Non dusting clumping animal litter

A process of creating cat litter which comprises forming a mixture of opal clay with one or more of the following three constituents: PA1 sodium bentonite PA1 calcium lignosulfonate PA1 binder The material is then mixed. The resulting mixed material is then pelletized in a disc pelletizer to form small round pellets. The resulting pellets are dried and then screened to produce a product having a fairly uniform pellet size averaging between a -6 and +30 mesh while removing substantially all dust and small particles. The resulting product forms a cat litter which has a clay base, yet is substantially dust-free and flushable. The litter will clump upon the absorption of liquids, such as cat urine and feces, allowing the trapped liquids and solids to be removed as a clumped ball for flushing or disposal.

BACKGROUND OF THE INVENTION 
This invention pertains to the field of animal litters, especially Cat 
Litter, a granular product used to receive and absorb animal wastes for 
subsequent disposal. Such materials have many existing problems. The 
earliest such materials were drawn from the field of spill adsorbing 
materials, such as had been widely used to adsorb oil and liquid spills. 
While such materials resembled sand or dirt, and thus were acceptable to 
the animal, representing an instinctive place to deposit and bury wastes 
(cats will not place wastes where they cannot be buried.), they only 
adsorbed and held urine. This decomposed, and became the source of odor, 
requiring frequent replacement and disposal of the litter. 
Subsequent developments have concentrated on providing a method for 
disposing of both solid wastes and liquid wastes. This led to the 
development of clumping litters, in the form of finely ground granules of 
certain clays, sometimes augmented by binders or additives. These granules 
clump in the presence of liquid wastes, which then can be scooped up and 
removed with the solid wastes. 
However these fine granular clays present additional problems. The most 
irritating is that these materials produce continual dusts, both during 
manufacture and shipment, and as the litter is disturbed during use. 
Consumer surveys have indicated that the presence of dust is the most 
common complaint about cat litter, because of the cleanliness problem 
animal litter dust presents in a household environment. Further, the dust 
clings to the fur and paws of the cat, and is tracked throughout the home, 
or is ultimately ingested by the animal during grooming; both results are 
equally undesirable. 
The composition and manufacture of these prior art litters are shown, for 
example, in the following: 
U.S. Pat. No. 4,704,989 to Rosenfeld discloses a process for producing cat 
box litter which comprises taking a fine clay dust, disclosed as either 
predominantly kaolin or bentonite, wetting it with a mixture including an 
adhesive-type soluble lignin (obtained as a by-product from paper 
treatment) and then extruding the wet mixture through a pellet or pin type 
agglomerator. The resulting pellets are screened and then dried to be not 
more than 29% by weight water and preferably 5% by weight water to create 
an absorbing clay litter. 
U.S. Pat. No. 4,459,368 to Jaffee and others discloses the use of a 
combination of Fuller's earth, preferably in the form of calcium 
bentonite, mixed with calcium sulfite dihydrate. In this patent, both the 
clay and the calcium sulfate dihydrate (synthetic granules) are 
individually screened to a desirable particle size, an example being 6 
mesh, and then are mixed as particles to form a mixture which is then the 
claimed cat litter. 
EUROPEAN PATENT 424001A1 to Hughes discloses an animal waste absorbent 
formed of water-expandable bentonite clay originally provided in discreet 
particles of between 50 and 3350 microns. This material is claimed to form 
clumps, after one to twenty-four hours exposure to liquid animal waste, 
which can be easily removed. The clumps are not physically bound and will 
dissolve in water but are physically stable enough to be removed from the 
remaining powder. 
U.S. Pat. No. 5,129,365 to Hughes is the U.S. Patent corresponding to the 
European patent discussed above. 
U.S. Pat. No. 5,188,064 to House claims a clumping cat litter comprising a 
mixture of a clumping clay such as shown in the Hughes' patent, together 
with cellulose and a material such as a non-swelling clay to adjust the 
density of the resulting cat litter. The mixture is provided as a mixed 
powder of the various ingredients, sized typically within the range of two 
hundred fifty microns to 2000 microns for both the clays and the 
cellulose. 
U.S. Pat. No. 5,101,771 to Goss discloses a clumping animal litter made of 
free-flowing clay particles coated with an organic biodegradable clumping 
agent suspended in an oil-like vehicle and distributed over the surface of 
the clay particles. This patent differs from the prior patents in that the 
principle clay component is chosen those clays considered not suitable for 
use in the House and Hughes patents. The clay particles are themselves 
screened particles stated to be between a 4 and 60 mesh, preferably 20 to 
60 mesh. The particles are then coated with the clumping agent, preferably 
a cellulosic ether such as methyl cellulose, carboxymethyl cellulose or 
hydroxypropylmethylcellulose. The clumping agent and an oil mixture are 
sprayed upon the clay particles. 
U.S. Pat. No. 4,591,581 to Crampton and others discloses a process for 
making absorbent clay mineral particles: mixing the dried particles with 
up to 5% by weight of a water-dispersed colloid; compacting the material 
in a press; and then breaking the compacted material into masses of 
smaller particles. The material is disclosed as useful for a litter. The 
suggested colloid is a vegetable gum such as guar gum or derivatives. 
