MANUFACTURE OF PHOSPHORIC ACID AND of "IMPROVEMENTS IN THE PHOSPHORUS
Year: 1871

page_text: LETTERS PATENT to Benjamin Tanner, of New Brighton, in the
County of Chester, Manufacturing Chemist, for the Invention
MANUFACTURE OF PHOSPHORIC ACID AND
of "IMPROVEMENTS IN THE
PHOSPHORUS."
Sealed the 24th October 1871, and dated the 7th August 1871.
PROVISIONAL SPECIFICATION left by the said Benjamin Tanner
at the Office of the Commissioners of Patents, with his Petition,
on the 7th August 1871.
I, BENJAMIN TANNER, of New Brighton, in the County of Chester,
Manufacturing Chemist, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHORIC ACID AND
PHOSPHORUS," to be as follows:-
In carrying out this Invention phosphate of lime, or phosphate of
alumina, or phosphate of iron, in any form or condition, or crystals
formed by the action of hydrochloric acid or phosphoric acid or mixtures

page_text: thereof upon the said phosphates, and also mixtures of any of the before-
mentioned phosphatic compounds are dissolved in hydrochloric acid or
phosphoric acid, or water or mixtures thereof, by means of arrangements
which are well known and which form no part of the present Invention.
It is preferred however to obtain such solutions by processes similar to
those described by me in the Provisional Specification of an Invention
for "Improvements in the Manufacture of Superphosphate of Lime,"
for which Provisional Protection has been granted to me, bearing date
the 28th day of April 1871, No. 1147. The phosphoric acid is thus
obtained in solution free from sand and insoluble matters.
These solutions, either with or without previous evaporation, but by
preference without such evaporation, are treated with sulphuric acid or
oxalic acid or silicic acid, or mixtures thereof, preferably in such
quantity that such acid or acids shall after such admixture be in equi-
valent or combining proportion to the lime, alumina, or iron, or mixtures
thereof present. When sulphuric acid has been used either wholly or
partly for the removal of the lime or calcium the precipitated sulphate
of lime thus formed is separated and washed either by filtration, de-
cantation, or otherwise, and the clear solution and washings are ready for
evaporation. When phosphate of lime only has been used the evaporation
is continued to any required density, and the phosphoric acid is drained
off from any insoluble matter, but when phosphate of iron or phosphate
of alumina or mixtures thereof has or have been used, or when iron or
alumina or mixtures thereof is or are present in the solution after the
removal of the lime or calcium, the evaporated liquor is allowed to cool
and stand until crystals are formed, from which the phosphoric acid is
drained off in a more or less pure state, the crystallising process being
repeated in the ordinary manner when it is found necessary to do so for
the more perfect removal of the sulphates. In some cases it is preferred
to evaporate the solutions of phosphates obtained as already described to
a dry or pasty condition preferably at a temperature of about 212°
Fahrenheit, or to grind the phosphates when they are not already in a
fine condition, and then add either sulphuric acid, or oxalic acid, or
silicic acid, or mixtures thereof, by preference in such quantity that
such acid or acids shall after such admixture be in equivalent or
combining proportion to the lime, alumina, or iron, or mixtures thereof
present, with or without the addition of water, and from such mixture
by means of hydrochloric acid or water, or mixtures thereof, the soluble

page_text: salts are sometimes dissolved out, and such solution is evaporated and
treated as already described.
When oxalic acid or silicic acid or mixtures thereof has or have been
used in any of the foregoing processes the solution is evaporated either
with or without previous filtration, and the phosphoric acid drained off
from insoluble matter, which is then washed and freed from phosphoric
acid either by filtration, decantation, or otherwise. The phosphoric acid
washings thus obtained are evaporated to any required density. By
these means phosphoric acid is obtained in a more or less pure condition,
and it is sometimes further purified in the following manner :-When
any sulphuric acid is intermixed with the phosphoric acid it is sometimes
removed by the addition of an equivalent proportion of lime (preferably
in solution), either in the form of lime, or chloride of calcium, or
carbonate of lime, or any of the forms of phosphate of lime or mixtures
thereof, either with or without the previous addition of hydrochloric
acid, and the sulphate of lime precipitated is separated and washed by
filtration, decantation, or otherwise. When iron is present it is some-
times found desirable to add nitric acid (either before or after the
removal of sulphuric acid) in sufficient quantity to peroxidize the whole
of the protosalts present. The evaporation is continued at a temperature
of about 212° Fahrenheit until acid fumes cease to come off, and the
liquor has attained the required density, when it is drained off from any
insoluble matter thrown down during the evaporation. Any fumes of
hydrochloric acid given off in any of the above processes are collected
and condensed in the usual manner.
For the production of phosphorus the phosphoric acid obtained in
accordance with this Invention is more or less perfectly freed from lime
in the manner described before the phosphoric acid is deoxidized by the
processes commonly employed in the manufacture of phosphorus.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of August, in the year
our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Benjamin Tanner, Her special licence
that I, the said Benjamin Tanner, my executors, administrators, and
assigns, or such others as I, the said Benjamin Tanner, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time, and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF PHOSPHORIC ACID AND PHOSPHORUS," upon the condition
(amongst others) that I, the said Benjamin Tanner, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Benjamin Tanner, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement :—
My said Invention relates to certain improved and advantageous
methods of obtaining phosphoric acid and phosphorus. For the con-
venience of description and reference the following paragraphs, in which
the processes embraced by my said Invention are described, are numbered
consecutively.
1. Phosphates of lime or phosphates of alumina, or phosphates of
iron, in any form or condition, or crystals formed by the action of
hydrochloric acid or phosphoric acid, or mixtures thereof, upon the said
phosphates, and also mixtures of the before-mentioned phosphatic com-
pounds, are dissolved in hydrochloric acid, or phosphoric acid, or water,
or mixtures thereof, by means of arrangements which are well known,
and which form no part of my said Invention. I prefer, however, to
obtain such solutions by processes similar to those described by me in
the Specification of an Invention for "Improvements in the Manu-

