Sodium bentonite-UAN suspension without chemical dispersants

A process for producing urea ammonium nitrate (UAN) sodium bentonite suspension from hot urea solution, hot ammonium nitrate solution and dry solid sodium bentonite clay. The dry sodium bentonite clay is added directly to the hot urea solution without the use of expensive chemical dispersants. There is no need for intermediate processing steps involving the dispersion of clay in water, said water normally containing expensive chemical dispersants. After the sodium bentonite has been dispersed in the hot urea solution, then, and only then can the hot ammonium nitrate solution be added. Unexpectedly, the order of addition of the feed material to this process is highly critical. This economical and innovative production process is readily adaptable to existing commercial nitrogen fertilizer production plants and has solved many of the problems which have kept sodium bentonite from being widely used in the production of suspension fertilizers.

INTRODUCTION 
The present invention relates to an improvement in the production of UAN 
clay suspensions prepared from mixtures of urea solution, ammonium nitrate 
solution, and dry sodium bentonite clay. 
UAN suspensions, which are actually eutectic urea-ammonium nitrate 
solutions containing 1 to 3 percent of bentonite clay, are both a source 
of supplemental nitrogen and a source of readily usable predispersed 
gelling clay. At the present time, about eight and one-half million tons 
of UAN solution are produced in the United States each year. 
Our new process provides for the direct incorporation of dry bentonite clay 
in UAN clay suspensions. It utilizes the normally produced hot 
concentrated urea solutions with sodium bentonite clay dispersed therein. 
The new process of the instant invention produces UAN suspensions that can 
be maintained with the eutectic urea ammonium nitrate composition. It does 
not involve the use of expensive chemical dispersants such as sodium acid 
pyrophosphate or tetrasodium pyrophosphate. Our new process is directly 
applicable to the hot concentrated urea and ammonium nitrate streams that 
are produced in urea ammonium nitrate plants now in existence. The 
successful development of this process is expected to lead to the 
widespread use of sodium bentonite in suspensions in the Midwest. Sodium 
bentonite is more economical for use in midwestern suspension markets than 
are other clay minerals since it is mined locally and is a superior 
gelling agent as compared with even attapulgite clay in suspensions. Our 
new process displays the distinct advantage of not introducing water in 
side streams that are added to the concentrated urea-ammonium nitrate 
solutions. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
About 11 years ago, i.e., TVA 10th Demonstration infra, production 
technology was developed to produce UAN suspensions with attapulgite clay 
and the chemical dispersant tetrasodium pyrophosphate (TSPP). About 7 
years ago, i.e., TVA 12th Demonstration infra, the process was improved to 
produce such UAN attapulgite clay suspensions containing TSPP. Work in 
recent years has shown that sodium acid pyrophosphate (SAPP) could be used 
to chemically disperse sodium bentonite clay, however, there is an acute 
economic problem with both of these chemical dispersants in that they cost 
ten to twenty times as much as the eutectic UAN solution in which they are 
used. These same dispersants also cost ten to twenty times as much as the 
attapulgite or sodium bentonite clay. The new technology discussed herein 
presents an economically advantageous production scheme which mixes dry 
sodium bentonite clay directly in hot concentrated urea solution. The hot 
concentrated ammonium nitrate solution can then be added to this 
urea-clay-water mixture. This new technology is readily adaptable to a 
nitrogen fluid fertilizer production facility which has these hot 
concentrated streams of urea and ammonium nitrate. This new simplified 
technology will greatly reduce the investment cost and operating cost of 
the processing equipment. 
For purposes of this disclosure the term UAN suspensions will be used even 
though at normally experienced ambient temperatures there are really no 
suspended crystals. The fluid fertilizer being discussed herein is 
actually a eutectic solution of urea, ammonium nitrate, and water in the 
presence of a sodium bentonite clay gel. Since the term UAN suspension is 
used within the fertilizer industry, the term will continue to be used in 
this disclosure. For more detailed information on the solubility isotherms 
and phase boundaries of the ammonium nitrate urea water system, as well as 
other properties thereof, see any number of references, including 
Agricultural Anhydrous Ammonia Technology and Use, Proceedings of the 
Agricultural Ammonia Institute, St. Louis, Mo., Sept. 29 and 30, 1965, of 
the Agricultural Ammonia Institute, Memphis, Tenn., Soil Science Society 
of America, Madison, Wis., Library of Congress Catalog Card No. 66-25830, 
specifically, but not necessarily exclusively, pages 46-48. 
