Granular slow release fertilizer composition and process

A carrierless granular slow release fertilizer composition is prepared by spraying a urea-formaldehyde resin composition having a U/F molar ratio ranging from 2.4 to 13.3 onto finely divided solid particulate raw materials and cooling the resulting sprayed product to solidify the resin composition providing a matrix within which the solid particulate raw materials are bound. The fertilizer composition is characterized by having desired physical and chemical properties in regard to chain length of nitrogen polymers in the product, nitrogen release patterns, hardness and dust free nature of the product and the dispersibility characteristics of the product. The product has an abrasion index of about 0.800-1.000.

BACKGROUND OF THE INVENTION 
This invention relates to a process for the production of a carrierless 
granular slow release fertilizer composition and to the resulting product. 
A variety of processes for producing carrierless granular slow release 
fertilizer compositions are known and, particularly, processes for 
producing controlled or slow release reaction products of urea and 
formaldehyde for fertilizer applications. For example, such carrierless 
products have been produced by reacting a urea-formaldehyde resin into a 
solid sheet which is milled and screened to provide a granular product 
having a desired particle size. A typical U/F mole ratio used for 
producing the product is in the range of 1.1 to 2.1 and the resulting 
product contains predominantly long chain methylene urea polymers (i.e., 
tetramethylene pentaurea (TMPU) and longer chain polymers). Such products 
and processes are disclosed, for example, in U.S. Pat. No. 3,198,761. 
Other known processes for producing carrierless granular slow release 
fertilizer products are disclosed, for example, in U.S. Pat. Nos. 
3,076,700; 3,705,794 and 3,989,470. Essentially, these carrierless 
products are produced by reacting urea-formaldehyde resins into rigid 
foams which are dried, milled and screened to the desired granular size. 
Typical U/F mole ratios used for these processes range from 1.3 to 2.4 
and; as opposed to the technology disclosed in U.S. Pat. No. 3,198,761 
which is suitable solely for production of nitrogen only products, the 
processes disclosed in these patents have the flexibility of producing 
complex fertilizers by slurrying other finely ground additives such as 
phosphorus and/or potassium salts into the resin prior to the foaming 
reaction. The products produced by these processes contain predominantly 
intermediate chain length methylene urea polymers (i.e., trimethylene 
tetraurea (TMTU) and longer chain polymers). 
U.S. Pat. No. 4,025,329 discloses another process for producing a 
carrierless product. In this process a granular product is formed, for 
example, in accordance with the disclosures in U.S. Pat. Nos. 3,705,794 
and 3,989,470 and then the granules are compacted with other nutrient or 
pesticide additives to produce a product of uniform composition and 
particle size. U/F mole ratios employed to produce this slow release 
product are in a range of 1.3 to 2.4, the density of the granule produced 
is greater than 1.4 and the granular size is greater then 30 mesh, with 
substantially all of the granules having a ratio of largest to smallest 
granule of less than 3:1. 
U.S. Pat. Nos. 4,378,238 and 4,411,683 disclose, inter alia, a process for 
producing carrierless slow release granular products having at least 60% 
of the polymeric nitrogen in the form of methylene diurea (MDU) and 
dimethylene triurea (DMTU). The process disclosed therein for producing 
carrierless product is a two stage process wherein an aqueous mixture of 
urea, formaldehyde and ammonia is first reacted at elevated temperatures 
to produce methylol ureas. Then, in a second stage, acid is added directly 
to the reaction mixture and the acidified mixture is reacted and the 
condensation reaction product is dried and milled into the final product. 
Typical U/F mole ratios for these carrierless products range from 1.9 to 
2.2. 
A further experimental process for producing ureaform fertilizer products 
is disclosed in an article entitled "Reactions of Molten Urea with 
Formaldehyde", by Thomas P. Murray et. al., published in Ind. Eng. Chem. 
Prod. Res. Dev., 1985, at 420-425. The process disclosed therein entails 
the reaction of molten urea with paraformaldehyde either by mixing 
paraformaldehyde into melted urea at temperatures of between 130 degrees 
and 140 degrees C. or by premixing the paraformaldehyde with the urea and 
heating the solid mixture to 130 degrees C. with stirring. Thereafter, the 
molten reaction mixture resulting from either of the procedures is cooled 
to form a solid sheet and the sheet is then ground. U/F mole ratios used 
under the laboratory-scale conditions described in the publication ranged 
from 0.5 to 16.2. 
However, each of the previously known processes for producing carrierless 
granular slow release fertilizer products has been found to have certain 
shortcomings in terms of the physical or chemical characteristics of the 
products produced thereby and/or the economics of production. For example, 
the process disclosed in U.S. Pat. No. 3,198,761 is restricted to nitrogen 
only fertilizers. Furthermore, products produced by this process have been 
found to demonstrate nitrogen release patterns which are not well suited 
to certain applications such as turf and short season crops. Similarly, 
the products resulting from use of the experimental process disclosed in 
the above referenced article are restricted solely to nitrogen only 
fertilizer compositions. 