page_text: facture of Superphosphate of Lime" for which Letters Patent have
been granted to me, bearing date the Twenty-eighth day of April One
thousand eight hundred and seventy-one, No. 1147. The phosphoric
acid is thus obtained in a condition free from sand and other insoluble
matters.
2. These solutions, either with or without any previous evaporation,
but by preference without such evaporation, are treated with sulphuric
acid, or oxalic acid, or silicic acid, or mixtures thereof, preferably in
such quantities that such acid or acids shall, after such admixture, be in
cquivalent or combining proportions to the lime, alumina, or iron, or
mixtures thereof present.
In order to determine the quantity of such acid or acids or mixtures
thereof to be added, the lime or calcium in the solution is estimated by
chemical analysis, and for every twenty-eight hundredweights of lime,
or twenty hundredweights of calcium present, forty hundredweights of
anhydrous sulphuric acid (in any more or less pure or dilute condition),
or forty-five hundredweights of silicic acid, or sixty-one and a half
hundredweights of crystallized oxalic acid, (or an equivalent quantity in
any other form or condition), or any proportional mixtures thereof is or
are used, but when treating solutions containing phosphate of iron, or
phosphate of alumina, or mixtures thereof, it is desirable to estimate
the phosphoric acid in combination with the iron or alumina or mixtures
thereof present, by suitable chemical examination, and for every seventy-
one hundredweights of real phosphoric acid ascertained to be present,
one hundred and twenty hundredweights of anhydrous sulphuric acid
(in any more or less pure or dilute condition), or one hundred and
thirty-five hundredweights of silicic acid, or one hundred and eighty-
four and a half hundredweights of crystallized oxalic acid (or an equi-
valent quantity in any other form or condition), or any proportional
mixtures thereof, is or are added in addition to the quantity required (as
above described), for the lime or calcium present, the quantity of either
of these acids being varied according to the purity and strength thereof,
but still adhering to the principle of using these acids, by preference,
in such proportions as to remove the whole of either of the bases or
mixtures thereof in the solution from the phosphoric acid. The ad-
mixture is easily accomplished by means of a wooden vat fitted with
rotating arms or other agitating arrangements, as will be well understood,
and the acids are by preference, added to the solution of the phosphate or

page_text: phosphates (the oxalic acid being dissolved in water) in a liquid form,
and in a more or less dilute condition. When sulphuric acid has been
used, either wholly or partly, for the removal of the lime or calcium,
the precipitated sulphate of lime thus formed is separated and washed,
either by filtration, decantation, or otherwise, and the clear solution
and washings are ready for evaporation. When phosphate of lime only
has been employed, the evaporation is continued to any required density,
and the phosphoric acid is drained off from any insoluble matter; but
when phosphate of iron or phosphate of alumina, or mixtures thereof
has or have been used, or when iron or alumina, or mixtures thereof
is or are present after the removal of the lime or calcium, the evapo-
rated liquor is allowed to cool and stand until crystals are formed,
from which the phosphoric acid is drained off in a more or less pure
state, the crystallising process being repeated in the ordinary manner,
when it is found necessary to do so, for the more perfect removal of the
sulphates. The evaporation of the prepared solutions and washings may
be conveniently accomplished in suitable furnaces heated in the ordinary
manner, but it is preferred to do so by means of steam, superheated steam,
or hot air or mixtures thereof, regulating the temperature accordingly,
and to have a temperature of from 212° to 280° Fahrenheit when any
dry heat is employed, and when superheated steam, or mixtures of steam
and hot air, or mixtures thereof is or are used for this purpose, a tem-
perature of from 250° to 450° Fahrenheit. When mixtures of hot air
and steam are employed the temperature is regulated according to their
relative proportions, that is to say, decreasing the temperature as the
proportions of hot air to the steam is increased. The evaporation is
usually continued till acid fumes cease to be evolved, which may be
condensed or utilized by any of the usual methods employed for this
purpose.
3. The solutions of phosphates obtained as already described are
evaporated to a dry or pasty condition, preferably at a temperature of
about 212° Fahrenheit, or the phosphates are ground or nulverized when