2. Description of the Prior Art 
In U.S. Defensive Publication T911,008, June 5, 1973, Getsinger discusses 
the gelling of clay directly into UAN solution. The described process 
produces improved fluid nitrogen fertilizers by the addition of a gelling 
type clay and utilizing agitation for dispersion of the clay. In this work 
mechanical agitation is relied upon to disperse and gel the clay in a UAN 
solution. 
In 1974 TVA researchers disclosed infra a method for producing a mixture of 
water, attapulgite clay, and tetrasodium pyrophosphate which could be 
added to urea ammonium nitrate solution. In this process a thirty weight 
percent clay dispersion was added to 34.3 percent nitrogen UAN solution to 
produce 32-0-0-2 clay. In 1978 a hot processing continuous production 
scheme was demonstrated by TVA researchers infra. 
In this continuous production of UAN suspension, TSPP solution is prepared 
batchwise by mixing bagged TSPP with water. This 20 percent TSPP solution 
is fed simultaneously with 75 percent urea solution and water to a 
dilution funnel. Urea is introduced into and used in the dispersion step 
to avoid excessive dilution of the product. Temperatures of the TSPP 
solution and the urea solution are 160.degree. F. and 194.degree. F. 
(71.degree. C. and 90.degree. C.), respectively. Sufficient water is added 
in the funnel to reduce the concentration of urea solution to 50 percent 
urea. This mixture then flows into the clay dispersion tank where 
attapulgite clay is added. After a retention time of about 8 minutes, 
material overflows through a trough and is mixed with UAN solution as it 
enters the clay gelling tank. The clay gelling tank is baffled in such a 
manner that essentially all of the material passes through the 
recirculation pump. 
SUMMARY OF INVENTION 
Prior to the discovery of this instantaneous process for the production of 
sodium bentonite UAN suspensions, no commercially feasible method was 
available to accomplish this production technology. Prior work did 
demonstrate the production of UAN suspensions from attapulgite clay using 
a chemical dispersant TSPP. Sodium bentonite clay could not be used 
without the incorporation of expensive sodium acid pyrophosphate 
dispersant in relatively large quantities and with a considerable water 
dilution which lowered the final grade of the UAN suspension. 
Several new and advantageous features of the instant process over 
conventional prior art processes are realized in the present invention. 
Among the advantageous features are: (a) the equipment required for the 
practice of the instant invention is simple, economical, and easy to 
operate. This process does not use chemical dispersants such as TSPP or 
SAPP which costs ten to twenty times as much as the UAN solution or the 
dry sodium bentonite clay; (b) sodium bentonite clay is the cheapest 
source of gelling clay in the midwestern United States since the mines are 
located in Wyoming and South Dakota; (c) the Midwest is also the area 
where the largest quantity of fertilizer suspensions are made and applied; 
(d) Sodium Bentonite has a higher gell strength in these UAN suspensions 
than does attapulgite or sepiolite clay; and (e) No dilution of the feed 
streams of normally 83 weight percent ammonium nitrate solution or 75 
weight percent urea solution is necessary in this process. The dry clay 
does not bring any water with it into the process as would be the case in 
the preparation of any predispersion of clay in water. With no additional 
water added in the process there would be energy savings in the production 
of any normally encountered grade of UAN suspension, 28 to 32 percent. Our 
new process is expected to greatly increase the amount of sodium bentonite 
clay which is used in suspension fertilizers. Prior to the discovery 
leading to the instant invention, there was not a practical production 
scheme for bentonite UAN suspensions. 
The gist underlying the concept of the instant invention is to effect the 
combination of the urea solution, ammonium nitrate solution, and bentonite 
clay, said clay preferably in the form of sodium bentonite, in a 
particular order or sequence. Although the exact reasons are not codified 
at this moment, we have discovered that, quite unexpectedly, we can 
directly combine these three ingredients to result in the production of 
suspensions eminently suitable for the normally intended uses thereof 
when, and only when, we combine the sodium bentonite and urea solution, 
preferably hot urea solution, and then after said combination and thorough 
mixing to insure dispersion of the clay homogeneously throughout said urea 
solution, the addition thereto of the ammonium nitrate solution. Any other 
sequence or permutation simply does not work. 