The processes disclosed in U.S. Pat. Nos. 3,076,700; 3,705,794 and 
3,989,470 represent an advancement in respect to their ability to produce 
a wide variety of N-P-K minor element ratios in the products and are not 
restricted to the production of nitrogen only products. However, even 
these processes are restricted in the range of N-P-K ratios in view of the 
limit on the amount of solids which can be slurried into the 
urea-formaldehyde resin without adversely impacting the condensation 
reaction. Furthermore, the products produced in accordance with the 
disclosure of U.S. Pat. Nos. 3,076,700; 3,705,974 and 3,989,470 have been 
found to be quite fragile and dusty. 
The process of patent 4,025,329 produces high density granular products of 
uniform granular size. The process also enables the incorporation of other 
fertilizer ingredients into the product and provides flexibility as to the 
N-P-K minor element ratios which can be produced. However, the product 
does present a dust plume problem resulting from surface adhesion of dust 
to the product during the manufacturing process when the product is poured 
from its storage container. Furthermore, the products produced present the 
same performance problems as noted above in regard to the processes 
disclosed in U.S. Pat. Nos. 3,076,700; 3,705,794 and 3,989,740. 
Additionally, these high density products have been found to present a 
dispersibility problem in regard to their use on turf. In this regard, 
these products do not disperse adequately to penetrate the turf canopy 
after application. Thus, the product remains on the surface to be picked 
up on shoes, golf balls and the like as they travel over the turf. 
In regard to the process disclosed in U.S. Pat. Nos. 4,378,238 and 
4,411,683 as it relates to carrierless products, it has been found that 
the process therein cannot be economically or feasibly conducted to 
produce commercially acceptable carrierless products. Carrierless products 
as referred to herein are intended to include products which do not employ 
an absorbent carrier capable of absorbing liquids to provide a granular 
structure to the final product. That is in carrier based systems, the 
volume of the product is quite close to the sum of the volumes of the raw 
materials. This is because the carrier creates the volume structure upon 
which the product is formed. Thus, the product to feed volume ratio (P/F) 
for absorbent carrier based fertilizers is essentially 1. Experimental 
determinations have shown a range of 0.9 to 1.1. Typical examples of 
commonly used carriers which are not required for use in forming products 
of the present invention are vermiculite, perlite and corncobs. 
Accordingly, none of the prior processes are suitable for producing 
carrierless granular slow release fertilizer compositions having the 
desired characteristics either because of process or product shortcomings 
such as the cost effectiveness of the process, the ability to include 
additive products in the urea-formaldehyde reaction product and the 
physical properties of the product. In terms of physical properties, the 
prior art products have exhibited undesirable characteristics regarding 
dusting and dispersibility. 
SUMMARY OF THE INVENTION 
It is a primary object of the present invention to provide a cost effective 
process for producing carrierless slow release nitrogen containing 
fertilizer products in granular form. 
Another object is to provide a process for producing carrierless slow 
release nitrogen containing fertilizer products which is readily adaptable 
for the inclusion of a wide variety of additive ingredients including 
plant nutrients, pesticides such as herbicides, insecticides, fungicides 
and the like in any desired concentration or amount without negatively 
impacting the physical and chemical properties of the products. 
A further object is to provide a carrierless slow release nitrogen 
containing fertilizer product having desired physical and chemical 
properties, for example, in regard to chain length of nitrogen polymers in 
the product, nitrogen release patterns provided in use of the products, 
hardness and dust free nature of the product and the dispersibility 
characteristics of the product. 
A more specific object of this invention is to provide a process for 
producing a slow release granular methylene urea fertilizer product 
without a carrier from small particulate raw materials bound together 
within a urea-formaldehyde resin matrix formed from a molten 
urea-formaldehyde resin having a U/F ratio in the range of about 2.4 to 
13.3 and to the product produced thereby. 
The foregoing and other objects of this invention are achieved by a process 
which comprises preparing a mixture of urea and formaldehyde, the molar 
ratio of urea to formaldehyde ranging from 2.4 to 13.3, heating the 
reaction mixture until essentially all of the formaldehyde in the mixture 
is fully reacted and a molten or liquid urea-formaldehyde resin is formed. 
Then, the molten urea-formaldehyde resin is sprayed on small finely 
divided solid raw material particles and the urea-formaldehyde resin acts 
as a binder to agglomerate the solid particles within a matrix formed by 
the urea-formaldehyde resin in order to produce a granular product of a 
desired size. The resulting product is allowed to cool and solidify into a 
hard granular carrierless product which exhibits slow release nitrogen 
properties. The final product has an abrasion index indicative of the 
granular material's ability to withstand mechanical processing (i.e., its 
resistance to attrition) in a range of about 0.850 to about 1.000 as 
determined by the following test procedure: 
1. A 100 gram test sample of granular product was prescreened to a lower 
limit of 14 US mesh for -6+14 mesh granules or 25 US mesh for -10+25 mesh 
granules and was deposited on a clean limit screen; 
2. Stainless steel balls (about thirty one 5/8 inch diameter balls having a 
total weight of 500 grams) were added to the screen with the test sample; 
3. The screen with the granular test sample and the stainless steel balls 
was introduced into a lidded Rotap sieve shaker (with hammer) having a 
collections pan positioned beneath the screen; 
4. The Rotap assembly was operated for five (5) minutes; and, thereafter, 
the balls were removed from the screen and the final product on the limit 
screen was weighed; and 
5. The abrasion index was calculated by determining the ratio of the final 
weights of product to its initial weight (i.e., 100 grams).

