IMPROVED PROCESS OF TREATING AND PURIFYING CRUDE PHOSPHORIC ACID, AND IN THE PRODUCTION Or SOLUBLE PHOSPHATES, ALSO FOR THE MANUFACTURE OF PHOSPHORUS, AND THE TREATMENT of certain ResiDUES RESULTING THEREFROM, AND PHOSPHATE OF ALUMINA
Year: 1872

page_text: .
ETTERS PATENT to Farnham Maxwell Lyte, Chemist, of the Firm
of Storck and Co., Asnières, France, for the Invention of "IMPROVED
PROCESS OF TREATING AND PURIFYING CRUDE PHOSPHORIC ACID, AND IN THE
PRODUCTION Or SOLUBLE PHOSPHATES, ALSO FOR THE MANUFACTURE OF
PHOSPHORUS, AND THE TREATMENT of certain ResiDUES RESULTING THEREFROM,
AND PHOSPHATE OF ALUMINA."-A communication from abroad by Henry ¨
Storck, Edouard Hentsch, Auguste Hentsch, André Lutscher, and
Frederic Grininger, constituting the Firm of Storck and Company,
residing at Asnières, near Paris, France.
PROVISIONAL SPECIFICATION left by the said Farnham Maxwell Lyte
at the Office of the Commissioners of Patents, with his Petition, on
the 28th November 1872.
I, FARNHAM MAXWELL LYTE, Chemist, of the Firm of Storck and
Co., Asnières, France, do hereby declare the nature of the said Inven-
tion' for "IMPROVED PROCESS OF TREATING AND PURIFYING CRUDE PHOSPHORIC
ACID, AND IN THE PRODUCTION OF SOLUBLE PHOSPHATES, ALSO FOR THE MANU-

page_text: PACTURE OF PHOSPHOROUS, AND THE TREATMENT OF CERTAIN RESIDUES RESULTING
THEREFROM, AND PHOSPHATE OF ALUMINA," a communication to me from
Henri Storck, Edouard Hentsch, Auguste Hentsch, André Lutscher,
and Frederic Grininger, constituting the Firm of Storck and Company,
residing at Asnières, near Paris, France, to be as follows:-
:-
This Invention consists,-
First. In the production of sulphuric acid from phosphoric acid and
certain of its compounds by means of barium and its salts.
Second. In the application of phosphoric acid thus purified to the
manufacture of phosphate of sodium, phosphate of ammonia, and other
phosphates, and its employment in manufactures per se.
Third. In the treatment of the residues as will be described.
Fourth. In the manufacture of a paste wherewith to charge retorts in
the manufacture of phosphorus, crude phosphoric acid or soluble acid.
phosphates (super-phosphates) are usually produced by acting on the
tribasic phosphate of calcium, phosphorites, coprolites, bone ash, or
other forms of so-called natural phosphates with sulphuric acid. It has
hitherto been found difficult to extract from the phosphoric acid or
super-phosphates thus produced the sulphuric acid employed in the
attack.
The object of the present Patent process is the extraction of this
sulphuric acid, and the application of the phosphoric acid or acid
phosphates thus purified to the manufacture of phosphates in general,
or the production of the said purified phosphoric acid. for employment,
per se, or for the manufacture of phosphorus. I take mineral phos-
phates, bone earth, or any other form of phosphate of calcium more
or less impure, and treat them with the quantity of sulphuric acid
requisite to convert them into phosphoric acid, or a soluble acid
phosphate of calcium, the former remaining in solution is drawn off.
This liquid is now treated with hydrate of barium, carbonate of barium,
sulphide. of barium, chloride of barium, or any convenient compound of
barium, by means of which the sulphuric acid may be withdrawn from
the solution of phosphoric acid or the acid phosphate. Oxides or salts
of lead or strontium may also be employed for this same purpose, but
are less efficacious.