page_text: present. The quantity of such acid or acids or mixtures thereof to be
added is determined in the manner detailed (for the same purpose in
treating solutions of these phosphates) in the paragraph hereof num-
bered 2. When the chemical action by these means is completed, or
nearly so, the mixture is treated with hydrochloric acid more or less
diluted with water (but acid of 10° to 15° Twaddel's hydrometer is
convenient for this purpose) and the soluble portion having been re-
moved the residue is washed by means of water. The solution and
washings are evaporated and treated as herein-before described.
The hydrochloric acid thus employed acts as a solvent, first, by
dissolving that portion acted upon by the acid or acids employed,
and secondly, by dissolving the phosphate not reached by the acid or
acids used, thus presenting the whole of the phosphate or phosphates
to the acid or acids in a more favourable condition for chemical action
to take place, and hastening the completion of the process. It is clear
that hydrochloric acid and water may be mixed with any of the above-
named acids or mixtures thereof prior to their addition to the phosphates,
as in both cases they act as solvents, and in a precisely similar manner.
When oxalic acid or silicic acid or mixtures thereof has or have been
used in any of the foregoing processes, the solution is evaporated as
already described either with or without previous filtration, and the
phosphoric acid drained off from any insoluble matter, which is then
washed or freed from phosphoric acid, either by filtration, decantation,
or otherwise. The phosphoric acid and washings thus obtained are
evaporated in the manner hercin-before described to any required
density.
4. By the means herein-before described the phosphoric acid is
obtained in a more or less pure condition, and it is sometimes further
purified in the following manner:-When any sulphuric acid is inter-
mixed with the phosphoric acid it is sometimes removed by the addition
of an equivalent proportion of lime or calcium (preferably in solution
or suspended in water in a fine state of division) either in the form of
lime, or chloride of calcium, or carbonate of lime, or any of the forms
of phosphate of lime or mixtures thereof; that is to say, supposing
for example, the phosphoric acid contained five per cent. of anhydrous
sulphuric acid, then twenty tons of such phosphoric acid would contain
one ton of anhydrous sulphuric acid, and for this fourteen hundredweights

page_text: of lime, or 27 hundredweights of chloride of calcium, or twenty-five
hundredweights of carbonate of lime, or an equivalent quantity of any of
the forms of phosphate of lime or any proportional mixture thereof, would
be employed, so that in either case fourteen hundredweights of lime, or
ten hundredweights of calcium shall be so added, varying the proportion
according to the purity of the lime or calcium salt employed. When any
insoluble phosphate of lime is employed for this purpose it is preferred
to dissolve it in hydrochloric acid and water prior to adding it to the
impure phosphoric acid, the sulphate of lime precipitated is separated
and washed by filtration, decantation, or otherwise, and when iron is
present, it is sometimes found desirable to add nitric acid (either before
or after the removal of sulphuric acid) in sufficient quantity to per-
oxidize the protosalts present. The evaporation is continued at the
temperature herein-before described until acid fumes cease to come off,
and the liquor has attained the required density, when it is drained off
from any insoluble matter thrown down during the evaporation. Any
fumes of hydrochloric acid given off in any of the above processes are
collected and condensed in the usual manner.
5. For the production of phosphorus, the phosphoric acid obtained
in accordance with my said Invention is more or less perfectly freed
from lime in the manner herein-before described before it is deoxidized
by the processes commonly employed in the manufacture of phosphorus.
It should be observed that the proportions of the substances employed
for the purposes of my said Invention are not in all cases precisely
such as are herein-before mentioned, as such proportions may, as will
be well known to persons experienced in the manufacture of analogous
chemical products, in some instances be varied without departing from
the principles of my said Invention.
Having thus declared and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I would observe in
conclusion, that what I consider novel and original, and therefore claim
as constituting the Invention secured to me by the said herein-before
in part recited Letters Patent are,-.
First. The manufacture of phosphoric acid by means of the processes
and treatment of the several substances. hercin mentioned, substantially
as herein-before set forth and described, or any mere modifications
thereof.

page_text: And, secondly. The production of phosphorus, substantially as herein-
before set forth and described.
In witness whereof, I, the said Benjamin Tanner, have hereunto
set my hand and seal, this Third day of February, in the year
of our Lord One thousand eight hundred and seventy-two.
BENJAMIN TANNER: (L.S.)