An economical process that combines bentonite, or similar clays,
that form a clump when in contact with cat urine, with waste cellulosic
fibrous materials, preferably paper mill sludge, to form a light
weight scoopable (clumping) cat litter product. In the process,
paper mill cellulose waste is combined with bentonite clay (preferably
sodium bentonite) in a mixing auger in varying percentages depending
upon the desired end weight of the finished product, transferred
to a secondary rotating drum mixer, then to a rotating drum dryer,
and from the dryer to a screening process. The finished product
is a granule weighing between 20 lbs./cubic foot and 50 lbs./cubic
foot. The granule is highly absorbent and capable of forming a distinct
clump that can be separated from the surrounding granules without
falling apart. A unique characteristic of the process is the combination
of heavy clay particles with light weight cellulose particles to
form a new composite particle.
What is claimed is:
1. A process for manufacturing a composite clumping absorbent material,
comprising: introduction of a material capable of clumping upon
wetting into a reaction vessel; adding paper mill sludge to said
material capable of clumping in said reaction vessel; mixing said
paper mill sludge and said material capable of clumping to form
a composite mixture; drying said composite mixture to form a base
2. The process of claim 1 wherein said composite mixture is comprised
of individual agglomerated particles.
3. The process of claim 2 wherein said composite agglomerated particles
are shaped prior to drying.
4. The process of claim 3 wherein said process becomes a batch
process during the shaping step.
5. The process of claim 2 further including separating said agglomerated
particles by size.
6. The shaped and dried agglomerated composite particles formed
in accordance with the process of claim 3.
7. The process of claim 1 wherein said paper mill sludge includes
between approximately 55 percent and approximately 75 percent by
weight water content.
8. The process of claim 7 wherein said material capable of clumping
is bentonite clay.
9. The process of claim 8 wherein said bentonite clay is sodium
10. The process of claim 8 wherein said bentonite clay includes
less than or equal to approximately 15 percent water by weight.
11. The process of claim 1 further including: drying said paper
mill sludge to form paper particles before adding to said material
capable of clumping; sizing said dried paper particles to a desired
particle size before adding to said material capable of clumping.
12. The process of claim 1 including: dry mixing said paper mill
sludge and said material capable of clumping; adding water to said
dry mixture to agglomerate said paper particles and said material
capable of clumping before drying.
13. The process of claim 1 wherein said process is a continuous
14. The process of claim 1 wherein an odor absorbing agent is added
to said composite mixture.
15. The process of claim 1 wherein a desiccant is added to said
16. The process of claim 1 wherein a clumping agent is added to
said composite mixture.
17. The base product mass formed in accordance with the process
of claim 1.
18. The composite clumping material formed in accordance with the
process of claim 1.
19. A process for manufacturing a composite clumping material,
comprising: introduction of a bentonite clay into a reaction vessel;
obtaining a cellulosic material; drying said cellulosic material
to form cellulosic particles; sizing said dried cellulosic particles
to a desired particle size; mixing said dried and sized cellulosic
particles with said bentonite clay in said reaction vessel to form
a supply of composite agglomerated particles; drying said supply
of composite agglomerated particles.
20. The process of claim 19 wherein said composite agglomerated
particles are shaped prior to drying.
21. The shaped and dried agglomerated composite particles formed
in accordance the process of claim 20.
22. The process of claim 19 including: dry mixing said cellulosic
material and said bentonite clay; adding water to said dry mixture
to agglomerate said cellulosic material and said bentonite clay.
23. The process of claim 22 further including separating said agglomerated
particles by size.
24. The composite clumping material formed in accordance with the
process of claim 19.
25. The process of claim 19 wherein an odor absorbing agent is
added to said agglomerated particles.
26. The process of claim 19 wherein a desiccant is added to said
supply of composite agglomerated particles.
27. The process of claim 19 wherein a clumping agent is added to
said supply of composite agglomerated particles.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to processes for manufacturing
cat litter products.
2. Background of the Invention
Materials traditionally used as cat litter due to their moisture
absorbent characteristics include bentonite (montmorillonite) clays.
Such bentonite clays include sodium bentonite, calcium bentonite,
potassium bentonite, lithium bentonite, magnesium bentonite, or
some combination of those clays. However, the moisture characteristics
of those clays are not equal. Sodium bentonite is known to have
better moisture absorbing properties than the other clays.