page_text: Another method consists in forming an acid phosphate of barium,
lead, or strontium, and adding this in sufficient quantity to the crude
phosphoric acid or super-phosphate. By either of these means the
sulphuric acid contained in the crude phosphoric acid is precipitated,
and the purified phosphoric acid or super-phosphate may be drawn off
by decantation or filtration.
I
may
here specify that the presence of any base in combination with
the phosphoric acid renders the extraction of the sulphuric acid either
more imperfect and slower so that in practice it is more convenient to add
sufficient sulphuric acid in the attack so as to precipitate as much as
possible the lime contained in the natural phosphate under treatment.
The phosphoric acid thus purified by what I may term barytation
may be employed for the manufacture of phosphate of sodium, neutral
or tribasic phosphate of ammonia, or other soluble phosphates exempt
from sulphuric acid, or for the manufacture of a paste suitable for the
production of phosphorous.
65
"
In illustration of the above I proceed summarily to describe my
process of manufacturing phosphate of sodium, which will resume at
the same time the production and barytation of phosphoric acid. I
employ large wooden vats, and the well-ground phosphorite or bone
earth is attacked with dilute sulphuric acid, about 5 of acid, 1.8 Baumé
to 100 of water, the quantity of acid employed being proportioned to
the quantity of phosphoric acid in the phosphorite.
•
If I employ chamber acid I use a proportionally larger quantity; the
unsoluble portions are after 10 hours of constant stirring allowed to
settle, and the liquor is syphoned into another vat. The residue is washed,
and the washings reserved for mixing with another 5 p.c. of sulphuric
acid for the next attack. The liquor which has been drawn off is crude
dilute phosphoric acid containing more or less sulphuric acid, and
according to the richness of the phosphorite employed will mark from
11° to 12° Baumé, and it should contain but little calcium. If it does
the barytation becomes more difficult, and sufficient sulphuric acid has
not been employed. Carbonate or hydrate of barium is now added, and
the liquid stirred up continually till a portion being taken no longer
gives any milkness with chloride of barium. I now add carbonate or
hydrate of baryta to some of the liquid to convert the phosphoric acid
it contains into an acid phosphate of barium, and I mix this in the

page_text: requisite proportions with other crude dilute phosphoric acid as it leaves
the attacking vat. I thus precipitate the whole of the sulphuric acid:
After barytation I evaporate the purified phosphoric acid to a density of
about 15° to 16° Baumé, neutralize the evaporated liquid with carbonate.
of sodium, filter off the phosphate of iron and phosphate of aluminium
insoluble residues formed during neutralization, bring the liquid to a
density of about 23° to 26° Baumé, and crystallize the phosphate of
sodium.
In making neutral phosphate of ammonia I concentrate my barytated
phosphoric acid to about 22° to 23° Baume, then neutralize with
ammonia and separate the iron alumina and unsoluble phosphates by
filtration. I concentrate to the crystallizing point, and then if the liquid
has become acid by loss of ammonia I neutralize again either with
ammonia or by adding some of the tribasic salt, and then crystallize.
If I desire to make the tribasic phosphate of ammonia I first
neutralize the barytated acid as for the neutral salt filter, then add to
the solution enough ammonia to precipitate the tribasic salt which I
separate by filtration and pressure from the mother liquor.
In all these cases, by the employment of barium, I separate the
sulphuric acid while the liquor is still acid, and it is advantageous as
above stated to have the least possible of any base in combination with
any portion of the phosphoric acid during barytation. Acid phosphates
can however be also deprived of their sulphuric acid where absolutely
requisite, but the process is rendered slower in proportion as more of the
acid is saturated or combined.
In either case I have a residue of more or less phosphate of iron and
phosphate of alumina precipitated together with more or less un-
decomposed phosphate of calcium, and often some phosphate of barium,.
if the barytation has been carried to even a slight excess. (The greater
portion however of the latter compound precipitates as acid phosphate-
during the concentration of the acid, liquid). These residues I treat
in one of four ways. .
First. I heat them with carbonate of sodium and convert the
phosphates of iron and aluminium into oxides, which being treated
with water and a little caustic soda, the aluminium dissolves
alumate of sodium; while the iron remains insoluble, the phosphoric acid
may be precipitated from the liquid by lime.
as

