New Process for the Preparation of Bi-calcic Phosphate soluble in Ammonic Citrate.
Year: 1893

page_text: Date of Application, 17th July, 1893
Complete Specification Left, 17th Mar., 1894-Accepted, 21st Apr., 1894
PROVISIONAL SPECIFICATION.
New Process for the Preparation of Bi-calcic Phosphate soluble in
Ammonic Citrate.
I, THEODORE CHANDELON, of 27 Rue Nysten, Liège, in the Kingdom of
Belgium, Doctor, do hereby declare the nature of this invention to be as follows:-
My invention relates to a new process for the preparation of hydrated bi-calcic
phosphate in a form soluble in ammonic citrate.
In carrying out my invention the earthy phosphates are in the first instance
treated in the ordinary way with sulphuric acid. This is employed dilute in the
form of a titrating solution of 15 to 25 per cent. of acid according to the richness of
phosphate, and in such quantity that the larger part of the phosphoric acid
dissolves in the form of acid phosphate, the rest passing into the state of free
phosphoric acid, but only in the quantity necessary to ensure the solution of the
acid phosphate. The mixture passed under the filter press gives a solution con-
taining an average of 7 to 12 per cent. of phosphoric anhydride (P2O³). The
water previously used for washing will with the addition of sulphuric acid serve to
treat new quantities of earthy phosphates.
The solution so obtained is neutralized by lime water, but the product obtained
by this neutralisation depends entirely upon the conditions under which it is carried
out. If to a solution containing 7 per cent. of phosphoric anhydride (P2O³) an
equal volume of lime water is added containing enough calcic hydrate to transform
the phosphoric acid into bi-calcic phosphate, a sensible evolution of heat is
produced, and the precipitated phosphate is anhydrous (CaHPO) insoluble in
ammonic citrate and contains 52 per cent. of phosphoric anhydride (P20³). Even
if the liquids are diluted with an equal volume of water, the result is still the same;
but if (and it is in this that my invention consists) care is taken to cool the
reacting bodies at the moment of the reaction, the bi-calcic phosphate precipitates
itself in the hydrated condition (CaHPO 2 aq.) containing 41 per cent. of phosphoric
anhydride (P2O). This product is entirely soluble in ammonic citrate, is not
gelatinous and is deposited with considerable rapidity. The cooling at the moment
of contact and reaction can be effected in different ways. I may, for instance,
employ very dilute solutions so as to distribute the heat evolved by the reaction
over large masses of liquids, but in that case the process is not industrially
practicable. I might alternatively lead 'the phosphoric solution through one tube,
the lime water through another, and cold water through a third, and by bringing
these three tubes to one point the mixture would be diluted and cooled at the
moment of reaction. Here however the expense in water is again too considerable.
The phosphoric solution and the lime water may alternatively be cooled before and
during their mixture by being caused to circulate across or round refrigerating
media. Brought to 0° cente. they yield in this way directly and without any
ddition of water bi-calcic phosphate soluble in ammonic citrate. The method
however which I regard as most practical is the following:-I use for the reaction
a jacketed pan of which the jacket may be filled with water of low temperature.
This pan is fitted with three tubes, one at the underside for the introduction of
cold water and one on either side for the introduction of phosphoric solution and
lime water respectively. An overflow tube is also provided at a higher level. By
means of a suitable stirrer I assure the intimate mixture of the solutions. The
phosphoric acid and the lime water are diluted and cooled by the water contained
in the jacketed pan, which is itself prevented from heating by the constant
introduction of cool water into the pan as well as by the circulation round the