DETAILED DESCRIPTION 
In the process of this invention a mixture of urea and formaldehyde is 
prepared having a molar ratio of urea to formaldehyde ranging from 2.4 to 
13.3 depending on the desired methylene urea chain length and the level of 
slow release nitrogen desired in the final product. This reaction mixture 
is then heated to a temperature of from about 250 degrees F. to about 285 
degrees F. and the heating of the mixture is continued for a period of 
time until essentially all of the formaldehyde in the mixture is fully 
reacted and a molten urea-formaldehyde resin is formed. Preferably, this 
heating is conducted over a period of time of about 1/2 to about 2 hours 
and, most preferably, for a period of about 1 hour. Normally, during this 
heating operation, at least about 60% of the water in the mixture is 
evaporated out of the mixture; although, the moisture may be removed 
subsequent to the reaction by appropriate techniques, if desired. 
The process of the present invention is intended to produce products which 
do not use carriers. Instead, small finely divided solid raw material 
particles are built up into a fertilizer granule by spraying the molten 
urea-formaldehyde resin resulting from the heating step onto these 
particles at a controlled rate and in a manner such that the particles are 
essentially "glued" together to form a final granular product. The size of 
the solid particles onto which the molten resin is sprayed is a critical 
factor in the production of the products of this invention. Specifically, 
particle sizes expressed in terms of Size Guide Numbers (SGN) in the range 
of about 40 to 90 have been found to be acceptable for use herein although 
an SGN range of about 45-65 is preferred. The term Size Guide Number (SGN) 
as employed herein is the calculated diameter of the "average particle" 
expressed in millimeters to the second decimal and then multiplied by 100. 
More precisely, SGN is that particle size which divides the mass of all 
particles in two equal halves, one having all the larger size particles 
and the other half having all smaller size particles. 
The composition of the finely divided solid particles for use herein to 
produce the final granular product is essentially a matter of choice among 
a wide variety of solid raw materials including sources of primary, 
secondary and minor element plant nutrients, pesticides, adjuvants or 
other desirable additives such as fillers. Thus, the present process 
provides a virtually limitless potential for producing suitable granular 
products having a wide range of N-P-K ratios by incorporating phosphorus 
and/or potassium nutrients therein, for example, as particulate P.sub.2 
O.sub.5 or K.sub.2 O or K.sub.2 SO.sub.4 and, if desired, including a wide 
diversity of other plant nutrients, micronutrients, pesticides and other 
additives and adjuvants. 
In the practice of the process of this invention, the molten 
urea-formaldehyde resin is sprayed on the finely divided solid particles 
in a suitable spray chamber such as a rotating drum or some other suitable 
agglomerator such as a fluid bed or pugmill. The rate of resin addition 
has been found to be important in the formation of the desired granules. 
For example, if the spray rate is too low, proper agglomeration will not 
be achieved. In this regard, it has been found that preferred rates for 
spraying the molten urea-formaldehyde resin on N-P-K particles (expressed 
in terms of weight percent resin/weight percent additives in the product) 
should be in a range of about 0.5-5.0. The temperature of the sprayed 
resin and of the ambient surroundings within the spray chamber during 
spraying have been found to be important in producing products having the 
desired physical properties. Specifically, the temperature of the resin 
must be cooled sufficiently after spraying to solidify in order to fuse or 
bond the finely divided particles within a matrix formed by the 
urea-formaldehyde resin. With regard to the temperature of the chamber, it 
must be maintained at a level such that the resin will be capable of 
cooling sufficiently to solidify without remaining in a liquid or molten 
state. Preferably, the temperature of the chamber should not exceed about 
160 degrees F. since the particles sprayed with the resin have been found 
to become "sticky" or "gummy" at temperatures above 160 degrees F. 
It should be noted that the process for producing the final granulated 
products herein is not pH dependent as is the case with many of the prior 
processes. Furthermore, it is of particular note that the products 
emerging from the spray chamber constitute the finished granular products 
of the present invention and no separate primary milling or crushing stage 
is required to produce the final granular product as has been standard 
practice in the production of essentially all prior products. This feature 
renders the present process more energy efficient in operation than prior 
systems and enables implementation thereof at lower capital expense than 
has been possible heretofore. 