page_text: Second. I boil the residues with carbonate of sodium, whereby the
phosphoric acid is partly extracted from its combination with the iron,
but the phosphate of aluminium remains undecomposed.
Third. I treat the residues with hydrochloric acid, adding either a salt
of calcium or some lime, but chloride of calcium answers well, or I add
to the hydrochloric solution of the residues a salt of barium or some
oxide of barium. On concentrating the liquor to 44° Baumé the acid
phosphate of calcium crystallizes, or the acid phosphate of barium, as
the case may be. These phosphates of calcium or of barium are able to
be employed for the manufacture of phosphoric acid or its compounds,
and I extend my claim to applying a similar mode of treatment to
natural phosphate of aluminium with a view to obtain from them the
phosphoric acid they contain, and to produce acetate of alumina for
which a fresh Patent is applied for.
Fourth. I further employ my purified or barytated phosphoric acid
alone or combined with phosphate of calcium, or with the phosphate of
any convenient base for the production of phosphorus. I find that by
these means I avoid the disengagement of sulphurus acid which
usually takes place, while the quantity of phosphorous is increased.
I evaporate my barytated phosphoric acid for this purpose to about.
45° Baumé, and make it into a paste with pounded phosphorite or bone
earth and charcoal, and treat by distillation the paste thus made in the
same manner as the similar paste is treated in phosphorous manu-
factories.

page_text: tribasic phosphate of calcium, phosphorites, coprolites, bone ash, or other
forms of so-called natural phosphates with sulphuric acid. It has
hitherto been found difficult to extract from the phosphoric acid or
super-phosphate thus produced the sulphuric acid employed in the
attack.
The object of this Invention is the extraction of this sulphuric acid,
and the application of the phosphoric acid or acid phosphates thus
purified to the manufacture of phosphates in general, or the production
of the said purified phosphoric acid for employment per se, or for the
manufacture of phosphorus. For this purpose I take mineral phos-
phates, bone earth, or any other. form of phosphate of calcium more or
less impure, and treat them with the quantity of sulphuric acid requisite
to convert them into phosphoric acid; or a soluble acid phosphate of
calcium, the former remaining in solution is drawn off. This liquid is
now treated with hydrate of barium, carbonate of barium, sulphide of
barium, chloride of barium, or any convenient compound of barium, by
means of which the sulphuric acid may be withdrawn from the solution
of phosphoric acid or the acid phosphate. Oxides or salts of lead or
strontium may also be employed for this same purpose, but are less
efficacious.
Another method consists in forming an acid phoshate of barium, lead,
or strontium, and adding this in sufficient quantity to the crude
phosphoric acid or super-phosphate. By either of these means the
sulphuric acid contained in the crude phosphoric acid is precipitated,
and the purified phosphoric acid or super-phosphate may be drawn off by
decantation or filtration.
I may here observe that the presence of any base in combination with
the phosphoric acid renders the extraction of the sulphuric acid either
more imperfect or slower, so that in practice it is more convenient to
employ sufficient sulphuric acid in the attack, so as to precipitate as
much as possible the lime contained in the natural phosphate under
treatment. The phosphoric acid thus purified by what I may term
'barytation" may be employed for the manufacture of phosphate of
sodium, neutral or tribasic phosphate of ammonia, or other soluble
phosphates exempt from sulphuric acid, or for the manufacture of a
paste suitable for the production of phosphorus. I however sometimes
find it advantageous in the preparation of the tribasic phosphate of
ammonia if I do not choose to employ baryta, or if I can find subsequent
**