ALTERNATE EMBODIMENT 
To those skilled in the art reviewing the spread sheet illustration of the 
operating parameters of the instant invention infra, it should be 
abundantly clear that although the preferred operating range is at or near 
the eutectic composition of the three-phase system, urea, ammonium 
nitrate, and water, we have shown that if the need arises, the invention 
may be practiced with compositions and slurrys resulting therefrom over a 
wide spectrum. For instance, in a situation wherein it is desirable to 
have essentially an ammonium nitrate suspension, the instant invention may 
be practiced in the manner wherein as little as about 25 percent of the 
finished suspension is composed of the components urea solution and/or 
water and bentonite clay. On the other end of the spectrum wherein it is 
desired to have as high a grade nitrogen solution/suspension as possible 
made exclusively from urea as the input nitrogen source, there is proviso 
in the practice of our invention for such an embodiment by the simple 
expedience of leaving out the stream of ammonium nitrate normally fed 
thereto. Depending on the geographical location of the producer/user, 
under the practice of the prior art a straight urea solution fertilizer is 
oftentimes thought to be normally limited to about 18 percent to 21 
percent nitrogen by weight. In that same climatic environment by pursuing 
the practice of the instant invention, straight urea solution/suspension 
can be produced and fully utilized having from about 2 to 12 percentage 
points more nitrogen by weight than such straight urea solution supra, 
i.e., a urea suspension of about 23 or 30 weight percent nitrogen. This 
spread of about 2 to 12 percentage points of our straight urea 
solution/suspension over the prior art straight urea solution appears to 
hold throughout the range of geographical climatic conditions that would 
be encountered within the continental United States. For purposes of 
clarification, the solution/slurry designation supra is herein utilized 
for such urea compositions since in the production thereof there will be 
clay particles therein contributing to the suspension characteristics 
thereof. However, as those skilled in this art will realize, it is 
oftentimes important to adjust the weight percent of the urea therein as 
high as possible to effect a saturated solution when said solution is 
subsequently utilized in the intended and expected environment, but not so 
high as to exceed saturation or super saturation and cause the nucleation 
and precipitation of any substantial amounts of urea crystals therein 
since the occurrence thereof will deleteriously effect the handling and 
storage characteristics of such materials. 
OBJECTS OF THE INVENTION 
A primary object of the instant invention is to discover and develop a 
method, means, and/or process that would use the hot concentrated streams 
of urea and ammonium nitrate normally produced in a commercial production 
facility. As stated above, our new and novel process will readily utilize 
the 75 weight percent urea solution as well as the 83 weight percent 
ammonium nitrate solutions produced in such a commercial facility at about 
190.degree. F. Our process can utilize feed temperatures in the range of 
from about said 190.degree. F. down to about ambient temperatures, i.e., 
about 80.degree. F. This is an important consideration and advantage over 
processes using attapulgite clay as the gelling agent when it is 
remembered that attapulgite clay's gelling properties are reduced by 
temperatures above about 140.degree. F. Sodium bentonite, on the other 
hand, is not temperature sensitive in these temperature ranges. Another 
object of the instant invention is that our newly discovered process 
eliminates the use of expensive chemical dispersants, such as sodium acid 
pyrophosphate. Still another object of the instant invention is to replace 
the use of attapulgite clay fertilizer suspensions produced in and for the 
Midwest by cheaper sodium bentonite clay which is mined nearby. 
Still further and more general objects and advantages of the present 
invention will appear from the more detailed description set forth below, 
it being understood, however, that this more detailed description is given 
by way of illustration and explanation only, and not necessarily by way of 
limitation since various changes therein may be made by those skilled in 
the art without departing from the true spirit and scope of the present 
invention.

DESCRIPTION OF THE DRAWING 
The present invention will be better understood from a consideration of the 
following description taken in connection with the accompanying drawing. 
The initial flow scheme for the production of urea ammonium nitrate 
suspension from attapulgite clay is depicted in the proceedings of the 
10th Demonstration, Tennessee Valley Authority, National Fertilizer 
Development Center, entitled New Developments in Fertilizer Technology, 
Oct. 1-2, 1974, Muscle Shoals, Ala., pages 47 and 48. In this initial 
process a small feed tank receives water and tetrasodium pyrophosphate to 
produce a TSPP water solution. A dry clay feeder introduces attapulgite 
clay along with the TSPP water solution to a clay dispersion mix tank. The 
clay dispersion is fed to a gellation tank along with concentrated urea 
ammonium nitrate solution fed from the UAN solution storage tank. The 
concentrated UAN solution when mixed with the clay dispersion produced the 
on-grade UAN suspension containing 2 percent clay. 
