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Патент USA US3028230

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April 3, 1962
E. H. BROWN
3,028,217
TRICALCIUM DIAMMONIUM PYROPHOSPHATE
Filed June 3, 1959
CALClUM
vn'nuous
METAPHOSPHATB
i ""I‘.“
EXTRACTION
AND
PHASE
SEPARATION
SUPLRNATANT
AQUEOUS PHAS a
VISCOQS
PHASE
CRYSTALl-IZATION
OF
C53 Hz (P2O7)z. 444,0
CRYSTA Ll-INE
MA 58
r- WATER
WASHING
CRYS TALS
WASHINGS
AMMONIUM
HYDROXIDE
‘—
CRYSTALLIZATION OF
TRI'CALCIUM
DIAMMONIUM PYROPHOSPHATU
MO'I’HIZR
LIQUOR
CRYSTALLINE
PRoDuc'r
\
(fan/(3m INVENTOR.
BY?’
United States Patent 0
1
3,028,217
ar
1C€
Patented Apr. 3, 1962
2.
3,028,217
dation products of calcium metaphosphate. The super
natant aqueous phase is formed in much greater volume
Valley Authority, a corporation of the United States
Filed June 3, 1959, Ser. No. 817,956
little phosphate. This supernatant solution must be drawn
otf continuously as it is formed it any reasonable degree
of purity of the viscous-phase material is to be attained,
TRICALCIUM DIAMMONIUM PYROPHOSPHATE
Earl H. Brown, She?ield, Ala., assignor to Tennessee
2 Claims. (Cl. 23-107)
(Granted under Title 35, US. Code (1952), sec. 266)
than the heavy viscous phase, but it contains relatively
because the aqueous solution may become su?iciently
concentrated in shorter chain calcium metaphosphate
polymers to cause the materials in the two phases to be
The invention herein described may be manufactured
and used by or for the Government for governmental pur 10 come partially miscible in each other.
When the supernatant solution is continuously drawn
poses without payment to me of any royalty thereon.
off, the viscous phase is a sirupy mixture of hydrated poly_
This invention is a new pyrophosphate and a process
mers of calcium metaphosphate containing from 30 to
for its production.
60 percent of Ca(PO3)2, polymerized in relatively long
Principal objects of the invention are to provide a
new material suitable for fertilizer and other uses and 15 chain molecules.
When extraction is complete, the heavy viscous phase is
to provide a process for its manufacture.
separated from any residual supernatant solution. The
The new material is tricalcium diammonium pyro
separated viscous phase is then held in a closed vesselv
phosphate. It may be produced by digesting crystalline
until crystallization occurs. On standing, this material
tricalcium dihydrogen pyrophosphate in an excess of am
monia. A process for the’production of tricalcium di 20 ?rst becomes a gel and then a mass of crystals.
The resulting crystalline material is tricalcium dihy
hydrogen pyrophosphate is shown and described in my
copending application Serial No. 817,952, ?led June 3,
1959, now abandoned.
drogen pyrophosphate, Ca3H2(P,O7)z-4H2O, mixed with
some orthophosphate. The crystals are washed with
water, which removes orthophosphate. Tricalcium di
I prefer to produce tricalcium diammonium pyrophos
phate from vitreous calcium metaphosphate by a process 25 hydrogen pyrophosphate is then treated with an excess of
ammonium hydroxide in high concentration. Reaction
which comprises soaking with water in a reaction vessel
between the tricalcium dihydrogen pyrophosphate crystals
?nely divided vitreous calcium metaphosphate to promote
hydrolysis thereof, producing an extract consisting of two
phases, namely, (1) a heavy substantially water-insoluble
and concentrated ammonia goes well at room tempera~
ture. A crystalline product, tricalcium diammonium py
viscous phase and (2) a supernatant aqueous solution of 30 rophosphate, Ca3(NH,)2(P2Oq)2-6H2O, is formed.
When fertilizer-grade vitreous calcium metaphosphate
water-soluble degradation products of vitreous calcium
is used as starting material, there is no separation of
metaphosphate; continuously separating the phases; con
phases in the aqueous extract produced. Apparently
tinuously withdrawing the supernatant solution during ex
silica present in the fertilizer-grade material causes the
traction; separating the viscous phase from residual super
natant solution; holding the separated viscous phase until 35 degradation reaction to proceed faster than the phases
will separate under the in?uence of gravity. The entire
it becomes crystalline; washing orthophosphate from the
extract is a single viscous phase. It is treated exactly as
resulting crystalline material; and digesting the resulting
described above for the viscous phase obtained from pure
crystalline tricalcium dihydrogen pyrophosphate with an
calcium metaphosphate. The end result is the same ex
excess, preferably about 6 times the theoretical quantity,
of concentrated ammonium hydroxide. The crystalline 40 cept that the product contains impurities derived from the
impure startm'g material.
'
product of the digestion is tricalcium diammonium pyro~
phosphate, which normally crystallizes with 2 molecules
Example
of water present.