In the present process, after the granular product is removed from the 
spray chamber, it is cooled to further harden the granules as well as to 
accommodate the handling of the finished product. Then, the granules are 
screened to separate out "oversize" granules and "fines". The "oversize" 
granules are milled in a secondary milling operation to reduce the granule 
size and are rescreened. The "fines" or undersized granules are recycled 
directly back into the spray chamber or agglomerator for further granule 
build up. The resulting screened "on-size" granular nitrogen containing 
fertilizer products are ready for packaging and distribution. These 
granular products have been found to exhibit high physical integrity and 
hardness, to be of uniform granular size and to be homogeneous in chemical 
composition. Additionally, the products produced by this process were 
found to be dust free, to be easily dispersed when contacted with water 
and to require significantly less push effort when applied to turf in 
"drop spreaders" as compared with prior N-P-K fertilizers of similar 
granule size. 
Furthermore, the U/F ratio of the urea-formaldehyde resin forming the 
matrix structure of the final product of the present invention dictates 
the methylene urea polymer distribution and the nitrogen release 
characteristics of the product. Thus, products produced in accordance with 
the present invention are slow release nitrogen products which include at 
least 15% of the total nitrogen therein as compounds possessing slow 
release properties such as methylene diurea (MDU) and are made with U/F 
ratios of up to about 13.3 in order to provide the required level of slow 
release nitrogen in the product. The lower limit of U/F ratios to be 
employed in the products of this invention has been found to be about 2.4 
and, the preferred range of U/F ratios is from about 2.7 up to about 13.3. 
In this regard, it should be noted that the relatively low quantities of 
formaldehyde employed herein relative to the urea content results in a 
significant economic advantage compared with prior commercially available 
formulations. 
The following examples are specific illustrations of the practice of the 
invention in accordance with the foregoing process. All parts and 
percentages are by weight unless otherwise indicated. 
EXAMPLE 1 
Finely divided particles of muriate of potash (KCl) and monoammonium 
phosphate (MAP) were metered at a rate of 189 lbs./hour KCl (2.7 cubic 
feet/hour) and 171 lbs./hour MAP (2.9 cubic feet/hour), as solids, into a 
drum granulator. The particle sizes of the solid KCl and MAP raw materials 
employed herein were as follows: 
__________________________________________________________________________ 
RAW U.S. SIEVE DISTRIBUTION SIZE 
MATERIAL 
10 
12 
14 
16 
18 
25 
40 
70 
100 
200 
-200 
(SGN) 
__________________________________________________________________________ 
KCl -- 
-- 
-- 
0.5 
5 20 
37 
24 
9 4 0.5 49.5 
MAP -- 
-- 
0.2 
2.4 
5 12 
25 
33 
16 5 1.4 47.4 
__________________________________________________________________________ 
Granulation of these particulate solids was accomplished by spraying the 
raw material particles on the moving bed of the rotating drum with a 
molten resin composition of urea and methylene ureas at a rate of 1639 
lbs./hour (21.0 cubic feet/hour). The molten resin composition had a U/F 
mole ratio of 4.0 and was prepared by mixing prilled urea fed at a rate of 
1488 lbs./hour and urea-formaldehyde concentrate fed at a rate of 327 
lbs./hour in a stirred tank reactor and heating the mixture to a 
temperature of 275 degrees F. The urea-formaldehyde concentrate used was 
UFC-85, a precondensed solution of formaldehyde and urea containing 
substantial amounts of free formaldehyde and dimethylol ureas. The 
residence time in the reactor was one hour during which time the mixture 
was maintained at 275 degrees F. During this one hour period, the U/F 
condensation reaction was essentially completed with essentially all of 
the formaldehyde in the mixture being fully reacted and the water in the 
mixture (water of reaction and water from the UFC-85) was removed by 
evaporation resulting in the production of 1639 lbs./hour of molten resin 
composition consisting of urea and polymerized methylene ureas containing 
3.8% water. 
The molten resin was sprayed onto the raw material particles at a resin to 
solids ratio of 4.6 (feed rate resin/feed rate solid raw materials which 
is equivalent to the ratio of weight percent resin/weight percent raw 
materials) and the resulting agglomerated granules were then cooled and 
screened to a minus 10 plus 25 mesh size (U.S. Sieves). Oversize granules 
were milled and rescreened. Undersize granules or "fines" were returned to 
the drum granulator for additional agglomeration. 
The resulting product had an abrasion index of 0.954 as determined by the 
procedure set forth hereinabove utilizing a 25 US mesh limit screen. 
Furthermore, the product had a bulk density of 42.0 lbs./cubic foot and 
was produced at a rate of 2000.0 lbs./hour (47.6 cubic feet/hour). The 
volume ratio of product to feed materials (P/F) for the product was 1.79. 
