Batch production of suspension fertilizers using lignosulfonate

In the production of suspension fertilizers the addition of an additive comprising lignosulfonate to the wet-process acid prior to the ammoniation step prevents severe thickening of the suspension during its formation, which severe thickening is normally associated with in situ mass crystallization of monoammonium phosphate and which mass crystallization results in (1) the total prevention of further ammoniation of said acid or, at the very least, extremely slow further ammoniation thereof, and/or (2) excessive ammonia losses. Also, addition of said lignosulfonate to the acid prevents the formation of metallic impurity gel-like compounds which cause extremely high viscosities, nonpourability, and complete destruction of fluidity.

INTRODUCTION 
The present invention relates to an improved method for the production of 
high-analysis ammonium orthophosphate suspension fertilizers of high 
quality from low-cost impure raw materials by a simple, economical batch 
type process. In particular, the present invention relates to a novel, 
economical method for ammoniation of wet-process impure orthophosphoric 
acid, using a batch process resulting in production of high-analysis 
ammonium phosphate suspension fertilizers. More particular, the present 
invention relates to means and methods of the direct ammoniation of 
wet-process acids to produce high-grade suspension of high quality with 
excellent long-term storage characteristics such as low viscosity and high 
pourability by a simple, economical batch process. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Heretofore, suspension fertilizers produced by the direct ammoniation of 
merchant-grade wet-process orthophosphoric acids in batch equipment were 
required to be of low grade because the acids had to be considerably 
diluted with water (i.e., from about 54% down to about 25-30% P.sub.2 
O.sub.5) prior to the ammoniation step to prevent severe thickening caused 
by a combination of excessive crystallization of monoammonium phosphate 
(MAP) and metallic impurity gel formation during the ammoniation step. 
Although pure mineral acids, such as for example, phosphoric acid 
theoretically have a pH of about 0, the commercial acids normally utilized 
in fertilizer production have initial pH's ranging anywhere between about 
0.1 to about 0.5. These higher than theoretical initial or "bottom" pH's 
are due, at least in part, to the congeneric impurities in such impure 
acids. Also, heavy ammonia losses occurred if the acids were not of the 
proper dilution because the slurry would "set up" in the pH range of 2 to 
4. Suspension fertilizers with such low analysis (such as 8-24-0) have a 
very distinct economic disadvantage as compared with higher analysis 
products because the costs of handling, freight, storage, and application 
are higher per unit of plant nutrient. 
In order to obtain higher grades, the phosphoric acid had to be added to a 
heel from a previous batch equal to at least 33 percent of the total batch 
volume. The heel increased the pH and avoided severe complications caused 
by the excessive crystallization of monoammonium phosphate and metallic 
impurity gel formation during the ammoniation step. The use of a heel in 
this large volume percentage (33% or higher) of the total batch volume 
would be detrimental for batch-plant sizing and cycle times. 
2. Description of the Prior Art 
The art of producing fluid fertilizers, both liquids and suspensions, is 
well known and fully described in the literature. 
The most common method of producing both liquid and suspension fertilizers 
containing nitrogen and phosphate is by the ammoniation of phosphoric 
acids or slurries of solid products derived therefrom, such as, for 
example, monoammonium phosphate. However, only in recent years was 
suitable technology developed for the production, from impure phosphoric 
acids or satisfactory concentrated orthophosphate suspension fertilizers, 
by methods which overcome the effect caused by the formation of the 
metallic impurity gel-like compounds, which compounds normally tend to 
destroy the fluidity of concentrated ammonium orthophosphate suspension 
fertilizers. Until the development of the latest technology, the only way 
known for increasing the fluidity of such orthophosphate suspensions was 
by means of dilution of same with water, which, of course, reduced the 
grades thereof. 