The hot mixing scheme used to produce attapulgite clay UAN suspensions, 
which is an improvement of the cold flow process just supra, is depicted 
in the proceedings of the 12th Demonstration, Tennessee Valley Authority, 
National Fertilizer Development Center, Muscle Shoals, Ala., entitled New 
Developments in Fertilizer Technology, Oct. 18-19, 1978, pages 74-79, see 
particularly pages 76 and 78. In this process bagged tetrasodium 
pyrophosphate and water are added to the TSPP solution tank wherein the 
resulting TSPP solution is heated to 160.degree. F. with steam. The hot 
solution is fed to the dilution funnel along with a urea solution which 
urea solution is maintained at a temperature of about 194.degree. F. The 
resulting hot urea TSPP solution is then fed to the dispersing tank along 
with dry clay fed from the clay feeder. The resulting hot water urea clay 
TSPP mixture is then fed to the gelling tank where said solution is mixed 
with UAN solution. The final UAN suspension product is then mixed with a 
corrosion inhibitor. 
For purposes of teaching, disclosing, and claiming the instant invention, 
the teachings and disclosure in both of said 10th and 12th TVA 
Demonstrations supra are herewith and hereby incorporated herein by 
reference thereto. Said references are also noted in both our Field of the 
Invention section, as well as in our Description of the Prior Art supra. 
Referring now specifically to the FIGURE, there is shown one embodiment of 
our new process which can be used for the production of concentrated UAN 
sodium bentonite suspensions. Urea solution 1 is metered through a flow 
meter 2 into dispersion tank 4. Dry sodium bentonite 3 is also added to 
dispersion tank 4 which is agitated by means of agitator 5 and 
recirculating pump 6. The resulting well-mixed hot urea solution, urea 
crystals (if cooling is effected therein to a sufficient degree) and 
dispersed sodium bentonite clay is fed via line 7 to mix tank 10 which is 
agitated by agitator 11. Subsequently, and this is of the utmost 
importance, mix tank 10 receives hot ammonium nitrate solution 8 metered 
through flow meter 9. Optionally, inhibitor 12 metered through flow meter 
13 may also be introduced to mix tank 10. The final urea ammonium nitrate 
sodium bentonite suspension is directed by means of pump 14 to storage 
tank 15. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The instant improved process relates to preparing UAN suspension with dry 
sodium bentonite clay. Although it has been known for many years that dry 
bentonite clay cannot be added directly to solutions such as UAN, our new 
improved process relies on an unexpected result obtained in laboratory 
research. As illustrated in Table VI, Example V infra, dry sodium 
bentonite clay was successfully added to hot concentrated urea solution 
with the urea solution serving as a dispersant for the dry sodium 
bentonite clay. Our new, novel, and heretofore unknown method relies on 
our discovery that bentonite clay can be effectively directly utilized in 
UAN suspensions if, and only if, it is added directly to the warm 
(80.degree. F.+) or hot (&gt;80.degree. F.+ up to about 260.degree. F.) urea 
solution, intimately mixed therewith and subsequently admixed with the 
warm or hot ammonium nitrate solution. The instant, new, novel, and 
improved process of the instant invention also does not need a side stream 
of urea, expensive chemical dispersant, clay, and water. Our new, improved 
process enables eutectic compositions of urea ammonium nitrate to be 
closely maintained. Our new process can be directly incorporated to 
existing commercial production plants producing 28 percent, 30 percent, or 
32 percent eutectic urea ammonium nitrate solution. 
With a successful demonstration of this process in laboratory test and with 
success in production of 5-gallon quantities of of the sodium bentonite 
UAN suspensions in the pilot plant, commercial test were arranged. The 
results of these tests are shown in Table I below. 
TABLE I 
______________________________________ 
Commercial Production 
UAN Sodium Bentonite Suspension 
29-0-0-2C 
______________________________________ 
Test Number 1 2 3 4 
Batch Size, tons 6 6 6 8 
Formulation, lb/ton 
(in order of addition) 
Urea Solution, 75%, 162.degree. F. 
960 960 960 960 
Dry Sodium Bentonite Clay 
40 40 40 40 
A/N Solution, 71%, 160.degree. F. 
1000 1000 1000 1000 
Mixing Times, min. 
After clay addition 
5 4 25 20 
After A/N Solution addition 
15 2 5 5 
Final Temperature, .degree.F. 
Urea-clay-water mixture 
158 158 150 152 
Mix Tank Agitator Used 
yes yes yes yes 
Recirculation Pump Used 
no yes yes yes 
Passes through Pump.sup.a 
-- 2.5 12 10 
Initial Viscosity.sup.b, cps, 80.degree. F. 