Furthermore, the final product had an average particle size expressed as a 
Size Guide Number (SGN) of 127.2 based on the following percentages of 
product retained on each sieve in a nest of sieves: 
__________________________________________________________________________ 
U.S. SIEVE DISTRIBUTION 
+6 6/8 
8/10 
10/12 
12/14 
14/16 
16/18 
18/25 
25/40 
40/70 
__________________________________________________________________________ 
-- -- 0.7 
9 29 21 19 17 4 0.3 
__________________________________________________________________________ 
The product produced was a carrierless controlled release granular N-P-K 
fertilizer having a high resin to solids ratio with the following chemical 
analysis (in weight percent): Total N--36.0; Total P.sub.2 O.sub.5 --4.2; 
Total K.sub.2 O--5.7; Total H2O--0.8 and the pH was 5.2. Also, the product 
has a fast release nitrogen content as a percent of total nitrogen of 54.8 
including 54.0% Urea N and 0.8% ammoniacal N. The slow or controlled 
release nitrogen content as a percent of total nitrogen was 45.2. 
EXAMPLE 2 
A second product was produced in accordance with the process of Example 1 
utilizing the same raw material particles fed at the same rates and resin 
composition sprayed at the same rate as in Example 1. However, the 
granular size of the products produced in this Example was enlarged by 
screening the granules (after they emerge from the drum granulator and 
have been cooled) to a minus 6 plus 14 mesh particle size (U.S. Sieves). 
Analysis of the resulting product indicated chemical properties which were 
essentially the same as the product of Example 1 but the physical 
properties set forth in the following table show a substantially larger 
granular size (SGN--197.4) with approximately the same bulk density (42.6 
lbs./cubic foot). The P/F volumetric ratio for this product was 1.78 and 
the abrasion index was 0.925, as determined by the procedure set forth 
hereinabove utilizing a 14 US mesh limit screen. 
__________________________________________________________________________ 
U.S. SIEVE DISTRIBUTION 
+6 6/8 
8/10 
10/12 
12/14 
14/16 
16/20 
20/25 
25/40 
40/70 
__________________________________________________________________________ 
-- 22 19 21 30 7 1 -- -- -- 
__________________________________________________________________________ 
EXAMPLE 3 
This Example illustrates the production of a slow release granular N-P-K 
product (31-3-12) produced with a relatively low resin to solids ratio 
without the use of an absorbent carrier. 
Finely divided particles of muriate of potash (KCl) and monoammonium 
phosphate (MAP) (having the same particle size as set forth for the raw 
materials in Example 1) were metered at a rate of 421 lbs./hour KCl (6.0 
cubic feet/hour) and 131 lbs./hour MAP (2.2 cubic feet/hour), as solids, 
into a drum granulator. 
Granulation of these particulate solids was accomplished by spraying the 
raw material particles on the moving bed of the rotating drum with a 
molten resin composition of urea and methylene ureas at a rate of 1448.0 
lbs./hour (18.6 cubic feet/hour). The molten resin composition had a mole 
ratio of 4.0 and was prepared by mixing prilled urea fed at a rate of 1315 
lbs./hour and urea-formaldehyde concentrate (UFC-85) fed at a rate of 289 
lbs./hour in a stirred tank reactor and heating the mixture to a 
temperature of 275 degrees F. The residence time in the reactor was one 
hour during which time the mixture was maintained at 275 degrees F. During 
this one hour period, the U/F condensation reaction was essentially 
completed with essentially all of the formaldehyde in the mixture being 
fully reacted and the water in the mixture (water of reaction and water 
from the UFC-85) was removed by evaporation resulting in the production of 
1448.0 lbs./hour of molten resin composition consisting of urea and 
polymerized methylene ureas containing 3.8% water. 
The molten resin was sprayed onto the raw material particles at a resin to 
solids ratio of 2.6 (feed rate resin/feed rate solid raw materials which 
is equivalent to the ratio of weight percent resin/weight percent raw 
materials) and the resulting agglomerated granules were then cooled and 
screened to a minus 10 plus 25 mesh size (U.S. Sieves). Oversize granules 
were milled and rescreened. Undersize granules or "fines" were returned to 
the drum granulator for additional agglomeration. 
The resulting product had an abrasion index of 0.992 as determined by the 
procedure set for hereinabove utilizing a 25 US mesh limit screen. 
Furthermore, the product had a bulk density of 43.4 lbs./cubic foot and 
was produced at a rate of 2000.0 lbs./hour (46.1 cubic feet/hour). The 
volume ratio of product to feed materials (P/F) for the product was 1.72 
and the final product had an average particle size expressed as a Size 
Guide Number (SGN) of 141.3 based on the following percentages of product 
retained on each sieve in a nest of sieves: 
__________________________________________________________________________ 
U.S. SIEVE DISTRIBUTION 
+6 6/8 
8/10 
10/12 
12/14 
14/16 
16/18 
18/25 
25/40 
40/70 
__________________________________________________________________________ 
-- -- 0.2 
12 39 28 14 6 0.7 0.1 
__________________________________________________________________________ 
The product produced had the following chemical analysis (in weight 
percent): Total N--31.7; Total P.sub.2 O.sub.5 --3.2; Total K.sub.2 
O--12.6; Total H.sub.2 O--0.9 and the pH was 5.4. Also, the product had a 
fast release nitrogen content as a percent of total nitrogen of 51.6 
including 51.0% Urea N and 0.6% ammoniacal N. The slow or controlled 
release nitrogen content as a percent of total nitrogen was 48.4. 