It is also known that sodium bentonite particles, upon absorbing
moisture, swell and bind together as a mass (agglomerate). This
is particularly desirable because the mass, including the liquid
waste contained therein, can be easily and integrally removed and
discarded. Thus, the source of odor in a litter box can be conveniently
removed without the necessity of changing out the entire box. The
result of this, however, is to place a premium on sodium bentonite
for cat litter purposes. A need, therefore, exists for a process
that combines clumping cat litter, such as sodium bentonite with
other materials of lesser value, which can result in a final product
which still provides for the clumping properties of the bentonite
It is well known that waste cellulosic fiber and paper mill sludge,
which are produced in large quantities in most industrial nations
of the world today, due to the large usage of paper, constitute
a substantial environmental problem. Paper mill sludge has substantially
little usage as a material that can be employed in other industrial
applications. Because of this non-utility, the paper mill sludge
is merely discarded, along with other waste cellulosic fiber. This
creates a tremendous disposal problem. A need, therefore, exists
for an integral process from which a single source of paper mill
sludge can be utilized in an economical continuous flow procedure
to output usable product.
A particular known problem with all clay cat litter products and
particularly clumping cat litter products is their weight/volume
ratio. A significant amount of cat litter product is necessary to
fill a litter box. It is known that such cat litter boxes are changed
every 5-10 days, depending on the number of animals, to avoid odor
problems. As a result, it is necessary to purchase a sufficient
volume of cat litter in order to avoid frequent trips to the pet
store or pet aisle of a grocery store. Moreover, as with most products,
there are certain economics to be gained through the purchase of
larger volumes. The problem is that the container for a sufficient
volume and economy of clumping cat litter product is generally heavy,
approximately 60 lbs./cubic foot or more for an all clay product.
Such weights are awkward, and in some cases, impossible for some
people to handle. A need, therefore, exists for an effective cat
litter product with a reduced weight/volume ratio.
SUMMARY OF THE INVENTION
The present invention is an economical process that combines bentonite,
or similar clays, that form a clump when in contact with cat urine,
with cellulosic materials, preferably paper mill sludge and waste
cellulosic fibrous material, to form a lighter weight scoopable
cat litter. The process includes: (1) component introduction; (2)
combining the component paper mill sludge including waste cellulosic
fibrous material with bentonite clay (preferably sodium bentonite)
in a mixing auger in varying percentages depending upon the desired
end weight of the finished product; (3) transferring the mixture
to a secondary rotating drum mixer for particle shaping; (4) drying
the mixed and shaped particles; and (5) particle size separation
The finished product is a granule weighing between 20 lbs./cubic
foot and 50 lbs./cubic foot. The granule is highly absorbent and
forms a distinct clump that can be separated from the surrounding
granules without falling apart. Unique characteristics of the process
are the combination of heavy clay particles with light weight cellulose
particles to form a new composite particle.
The process can be accomplished by using paper mill sludge or any
such cellulosic material. As used herein the term "paper mill
sludge" encompasses bi-products of the production of paper
as described above, mixtures of said bi-products and waste cellulosic
fibrous materials, slurried waste cellulosic fibrous materials and
slurried plant fibrous materials. Paper mill sludge for this process
contains approximately 55-75% H.sub.2 O by weight and clay that
is 15% or less H.sub.2 O. The H.sub.2 O in the cellulose creates
an environment conducive to blending the two materials in an agglomeration/swelling
action that is characteristic of bentonite clay. When this agglomeration
is dried, the particle decreases in size thus binding the two materials
tightly to create a low dust, absorbent particle that has a lower
weight/volume ratio than an all clay particle, that swells and forms
a scoopable clump. Thus, the swelling/clumping properties of the
bentonite clay are retained. The lighter weight/volume ratio is
desirable for a variety of reasons: (1) less weight for the consumer
to carry in the same volume; (2) less cost to ship from manufacture
to retailer; and (3) a higher cost per pound for the manufacturer
yet still providing the retailer the ability to sell the same volume
for the same price as heavier scoopable cat litter products.