These colloids are described as particularly enhancing the clumping 
properties of the litter. The process disclosed mixes the clay fines with 
a water-dispersed additive having such colloidal properties, disclosed 
types including a silicate, a pyrophosphate, or a polysaccharide. The 
amount of the colloidal agent is limited to 5% or less by weight to the 
clay. The clay mixture is compacted in a roll mill and then broken into 
smaller particles to form a particulate litter. 
U.S. Pat. No. 5,193,489 to Hardin discloses that the clumping ability of a 
poorly clumping clay may be enhanced for use as a litter by mixing the 
clay with a water-soluble or dispersed gum such as a guar gum or 
derivatives. This patent includes the disclosure that a polysaccharide may 
be used as one of the agglomerating gums. 
SUMMARY OF THE INVENTION 
The Invention is a improved clay based litter which avoids the dust 
generating properties of the prior art, while retaining the desirable 
clumping characteristics of current cat litters. The invention includes 
the method of forming the litter. 
The improved litter is formed in the form of a relatively smooth, spherical 
diameter, screened, small round balls. By screening the litter, a smooth, 
spherical size ball is produced; by forming the clay litter as round 
balls, almost all tendency of the litter to abrade, forming dusts, is 
eliminated. It is part of the invention that the inventor has found that 
the irregular shape of prior art cat litters is a principal source of 
dust, and the particles abrade each other during shipment, movement and 
use. 
It is a further part of the invention that the density of the litter is 
reduced, and is lighter than most prior art non-tracking clay litters, 
providing a more efficient liquid absorbent by weight. 
The invention in process form is a process of creating cat litter which 
comprises forming a mixture of opal clay with one or more of the following 
three additional constituents: 
sodium bentonite 
calcium lignosulfonate 
binder 
The mixed material is then pelletized or mixed in a disc pelletizer to form 
small round clay pellets. The resulting pellets are dried and then 
screened to produce a product having a fairly uniform pellet size 
averaging between a-6 to +30 mesh while removing substantially all dust 
and small particles. 
The resulting product forms a cat litter which has a clay base, yet is 
substantially dust-free and flushable. The additional ingredients enhance 
the tendency of the litter to clump upon the absorption of liquids, such 
as cat urine and feces, allowing the trapped waste to be removed as a 
clumped ball for flushing or disposal.

DETAILED DESCRIPTION OF THE INVENTION 
The described process is necessary to understand the inventive product, 
which insofar as the inventor is aware, may only be made by the process. 
Clearly the most important feature of a successful animal litter is that it 
is absorbent. Vermiculite, a standard moisture absorbent, is too light 
(insufficiently dense) to make a successful animal litter as it is too 
easily displaced and tracked throughout the house by the actions of the 
animal. A survey of 1000 cat owners by the Advisory Council of Cat Lovers 
Association of America, the publisher of "Cat Fanciers" magazine, 
indicates that the two most important characteristics of an animal litter 
is that there be little or no dust in the litter, and that the litter not 
be tracked by the animal. This latter requirement is equivalent to 
minimizing adhesion of the litter particles to cat fur or feet. 
As is known various litters for absorption or receipt of animal wastes, are 
made from certain natural clays which have beneficial clumping properties 
in the presence of moisture. Such clays are predominantly sodium bentonite 
and atapulgite clays. These clays combine absorption with clumping 
tendencies in the presence of moisture. However these litters are rough 
edged, irregular shaped particles, and break down from the friction of 
movement in transit, in storage, and in use, forming fine powders or dusts 
which spread in the air, and which further stick to the animal's fur and 
feet. 
Typical processing of clays to form litter usually compresses the clay. 
Thus a test mixture of opal clay and starch, when processed into a litter 
with a pin mixer, such as the Ferro Tech Turbulator.TM., has a density of 
55.1 pounds per cubic foot. This test mixture, of opal clay with starch 
additive, has an unprocessed density of 30.8 pounds per cubic foot. The 
prior art has considered these higher density litters beneficial to 
prevent tracking of the litter by the animal's paws and fur. 
The inventive litter 2 is a clay mixture with optional addition of a 
binder, in the form of substantially round smooth particles 2 having a 
lower density than prior art non-tracking litters and has significantly 
reduced dust generation. The round shape is believed to substantially 
reduce or eliminate the generation of powder fines or dusts in storage and 
shipment. The particles additionally have little adhesion to a cat's fur 
or feet, primarily due to their round shape and relatively smooth surface. 
They thus reduce tracking even though they are less dense than has 
previously been believed desirable to prevent tracking. Nevertheless, the 
particles retain the beneficial clumping characteristics of clay based 
clumping litters. The lessened density also means that the inventive 
litter 2, on an equal weight basis, is more absorbent, and the customer 
receives a greater volume of litter than with other non-tracking products 
presently available (litter is sold universally on a weight basis). 
The inventive litter resists crushing in shipment, storage or use. It does 
not form powder fines or dusts. 