In U.S. Pat. No. 3,019,099, Walters, Jan. 30, 1962, assigned to the 
assignee of the present invention, produced a low-analysis (8-24-0 grade) 
ammonium orthophosphate suspension fertilizer by both batch- and 
continuoustype ammoniation of wet-process orthophosphoric acids. In the 
preparation of this suspension fertilizer product, Walters recognized that 
the impurities in the acid imparted a thixotropic characteristic causing 
higher grade suspension fertilizers to be excessively viscous. Walters 
used the gel-like impurity compounds for prevention of sedimentation in 
his suspension fertilizer products. Later in U.S. Pat. Nos. 3,109,729, 
Slack et al., Nov. 5, 1963 and 3,113,858, Slack et al., Dec. 10, 1963, 
both assigned to the assignee of the present invention, produced NPK 
suspension fertilizers in which they added both polyphosphate, for 
increasing the grade, and clay as both a nucleating and suspending agent. 
In U.S. Pat. No. 3,813,233, Kendrick, May 28, 1974, assigned to the 
assignee of the present invention, fully described the techniques and 
conditions under which ammonia can be reacted with impure wet-process 
orthophosphoric acid without producing the gel-like impurity compounds 
that previously completely destroyed the fluidity of such high-grade 
orthophosphate suspension products. Kendrick's teachings were based 
primarily on ammoniation of the impure wet-process acid in two continuous 
stages or steps and, through the techniques he developed, he was able to 
make much higher grade products (e.g., 11-39-0 versus 10-30-0) with good 
flow characteristics and longer static storage life than had theretofore 
been possible. Kendrick also made similar products by a batch-simultaneous 
procedure which he indicated did not work quite as well as did his 
continuous process. However, when products that were made by Kendrick's 
teachings were shipped by rail, the solid portion of the suspensions 
settled and packed. The resulting packed crystals held tenaciously to the 
bottom of the railroad tank cars. In U.S. Pat. No. 4,066,432, Jones, Jan. 
3, 1978, assigned to the assignee of the present invention, found that 
settling of the crystals changed the composition of the fluid, and the 
packed crystals could not be removed from the tank by ordinary procedures, 
thereby greatly reducing the value of the suspension fertilizer. Using 
this phenomenon, Jones developed a three-stage, continuous-type process 
for the production of satisfactory high-analysis suspension fertilizers 
(e.g., 13-38-0) by the ammoniation of wet-process orthophosphoric acid 
under conditions wherein gel-like impurity compounds were not formed. In 
the materials produced by the teachings of Jones supra, the resulting 
crystals did not settle and pack due to the application thereto of 
vibrational energy such as that which occurs during shipment by rail. In 
U.S. Pat. No. 4,511,388, Jones et al., Feb. 27, 1984, assigned to the 
assignee of the present invention, developed a batch-type process for 
production of satisfactory high-analysis suspension fertilizers (e.g., 
13-38-0) by the direct ammoniation of impure wet-process orthophosphoric 
acid. The process developed by Jones et al. in '388 supra consisted of 
leaving a heel of hot product in the reactor from a previous batch equal 
to at least 33 percent of the total batch volume. The hot heel served to 
prevent severe thickening or near solidification due to mass 
crystallization of monoammonium phosphate salts in the pH region of about 
2 to 4 during the ammoniation step and provided the nuclei and environment 
in the reactor for effecting the production of metallic impurity crystals 
instead of the gel-like impurity compounds which normally cause complete 
destruction of fluidity. However, until the present time, all efforts to 
produce high-analysis ammonium orthophosphate (N:P.sub.2 O.sub.5) base 
suspensions (e.g., 12-36-0, 1.5% clay) with satisfactory physical 
properties by the direct ammoniation of wet-process orthophosphoric acid 
in simple, economical batch equipment, instead of the more expensive and 
more complicated batch procedure described by Jones in '388 supra, have 
been unsuccessful. 