In an alternate embodiment of the process of the present invention,
the paper mill sludge may be first dried and then run through a
hammer mill in order to create a dry, small particle size cellulosic
material. These small, dried particles are then dry blended with
the bentonite clay. Moisture is then added to aggregate the cellulosic
material and the bentonite clay. The resulting aggregate particles
may then be shaped, dried and separated as in the process described
Odor control agents could also be added to the process during the
component introduction step. Such odor control agents could include
activated carbon, chabazite (zeolite) or any other known suitable
material. When the particles are agglomerated according to the present
process and then dried, the odor control agent is then trapped inside
the particle. As a result, the odor control agent forms an integral
part of the particle itself as opposed to added separately or sprayed
onto the particles.
It is therefore an object of the present invention to provide an
integral system for reclaiming paper mill sludge and waste cellulosic
fibrous material into an environmentally acceptable product.
It is a further object of the present invention to utilize paper
mill sludge and waste cellulosic fibrous material in the manufacture
of a clumping cat litter.
It is still a further object of the present invention to combine
bentonite clay with paper mill sludge and waste cellulosic fibrous
material in the manufacture of a cat litter.
It is an additional object of the present invention to combine
bentonite clay with paper mill sludge and waste cellulosic fibrous
material in the manufacture of a clumping cat litter.
It is yet a further object of the present invention to combine
bentonite clay with paper mill sludge and waste cellulosic fibrous
material in the manufacture of a cat litter product with a lower
weight/volume ratio that an all clay product.
It is still another object of the present invention to form a composite
cat litter product containing an odor control agent(s) which are
contained within the composite agglomerated particles.
A better understanding of the invention and its objects and advantages
as well as further objects will become apparent to those skilled
in this art from the following detailed description, taken in conjunction
with the attached drawings, whether is shown and described only
the preferred embodiment of the invention, simply by way of illustration
of the best mode contemplated for carrying out the invention. As
will be realized, the invention is capable of modifications and
various obvious respects, all without departing from the scope of
the invention. Accordingly, the description should be regarded as
illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall process sketch of the method of manufacture
of an absorbent particle of the present invention identified with
its component substeps.
FIG. 2A depicts the component introduction substep 2A of FIG. 1.
FIG. 2B depicts the component mixing substep 2B of FIG. 1.
FIG. 2C shows the particle shaping substep 2C of FIG. 1.
FIG. 2D depicts the particle drying substep 2D of FIG. 1.
FIG. 2E shows the particle separation substep 2E of FIG. 1.
FIG. 3 is a view taken along line 3--3 of FIG. 2A.
FIG. 4 is a detail view of the double ribbon flighting of FIG.
FIG. 5 is a detail view of the cut and fold auger flighting of
FIG. 6 is a cross sectional view taken along line 6--6 of FIG.
4 showing the cross section of the double ribbon auger flighting
of the present invention.
FIG. 7 is a cross section view taken along line 7--7 of FIG. 5
depicting the cut and fold auger flighting of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The process of this invention includes combining of bentonite,
or similar clay, that forms a clump when in contact with cat urine,
with cellulose materials, preferably paper mill waste, to form a
light-weight, scoopable, clumping cat litter. With reference to
FIG. 1 the process can be broken down for the purpose of illustration
into five main substeps: (1) Reactant stream introduction (2A);
(2) component mixing (2B); (3) particle shaping (2C); (4) drying
(2D); and, (5) separation (2E). This general description is for
the purpose of illustration herein and shall not be considered limiting.
According to this process, a bentonite clay, preferably sodium bentonite,
is combined with paper mill sludge including waste cellulosic fibrous
material in the manufacture of a cat litter product which retains
the moisture swellable and clumping properties of the bentonite
clay but has a lower weight/volume ratio than does an all clay product.
Throughout the specification, the preferred equipment is referenced.
It should be understood, however, that this equipment is provided
to illustrate the best mode known at the time for carrying out the
invention. The use of equivalent equipment or equipment of different
dimensions should be understood to fall within the scope of this
Reference will now be made to FIGS. 2A and 3 in the preferred process
of manufacturing a composite clumping cat litter. In the preferred
process, sodium bentonite clay of a particle size capable of passing
through a 20 mesh sieve and is deposited and stored in a dump hopper
10. At the bottom of dump hopper 10 there is an auger 12 for conveying
the sodium bentonite clay to the upstream end of a mix-auger 14.
