40 mesh.
18. The animal litter of claim 17 wherein light density particles
have a density generally in the range of 20 to 26 lb/cu ft.
19. The animal litter of claim 17 wherein each of said plurality
of heavy density particles and each of said plurality of fight density
particles have a coating of oil.
20. An animal litter comprising:
a mixture of a plurality of biomass heavy density particles and
a plurality of biomass light density particles, at least 70% of
said light density particles being pelletized corncob chaff and
pith, said mixture being between 30 to 70% by weight of said heavy
density particles and a remainder of said mixture being said plurality
of light density particles, and each of said plurality of heavy
density particles and each of said plurality of light density particles
having a coating of oil.
Description BACKGROUND OF THE INVENTION
I. Field of the Invention
The invention relates to disposable cat litter and a method of
making the same. More particularly, the invention relates to a cat
litter formed primarily of corncob grit and sized pellets of corncob
chaff and pith and a method for producing the same.
II. Description of the Prior Art
Corncob grit has been used as animal litter for some time. Grit
is the woody pulp portion of the cob, the remainder of the cob being
pith and chaff. Corncob grit is used as litter because it is compostable,
biodegradable, and has superior odor control properties. However,
only 60% of the cob is grit, so the remaining 40% of the cob is
waste. Additionally, the sorption rate of grit is not fast enough
to absorb all of the urine before it reaches the bottom of the tray.
When urine reaches the bottom of the tray, it collects and bonds
litter to the tray as it dries. Accordingly, it would be desirable
to produce a litter which has superior odor control and sorption
rate.
Clumpable animal litter formed of particles of bentonite clay,
as disclosed in U.S. Pat. No. 5000115 has also been used for
some time. The particles of the bentonite clay adhere together and
form a clump when moistened by animal dross. The clump of the moistened
litter may then be easily removed from the litter box with a scoop
and discarded, thereby extending the useful life of a batch of litter.
However, bentonite clay used in clumpable cat litter contains mica.
Mica is carcinogenic, accordingly, use of such a compound raises
health concerns for both the animal concerned and the person changing
the litter.
Known animal litters are easily "tracked" by the animals.
Tracking occurs when litter adheres to the paws or feet of the animal
and is carried outside the litter box when the animal leaves. The
litter then gradually leaves the paws or feet of the animal, leaving
a "track" of litter particles. Accordingly, it would be
advantageous to produce a clumpable, biodegradable animal litter
which was safe to use, easily disposed of, and has minimal tracking.
Accordingly, it is an object of the invention to produce an economical
animal litter from fully natural biodegradable products which is
completely compostable and has a low degree of tracking.
SUMMARY OF THE INVENTION
Accordingly, an animal litter formed of a mixture of heavy density
and light density particles has been developed. Both the heavy density
and light density particles are formed of natural materials which
are biodegradable and compostable. In the preferred embodiment,
the heavy density particles are formed of corncob grit and the light
density particles are formed of pelletized corncob chaff and pith
or other natural materials. The litter is composed of 30% to 70%
by weight of the heavy density particles which have a density of
about 30 lb/cu ft. The remainder of the litter is light density
particles having a density of about 23 lb/cu ft. In the preferred
embodiment, the light density particles are formed from pellets
of corncob chaff and pith. Both types of particles are reduced to
a predetermined size distribution by roller milling and hammer milling
techniques.
The method includes reducing to size and screening the heavy density
material, forming the pellets of light density material having a
predetermined density, reducing to size and screening the sized
pellets and forming a homogenous mixture. Additionally, mineral
oil and guar gum may be added to coat the particles to reduce dust
and improve the integrity of the clump. The animal litter according
to the invention has excellent odor control, light weight for given
volume, better sorption properties than clay materials, and excellent
clumping characteristics. The material is essentially dust free,
totally free of carcinogens, and has an aesthetically appealing
color.