70 160 610 400 
1 Week Viscosity.sup.b, cps, 80.degree. F. 
65 155 410 285 
1 Week Gel Strength.sup.c g-cm, 80.degree. F. 
1 3.5 11 6 
______________________________________ 
.sup.a Pump Capacity 275 gpm 
.sup.b Measured with Brookfield Viscometer, Model RVT, 100 rpm Spindle No 
4 
.sup.c Measured with gelometer. 
A total of 26 tons of 29-0-0-2 weight percent sodium bentonite clay 
material was produced. These commercial tests were carried out in a 
production facility which contained an 8-ton capacity mix tank. Tests 4 
and 3 show that even with a low number of pump passes, i.e., 10 and 12 
respectively, good quality UAN suspension was produced. The direct 
addition of dry clay to hot urea solution was employed. In this commercial 
test work, transport trucks were used to bring the hot urea and hot 
ammonium nitrate solution to the test facility 75 miles from the 
commercial nitrogen solution production facility. Although 71 weight 
percent ammonium nitrate solution was used in these tests, normally 
produced 83 percent ammonium nitrate solution could be used in 
large-scale, continuous commercial production. Plans are being made to 
produce large quantities of UAN sodium bentonite clay suspensions in 
continuous processing. 
EXAMPLES 
In order that those skilled in the art may better understand how the 
present invention can be practiced, the following examples are given by 
way of illustration only and not necessarily by way of limitation, since 
numerous variations thereof will occur and will undoubtedly be made by 
those skilled in the art without substantially departing from the true and 
intended scope of the instant invention herein taught and disclosed. 
It is respectfully noted that Examples I-VI infra are set forth somewhat in 
the nature of a chronological development. Some of the background involved 
work by ourselves, while portions thereof reflect the work of other 
engrossed in developments relating to improving the state of the art for 
the production of suspension fertilizers, and in particular, urea ammonium 
nitrate suspensions. In this sense, these examples tend to trace some of 
the evolution of this art. We could add a plethora of additional examples 
offered for purposes of negation to illustrate that unless the specific 
procedures discovered by us and now set forth, taught, described, 
illustrated, and recited in the claims appended hereto are followed, the 
objectives of the instant invention can not be achieved. For example, we 
could include data showing what would happen if the sodium bentonite is 
added to the ammonium nitrate solution warm or hot rather than being added 
directly to the warm or hot urea solution. We also could offer numerous 
examples of the deleterious effects of adding the ammonium nitrate 
solution to the urea solution prior to the proper dispersal of the sodium 
bentonite in said urea solution alone. However, we believe that we have 
made our point that if such variations just mentioned are made from the 
specific dictates taught and recited herein, then those practicing in such 
unprescribed manner will find, as we have, that sodium bentonite can not 
be directly applied in the production of urea ammonium nitrate suspension. 
Indeed, the only viable alternative to preparing such urea ammonium 
nitrate suspensions is to literally give up altogether on the utilization 
of bentonite clay therein and revert back to the use of the less desirable 
clay mineral attapulgite and then only unless one reverts to the 
heretofore illustrated and described rather expensive remedies developed 
in the evolution of the prior art, to wit, the use of less desirable 
attapulgite clay in combination with rather expensive dispersants such as 
TSPP or SAPP. The exact mechanism that comes into play when the steps and 
order thereof of our process are practiced and which effects for the first 
time the utilization of bentonite as a gelling and/or suspending clay 
material in the production of ammonium nitrate suspensions, is not 
completely known to us at this time. What is known to us, however, is that 
the bentonite must be mixed with the warm or hot urea solution before 
either of these materials contact the warm or hot ammonium nitrate. For 
purposes of edification, we have spoken of warm or hot solutions of urea 
and ammonium nitrate. Those skilled in the art, of course, realize that at 
least to the material urea solution that for all practical purposes they 
must be worked with at temperatures elevated above ambient in order that 
the viscosity thereof is sufficiently decreased to provide for easy and 
thorough mixing of the sodium bentonite therein. Since in this instance of 
one embodiment of the instant invention the use of urea solution is being 
contemplated, the problem of urea melts freezing is not one of concern and 
therefore, theoretically, accomplishment of dispersal of the bentonite 
clay in the urea solution could be effected if enough time were available 
and energy were expended at the temperatures near ambient. However, since 
the urea solutions oftentimes are directly available at elevated 
temperatures from the urea ammonium nitrate production facilities, it is 
strongly urged that they be utilized at said elevated temperatures for 
purposes of bentonite clay dispersal therein. 