By varying the size or speed of rotation of auger 12 the amount
of clay processed into mix-auger 14 can be controlled. A predetermined
amount of sodium bentonite is delivered by auger 12 into the mix-auger
Mix-auger 14 functions to mix the sodium bentonite clay with cellulosic
fibrous material, preferably derived from paper mill waste. The
waste cellulosic fibrous material is introduced into mix-auger 14
through sludge storage reservoir 18 to mix with the sodium bentonite
clay to form a reactant stream. The cellulosic fibrous material
is discharged into the bentonite clay by a metering conveyor 20
thus allowing control of material ratios.
In the alternate embodiment of the present invention, the cellulosic
paper mill sludge is dried through the drier and then processed
through a hammer mill in order to reduce the size of the particles.
Once dried and sized, the small dry particles of paper (cellulosic
material) are dry blended (mixed) with the bentonite clay in mix
auger 14. Once dry mixed, water is added to the paper/bentonite
clay dry mix to form agglomerated particle which are further processed
in the same manner as described below.
Paper mill sludge is a by-product of the production of paper and
typically is an environmental contaminant. The disposal of paper
mill sludge has been an ecological problem throughout the world.
Heretofore utilized methods of disposing of paper mill sludge typically
include burning or burial. Burning of the paper mill sludge is an
expensive method of disposal, since before the paper mill waste
can be burned, it must be dried. Burial of the material takes up
large volumes of land fills and only conceals the waste which takes
a long period of time to decay. Under the principals of this invention,
paper mill sludge is moved directly from the paper manufacturing
process into sludge storage reservoir 18 from which it is continuously
fed into an integrated process for its reclamation thereby eliminating
the waste and forming a commercially useful product.
The composition of paper mill sludge varies slightly depending
upon the particular manufacturer from which it is obtained. Paper
mill sludge generally comprises cellulosic fibrous materials, water,
and fillers, in addition to contaminants. Normal paper mill sludge
has a solids content of 40-90 weight percent fiber (the fibers are
typically 500-1000 microns in length) and 10-60 weight percent filler.
Fillers include such materials as kaolin clay, barytes, titanium
dioxide and other plant fibers. Clay is the most important of the
filler components. Some paper mill sludges might have a negligible
or very low (3%) clay content by weight, while others might have
up to a 40% clay content by weight. Raw paper mill sludge has a
usual water content ranging from 60-90 weight percent. In the preferred
combination, the cellulosic fibrous material has an H.sub.2 O content
of between 55% and 75% by weight while the H.sub.2 O content of
the bentonite clay is 15% or less. The water content in the paper
mill sludge facilitates agglomeration of the composite particles.
Odor control agents may be added during the reactant introduction
step through an additional silo and metering conveyor (similar to
silo 18 and metering conveyor 20 of FIG. 2A) into the reactant stream.
In the preferred embodiment, chabazite, having a particle size of
0 to 5 .ANG. is added in an amount so as to provide an end product
that is 1-15% by weight chabazite. Chabazite is a naturally hydrated
calcium ammonium silicate zeolite (CaAl.sub.2 Si.sub.4 O.sub.12
6H.sub.2 O) available commercially. Chabazite is frequently used
in water treatment and particularly water softening by providing
cationic exchange of the sodium of the zeolite of the calcium or
magnesium contained hard water. In the present process, however,
the chabazite is introduced to provide its known odor elimination
properties of the final product. Another additive contemplated in
the present process is activated carbon added in powder form of
approximately 5-15 .ANG. particle sizes also for the purpose of
odor control/elimination. The powder activated carbon and the chabazite
are sealed within the composite particle as the particles are agglomerated
according to the present process and function to absorb (trap) gas
molecules in the final product.
Yet another additive contemplated is a desiccant pellet dust to
provide increased moisture absorbency to the composite. The addition
of the desiccant is also intended to absorb ammonia from cat urine
thereby trapping/neutralizing odor. Known desiccants include activated
alumina, calcium chloride, silica gel, or zinc chloride.
Clumping of the product produced by the process of the present
invention is desirous so as to facilitate removal of the animal
waste from the litter box. If the product clumps when subjected
to the moisture in the animal waste, the clump, including the waste
and the odor associated therewith, can be easily removed. The clumping
properties of the product can be improved by the addition of agents
such as natural resins and plant gums.
