Method for producing monocalcium phosphate and products produced therefrom

Methods of producing monocalcium phosphate and products created therefrom are provided. The method includes the steps of mixing phosphoric acid and water with brown mud. Preferably, the phosphoric acid is added to water so that it comprises approximately 3% to about 50% of the phosphoric acid/water mixture by weight, and the water comprises approximately 50% to about 97% of the phosphoric acid/water mixture by weight. The brown mud is added to the phosphoric acid/water mixture in a weight ratio of approximately 1:1 to about 1:3. The method of the present invention results in improved monocalcium phosphate products.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for producing monocalcium 
phosphate and products created from same. 
Monocalcium phosphate heretofore, was typically produced by mixing 
dicalcium silicate with phosphoric acid. This prior process typically 
suffered two disadvantages. During the prior process of mixing dicalcium 
silicate with phosphoric acid, a great deal of heat is generated. This is 
due to the exothermic nature of the process. The amount of heat generated 
during the prior process made the process difficult to carry out on a 
commercial basis. 
Moreover, the prior process of mixing dicalcium silicate with phosphoric 
acid does not provide an efficient method for creating monocalcium 
phosphate. To this end, in the prior process, not all of the calcium in 
the dicalcium silicate is leached out during the process, instead some of 
the calcium separates out of the mixture and does not form monocalcium 
phosphate. 
Accordingly, there is a need for an improved method for making monocalcium 
phosphate. 
SUMMARY OF THE INVENTION 
The present invention provides an improved method for making monocalcium 
phosphate. The method includes the steps of mixing phosphoric acid with 
water and then adding to that mixture what is defined in the specification 
as "brown mud". Brown mud comprises dicalcium silicate and: hematite; 
calcite; gehlenite; perovskite; anatase; sodalite; calcium aluminum 
sulfate; and sodium salts. 
Preferably, the method of the present invention includes the step of mixing 
approximately 3% to about 50% by weight phosphoric acid with approximately 
50% to about 97% by weight water. The phosphoric acid/water mixture is 
then mixed with brown mud in an approximately 1:1 to about 3:1 weight 
ratio of phosphoric acid/water to brown mud. 
In an embodiment of the present invention, the method includes the steps of 
mixing phosphoric acid with water and slowly adding thereto brown mud. The 
resultant product is then fed to a heating apparatus and dried so that the 
resultant product has a moisture content of 10% or less by weight. 
The resultant product of the present invention has many applications, as 
set forth in the detailed description of the presently preferred 
embodiments, including: industrial waste disposal; agricultural chemical; 
plant food; ammonia suppressants; calcium food additives; diaper batting; 
and as a pharmaceutical source of calcium. 
In an embodiment of the present invention, the resultant product created 
will comprise approximately 3% to about 22% calcium phosphate with the 
remainder of the product including the other components in the original 
brown mud and mixture. 
Additional features and advantages of the present invention are described 
in, and will be apparent from, the detailed description of the presently 
preferred embodiments. 
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
The present invention provides an improved method for making monocalcium 
phosphate and an improved product produced therefrom. The improved method 
includes mixing a phosphoric acid and water mixture with what is known as 
"brown mud" or "brown lime". Brown mud is a residue substance derived as a 
result of the application of dehydrated lime in the foundary process of 
purifying bauxite for the purpose of producing aluminum. Due to the soil 
content in Selina County, Ark., the Bayer process (a method for producing 
alumina from bauxite by heating it in a sodium hydroxide solution) is 
utilized to purify bauxite found in the soil, for the purpose of producing 
aluminum. Because of the soil content in Selina County, Ark. and the use 
of the Bayer process, brown mud is produced as a residue during this 
process. As used herein, the term "brown mud" refers to this residue 
product which the inventor believes is only found in Selina County, Ark. 
Brown mud has a pH above approximately 10.5 and its chemical composition is 
approximately as follows: 
______________________________________ 
Component 
Component Name 
Component Formula % 
______________________________________ 
Dicalcium silicate 
2CaO'SiO.sub.2 57 
Hematite Fe.sub.2 O.sub.3 6 
Calcite CaCO.sub.3 8 
Gehlenite 2CaO'Al.sub.2 O.sub.3 'SiO.sub.2 
22 
Perovskite CaO'TiO.sub.2 5 
Anatase TiO.sub.2 3 
Sodalite 3Na.sub.2 O'3Al.sub.2 O.sub.3 '6SiO.sub.2 'Na.sub.2 SO 
25 
Calcium aluminum 
4CaO'3Al.sub.2 O.sub.3 'SO.sub.3 
5 
sulfate 
Sodium salts 
Na.sub.2 CO.sub.3 and NaAlO.sub.2 
trace 
______________________________________ 
The method of the present invention comprises mixing phosphoric acid with 
water and then adding thereto brown mud. In a preferred embodiment of the 
present invention, the method includes the step of heating the resultant 
phosphoric acid, water, and brown mud mixture in a drying apparatus to 
reduce its moisture content to 10% or less by weight. Preferably, 
approximately 3% to about 50% by weight of phosphoric acid is added to 
approximately 50% to about 97% by weight of water. To the phosphoric 
acid/water mixture, brown mud is added in a weight ratio of approximately 
1:1 to about 1:3 brown mud to phosphoric acid/water. 