EXAMPLE I 
Several years ago researchers began studying the use of sodium bentonite 
clay in currently existing suspension fertilizer systems. As the data in 
Table II below indicates, sodium bentonite showed very high gel strengths 
in urea ammonium nitrate, ammonium polyphosphate and ammonium 
ortho-phosphate suspensions when compared with the same suspensions made 
with attapulgite or sepiolite clays. The one problem, though, was that the 
sodium bentonite has to be added to the suspension as a 12 weight percent 
clay dispersion. The water of dilution in the final grade made such a 
production scheme commercially unattractive. 
TABLE II 
______________________________________ 
Comparison of Various Clays as Suspending Agents 
in Fluid Fertilizers 
Final Grade 
Clay Gel Viscosity,.sup.c 
Pour- 
Suspension.sup.a 
Content, Strength,.sup.b 
at 80.degree. F. 
ability,.sup.d 
(Initial Grade) 
wt % g-cm (28.degree. C.), cP 
vol % 
______________________________________ 
Attapulgite clay 
27.1-0-0 1.5 3.8 250 100 
(31-0-0 UAN) 
10.5-33.3-0 
1.5 0.8 250 100 
(12-38-0 APP) 
11.4-33.3-0 
1.5 6.8 750 100 
(13-38-0 AOP) 
Sepiolite clay 
27.1-0-0 1.5 2.3 200 100 
(31-0-0 UAN) 
10.5-33.3-0 
1.5 0.4 250 100 
(12-38-0 APP) 
11.4-33.3-0 
1.5 4.5 550 100 
(13-38-0 AOP) 
Sodium Bentonite 
Clay 
27.1-0-0 1.5 11.0 410 100 
(31-0-0 UAN) 
10.5-33.3-0 
1.5 12.0 900 100 
(12-38-0 APP) 
11.4-33.3-0 
1.5 8.7 750 100 
(13-38-0 AOP) 
______________________________________ 
.sup.a Initial grades were mixed with 12 wt % clay dispersions in water. 
.sup.b Fresh product "as is" gel strength determined as the initial 
measurement by gelometer. 
.sup.c Viscosity measured with Brookfield Model LVT viscometer operating 
at 60 r/min using a No. 3 spindle. Viscosity in Pa = cP/1,000. 
.sup.d After mild agitation supplied by gently passing stirring rod aroun 
inside of container. 
EXAMPLE II 
Summarized herein in Table III below are tests that were made to find the 
best dispersing agent for use with sodium bentonite clay. Sodium acid 
pyrophosphate is the chemical dispersing agent of choice when using sodium 
bentonite clay. 
TABLE III 
______________________________________ 
Comparison of Phosphate Dispersing Agents in 
10 Wt Percent Dispersions of Sodium Bentonite.sup.a 
Concentration 
Viscosity 
Dispersing Agent Wt % cps 
______________________________________ 
Sodium tripolyphosphate (STPP) 
2 150 
STPP 1 290 
STPP 0.5 6025 
Sodium acid pyrophosphate (SAPP) 
2 130 
SAPP 1 165 
SAPP 0.5 202 
______________________________________ 
.sup.a American Colloid AgroGel-S .RTM. (FD181) 
EXAMPLE III 
Some of the work that was done to determine the proper amount of SAPP that 
should be added to the sodium bentonite clay water mixtures is shown in 
Table IV below. A 10 weight percent mixture of sodium bentonite clay 
containing 0.6 percent SAPP with the remainder being water gave good 
results. Two problems hamper the commercial use of such a 10 percent clay 
dispersion. The SAPP costs almost twenty times as much as the clay and the 
89.4 percent water content would seriously dilute the final grades of 
suspensions. 