SUMMARY OF THE INVENTION 
The present invention relates to an improved batch-type method for the 
production of high-analysis (N:P.sub.2 O.sub.5) suspension fertilizers 
effected by the direct ammoniation of wet-process orthophosphoric acids or 
slurries of solids produced from such acids. The instant method involves 
the addition of a lignosulfonate, including water-soluble metal or 
ammonium salts of lignosulfonic acid, or both, such as for example calcium 
lignosulfonate, but preferably ammonium lignosulfonate, to the feed acid 
prior to the ammoniation step. The ammonium lignosulfonate (ALS), in 
essence, is a by-product of the paper industry and thereby plentiful and 
inexpensive. The ALS was obtained from about a 25 percent solution and 
contained 1.8 percent nitrogen and 3 percent sulfur. The lignosulfonate 
additive allows the wet-process acid to be directly ammoniated through the 
pH range of 2 to 4 without severe thickening or solidifying as mass 
crystallization of monoammonium phosphate occurs. The lignosulfonate 
additive also prevents metallic impurity gel-like compounds, which 
normally cause the complete destruction of fluidity in high-analysis 
orthophosphate suspensions, from forming during production and/or storage. 
Although lignosulfonates are known in the literature, no mention has been 
noted for use of ammoniation of wet-process orthophosphoric acid or 
improvement of the storage characteristics of suspension fertilizers. 
OBJECTS OF THE INVENTION 
It is therefore the principal object of the present invention to provide a 
simple, economical batch-type process for the production of high-analysis, 
high-quality orthophosphate suspension fertilizers from low-cost raw 
materials, such as ammoniation of wet-process or other impure phosphoric 
acids. 
Another object of the present invention is to produce concentrated 
free-flowing suspension fertilizers by a simple, economical batch process 
that can be used by small or large fertilizer producers alike and can be 
operated under conditions that prevent mass crystallization of 
monoammonium phosphate that normally causes intolerable slowing down or 
stoppages in the ammoniation procedure. 
A still further object of the present invention is to produce high-grade 
ammonium orthophosphate suspension fertilizers under conditions that 
prevent formation of gelatinous metallic impurity compounds, which 
compounds cause intolerably high viscosities, nonpourability, and complete 
destruction of the fluidity of concentrated ammonium orthophosphate 
suspension fertilizers during production and/or storage. 
Still a further object of the present invention is to develop a process 
which economically produces high-grade orthophosphate suspension 
fertilizers from low-cost materials by a simple batch-type process without 
sacrifice in suspension quality, grade, or versatility. 
Still further and more general objects and advantages of the present 
invention will appear from the more detailed description set forth in the 
following descriptions and examples, 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 scope and spirit of the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In carrying out the objects of our invention in one form thereof, we have 
found that ammonium orthophosphate base suspension fertilizers with both 
high concentration and excellent physical properties can be produced by 
the direct ammoniation of impure wet-process orthophosphoric acids derived 
therefrom in a batch-type reactor containing a lignosulfonate additive, 
said additive including water-soluble metal or ammonium salts of 
lignosulfonic acid such as for example, calcium lignosulfonate, but 
preferably ammonium lignosulfonate added to said acid prior to the 
ammoniation step. We have found quite unexpectedly that the lignosulfonate 
additive serves as a "nucleation inhibitor" to prevent the normally 
encountered severe thickening or near solidification, due to mass 
crystallization of fertilizer salts (primarily monoammonium phosphate), in 
the pH range of about 2 to 4. We have found still further that the 
lignosulfonate additive prevents the metallic gel-like compounds from 
forming during production and/or storage. This is evidenced by the fact 
that the viscosity of the said produced ammonium orthophosphate 
suspensions decreased during their 60-day storage tests. Generally, 
metallic impurity gels would form in suspensions made by procedures 
outlined in the prior art that would completely destroy the fluidity of 
such suspension products. We have further discovered that the ammonium 
lignosulfonate additive is most effective as a "nucleation inhibitor" in 
the prevention of severe thickening or solidification of the resulting 
ammonium orthophosphate slurry as it is ammoniated through the pH range of 
about 2 to 4. This is evidenced by the fact that the loss of ammonia over 
the material in the reactor as it is ammoniated through the pH range 2 to 
4, is negligible. The amount of lignosulfonate additive (normally added as 
a 25% weight percent solution) can be varied up to about 10 percent of the 
total batch weight; however, the most efficient and most effective amount 
is generally as little as 2 percent, and usually no more than about 5 
percent of the total batch weight. This amount is very effective with most 
raw materials used and the grades of products produced. The cost of said 
lignosulfonates range from 1 to about 10 cents per pound and represents 
from about 20 cents to usually not more than about a few dollars per ton 
of product. 