The grade of phosphoric acid to be utilized in the method of the present 
invention is dependent upon, in part, the desired resultant product. To 
this end, in certain applications, especially those subject to Food and 
Drug Administration (FDA) approval, the grade of phosphoric acid utilized 
is critical. Accordingly, the grade of phosphoric acid to be utilized 
should be consistent with the desired application of the resultant product 
to be created. 
Typically, phosphoric acid is sold in three grades: food grade; tech grade; 
and FS grade. In applications of the resultant product that are subject to 
FDA approval, and certain other applications of the resultant product, the 
food grade quality of phosphoric acid should be utilized. Usually, the FS 
grade is only utilized for fertilizer and like type applications of the 
resultant product. 
The method of the present invention provides an improved process for 
producing monocalcium phosphate. To this end, the method of the present 
invention does not result in the generation of a great deal of heat as in 
the prior method of adding dicalcium silicate to phosphoric acid. 
Furthermore, the monocalcium phosphate yield is enhanced through the 
present method. 
As stated above, the method of the present invention produces a monocalcium 
phosphate product. In a preferred embodiment of the method of the present 
invention, the resultant monocalcium phosphate product will initially have 
a monocalcium phosphate content of approximately 3 to about 22 weight 
percent. The remaining content of the resultant product will typically 
include the remaining products in the original brown mud mixture. In a 
preferred embodiment of the method of the present invention, the resultant 
product will have the approximate following composition, by weight: brown 
mud --70% to about 87%; phosphoric acid --3 to about 20%; and water --10%. 
The resultant product of the present invention has many applications 
including, inter alia: industrial waste disposal; agricultural chemical; 
plant foods; ammonia suppressants to be utilized with poultry and other 
livestock; calcium feed additives; pharmaceutical applications; and 
treatment of and batting for infant diapers. For example, the resultant 
product can be used in industrial waste disposal in its anhydrous state as 
a cool down for a scrubber. In the agricultural chemical area, an example 
of the use of the monocalcium phosphate of the present invention is as a 
type of fertilizer. The monocalcium phosphate can also provide a source 
for plant food through the addition of ammonia to the product. 
Due to the monocalcium phosphate's excellent properties as an ammonia 
suppressant, monocalcium phosphate is especially useful in suppressing the 
odors generated from uric acid. To this end, experiments have indicated 
that 100 lbs. of a monocalcium phosphate product made pursuant to the 
method of the present invention per 12,000 square feet of a chicken grow 
out area (a chicken feed area) applied approximately every 6 to 8 weeks 
will limit any ammonia build-up in the area to below approximately 20 
parts per million. Furthermore, initial indications indicate that the 
monocalcium phosphate produced by the method of the present invention has 
no adverse effect on poultry when phosphoric acid of food grade quality is 
utilized.

By way of example and not limitation, examples of the present invention 
will now be set forth: 
EXAMPLE 1 
A slurry mixer, having a stainless steel construction, was filled with 
approximately 11 lbs. of phosphoric acid and approximately 11 lbs. of 
water. Because the desired resultant product was to be an ammonia hold for 
use in suppressing the ammonia generated by poultry and other livestock, 
food grade phosphoric acid was utilized. 
To the resultant phosphoric acid and water mixture, brown mud was slowly 
added while the mixing means of the slurry tank mixer was engaged. A 
foaming action initially occurred with a corresponding slight rise in the 
temperature of the phosphoric acid and water mixture. However, the foaming 
action subsided as the mixing continued. The addition of brown mud 
continued until approximately 11 lbs. of brown mud was added to the 
phosphoric acid and water mixture. The mixing action was continued for 
approximately 8 to about 10 minutes. 
The resultant slurry mixture was then discharged from an auger at the 
bottom of the slurry tank. The slurry was fed from the auger onto a heat 
resistant belt that fed the slurry into a drying kiln. The drying kiln 
utilized was a Louisville-type gas fired kiln. However, any type of drying 
apparatus can be utilized such as, for example, a high temperature kiln, 
blower type, or steam supplied pelleting machine. The slurry was dried at 
a temperature of approximately 500.degree. to about 700.degree. F. for 
approximately 3 to about 12 minutes, so that the resultant product had a 
moisture content equal to or less than 10%. 