Vitreous pure calcium metaphosphate was crushed and
The attached drawing is a ?owsheet illustrating dia
screened to separate a fraction of size to pass a standard
grammatically a method for the preparation of this new 45 20-mesh screen and be retained upon a 60-mesh screen.
material from calcium metaphosphate.
About 50 grams of the sized calcium metaphosphate was
The preferred starting material is ordinary vitreous cal
introduced into an extraction vessel. Distilled water was
cium metaphosphate. Either chemically pure or fertiliz
added to the extraction vessel dropwise while the vessel
er-grade material is satisfactory. This calcium meta
and contents were maintained at a temperature of about
phosphate is ground to a degree of ?neness which will 50 50° C. An extract consisting of two phases was formed.
depend upon the method of extraction used. For exam
These phases were: (1) a dilute aqueous solution of
ple, simple percolation of water through a bed of crushed
short-chain degradation products of calcium metaphos
calcium metaphosphate at room temperature is one satis
phate, and (2) a heavy viscous phase which was substan
factory method for carrying out extraction.
immiscible with water or with the dilute aqueous
When this method is used, the calcium metaphosphate 65 tially
solution. The phases were separated as formed by dif
preferably is in particles from —20 to +60 mesh in size.
ference in speci?c gravity. The supernatant aqueous
Inclusion of much material ?ne enough to pass a ‘60
phase was continuously drawn off during extraction.
mesh screen will cause a bed of calcium metaphosphate
The viscous phase was then separated from residual
particles to mat together, and the resulting mass does not
supernatant aqueous solution and was placed in a closed
have enough voids to permit free passage of liquid.
60 vessel and there held until it became a crystalline mass,
Preferably, the extraction may be carried out with
consisting essentially of tricalcium dihydrogen pyrophos
use of a stirring device arranged to keep the particles of
phate in admixture with a small proportion of orthophos
calcium metaphosphate in motion in extraction water.
phate. The mass was then washed with su?cient water
When exn'action is conducted in this manner the calcium
metaphosphate may be of smaller particle size, since the 65 to remove orthophosphate.
The resulting crystals of tricalcium dihydrogen pyro
material dies not adhere while in motion in water, and
phosphate were then treated with an excess (about 6
the advantage of greater surface contact with extraction
water per pound of calcium metaphosphate is gained.
times the theoretical quantity) of concentrated ammonium
hydroxide at about 20° to 35" C. The resulting mixture
I have found that the extract consists of two phases
when pure calcium metaphosphate is used as starting ma 70 was held in a closed vessel until reaction was complete.
The process just described was repeated twice. In each
terial: (1) a heavy viscous phase immiscible with water,
and (2) a supernatant dilute aqueous solution of degra
case the crystalline product produced was tricalcium di
3,028,217
4
ammonium pyrophosphate having the compositions shown
soluble degradation product of vitreous calcium meta
by the following table. '
phosphate; continuously separating said phases; continu
ously withdrawing the supernatant solution from said re
Composition, percent
Mole ratio
action vessel; separating said viscous phase from the re~
P105
sidual supernatant solution; holding said separated vis
cous phase until it becomes crystalline; washing ortho
Run
CEO
1 ________ -.
2 ........ _3 ........ --
27.42
27.59
27.26
Pros
46.34
46. 61
46.38
NH:
5.5
5.3
5.5
H_:O CaO
(di?'.)
20.74
20.50
20.86
1.50
1.50
1.49
NHs H2O
phosphate from the resulting crystalline material; digest
ing the resulting crystalline tricalcium dihydrogen pyro
1.0
1.0
1.0
0.99
0.95
0.99
3.53v
3.48
3.54
phosphate with an excess, of the theoretical quantity, of
10 concentrated ammonium hydroxide; and withdrawing the
crystalline product ‘from said digestion step as tricalcium
These products had the same characteristic optical prop
crties and X-ray diffraction pattern.
I claim as my invention:
diammonium pyrophosphate having the formula
.
1. A process for the production of tricalcium diam 15
monium pyrophosphate which comprises the steps of soak
ing with water in a reaction vessel ?nely divided vitre
ous calcium metaphosphate to promote hydrolysis there
of whereby a mixture of hydrated polymers of rela
2. The process of claim 1 wherein the step of digest
ing the crystalline tricalcium- dihydrogen pyrophosphate
with an excess of concentrated ammonium hydroxide is
carried out at a temperature of about 20° to 35° C.
tively long-chain molecules of calcium metaphosphate 20
containing from about 30 to about 60 percent of Ca( PO3)2
is formed, producing an extract from said water-soaked
calcium metaphosphate consisting of two phases, name
1y, (1) a heavy, substantially water-insoluble viscous
phase and (2) a supernatant aqueous solution of water 25
References Cited in the ?le of this patent
Journal of Physical Chemistry, Brown et al., “Crystal
line
Intermediates . . . Calcium
Polymetaphosphate,”
vol. 61, July-December 1957, pages 1669 and 1670.
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