The inventive litter is produced from a mixture of opal clay, a clay found 
in central Mississippi. This clay is mixed with Sodium Bentonite (it is 
known that calcium bentonite clays do not clump, and are thus less suited 
for use in making clumping cat litters; sodium bentonite will clump in the 
presence of water.) Typically, the mixture ranges from ninety percent to 
fifty percent Opal clay by weight; ten percent to fifty percent sodium 
bentonite, from zero to ten percent calcium lignosulfonate to modify 
density and hardness; optionally zero to five percent binder, such as FFS 
Binder System 29137, available from Flavor and Fragrance Specialties of 
Franklin Lakes, N.J.; and optionally about one half percent (0.5%) polymer 
surfacing agent such as Flavor and Fragrance Specialties' DeDuster 
90-24277.TM. polymer. Optionally, trace additives for ammonia and odor 
control can be used. The proportions chosen from the ranges specified are 
such that the total of the opal clay, the Sodium Bentonite and the 
Lignosulfonate is about ninety nine percent by weight of the entire 
mixture. 
Two example mixtures are, first, a mixture of opal clay with additionally 
twenty five percent by weight sodium bentonite, and eight percent by 
weight calcium lignosulfonate as a hardener. A second mixture is opal clay 
with additionally twenty five percent by weight sodium bentonite, three 
percent by weight calcium lignosulfonate, and four percent by weight 
binder. Either mixture can additionally comprise about one half percent 
polymer surfacing agent. 
The clays are provided in a powder form and fed from holding bins 4 through 
feeders 5, which maintain the desired proportions of the clays, to a screw 
conveyor 6, which feeds the clay mixture 10 into a blender 8. Blender 8 
mechanically blends the clays to form a uniform mixture. The optional 
additives, comprising the lignosulfonate, the binder and the surfacing 
agent, are blended 21 to form a liquid 20,22. One part of the liquid 
additives 20 are added to the clay mixture 10 in the blender 8. This 
blended mixture 11 is then fed into a Disc Pelletizer 12, a machine which 
rolls the material together without significant compression of the 
mixture, to form round smooth pellets 13. The remaining liquid optional 
aditives 22 are directly applied in the disc pellitizer 12 to the mixture 
11. A suitable disc pellitixer 12 is the Ferro-Tech Disc Pellitizer as 
described in the catalog of the Ferro Tech Company of Wayandotte, Mich. 
Calcium lignosulfonate is not added to the inventive mixture 10 to create a 
clumping characteristic in the resulting litter 2, as with the prior art, 
which has used lignosulfonates in higher proportions to clays to enhance 
the clumping properties of cat litter in the presence of liquids. Rather, 
the smaller proportions of calcium lignosulfonate used in the invention 
helps form and maintain the smooth round shape in the resulting litter. It 
is used as a hardening agent to reduce dust and increase production. 
Disc pelletizer 12 has been discovered by the inventor to form smooth round 
pellets 13 of clay based materials, but not to compress the clays. Thus 
the resulting pellets have a density as low as 39 pounds per cubic foot 
for a mixture of 25% sodium bentonite and 75% opal clay, which is 
considerably lighter than the typical 55.1 pounds per cubic foot of a pin 
mixed mixture of similar composition. 
The output from the disc pellitizer 12 is in the form of round pellets 13 
of varying sizes. The moisture content of the pellets 13 as formed from 
the disc pellitizer 12 is fifteen (15) to twenty (20) percent moisture. 
These pellets are then dried in a fluid bed dryer 14. The dried pellets 
are then screened in a standard mesh screener 16 to pass a 6 mesh screen 
but not to pass a 30 mesh screen. Both oversize and undersize particles 
are returned 18 for re- processing, thus reducing waste. 
The resulting product is a nearly uniform -6 to +30 mesh size round smooth 
bead of some hardness. The tendency of the material to form dusts was 
tested by bagging samples of the inventive litter, and then handling bags 
of the inventive material and of prior art clay based cat litters so as to 
simulate equally the effects of shipment and storage. The materials were 
then screened, interpreting all materials which passed a 100 mesh screen 
as being dust. The inventive material showed less than one half percent 
dust (0.5%); the prior art materials generated from 1 to 5 percent dust 
under identical conditions. 
The resulting litter is a perceptible small bead 2, visually similar to a 
fine bird shot, in comparison to the prior art clumping litters, which 
resemble fine granules; the clumping ability and absorbance of the 
inventive material are unimpaired. The inventive litter still forms 
absorbent clumps in the presence of liquid, such as animal urine and 
feces, and the clumps are easily removed form the litter or disposal. 
Opal clay, as used in this specification, makes reference to a clay known 
as opaline silica or opal-ct. 
The invention is thus a novel physical form of cat litter, and a novel 
process of producing the inventive litter. The litter is lighter than most 
non-tracking litters, more absorbent, and substantially dust and tracking 
free in use, while retaining the desirable clumping properties of prior 
art clay litters. The invention therefore extends to those physical 
equivalents of the claimed litter.