The resultant product produced pursuant to the method of this example has 
specific applications as an ammonia hold. Indeed, because food grade 
phosphoric acid was utilized, the resultant product of this example can be 
utilized as an ammonia hold for poultry, livestock, and even as a batting 
for diapers. 
EXAMPLE 2 
In this example, the same procedure was followed as set forth above for 
Example 1, except the grade of phosphoric acid was not food quality, but 
rather was tech quality. The resultant product produced pursuant to this 
example has applications as an odors suppressant for stockyards, zoos, and 
the like, or for suppressing odors generated by garbage. 
EXAMPLE 3 
In this example, the same procedure as set forth above for Example 1 was 
utilized except that the grade of phosphoric acid utilized was FS grade. 
The resultant product produced pursuant to the method of this example has 
applications as a fertilizer. 
EXAMPLE 4 
In this example, food grade phosphoric acid having a purity of 87% was 
mixed in a stainless steel slurry tank with water to obtain a solution of 
42% phosphoric acid by weight. The resultant mixture had a volume of 
approximately 2.3 gallons. Although the mixing vessel was a stainless 
steel slurry tank, any type of holding tank and pump or mixer that meets 
requisite food grade requirements can be utilized. 
Approximately 11 lbs. of brown mud was slowly added to the mixture. The 
brown mud mixture was then mixed for approximately 8 to 10 minutes. 
Sufficient brown mud was added to create an end product that comprised 
approximately 17% monocalcium phosphate. If desired, binders to create a 
desired powder, pellet, or granular form can be added to this mixture. 
The slurry was discharged onto an auger or belt for movement into a drying 
apparatus. In this example, the drying apparatus was a tumbler-type dryer. 
The slurry was dried at approximately 700.degree. F. for approximately 10 
minutes to obtain a resultant product that had a moisture content equal to 
or less than 10% by weight. After the product cooled down, the material 
was moved out of the drying apparatus, via, for example, a conveyor belt 
and packaged. 
The resultant material of this example has specific applications as an 
ammonia hold. Specifically, an ammonia hold for utilization with poultry 
and other livestock. 
EXAMPLE 5 
In this example, the same procedure as set forth previously for Example 4 
was followed except that sufficient water was added to the phosphoric acid 
to make a final solution that was only 12% phosphoric acid. Example 4 was 
further modified in that approximately 5.5 lbs. of brown mud was added to 
create an end product having only 6% monocalcium phosphate by weight. The 
resultant product has specific applications as a liquid form of an ammonia 
hold. 
EXAMPLE 6 
In this example, tech grade phosphoric acid 75% was mixed with water to 
create a resultant solution comprising 40% phosphoric acid. The total 
volume of the mixture was approximately 2.3 gallons. To the slurry tank 
having this mixture, brown mud was added in the amount of approximately 11 
lbs. This will create a resultant product having approximately 20% by 
weight monocalcium phosphate. 
The slurry tank was emptied through a discharge auger and then dried in the 
drying apparatus at a temperature of approximately 700.degree. F. for 
approximately 12 minutes to achieve a resultant product having a moisture 
content of 10% or less by weight. The resultant product of this example 
has specific applications for use as an ammonia hold in stockyards, dog 
pounds, rodeo arenas, horse stalls, and the like. These areas of 
application do not require FDA approval and therefore, do not require food 
quality phosphoric acid. 
EXAMPLE 7 
In this example, fertilizer grade phosphoric acid 75% was mixed with water 
to achieve a 40% solution of phosphoric acid by weight. The resultant 
product had a volume of approximately 2.3 gallons. To the slurry tank 
having this mixture brown mud in an amount of approximately 11 lbs. was 
slowly added to achieve a resultant product having 20% monocalcium 
phosphate by weight. The same mixing and drying procedure was followed as 
in Example 6. l 
The resultant product of this example has specific applications for being 
further processed to create a plant food. To this end, by way of example, 
to the resultant product, before it is dried, ammonia can be slowly added, 
either in liquid or gas form, during the mixing in the slurry tank. The 
end product will be a monoammonium phosphate having applications as a 
plant food or fertilizer. Of course, the resultant product of this example 
can be further processed or treated differently to create a different 
desired end product. 
It should be understood that various changes and modifications to the 
presently preferred embodiments described herein will be apparent to those 
skilled in the art. Such changes and modifications can be made without 
departing from the spirit and scope of the present invention and without 
diminishing its attendant advantages.