EXAMPLES 
In order that those skilled in the art may better understand how the 
present invention may be practiced to effectively product high-grade 
orthophosphate suspension fertilizers with small crystals, good flow 
characteristics, and excellent storage properties, the following examples 
are given by way of illustration only and not necessarily by way of 
limitation. 
EXAMPLE I 
The tests comprising this example illustrate the differences in suspensions 
made by the normal batch-type process and batch-type process using a heel 
from ammonia and wet-process orthophosphoric acid with those prepared in 
accordance with the main embodiment of the present invention. 
High-quality phosphate base suspensions of 12-36-0 grade containing 2 
percent by weight of clay were produced by our new process by ammoniation 
of merchant-grade wet-process orthophosphoric acid derived from central 
Florida ore. The majority of the test work was carried out in a 50-pound 
batch pilot plant, while some tests were made in the laboratory on a 
smaller batch size scale. These suspensions were determined to be suitable 
for shipment and for long-term storage (6 months or longer). At this grade 
level, they are primarily intended for use in the subsequent production of 
various N-P.sub.2 O.sub.5 -K.sub.2 O ratio mixed-grade suspension products 
by well known cold-blending procedures, but can be, if desired, applied 
directly to the soil. 
The batch procedure for production of the base suspensions comprised the 
direct ammoniation of the acid using an additive of ammonium 
lignosulfonate. The amount of additive of ammonium lignosulfonate (an 
aqueous 25 weight percent solution) used in the tests was equal to about 5 
percent of the total batch weight. The ammonium lignosulfonate allowed the 
merchant acid to be ammoniated through the pH range of about 2 to 4 
without encountering severe complications caused by excessive 
crystallization of monoammonium phosphate. As ammoniation proceeded 
through this pH range of about 2 to about 4, no thickening or "set-up" of 
the slurry was evidenced nor was any ammonia loss noted due to the slurry 
being too thick; i.e., the slurry was fluid and easily handled during the 
entire batch cycle. 
In the batch procedure, ammonium lignosulfonate, wet-process acid, and 
water of formulation were added to the reactor with stirring. The mixture 
was then rapidly ammoniated to a pH of about 6.8 after which the hot 
slurry (230.degree. F.) was transferred to the cooler-clay mixer. In the 
cooler-clay mixer, the slurry was quickly cooled to the range of 
120.degree. to 140.degree. F. for production of an abundance of small 
monoammonium and diammonium phosphate crystals required for prevention of 
excessive crystal growth during storage. About 2 percent by weight of 
attapulgite clay was added to the slurry (120.degree. to 140.degree. F.) 
and gelled with a turbine-type agitator and recirculation pump to suspend 
the crystals. The total time required in these tests for the production of 
a 50-pound batch was about 25 to 30 minutes. 
The resulting product suspensions are compared in Table I infra along with 
similar suspensions that were produced by a batch-type process according 
to the teachings of Jones ('388 supra) as well as with suspensions of 
highest possible satisfactory grade produced by the normal prior art type 
single-stage batch process. 
Satisfactory base suspension fertilizers are required to have viscosities 
that do not exceed the limits of 1,000 centipoises at 80.degree. F. and 
1,500 centipoises at 32.degree. F. when measured with a Brookfield 
viscometer (Model RVT). They are also at least 98 percent pourable in one 
minute at both 80.degree. and 32.degree. F. and contain no large (+20 
mesh-850 micrometers) crystals. NOTE: Any references made herein to 
materials and/or apparatus which are identified by means of trademarks, 
tradenames, etc., are included solely for the convenience of the reader 
and are not intended as, or to be construed, an endorsement of said 
materials and/or apparatus. 