TABLE IV 
__________________________________________________________________________ 
Effect of Concentration of Sodium Acid Pyrophosphate (SAPP) 
in 10 Wt Percent Dispersions of Sodium Bentonite 
89.5% Water 
89.5% Water 
89.4% Water 
89.25% Water 
89.0% Water 
10.0% FD-181.sup.a 
10.0% FD-181 
10.0% FD-181 
10.0% FD-181 
10.0% FD-181 
0.5% SAPP 
0.5% SAPP 
0.6% SAPP 
0.75% SAPP 
1.0% SAPP 
__________________________________________________________________________ 
Initial viscosity.sup.b 
360 340 250 250 185 
(70.degree. F.) cps 
1 week viscosity 
550 550 350 300 150 
(70.degree. F.) cps 
1 week pourability.sup.c 
-- 95 95 95 -- 
(70.degree. F.) % 
1 week viscosity 
-- 600 380 290 -- 
(35.degree. F.) cps 
1 week pourability 
-- 95 95 95 -- 
(35.degree. F.) % 
1 month viscosity 
1040 740 480 470 670 
(70.degree. F.) cps 
1 month pourability 
95 95 98 98 98 
(70.degree. F.) % 
not uniform.sup.d 
not uniform 
1 month viscosity 
-- 550 360 320 -- 
(35.degree. F.) cps 
1 month pourability 
-- 90 95 97 -- 
(35.degree. F.) % 
not uniform 
__________________________________________________________________________ 
.sup.a American Colloid sodium bentonite AgroGel-S 
.sup.b Brookfield Viscometer RVT, 100 rpm, Spindle No. 3, &lt;1000 cps, 
Spindle No. 4, &lt;2000 cps 
.sup.c Pourability the percent that pours after a stirring rod is moved 
two complete turns around the inside of the jar and the jar is tilted to 
45.degree. angle for 30 seconds 
.sup.d Not uniform pours in blobs 
EXAMPLE IV 
In this example data, which is summarized in Table V below, indicates good 
results that were obtained when sodium bentonite clay was used in 
suspensions produced from MAP. The initial and one week viscosities are 
comparable when the 11-33-0 and 7-21-0 suspensions are compared, having 
been made either with attapulgite or bentonite clays. This earlier 
research shows that bentonite clay performs well in fluid fertilizer 
suspensions but the problem is how to incorporate the sodium bentonite 
clay into these suspensions. 
TABLE V 
______________________________________ 
Comparison of MAP Suspensions Using Attapulgite 
and Sodium Bentonite Clays 
7-21-0-1.0 
Grade 11-33-0-1.0 Clay 
Clay 
______________________________________ 
Raw Materials 
Water 396 216 360 180 896 716 
Attapulgite 20 -- 20 -- 20 -- 
10% FD-181.sup.b, 1% SAPP 
-- 200 -- 200 -- 200 
11-55-0 MAP 1200 1200 -- -- -- -- 
11-52-0 MAP -- -- 1270 1270 -- -- 
10-50-0 MAP -- -- -- -- 840 840 
23-0-0 aqua ammonia 
384 384 350 350 244 244 
Initial viscosity 
280 310 260 260 280 270 
(70.degree. F.) cps 
1 week viscosity 
500 440 380 440 210 330 
(70.degree. F.) cps 
1 week pourability 
98 98 98 98 98 98 
(70.degree. F.) % 
1 week liquor layer 
0 1 0 0 0 0 
(70.degree. F.) % 
1 week viscosity 
470 570 720 870 210 260 
(35.degree. F.) cps 
1 week pourability 
98 98 98 98 98 98 
(35.degree. F.) % 
1 week liquor layer 
0 1 0 0 0 0 
(35.degree. F.) % 
______________________________________ 
.sup.a All samples contain 1 wt percent clay 
.sup.b American Colloid AgroGel-S .RTM., sodium bentonite clay 
EXAMPLE V 
With an effort to find the commercially feasible, advantageous way to add 
sodium bentonite to these suspensions, tests were made to see if the dry 
sodium bentonite clay could be dispersed into hot urea solution. The 
results were unexpectedly good and are shown below in Table VI infra. In 
this example, laboratory data shows the effect of the addition of the dry 
bentonite clay to 180.degree. F., 75 weight percent urea solution. This 
discovery is considered a major breakthrough in the widespread use of 
sodium bentonite clay in suspensions. Fluid fertilizer materials 
containing already gelled clay are very popular with retail fluid 
fertilizer dealers. On the other hand suspensions made with attapulgite 
clay have been well received by fluid fertilizer dealers, but until our 
discovery there literally was no commercially feasible way to introduce 
sodium bentonite into fluid fertilizers. 
TABLE VI 
______________________________________ 
Urea Ammonium Nitrate Suspensions Using Bentonite Clay.sup.a 
Pounds Per Ion 
31-0-0-2.0 
30.8-0-0- 
30.6-0-0- 
Raw Materials Clay 2.5 Clay 3.0 Clay 
______________________________________ 
Water 232 230 230 
Urea (46% N) 696 690 685 
Bentonite clay 40 50 60 
Water 174 175 175 
Ammonium nitrate (35% N) 
858 855 850 
Initial viscosity (cps) (70.degree. F.) 
850 950 840 
2 week viscosity (cps) (70.degree. F.) 
290 320 320 
2 week pourability (%) (70.degree. F.) 
100 100 100 
2 week liquor layer on bottom 
30 25 20 
(%) (70.degree. F.) 