EXAMPLE 4 
This Example illustrates the production of a slow release granular N-P-K 
product similar to the product produced in Example 3 except that particles 
of sulfate of potash (K.sub.2 SO.sub.4) were substituted as the potassium 
source in the product and the urea-formaldehyde resin employed had a 
significantly lower U/F mole ratio (U/F-3.4). 
Finely divided particles of sulfate of potash (K.sub.2 SO.sub.4) and 
monoammonium phosphate (MAP) were metered at a rate of 433 lbs./hour 
K.sub.2 SO.sub.4 (4.9 cubic feet/hour) and 135 lbs./hour MAP (2.2 cubic 
feet/hour), as solids, into a drum granulator. The particle sizes of the 
solid K.sub.2 SO.sub.4 and MAP raw materials employed herein were as 
follows: 
__________________________________________________________________________ 
RAW U.S. SIEVE DISTRIBUTION SIZE 
MATERIAL 
10 
12 
14 16 18 
25 
40 
70 
100 
200 
-200 
(SGN) 
__________________________________________________________________________ 
K.sub.2 SO.sub.4 
0.4 
2.0 
11 14 16 
20 
18 
10 
5 2 1.6 88.8 
MAP -- 
-- 
0.2 
2.4 
5 
12 
25 
33 
16 5 1.4 47.4 
__________________________________________________________________________ 
Granulation of these particulate solids was accomplished by spraying the 
raw material particles on the moving bed of the rotating drum with a 
molten resin composition of urea and methylene ureas at a rate of 1432.0 
lbs./hour (18.4 cubic feet/hour). The molten resin composition had a mole 
ratio of 3.4 and was prepared by mixing prilled urea fed at a rate of 1277 
lbs./hour and urea-formaldehyde concentrate (UFC-85) fed at a rate of 333 
lbs./hour in a stirred tank reactor and heating the mixture to a 
temperature of 275 degrees F. The residence time in the reactor was one 
hour during which time the mixture was maintained at 275 degrees F. During 
this one hour period, the U/F condensation reaction was essentially 
completed with essentially all of the formaldehyde in the mixture being 
fully reacted and the water in the mixture (water of reaction and water 
from the UFC-85) was removed by evaporation resulting in the production of 
1432.0 lbs./hour of molten resin composition consisting of urea and 
polymerized methylene ureas containing 3.8% water. 
The molten resin was sprayed onto the raw material particles at a resin to 
solids ratio of 2.5 (feed rate resin/feed rate solid raw materials which 
is equivalent to the ratio of weight percent resin/weight percent raw 
materials) and the resulting agglomerated granules were then cooled and 
screened to a minus 10 plus 25 mesh size (U.S. Sieves). Oversize granules 
were milled and rescreened. Undersize granules or "fines" were returned to 
the drum granulator for additional agglomeration. 
The resulting product had an abrasion index of 0.981 as determined by the 
procedure set forth hereinabove utilizing a 25 US mesh limit screen 
Furthermore, the product had a bulk density of 42.9 lbs./cubic foot and 
was produced at a rate of 2000.0 lbs./hour (46.6 cubic feet/hour). The 
volume ratio of product to feed materials (P/F) for the product was 1.83. 
Furthermore, the final product had an average particle size expressed as a 
Size Guide Number (SGN) of 145.4 based on the following percentages of 
product retained on each sieve in a nest of sieves: 
__________________________________________________________________________ 
U.S. SIEVE DISTRIBUTION 
+6 6/8 
8/10 
10/12 
12/14 
14/16 
16/18 
18/25 
25/40 
40/70 
__________________________________________________________________________ 
-- -- 4 15 33 29 17 2 -- -- 
__________________________________________________________________________ 
The product produced had the following chemical analysis (in weight 
percent): Total N--31.5; Total P.sub.2 O.sub.5 --3.3; Total K.sub.2 
SO.sub.4 --10.5; Total H.sub.2 O--1.1 and the pH was 5.3. Also, the 
product had a fast release nitrogen content as a percent of total nitrogen 
of 46.6 including 46.0% Urea N and 0.6% ammoniacal N. The slow or 
controlled release nitrogen content as a percent of total nitrogen was 
53.4. 
EXAMPLE 5 
An N-P-K product (16-0-30) was produced by metering finely divided solid 
particles of sulfate of potash (K.sub.2 SO.sub.4) at a rate of 2511 
lbs./hour K.sub.2 SO.sub.4 (28.2 cubic feet/hour) into a drum granulator. 
The particle sizes of the solid K.sub.2 SO.sub.4 raw material employed 
herein were the same as set forth in Example 4 having an SGN of 88.8. 