TABLE I 
______________________________________ 
Phosphate Base Suspension Fertilizers Made by 
Batch Ammoniation of Wet-Process Orthophosphoric Acid.sup.a 
Comparison of Products Made by Our New Batch Procedure.sup.b 
With Those Made Using Our Prior Art Procedure 
Initial After 30-day storage at 80.degree. F. 
Test viscosity.sup.d 
Viscosity,.sup.d 
Pourability,.sup.e 
No. Grade.sup.c 
at 80.degree. F., cP 
cP % by volume 
______________________________________ 
Batch-type process of the instant invention 
1 12-36-0 600 430 100 
2 11-37-0 600 550 100 
3 11-35-0 340 250 100 
Batch-type process using a heel.sup.f 
4 13-38-0 650 600 100 
5 12-36-0 300 350 100 
Normal batch-type process.sup.g 
6 12-36-0 1400 --.sup.h 0 
7 11-33-0 800 --.sup.h 0 
8 10-30-0 300 450 100 
______________________________________ 
.sup.a Derived from Central Florida phosphate ore. Contained 53.3% P.sub. 
O.sub.5, 3.8% SO.sub.4, 1.6% Al.sub.2 O.sub.3, 1.6% Fe.sub.2 O.sub.3, 0.9 
MgO, 1.1% F, and 0.7% CaO. 
.sup.b Process consisted of equipment shown in the FIGURE. 
.sup.c Suspensions in tests 1 and 3 contained 2% by weight of clay; in 
tests 2, 4, 5, 6, 7, and 8, products contained 1.5% by weight of clay. 
.sup.d Suspensions were mixed 5 minutes with a propellertype stirrer 
operating at a tip speed of 7 ft/s before measurements were made. 
.sup.e After agitation supplied by gently rotating a stirring rod twice 
around the inside of container. 
.sup.f Process described by Jones ('388 supra) in which the heel supplied 
about 33% of the total reactor volume. 
.sup.g Singlestage ammoniation process; batch time was about 25 minutes. 
.sup.h Products "set up" during storage. 
The results shown in Table I supra clearly indicate that the high-quality 
suspensions produced by our new batch process are about equal in grade and 
quality to those prepared by the more costly and involved batch process 
utilizing a heel (tests 4 and 5) and are significantly superior in grade 
and quality to those produced by the usual single-stage batch process 
(tests 6, 7, and 8). 
EXAMPLE II 
Phosphate base suspension fertilizers of 12-36-0 grade and, 2 percent clay, 
were produced by our new batch-type procedure from merchant-grade 
wet-process orthophosphoric acid derived from central Florida ore as 
described in Example I above. The formulation and operating conditions for 
production of such grade with good physical properties are shown in Table 
II infra. The physical properties both before and after 60 days of storage 
at 80.degree. and 100.degree. F. are shown in Table III infra for the 
product made by our new batch-type procedure. This example illustrated 
that 12-36-0 grade suspensions made by our new batch-type procedure were 
entirely satisfactory for direct application to the soil, for use in 
production of mixed suspension fertilizers (NPK) with various ratios and 
grades, and for long-term storage. 
TABLE II 
______________________________________ 
Operating Conditions for Production of l2-36-0, 2% Clay, 
Suspension Fertilizers from Merchant-Grade Wet-Process 
Orthophosphoric Acid by the Instant New Batch-Type Procedure 
______________________________________ 
Batch reactor feed, lb (kg) 
Ammonium lignosulfonate.sup.a 
25 (11) 
Water 117 (53) 
WPA (54% P.sub.2 O.sub.5) 
333 (151) 
Ammonia 73 (33) 
Temperature (boiling),.sup.b .degree.F. (.degree.C.) 