2 week gel strength 
19.9 19.0 17.3 
(g-cm) (70.degree. F.) 
4 week viscosity (cps) (35.degree. F.) 
220 210 210 
4 week pourability (%) (35.degree. F.) 
100 100 100 
4 week liquor layer on bottom 
30 25 20 
(%) (35.degree. F.) 
6 week viscosity (cps) (70.degree. F.) 
250 260 275 
6 week pourability (%) (70.degree. F.) 
100 100 100 
6 week liquor layer on bottom 
30 25 20 
(%) (70.degree. F.) 
______________________________________ 
.sup.a American Colloid's AgroGel-S 
EXAMPLE VI 
The UAN-Bentonite clay suspensions in Table VI supra were then tried in a 
very difficult X:O:X grade suspension fertilizer. Shown below in Table VII 
are the results when 18-0-18 suspensions were made from the urea ammonium 
nitrate sodium bentonite suspensions. Although there was some liquor layer 
on the bottom of the samples containing 1.2 and 1.5 percent clay, this is 
not considered a problem. The gels formed with sodium bentonite clay are 
so strong that when air bubbles are trapped in them they will rise 
somewhat from the bottom of their containers. Although there was a little 
bit of rising of the gel, the potash crystals were maintained in the gel. 
TABLE VII 
______________________________________ 
18-0-18 Suspensions from Urea Ammonium Nitrate Suspensions 
Using Bentonite Clay.sup.a 
Pounds Per Ton 
18-0-10- 18-0-18- 18-0-18- 
Raw Materials 1.2 Clay 1.5 Clay 1.8 Clay 
______________________________________ 
Water 257 250 242 
31-0-0-2 clay 1162 -- -- 
30.8-0-0-2.5 clay -- 1169 -- 
30.6-0-0-3 clay -- -- 1177 
0-0-62 581 581 581 
Initial viscosity (cps) (70.degree. F.) 
300 540 460 
1 week viscosity (cps) (70.degree. F.) 
450 700 570 
1 week pourability (%) (70.degree. F.) 
85 98 98 
1 week liquor layer on bottom 
20 30 3 
(%) (70.degree. F.) 
1 week crystal settling 
nil nil nil 
______________________________________ 
.sup.a American Colloid's AgroGel-S 
INVENTION AMETERS 
After sifting and winnowing through the data supra as well as other results 
and operations of our new, novel, and improved method for effecting the 
production of sodium bentonite-UAN suspensions without chemical 
dispersants, we now present the principal operating parameters and 
variables, it being understood that other variables, as considered and 
discussed supra may alone, or in various combinations be additional viable 
operation considerations and parameters. 
______________________________________ 
Invention Parameters 
Most 
Variables Limits Preferred 
Preferred 
______________________________________ 
Feeds 
Urea Solution 
% Concentration 10-88 70-80 75 
Temperature, .degree.F. 
80-260 140-180 160 
Ammonium Nitrate Solution 
% Concentration 1-100 70-85 83 
Temperature, .degree.F. 
32-340 90-170 160 
Mixing Times 
Urea Solution-Clay, min 
5-30 20-30 30 
Urea Solution-Clay- 
5-30 5-10 10 
Ammonium 
Nitrate Solution, min 
Agitation of urea solution-clay 
Tip Speed of Agitator, ft/sec 
20-100 80-100 100 
Tip Speed of Pump 
20-100 80-100 100 
Impeller, ft/sec 
Passes thru Pump 10-40 30-40 40 
Product 
Concentration, % N 
15-38 28-32 30 
Concentration, % Ammonium 
0-75 40-45 42 
Nitrate 
Concentration, % Urea 
10-65 30-35 33 
Concentration, % Water 
15-68 20-30 25 
Concentration, % Clay 
0.5-6 1-3 2 
Viscosity (cps, 80.degree. F.) 
100-2000 300-600 400 
Gel Strength, (gm-cm, 80.degree. F.) 
1-20 10-20 10 
Pourability (%) 95-100 98-100 100 
Saturation Temperature, .degree.F. 
0-120 10-30 20 
Product Use 
Urea-Ammonium Nitrate 
Sodium 
Bentonite Suspension in X-O-Y 
Grade Final Suspension 
X, % N 3-36 3-36 -- 
Y, % K.sub.2 O 3-36 3-36 -- 
______________________________________ 
While we have shown and described particular embodiments of our invention, 
modifications and variations will occur to those skilled in the art. We 
wish it to be understood, therefore, that the appended claims are intended 
to cover such modifications, and variations which are within the true 
scope and spirit of our invention.