Once the reaction components are introduced into mix-auger 14
the reactant stream is conveyed by mix-auger 14 and deposited into
reaction mixer unit 16. It is within reaction mixer unit 16 that
intimate mixing takes place between the components in the manufacture
of a composite particle.
Reference is next made to FIG. 2B for a discussion of reaction
mixer unit 16. Reaction mixer unit 16 is a 60' long reaction chamber
in the preferred embodiment. The length of reaction mixer unit 16
is divided into two major phases. The first phase includes subjecting
the reactant stream to a thorough mixing/agitation process, and
the second phase includes intimate mixing/agitation/shear of the
component particles comprising the reactant stream.
The length of the reaction mixer unit 16 is set at a 10.degree.
incline and powered by motor 17. The total 60' length is divided
into auger flighting, each flight being 12' in length. The mixing/agitation
phase within reaction mixer unit 16 is accomplished by a 12' double
ribbon auger flighting 22. The intimate mixing/agitation/shear phase
is carried out by cut and fold auger flighting 24. In the preferred
embodiment there are four (4) cut and fold auger flighting segments,
each 12' in length. Reaction mixer unit 16 comprised of its two
phases operates at a speed of 60 rpm in order to convey a desired
discharge of 19 cubic tons per hour, weighing between 20 pounds
per cubic foot and 50 pounds per cubic foot.
FIG. 4 is a detailed view of double ribbon auger flighting 22 of
FIG. 2B. As can be seen, double ribbon auger flighting 22 includes
an outer ribbon 28 and an inner ribbon 30. The double ribbon auger
flighting 22 acts to convey the reactant stream while providing
thorough mixing and agitation of the component particles conveyed
Outer ribbon 28 includes a 2" wide blade with a 12" inner
diameter, while inner ribbon 30 includes a 1" blade and 9"
outer diameter in the preferred embodiment. Such double ribbon auger
configurations are available commercially. Outer ribbon 26 and inner
ribbon 28 are mounted on and supported from a 5" diameter central
FIG. 6 depicts double ribbon auger flighting 22 from a cross-section
showing outer ribbon 28 and inner ribbon 30 supported from central
pipe 32. The support structure for outer ribbon 28 and inner ribbon
30 are depicted in FIG. 6.
Referring back to FIG. 2B, cut and fold auger flighting 24 provides
intimate mixing, shearing, and agitation of the component particles
of the reactant stream. The water contained within the cellulose
creates an environment to blend the two components along with the
sticking/swelling action that is characteristic of sodium bentonite
in a process to form an agglomerated particle.
FIG. 5 is a detail of cut and fold auger flighting 24 of FIG. 2B.
Cut and fold auger flighting is known commercially to provide intimate
mixing, agitation, and particle shear. Cut and fold auger flighting
24 includes a blade 38 on a 5' center shaft 40. Screw blade 38 is
16" in diameter and is notched along its outer circumference.
The reactant stream covers a 45% area of screw blade 38 such that
70% of the reactant stream is conveyed and 30% is dropped so as
to be worked back into the reactant stream thereby providing the
intimate mixing/agitation/shear described herein. The mixing/agitation/shear
in the presence of the water contained in the cellulose acts to
bind the two component materials as described above. Sodium bentonite
is known to swell when absorbing moisture. The water in the cellulose
serves the purposes of a transport means to infuse the fibrous material
into the porous sodium bentonite particle to provide mechanical
cohesion and serves an agglomeration and lubricity function by cementing
the particles together. In the event that the volume of water in
the cellulose is insufficient to facilitate particle agglomeration,
water may be added via water conduit 34 and spray nozzles 36 to
provide for sufficient agglomeration.
FIG. 7 depicts cut and fold auger flighting 24 in cross-section.
Notches 46 and blade 42 allow material in the reactant stream to
be dropped and folded back into the reactant stream. The aggressive
shape of the cut and fold blades provide for the particle shear.