230 (110) 
Agitator tip speed, ft/s (m/s) 
33 (10) 
Mixing time, min 15 
Cooler 
Temperature,.sup.c .degree.F. (.degree.C.) 
130 (54) 
Clay added, lb (kg) 10 (4.5) 
Agitator tip speed, ft/s (m/s) 
33 (10) 
Mixing time, min 10 
Product (12-36-0, 2% clay) 
Batch size, lb (kg) 500 (227) 
Total batch time, min 25 
pH 6.8 
Specific gravity at 80.degree. F. (27.degree. C.) 
1.47 
Temperature (as sent to storage), 
100 (38) 
.degree.F. (.degree.C.) 
Initial viscosity,.sup.d cP (Pa.cndot.s) 
80.degree. F. (27.degree. C.) 
600 (0.6) 
32.degree. F. (0.degree. C.) 
1100 (1.1) 
Initial pourability,.sup.e % by volume 
80.degree. F. 100 
32.degree. F. 100 
Initial crystal size,.sup.f .mu.m 
625 
______________________________________ 
.sup.a Weight of ammonia lignosulfonate fed as 25% solution, weight basis 
ALS contained 1.8% N and 3% S. 
.sup.b Highest temperature to which the mixture reached during addition o 
anhydrous ammonia. Water loss due to boiling was about 58 pounds (26 kg). 
.sup.c Temperature to which suspension is cooled before addition of clay. 
.sup.d Measurements after agitating sample for 5 minutes with a 
propellertype stirrer operating at a tip speed of 7 ft/s. 
.sup.e Measurements after agitation supplied by gently rotating a stirrin 
rod twice around the inside of the container. 
.sup.f Limit, 850 .mu.m (20 mesh). 
TABLE III 
______________________________________ 
Physical Properties of 12-36-0, 2% Clay, Suspensions Made 
by Instant New Batch-Type Procedure from Wet-Process 
Orthophosphoric Acid (54% P.sub.2 O.sub.5).sup.a Derived from Central 
Florida Ore 
After quiescent storage for 60 days 
80.degree. F. 
100.degree. F. 
Initial Vis- Vis- 
viscosity.sup.b 
cosity.sup.b 
Pour- cosity.sup.b 
Pour- 
at 80.degree. F. 
at 80.degree. F. 
ability,.sup.c 
at 80.degree. F, 
ability.sup.c 
Grade cp cp % by vol 
cP % by vol 
______________________________________ 
11.6-35.8-0 
600 440 100 430 100 
______________________________________ 
.sup.a Contained 53.3% P.sub.2 O.sub.5, 3.8% SO.sub.4, 1.6% Al.sub.2 
O.sub.3, 1.6% Fe.sub.2 O.sub.3, 0.9% MgO, 1.1% F, and 0.7% CaO. 
.sup.b Suspensions were mixed 5 minutes with a propellertype stirrer 
operating at a tip speed of 7 ft/s before viscosity measurements were 
made. 
.sup.c Measurements after agitation supplied by gently rotating a stirrin 
rod twice around the inside of the container. 
EXAMPLE III 
Several tests were made to determine the optimum level of ammonium 
lignosulfonate (ALS) required to give a satisfactory operation and yield 
an acceptable product with good storage characteristics. In making the 
tests, variables such as the product grade, acid impurity level, N to 
P.sub.2 O.sub.5 weight ratio, and retention time (production time) that 
are known to have effects on viscosity and pourability were kept constant 
throughout the series. The product grade in all cases was 11-37-0 
containing 2 percent clay and the production time was 20 minutes. The 
amount of ALS added was varied in amounts up to 10 weight percent. 
Results obtained from these tests, shown in Table IV infra, indicate that 
the most preferred level of ALS added ranged from 3 to 5 weight percent as 
determined by viscosity and pourability measurements for both satisfactory 
operation and storage of the suspensions, as made by the procedure shown 
in Example I, supra. Suspensions containing less than 3 and more than 5 
weight percent ALS were either unsatisfactory because of high viscosity 
(&gt;1000 cP) or low pourability (&lt;98% by volume). 