page_text: employment for the washing water to simply purify the said tribasic
phosphate by washing it thoroughly on a filter or by decantation with a
solution of ammonia. The tribasic phosphate is but slightly soluble in
aqueous ammonia, and the washing removes from it the sulphuric
acid, as well as chlorides, nitrates, or other impurities; or if I choose I
still further vary my process of purification by dissolving the phosphate
of ammonia or the tribasic phosphate of ammonia in water, and repre-
cipitating it by an addition of ammonia.
In illustration of the above I now proceed to describe my process of
manufacturing phosphate of sodium, which will effect at the same time
the production and barytation of phosphoric acid. For this purpose I
employ large wooden vats, and the well-ground phosphorite or bone
earth is attacked with dilute sulphuric acid, about 5 parts of acid of
the strength of 1·8 Baumé to 100 parts of water, the quantity of acid
employed being proportioned to the quantity of phosphoric acid in the
phosphorite.
"
If I employ chamber acid I use a proportionately larger quantity;
the insoluble portions are then after 10 hours of constant stirring
allowed to settle, and the liquor is syphoned into another vat. The
residue is washed, and the washings reserved for mixing with another
5 cent. of sulphuric acid for the next attack. The liquor which
per
has been drawn off is crude dilute 'phosphoric acid containing more or
less sulphuric acid, and according to the richness of the phosphorite
employed will indicate from 11° to 12° Baumé, and it should contain but
little calcium. If it does the barytation becomes more difficult, and
shews that sufficient sulphuric acid has not been employed. Carbonate or
hydrate of barium is now added, and the liquid stirred up continually
till it no longer gives any milkiness with chloride of barium. I now
add carbonate or hydrate of baryta to some of the liquid to convert the
phosphoric acid it contains into an acid phosphate of barium, and I mix
this in the requisite proportions with other crude dilute phosphoric acid
as it leaves the attacking vat. I thus precipitate the whole of the
sulphuric acid. After barytation I evaporate the purified phosphoric
acid to a density of about 15° to 16° Baumé, neutralize the evaporated
liquid with carbonate of sodium, then filter off the phosphate of iron and
phosphate of aluminium insoluble residues formed during neutralization,
and thus bring the liquid to a density of about 23° to 26° Baumé, and
crystallize the phosphate of sodium...
.....

page_text: In making neutral phosphate of ammonia I concentrate my barytated
phosphoric acid to about 22° to 28° Baumé, then neutralize with
ammonia, and separate the iron alumina and insoluble phosphates by
filtration. I concentrate to the crystallizing point, and then if the liquid
has become acid by loss of ammonia I neutralize again either with
ammonia, or by adding some of the tribasic salt, and then crystallize.
If I desire to make the tribasic phosphate of ammonia I first neutralize
the barytated acid as for the neutral salt filter, then add to the solution
enough ammonia to precipitate the tribasic salt, which I separate by
filtration and pressure from the mother liquor.
In all these cases, by the employment of barium, I separate the
sulphuric acid while the liquor is still acid and it is advantageous as
above stated to have the least possible of any base in combination with
any portion of the phosphoric acid during barytation. Acid phosphates
can however be also deprived of their sulphuric acid where absolutely
requisite, but the process is rendered slower in proportion as more of
the acid is saturated or combined.
In either case I have a residue containing more or less phosphate
of iron and phosphate of alumina precipitated together with more or
less undecomposed phosphate of calcium, and often some phosphate of
barium, if the barytation has been carried to even a slight excess. (The
greater portion however of the latter compound precipitates as acid phos-
phate during the concentration of the acid liquid). These residues I treat
in one of four ways, as follows:—
Example First.-I treat them with carbonate of sodium and convert the
phosphates of iron and aluminium into oxides, which being treated with
water and a little caustic soda the aluminium dissolves as alumate of
sodium; while the iron remains. insoluble, the phosphoric acid may be
precipitated from the liquid by lime.
Example Second.-I. boil the residues with carbonate of sodium,
whereby the phosphoric acid is partly extracted from its combination
with the iron, but the phosphate of aluminium remains undecomposed.
Example Third. I treat the residues with hydrochloric acid, adding
either a salt of calcium or some lime, but chloride of calcium answers
well, or I add to the hydrochloric solution of the residues a salt of barium
or some oxide of barium. On concentrating the liquor to 44° Baumé

page_text: Under example the second. Boiling with carbonate of sodium, as above
described.
Under example the third. Crystallizing out the acid phosphates of
calcium or of barium by the treatment above described. I further
employ purified phosphoric acid or acid phosphate in the manufacture of
phosphorus, as above described.
In witness whereof, I, the said Farnham Maxwell Lyte, have here-
unto set my hand and seal, this Twelfth day of May, in the year
of our Lord One thousand eight hundred and seventy-three.
F. MAXWELL LYTE. (L.s.)