Granulation of the particulates was accomplished by spraying the raw 
material particles on the moving bed of the rotating drum with a molten 
resin composition of urea and methylene ureas at a rate of 1489 lbs./hour 
(19.1 cubic feet/hour). The molten resin composition had a mole ratio of 
4.0 and was prepared by mixing prilled urea fed at a rate of 1352 
lbs./hour and urea-formaldehyde concentrate (UFC-85) fed at a rate of 297 
lbs./hour in a stirred tank reactor and heating the mixture to a 
temperature of 275 degrees F. The residence time in the reactor was one 
hour during which time the mixture was maintained at 275 degrees F. During 
this one hour period, the U/F condensation reaction was essentially 
completed with essentially all of the formaldehyde in the mixture being 
fully reacted and the water in the mixture (water of reaction and water 
from the UFC-85) was removed by evaporation resulting in the production of 
1489 lbs./hour of molten resin composition consisting of urea and 
polymerized methylene ureas containing 3.8% water. 
The molten resin was sprayed onto the raw material particles at a resin to 
solids ratio of 0.6 (feed rate resin/feed rate solid raw materials which 
is equivalent to the ratio of weight percent resin/weight percent raw 
materials) and the resulting agglomerated granules were then cooled and 
screened to a minus 10 plus 25 mesh size (U.S. Sieves). Oversize granules 
were milled and rescreened. Undersize granules or "fines" were returned to 
the drum granulator for additional agglomeration. 
The resulting product had an abrasion index of 0.860 as determined by the 
procedure set forth hereinabove utilizing a 25 mesh US limit screen. 
Furthermore, the product had a bulk density of 56.7 lbs./cubic foot and 
was produced at a rate of 4000.0 lbs./hour (70.5 cubic feet/hour). The 
volume ratio of product to feed materials (P/F) for the product was 1.49. 
Furthermore, the final product had an average particle size expressed as a 
Size Guide Number (SGN) of 107.3 based on the following percentages of 
product retained on each sieve in a nest of sieves: 
__________________________________________________________________________ 
U.S. SIEVE DISTRIBUTION 
+6 6/8 
8/10 
10/12 
12/14 
14/16 
16/18 
18/25 
25/40 
40/70 
__________________________________________________________________________ 
-- -- -- 2 15 18 20 34 11 -- 
__________________________________________________________________________ 
The product produced had the following chemical analysis (in weight 
percent): Total N--16.0; Total P.sub.2 O.sub.5 --0; Total K.sub.2 SO.sub.4 
--30.6; Total H.sub.2 O--0.4 and the pH was 8.0. Also, the product had a 
fast release nitrogen content as a percent of total nitrogen of 55.0 
derived from Urea N. The slow or controlled release nitrogen content of 
the product as a percent of total nitrogen was 45.0. 
EXAMPLE 6 
Control samples were prepared of prior art compositions with UF ratios 
greater than 2.4 utilizing expanded vermiculite as an absorbent carrier to 
provide the granular structure of the final product. The presence of this 
absorbent carrier diluted the N-P-K analysis of the product. For example, 
a carrier based product with an N-P-K ratio similar to the product 
produced in Example 1 was found to have a 30.2-3.1-4.0 analysis because of 
the dilution of the absorbent carrier. 
The control products used for analysis in this Example were produced by 
spraying 67.9% (by weight) of a urea/methylene urea resin (u/F=4.0) onto 
expanded vermiculite, and finely divided KCl and MAP at weight percents of 
19.5%, 6.5%, and 6.1 respectively. The resin was absorbed into the porous 
vermiculite and simultaneously wet the surface of the carrier. The finely 
divided P and K salts adhered to the wetted surface. The final product had 
a bulk density of 25 lb/cu ft and an average particle size (SGN) of 118.0. 
Due to the presence of the absorbent carrier, the volume of the product 
was essentially equal to the volume of the raw materials (P/F volume 
ratio=0.9). 
Additional products were prepared in order to determine the minimum amount 
of vermiculite carrier which could be used in producing the control 
products of this Example. These products were produced as described above 
except that the amount of expanded vermiculite was reduced to the point 
where it could no longer absorb the UF resin. This level was equal to 8.9 
percent by weight of the raw materials. The resulting product had a 
34.6-3.7-4.6 analysis Its bulk density was 34.0 lb/cu ft. The volumetric 
ratio of product to feed (P/F) was 1.1 demonstrating that with absorbent 
carrier based products, the volume of the product essentially equals the 
sum of the volumes of the raw materials. 
EXAMPLE 7 
This example illustrates the advantages of the products of the present 
invention in terms of dispersibility, dusting and product utilization as 
compared with prior carrierless products produced in accordance with the 
disclosure of U.S. Pat. No. 4,025,329. For purposes of the comparative 
testing, the products of Example 3 and 5 were employed as representative 
samples of the present invention. 
In regard to dispersibility of the products, it should be noted that this 
is an important product feature in that it relates to the potential for a 
product to disperse down into the turf canopy after watering. This is 
especially important on dense turf such as putting greens. Failure to 
disperse leads to performance problems such as speckled greening response, 
particle pickup by shoes and equipment, and prolonged product visibility. 