TABLE IV 
______________________________________ 
Production of 11-37-0 Grade 2% Clay Suspension Fertilizers from 
Central Florida Wet-Process Orthophosphoric Acid.sup.a - Effect of 
Ammonium Lignosulfonate.sup.b Added on Quality of 
Suspension Product as Shown by Viscosity and Pourability 
Measurements 
As Produced After 30 days 
(80.degree. F.) of Storage 
Vis- Pour- Pour- 
ALS.sup.b 
cosity.sup.c 
ability.sup.d 
Evaluation 
Viscosity.sup.c 
ability.sup.d 
% by wt. 
cP % by vol. 
Temp., .degree.F. 
cP % by vol. 
______________________________________ 
0 900 100 80 1600 50 
100 &gt;2000 0 
1 700 100 80 900 100 
100 &gt;2000 0 
2 600 100 80 850 100 
100 1400 100 
3 600 100 80 500 100 
100 850 100 
4 650 100 80 500 100 
100 850 100 
5 650 100 80 600 100 
100 850 100 
7 700 100 80 600 100 
100 900 75 
10 750 100 80 650 100 
100 850 50 
______________________________________ 
.sup.a Contained 53.4% P.sub.2 O.sub.5, 2.1% Al.sub.2 O.sub.3, 1.8% 
Fe.sub.2 O.sub.3, 0.7% MgO, 1.2% F, 0.20% CaO, and 3.8% SO.sub.4. 
.sup.b 25% solution by weight basis. Contained 1.8% N and 3% S. 
.sup.c Suspensions were agitated for 5 minutes before measurements were 
made. 
.sup.d After agitation supplied by gently rotating a stirring rod twice 
around the inside of the container. 
INVENTION AMETERS 
After sifting and winnowing through the data supra, as well as other 
results and operations of our new, novel, and improved technique, 
including methods and means for the effecting thereof, the operating 
variables, including the acceptable, the preferred conditions, and the 
most preferred conditions for carrying out our invention are summarized 
below. 
______________________________________ 
Operating Most 
Range Preferred Preferred 
______________________________________ 
Reactor.sup.a 
Acid concentration, 
38-54 48-54 52-54 
% P.sub.2 O.sub.5, by wt. 
Temperature, .degree.F. 
200-230 220-230 225-230 
Lignosulfonate,.sup.b 
1-10 2-8 4-5 
% by wt. 
Retention time, min 
5-30 10-20 10-15 
N:P.sub.2 O.sub.5 weight ratio 
0.31:1-0.38:1 
0.32:1-0.36:1 
0.32:1-0.34:1 
Agitator tip speed, 
10-90 20-50 30-50 
ft/s 
pH (diluted 1:9 
6.0-7.2 6.5-7.0 6.8-7.0 
with H.sub.2 O) 
Cooler-Clay Mixer.sup.c 
Temperature, .degree.F..sup.d 
100-140 120-140 130-140 
Retention time, min 
5-30 5-20 5-10 
Clay added, 1-2.5 1.5-2.5 2 
% by weight 
Agitator tip speed, 
10-90 20-50 30-50 
ft/s 
______________________________________ 
.sup.a In production of suspension, the acid, water of formulation, and 
ammonium lignosulfonate are added to the reactor and ammoniated as quickl 
as possible. No odor of ammonia or thickening of the slurry was evidenced 
during the operation. 
.sup.b Ammonium lignosulfonate preferred. 
.sup.c In the second embodiment, no separate coolerclay mixer means is 
utilized and these condition are effected in the reactor means subsequent 
to the ammoniation of the feed acids or derivatives thereof. 
.sup.d For production of an abundance of ammonium phosphate crystals, the 
temperature of the cooler should not exceed about 140.degree. F. 
While we have shown and described particular embodiments of our invention, 
modifications and variations thereof 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.