page_text: If
jacket. The bi-calcic phosphate held in suspension in the liquid flows away by
the overflow pipe. The dimensions of the pan depend in the first place on the rate
of flow of the phosphoric solution, of the lime water, and of the cooling water.
the pan has a sufficiently large capacity only a small quantity of cooling water will
be required. In the second place the dimensions depend on the degree of con-
centration of the phosphoric solution and the lime water. For example, for the
same quantity of cooling water introduced into the pan a larger capacity would be
required for the pan in order to treat solutions containing 12 per cent. of phosphoric
acid than to treat solutions containing 7 per cent.
The product so obtained is filtered and dried and will contain on titration
39 to 40 per cent. of phosphoric anhydride (P2O). It is entirely soluble in ammonic
citrate, entirely assimilable by vegetables, and absolutely free from acidity.
If it is desired to obtain, as is customary, a product containing also phosphoric
acid soluble in water, the solid product may be steeped in a phosphoric solution
consisting of a mixture of acid and of acid phosphate. A hundred parts by weight
of bi-calcic phosphate obtained as above absorb casily eighty parts by volume of
a 24 per cent, solution of phosphoric acid (H3PO4) and give an almost dry product
which on titration yields 46 to 48 per cent. of phosphoric anhydride, soluble in
water and ammonic citrate, of which half of the phosphoric anhydride is soluble in
water.
Dated this 17th day of July 1893.
COMPLETE SPECIFICATION.
New Process for the Preparation of Bi-calcic Phosphate soluble in
Ammonic Citrate.
I, THEODORE CHANDELON of 27 Rue Nysten Liège in the Kingdom of
Belgium, Doctor, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
My invention relates to a new process for the preparation of hydrated bi-calcic
phosphate in a form soluble in ammonic citrate.
In carrying out my invention the earthy phosphates are in the first instance
treated in the ordinary way with sulphuric acid. This is employed dilute in the
form of a titrating solution of 15 to 25 per cent. of acid according to the richness of
phosphate, and in such quantity that the larger part of the phosphoric acid
dissolves in the form of acid phosphate, the rest passing into the state of free
phosphoric acid, but only in the quantity necessary to ensure the solution of the
acid phosphate. The mixture passed under the filter press gives a solution con-
taining an average of 7 to 12 per cent. of phosphoric anhydride (PO). The water
previously used for washing will with the addition of sulphuric acid serve to treat
new quantities of earthy phosphates."
out.
The solution so obtained is neutralised by lime-water, but the product obtained
by this neutralisation depends entirely upon the conditions under which it is carried
If to a solution containing 7 per cent. of phosphoric anhydride (P²O³) an
equal volume of lime water is added containing enough calcic hydrate to transform
the phosphoric acid into bi-calcic phosphate, a seusible evolution of heat is produced,
and the precipitated phosphate is anhydrous (CaHPO) insoluble in ammonic
..citrate and contains 52 per cent. of phosphoric anhydride (P2O5). Even if the
liquids are diluted with an equal volume of water, the result is still the same ;
if (and-it-is-in-this-that my invention consists) care is taken to cool the reacting
bodies at the moment of reaction, the bi-calcic phosphate precipitates itself in the
but

page_text: hydrated condition (CaHPO₁ 2 aq.)-containing 41 per cent. of phosphoric anhy-
dride (P2O5). This product is entirely soluble in ammonic citrate, is not gelatinous
and is deposited with considerable rapidity. The cooling at the moment of the
contact and reaction can be effected in different ways. I may for instance employ
very dilute solutions so as to distribute the heat evolved by the reaction over large
masses of liquids; but in that case the process is not industrially practicable.
I might alternatively lead the phosphoric solution through one tube, the lime
water through another, and cold water through a third, and by bringing these tubes
to one point the mixture would be diluted and cooled at the moment of reaction.
Here however the expense in water is again too considerable. The phosphoric
solution and the lime water may alternatively be cooled before and during their
mixture by being caused to circulate across or around refrigerating media.
Brought to 0° cent.; they yield in this way directly and without any addition of
water, bi-calcic phosphate soluble in ammonic citrate.
The method however which I regard as most practical is hereafter described and
will be understood by reference to the accompanying drawings upon which-
Figure 1 represents a vertical section through line x-x of the apparatus used in
my new process.
Figure 2 being a vertical section of the same through line y-y, and
Figure 3 a plan thereof.
I use for the reaction a jacketed pan A of which the jacket B may be filled
with water of low temperature. This pan A is fitted with three tubes, one a at the
underside for the introduction of cold water, and one on either side b and c for the
introduction of phosphoric solution and lime-water respectively. An overflow
tube d is also provided at a higher level. By means of a suitable stirrer I assure
the intimate mixture of the solutions. The phosphoric acid and the lime water are
diluted and cooled by the water contained in the jacketed pan A, which is itself
prevented from heating by the constant introduction of cool water into the
pan as well as by the circulation of water of low temperature round the jacket B.
The bi-calcic phosphate held in suspension in the liquid flows away by the
overflow pipe d. The dimensions of the pan A depend in the first place on the
rate of flow of the phosphoric solution, of the lime water, and of the cooling water.
If the pan A has a sufficiently large capacity only a small quantity of cooling water
will be required. In the second place the dimensions depend on the degree of
concentration of the phosphoric solution and the lime-water. For example, for the
same quantity of cooling water introduced into the pan a larger capacity would be
required for the pan in order to treat solutions containing 12 per cent. of phosphoric
acid than to treat solutions containing 7 per cent.
The arrangement of the tubes a b, c and d may be modified according to
particular circumstances.
The product so obtained is filtered and dried and will contain on titration
39 to 40 per cent. of phosphoric anhydride (P2O5). It is entirely soluble in
ammonic citrate, entirely assimilable by vegetables, and absolutely free from
acidity.
If it is desired to obtain, as is customary, a product containing also phosphoric
acid soluble in water, the solid product may be steeped in a phosphoric solution
consisting of a mixture of acid and of acid phosphate. A hundred parts by weight
of bi-calcic phosphate obtained as above absorb easily eighty parts by volume of
a 24 per cent. solution of phosphoric acid (H³PO), and give an almost dry
product which yields on titration 46 to 48 per cent. of phosphoric anhydride, soluble
in water and ammonic citrate of which half of the phosphoric anhydride is soluble
in water.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
A process for the nu

page_text: citrate, characterised by the neutralisation of a phosphoric solution in lime water
by cold, (that is-by cooling the re-acting bodies) for the purpose of obtaining a
product soluble in ammonic citrate, in the manner herein described.
Dated this Seventeenth day of March 1894.
e Applicant,
GEDGE & FEENY,
Agents.