A laboratory test was devised to quantify dispersibility. The following 
procedure was employed: 
1. Screen materials to a -12+16 mesh (U.S. Sieves) size to remove any 
effects of differing particle size. 
2. Weigh 10.00 grams of sample into a 400 ml beaker. 
3. Add 100 ml of distilled water. 
4. Stir constantly on a magnetic stirrer for 3 minutes (speed #2 on a 6 
speed unit). 
5. Pour the beaker contents onto a 25 mesh sieve (U.S. Sieves). Rinse the 
beaker with 100 ml of distilled water. 
6. Rinse the fertilizer on the sieve for 15 seconds with a low pressure 
water stream through a flaring nozzle. 
7. Transfer the contents of the sieve to a preweighed sheet of brown paper. 
Sharp raps with the screen to a counter top sufficiently removes the 
fertilizer. 
8. Place the paper in a drying oven (50.degree.-70.degree. C.) until dry. 
9. Allow the paper to cool. Weigh the paper plus fertilizer and determine 
weight of remaining fertilizer. 
10. Calculate the % dispersibility 
EQU 100.times.(10.00-r)/10.00=% dispersibility 
where r=weight of remaining fertilizer. 
In accordance with this test procedure, the dispersibilities were 
determined for the products of Examples 3 and 5 and for products of 
similar analysis (N-P-K) produced in accordance with the disclosure in 
U.S. Pat. No. 4,025,329. The results of this testing were as follows: 
______________________________________ 
Test 
Product N-P-K Dispersibility 
______________________________________ 
Example 3 31-3-12 99.4% 
Prior Art 31-3-10 96.8% 
Example 5 16-0-30 95.9% 
Prior Art 16-0-30 74.8% 
______________________________________ 
From the forgoing tabulated test results, it can be seen that the products 
of this invention display superior dispersibility characteristics. 
Another test was conducted to illustrate that products of this invention 
require less push effort and are better suited to "drop spreaders" than 
prior art products having similar analysis which are produced in 
accordance with the disclosure in U.S. Pat. No. 4,025,329. 
To demonstrate this, all samples were screened to a specific sieve size 
(-12+16 mesh, U.S. Sieves) to eliminate particle size effects. The hopper 
of a laboratory model "drop spreader" (Scott Model PF-3) was filled with 
material, so that the agitator bar was covered. The spreader setting was 
set at "8". The push effort was determined by measuring the torque needed 
to turn the axle of the spreader with the flow control bar in the "closed" 
position. Results of this testing were as follows: 
______________________________________ 
Push Effort-Torque 
Product N-P-K (in-lb) 
______________________________________ 
Example 3 31-3-12 3-6 
Prior Art 31-3-10 6-16 
Example 5 16-0-30 2-4 
Prior Art 16-0-30 5-13 
______________________________________ 
As shown, products of this invention were shown to require substantially 
less push effort to apply with a "drop spreader" than the comparative 
samples. 
A further test was conducted to demonstrate that products of this invention 
do not have the inherent problems with dusting characteristics common to 
prior art samples of similar analysis. 
Samples from Examples 3 and 5 and corresponding prior art samples produced 
in accordance with the disclosure in U.S. Pat. No. 4,025,329 were screened 
to a specific granular size (-12+16 mesh, U.S. Sieves) to remove any 
effects of small granules. Each screened material (300 grams) was then 
poured through a funnel with a 3/8 inch orifice at a rate of 10-16 grams 
per second and was collected in a 400 ml beaker positioned one foot below 
the funnel. Visual notation was made of any dust plume coming off the 
beaker and the results were tabulated as follows: 
______________________________________ 
Product N-P-K Dust Plume 
______________________________________ 
Example 3 31-3-12 No 
Prior Art 31-3-10 Yes 
Example 5 16-0-30 No 
Prior Art 16-0-30 Yes 
______________________________________ 
Although all of the test samples were prescreened to remove fine granules, 
the prior art samples still generated a dust plume when poured from the 
bag. This is due to surface adhesion of dust during the manufacturing 
process. Products in accordance with the present invention had no surface 
dust adhering to them an consequently produced no dust plume. 
The invention has been illustrated with specific examples of fertilizer 
compositions. Many other nutrients, as well as micronutrients, and control 
chemicals such as herbicides, fungicides and insecticides may be employed 
in the products produced by the process of the invention. Examples of 
other additives are shown in the aforementioned U.S. Pat. Nos. 3,076,700, 
3,231,363 and 3,705,794. Other additives are likewise set forth in Farm 
Chemicals '90, Meister Publishing Company, 1990. Other pesticides which 
may be used are shown in the Pesticide Manual, 6th Edition, British Crop 
Protection Council, 1980. Other herbicides which may be used are shown in 
Weed Control, 2nd Edition, 1962, Robbins et al., McGraw-Hill Book Company, 
Inc., New York, N.Y. Other fertilizer nutrients which may be used in 
combination are shown in Commercial Fertilizers, 5th Edition, 1955, 
Collings, McGraw-Hill Book Inc., New York, N.Y.