IMPROVEMENTS IN THE METHOD OF AND IN APPARATUS FOR MANU- A communication FACTURING PHOSPHORIC ACID AND SUPERPHOSPHATES
Year: 1878

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company, Patont
Solicitors, at Frankfort-on-the-Main, in the Empire of Germany, for the Inven-
tion of "IMPROVEMENTS IN THE METHOD OF AND IN APPARATUS FOR MANU-
A communication
FACTURING PHOSPHORIC ACID AND SUPERPHOSPHATES."
from Carl Müller and Arthur Packard, persons trading under the Firm of
Müller Packard & Co., of Wetzlar, in the Empire of Germany.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office of
the Commissioners of Patents on the 31st May 1878.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
"IMPROVEMENTS IN THE
Frankfort-on-the-Main, in the Empire of Germany.
NETHOD OF AND IN APPARATUS FOR MANUFACTURING PHOSPHORIC ACID AND
SUPERPHOSPHATES. [A communication from Carl Müller and Arthur Packard,
persons trading under the Firm of Müller, Packard, & Co., of Wetzlar, in the Empire
of Germany.]
This Invention relates to improvements in the method of and apparatus for
producing phosphoric acid in large quantities from phosphates containing either
large or small quantities of iron clay earth.
The production of rich phosphoric acid from poor phosphates have not hitherto
been accomplished in such a manner as to be remunerative, as large quantities of
phosphoric acid are lost, partly through partial decomposition of the phosphates,
and partly by reason of the great waste in washing the muddy product.
This Invention comprises an improved method of working by machinery and
a systematic method of manufacturing, that is to say,-
In the dissolution of the finely powdered phosphorites by sulphuric acid, and in
separating the phosphoric acid in solution, I use a mechanical mixing apparatus, so
that the phosphorite powder cannot sink to the bottom, thus counteracting the
action of the sulphuric acid, as is often the case with hand manipulation. All the

page_text: °
phosphoric acid contained in the phosphates, which is about 1-11% of the whole
is thus placed in solution.
The mixing apparatus consists of an upright wooden bar with a short projecting
iron pivot running in a step bearing; the other end of the wooden bar is projected
into an iron bar carried in suitable bearings and driven by conical wheels. The
wooden centre bar is provided with horizontal arms, which by their slanting
position keep the contents of the vat in continual motion. After a thorough
dissolution of the phosphates has taken place, this requiring about one hour, the
mass consisting of phosphoric acid and sulphate of lime, which has formed during
the process, together with the undissolved solid portions of the phosphate, are let
into a lower vat provided with a similar mixing apparatus, in which the further
process is continued; and at the same time a second quantity of phosphate powder
is placed in the first vat and dissolved by thinned sulphuric acid from a reservoir
placed at a proper
elevation.
The mass of phosphoric acid and solid residue is manipulated in wooden filter
presses provided with frames to take up the cakes of matter and double water
apparatus.
All the mountings, valves, and like parts, I prefer to construct of hard lead or
ebonite, as even the best bronze is eaten away.
The presses are filled by membrane pumps of hard lead, ebonite, or the best
bronze, free from zinc; I also prefer to use membrane pumps for the washing
water.
The pure solution of phosphoric acid, containing from 7 to 8 per cent. of phos-
phoric acid, is conducted into a collecting vat, and from this to the concentrating
apparatus herein-after described.
.
After the presses have been filled, the phosphoric acid mechanically retained in
the cakes has to be separated by washing. This is effected by closing the entrance
valve and forcing water through several small escape cocks by means of a good
working force pump or a membrane pump. When the wash water has less than
1° Baumé the operation is finished.
In order to save fire the wash water is used to dilute the sulphuric acid used at
the commencement of the operation for dissolving the phosphates; it is best to pass
as much wash water through the press as is wanted to dilute the acid for the next
lot of phosphates.
The solution obtained from the presses, if wanted as pure as possible for technical
purposes, is run into wooden vats with lead lining, and is held under pressure until
it has attained a specific gravity of 1.5, and contains some 40 to 42° of phosphoric
acid free from water, or it is evaporated in pans made of fire and acid proof
material; these pans are completely surrounded with a lead casing, so that should
phosphoric acid penetrate the masonry it cannot sink into the floor.
The fire is separated from the lead by an air channel, and arranged in such a
manner that the flames and fire gases. passing over the surface of the liquid cause
the evaporation, and carrying with them the steam, pass up the chimney.
The concentrated solution of phosphoric acid, of 15-16 specific gravity, obtained
by the last process is somewhat impure, owing to the ashes contained in the same,
but can, notwithstanding this, be advantageously used for the manufacture of
superphosphates; and the method of producing the same is new.
I employ the phosphoric acid for dissolving poor phosphates in place of sulphuric
acid, heretofore used, to obtain rich superploshate. In this process one part of
phosphate of chalk to two parts of phosphoric acid are used, so that three parts
soluble one base salt are produced from three base insoluble lime salt.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frank Wirth in the Great Seal Patent Office on the 28th November
1878.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort-on-the-Maine, in the Empire of Germany. "IMPROVEMENTS IN THE
METHOD OF AND IN APPARATUS FOR MANUFACTURING PHOSPHORIC ACID AND SUPER-
PHOSPHATES." A communication from Carl Müller and Arthur Packard, persons
trading under the Firm of Müller, Packard, and Co., of Wetzlar, in the Empire of
Germany.
This Invention relates to improvements in the method of and apparatus for
producing phosphoric acid in large quantities from phosphates containing either
large or small quantities of iron or alumina.
:
The production of rich phosphoric acid from poor phosphates has not hitherto
been accomplished in such a manner as to be remunerative, as large quantities of
phosphoric acid are lost, partly through partial decomposition of the phosphates,"
and partly by reason of the great waste in washing the muddy product.
This Invention comprises an improved method of working by machinery, also an
improved and systematic method of manufacturing, and can be performed as
follows:-
First. For dissolving the finely powdered phosphorites by sulphuric acid, and in
separating the phosphoric acid in solution, a mechanical mixing apparatus is used, so
that the phosphorite powder cannot sink to the bottom, thus counteracting the action
of the sulphuric acid. All the phosphoric acid contained in the phosphates, with
the exception of about one or one and a half per-centum of the whole, is thus
rendered soluble.
The mixing apparatus consists of a vat furnished with an upright wooden bar
fitted with a short projecting iron pivot running in a step bearing, the other end
of the wooden bar being projected into an iron bar carried in suitable bearings, and
driven by conical wheels; the wooden centre bar being provided with horizontal
arms, which by their slanting position keep the contents of the vat in continual
motion; or other mechanical means of stirring may be used. After a thorough
dissolution of the phosphates has taken place, which requires about an hour, the
mass consisting of phosphoric acid and sulphate of lime which has been formed
during the process, together with the undissolved solid portions of the phosphates
are led into a lower vat provided with a similar mixing apparatus as that above
described, or otherwise, in which the further process is continued; and at the same
time a second quantity of phosphate powder is placed in the first vat, and dissolved
by weak sulphuric acid supplied from a reservoir placed at a proper elevation.
Second. The mass of phosphoric acid and solid residue is manipulated in wooden
filter presses provided with frames to take up the cakes of matter and duplicate
water supply.
All the mountings, valves, and like parts, must be constructed of hard lead or
ebonite, as even the best bronze is eaten away.
The presses are filled by membrane pumps, in which all parts coming into
contact with the acid are made of hard lead, or of the best bronze, free from zinc.
It is preferred to use the same kind of membrane pumps for the washing process.
The pure solution of phosphoric acid, containing from seven to ten per-centum
of phosphoric acid, is conducted into a collecting vat, and from this to the con-
centrating apparatus herein-after described.
Third. After the presses have been filled, the phosphoric acid mechanically
retained in the cakes has to be separated by washing. This is effected by closing
the entrance valve and forcing water through several small escape cocks by means
of a good working force pump or a membrane pump. When the wash water has
a temperature less than 1° Baumé the operation is finished,