Once the composite particles are manufactured, the reactant stream
is conveyed for further processing. A belt conveyor 48 transports
the reactant stream to a shaper/mixer 50. The shaper/mixer 50 shapes
the composite particles into generally spheroidal granules. Shaper/mixer
50 is comprised of a truck-mixer, such as a standard cement mixer,
mounted on a skid and capable of rotation by rollers 52. Once the
reactant stream reaches the shaper/mixer 50 the process becomes
a batch process in that a batch of composite particles is supplied
to shaper/mixer and then rolled therein. Once the step of shaping/mixing
is completed, the batch reactant stream is transferred from shaper/mixer
50 through a transfer point 54 and supplied to a conveyor 56 such
that the shaped composite particle may be conveyed to surge hopper
58. Surge hopper 58 acts to shake the agglomerated particles thereby
separating adjacent particles to form a granulated mixture of individual
composite particles. Surge hopper 58 also acts to control the volume
of granulated mixture process through the dryer as shall be next
described. As a result, the moisture content of the manufactured
composite product is controlled.
From surge hopper 58 the granulated mixture is transferred via
a conveyor 60 to a dryer 62. Reference is next made to FIG. 2D.
Dryer 62 is in a declined orientation so as to assist the flow of
the granulated mixture along its length. Dryer 62 may be a rotating
dryer, a fluid bed dryer, or a straight air dryer. The dryer 62
illustrated in the drawings for the purpose of exemplification is
a rotating dryer having a firing cone 64 at which the temperature
is approximately 1600.degree. F.-1700.degree. F. Dryer 62 is rotated
by a plurality of rollers, collectively 66.
The granulated mixture is conveyed through dryer 62 and has a residency
time of approximately 8 minutes. The exit temperature of the composite
mixture is approximately 250.degree. F. The rolling and heating
action of dryer 62 accomplishes the purpose of removing moisture
from the manufactured particles comprising the granulated mixture.
When the composite particles are dried, the particle decreases in
size, thus binding tighter the two component materials to create
a low dust, absorbent particle that is lighter in weight than an
all clay particle of the same volume.
Fresh air is then put into dryer 62 through several air intake
68. An air pump 70 is ducted to a heat exchanger 72 to provide fresh
air and evacuate dead air. The dead air is taken off through a heat
exchanger/steam vent 74 which is exhausted into an emissions control
device (not shown) such as a cyclone for the recovery of aerosolized
materials. Thus, all emissions, including vaporized water and any
contaminants released therewith are recovered. Heat exchanger 72
is also ducted to fresh air ducts via conduit 76. A dry granule
mixture 78 is thus output from dryer 6 and deposited on a conveyor
Reference is next made to FIG. 2E wherein the dry granule mixture
78 is conveyed by conveyor 80 onto a shaking conveyor 82. The shaking
conveyor 82 functions as a separator for receiving the dry composite
particles of the granulized mixture 78 for separation based upon
particle size to form piles of segregated product particles. The
dry granule mixture is passed over screens of various mesh sizes
to segregate the product which is then dispensed into piles through
chutes 84 86 88 and 90.
Referring back to FIG. 2E, particles larger than approximately
1/2" are removed from shaking conveyor 82 and deposited in
bin 92 through chute 90. These large particles are transported and
recirculated through the process. In the process of the alternative
embodiment, the larger particles are again processed through the
hammer mill and processed as described above.
The particles exiting through chutes 84 pass through a 20 mesh
sieve screen and are collected in a first bin 104. These particles
are usually considered too fine and are also efficiently reprocessed
and thereby re-manufactured into a useable particle size. Thus,
substantially all raw material becomes useful.
The remaining particles are preferably divided into two or more
groups. The screen sizes utilized to divide these particles may
vary, but are generally between 40 mesh, up to 6 mesh. As an example,
particles passing through a 12 mesh sieve screen, may be exited
through chute 88 into a bin 106. Larger particles may be passed
through an 8 mesh sieve screen and exited through chute 86 into
a bin 108. The particles processed into the bins may then be bagged
and shipped for use as a cat litter product.
While the invention has been described with a certain degree of
particularity, it is manifest that many changes may be made in the
details of construction without departing from the spirit and scope
of this disclosure. It is understood that the invention is not limited
to the embodiment set forth herein for purposes of exemplification,
but is to be limited only by the scope of the attached claim or
claims, including the full range of equivalency to which each element
thereof is entitled.