BRIEF DESCRIPTION OF THE DRAWING
A better understanding of the present invention will now be had
upon reference to the following detailed description, when read
in conjunction with the accompanying drawing, wherein like reference
characters refer to like parts throughout the several views, and
in which:
FIG. 1 is a perspective drawing of animal litter in a tray in accordance
with the invention;
FIG. 2 is a partial cross-sectional view of particles of the animal
litter in accordance with the invention; and
FIG. 3 is a flow chart showing the steps of the method in accordance
with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1 clumpable animal litter 10 in accordance with
the invention is shown in a litter box 20. The animal litter is
a mixture of heavy density particles 12 and light density particles
14. Both types of particles 12 14 are formed of organic materials.
In the preferred embodiment, the heavy density particles 12 are
formed of corncob grit 13 i.e., the woody ring portion of a corncob,
and the light density particles 14 are formed of sized pellets 15
of the light portions of the corncob. The light portions of the
corncob are coarse chaff, fine chaff, and pith which constitute
approximately 40% of the corncob by weight.
The heavy density particles 12 are formed by reducing corncob grit
to size by using conventional hammer milling and roller milling
techniques. The heavy density particles have a density of about
30.+-.3 lb/cu ft. The grit particles are screened to be generally
10-30 mesh with about 90% of the particles sized 10-20 mesh (U.S.
Standard). A preferred distribution is set forth below.
______________________________________ GRIT PARTICLES OR HEAVY
DENSITY PARTICLES ______________________________________ Screen
Size +10 10-14 14-20 20-30 30-40 -40 % by weight <1 39 50 10
1 <1 ______________________________________
The size of the particles affects both the tracking and clumping
characteristics of the animal litter. Heavier density and/or larger
sized particles are less likely to adhere to the animal and be tracked.
The light density particles 14 are formed from pellets of beeswing
or other natural materials. In the preferred embodiment, the pellets
of chaff and pith are formed in accordance with the process described
in U.S. Pat. No. 5207389 in such a manner as to form pellets having
a density of approximately 28 to 35 lb/cu ft. The pellets are reduced
to an appropriate size by roller milling and hammer milling. After
sizing, the light density particles 14 have a density of about 23.+-.3
lb/cu ft. The light density particles 14 are screened to be generally
10-60 mesh (USS). In the preferred embodiment, 78% of the particles
are 14-40 mesh (U.S. Standard). A typical size distribution for
light density particles 14 is shown in the chart below.
______________________________________ LIGHT DENSITY PARTICLES
______________________________________ Screen +10 10-14 14-20 20-40
40-60 60-80 -80 Size % by 0 10 43 35 10 2 <1 weight ______________________________________
The animal litter is then formed of a mixture of heavy density
and light density particles 12 14 so that between 30% to 70% by
weight of the mixture is heavy grit particles 12 and the remainder
of the mixture is between 70% to 30% by weight, light weight particles
14.
In the preferred embodiment, the mixture is 60% by weight heavy
density particles 12 and 40% by weight light density particles 14.
This proportion is generally the same as the proportion of heavy
weight components or grit to lightweight components or chaff and
pith found in a corncob. Thus, in addition to the excellent sorption,
odor control, clumping, and tracking properties of the mixture,
the mixture is economical because there is little or no waste.
The mixture has a combined density of approximately 28 lb/cu ft.+-.3
lb/cu ft. It has been found that this mixture provides an appropriate
balance of densities and sizes to minimize tracking, and maximize
animal urine sorption, and clumpability. The particle size distribution
set forth above provides excellent clumping and a proper urine sorption
rate. If the size of the particles is either too large or too small,
the clumping ability is negatively affected. The slightly smaller
average size of the light density material facilitates clumping
with the larger heavy density material. The clump 22 of litter disintegrates
in the water of a toilet and is easily flushed away. If a clump
22 is not to be flushed, it will remain formed as a clump for other
manners of disposal.
If the urine absorption rate is too low, urine is absorbed too
slowly and some of it flows to the bottom of the litter pan 20
where the litter forms clumps which adhere to the pan 20. These
clumps are difficult to remove. When both particles 12 14 are sized
as set forth above, the light density particles have a sufficiently
high sorption rate to take up the urine in the top layers of the
litter. A clump 22 is then formed in the top layer of the litter
which is easily scooped out of the litter box 20 for disposal by
flushing down the toilet or other suitable manner.
It has been found that other organic materials such as peanut shells
can be substituted for a portion of either the heavy density or
light density corncob components to form the light weight particles.
The other organic materials include grasses, straw, soy hulls, sunflower
hulls, oat hulls, rice hulls, corn stalks, pecan shells, corn husks,
spelt hulls, or kenaf. These materials may be added at up to one-third
by weight of either the heavy weight or light weight corncob particles.