page_text: Fourth. In order to save fire the wash water is used to dilute the sulphuric acid
used at the commencement of the operation for dissolving the phosphate; it is best
to pass as much waste water through the press as is wanted to dilute the acid for
the next lot of phosphates.
Fifth. The solution obtained from the presses, if wanted as pure as possible for
technical purposes, is run into wooden vats with lead linings, and is held therein
under pressure until it has attained a specific gravity of 1-5, and contains some 40
to 42 per-centum of phosphoric acid free from water, or it is evaporated into pans
made of fire and acid proof material; these pans are to be completely surrounded
with a lead casing, so that should phosphoric acid penetrate the masonry it cannot
sink into the floor.
The fire is separated from the lead by an air channel, and arranged in such a
manner that the flames and fire gases, passing over the surface of the liquid, cause
the evaporation, and carrying with them the steam, pass up the chimney.
The concentrated solution of phosphoric acid, of 15 to 16 specific gravity,
obtained by the last process is somewhat impure, owing to the ashes contained in
the same, but can, notwithstanding this, be advantageously used for the manu-
facture of superphosphates; and the method of producing the same is new.
The phosphoric acid is employed for dissolving poor phosphates in place of
sulphuric acid heretofore used to obtain rich superphosphates. In this process one
part of phosphate of lime is calculated to be equal to two parts of phosphoric acid,
so that three parts soluble one base salt is produced from three base insoluble lime
salts.
2nd. The mode of separating the solid mass from the liquid and by means of
filter presses, substantially as set forth.
3rd. The mode of washing out the phosphoric acid mechanically retained in cakes,
substantially as described.
4th. Employing the wash water to dilute the sulphuric acid used for dissolving
the phosphates, substantially as described.
5th. The mode of concentrating the solution obtained from presses, substantially
as described.
6th. Employing the concentrated phosphoric acid for dissolving poor phosphates
without the aid of sulphuric acid, substantially as described.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand and
seal, this Twenty-fifth day of November, in the year of our Lord One
thousand eight hundred and seventy-eight.