The other materials should be sized and have sorption rates or densities
generally the same as the particles which are being replaced. However,
these other materials do not have the odor control ability of the
corncob components.
As shown in FIG. 2 both the heavy density particles 12 and light
density particles 14 are provided with a coating 16 of oil. In the
preferred embodiment, the coating 16 is mineral oil and is added
as 4% by weight of the total weight of the particles 12 14. The
oil eliminates dust during mixing, handling, packaging, and use.
Other oils such as kerosene, mineral seal oil, vegetable oils, or
any of a series of paraffinic or naphthinic distillates may also
be used.
Although the mixture of sized pellets of light density material
and sized heavy density material readily forms clumps, these clumps
tend to degrade over time. Accordingly, in the preferred embodiment
the integrity of the clump is maintained by adding particles 18
of guar gum. In the preferred embodiment, the clumping agent 18
is guar gum. Guar gum is added to be in the range of 3 to 7% by
weight of the total weight of the heavy and light weight particles
12 14 and preferably about 5% by weight. The particle size distribution
and viscosity of the guar gum is critical to achieve good clumping.
In the preferred embodiment, 95% of the guar gum particles are smaller
than 200 mesh (U.S. Standard). The viscosity of the guar gum should
be more than 4500 cps in a 1% aqueous solution after 24 hours. Although
the guar gum can be in the range of 3% to 7% of the total weight,
lesser amounts of clumping agent 18 result in crumbly or less manageable
clumps for disposal and greater amounts of clumping agent result
in excessive firmness of the clumps.
Advantageously, an odor control agent, fungicide, lime, sodium
bicarbonate, or materials identified in U.S. Pat. No. 5195465
to prolong the life of cellulosic-based litters may be added at
0 to 1% of weight of the mixture. Additionally, an odor control
material and fragrance as well as a bactericide such as Myacide
S2 produced by Angus Chemical, may be added.
Method of Preparation
As shown in FIG. 3 after separating the grit from the pith and
chaff, the corncob grit is subjected to roller milling and hammer
milling and screened to form the proper size distribution as set
forth above. The light weight corncob components are formed in pellets
according to a suitable method such as described in U.S. Pat. No.
5207389. The pellets are formed to have a density of approximately
28-35 lb/cu ft. The pellets are then reduced to the appropriate
size by roller milling and hammer milling techniques and screened
to obtain the light density particles 14. A predetermined amount
of at least 30% by weight of the heavy weight particles 14 and the
remainder to be light density particles are placed in a low shear,
fluidizing mixer. The mixer should impart no shear or heat to the
mixture. The mixer is run sufficiently long, such as 15-20 seconds,
to provide a homogenous mixture. The oil is added to fully coat
the particles. The oil is added to the mixer in an amount from 0%
to 6%, preferably 4%, of the weight of the mixture of particles.
It has been found that the oil facilitates the adherence of the
guar gum as well as reducing dust. The next step is adding the guar
gum to the mixture and thoroughly blending the mixture. During the
mixing process, the guar gum adheres to the cob particles 12 14.
It has been found that the uniform covering of the oil on the corncob
particles facilitates the adherence of the guar gum to the cob particles
12 14. The odor control material with fragrance is then added at
a rate of 2 to 3 lb/ton of cob components and thoroughly blended.
Additionally, at this time fungicide, bactericides or other odor
control materials may be added. The litter 10 is then thoroughly
blended and is ready for packaging in bags, jugs, boxes, etc.
The litter thus produced is biodegradable and compostable and made
from a renewable resource which is free of carcinogens. The litter
is half the weight for a given volume of conventional clay litter
which makes handling of the litter easier. The litter has better
sorption than clay materials and excellent clumping characteristics,
making it easy to remove the urine from the litter pan. The litter
is essentially free of dust and has excellent odor control properties.
The blend produces a litter with a minimal amount of tracking compared
with previous litters.
Finally, the color of the litter is aesthetically appealing. The
color is controlled by the combination of light color of the heavy
portion of the cob and the darker color of the light density components
of the cob.
Having described my invention, many different embodiments will
become apparent to one skilled in the art to which the invention
pertains without deviating from the scope of the disclosure as set
forth in the appended claims. |