IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC ALKALIES AND IN APPARATUS OR APPLIANCES USED THEREIN
Year: 1877

page_text: LETTERS PATENT to Edward William Parnell, of Liverpool, in the County
of Lancaster, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF CAUSTIC ALKALIES AND IN APPARATUS OR APPLIANCES USED THEREIN."
Sealed the 29th April 1878, and dated the 7th November 1877.
PROVISIONAL SPECIFICATION left by the said Edward William Parnell at
the Office of the Commissioners of Patents on the 7th November 1877.
EDWARD WILLIAM PARNELL, of Liverpool, in the County of Lancaster.
IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC ALKALIES, AND IN APPA-
RATUS OR APPLIANCES USED THEREIN."
The object of my Invention is to reduce the cost of producing caustic soda and
potassa from their carbonates, and to provide apparatus or appliances to be used in
the said production.
In the present mode of manufacturing caustic soda and potassa from their
carbonates, a solution of alkaline carbonate of a density seldom exceeding 1,110
specific gravity is heated and agitated in an open vessel in the presence of caustic
lime. When the specific gravity of such solution is materially grater than the
above mentioned, the lime and the carbonate or carbonates will not re-act upon each
other, except to a very limited extent, at any temperature obtainable under ordinary
atmospheric pressure.
Now, my Invention consists essentially in rendering solutions of alkaline car-
bonates of greater density than those above given, available in the manufacture of
caustic alkalies. For that purpose, and in carrying my Invention into practice, I
proceed as follows:-
First. I heat the alkaline carbonate or alkaline carbonates, mixed with caustic
lime, under a pressure greater than the ordinary atmospheric pressure, so as to

page_text: obtain sufficiently high temperature to cause the alkaline carbonate or carbonates
and the caustic lime to re-act upon each other. Thus it is possible under a pressure
of 50 lbs. per square inch to effect the re-action with a solution of 1,200 specific
gravity, or over.
Second. I agitate the mixed alkaline carbonate or alkaline carbonates and lime
during treatment, in the manner above described, in order to facilitate the re-action
and hasten its completion.
Third. After the re-action has taken place, I maintain the pressure upon the pro-
ducts, and keep the temperature constant until I have separated the caustic soda or
potassa, or both, from the carbonate of lime produced, in order that the re-action may
not be reversed by a reduction of temperature taking place whilst the caustic
alkali or alkalies and the carbonate of lime are in contact.
Fourth. As means for carrying my improved manufacture into effect, I employ a
vessel into which the materials to be treated are placed, and I obtain the requisite
temperature and pressure by means of steam admitted from a boiler or generator
connected by a pipe or pipes into the said vessel.
Fifth. I apply within the vessel, described under the above fourth head, an
agitator or agitators, or I give motion to the said vessel.
=
Sixth. I fit the said vessel with cocks or valves, suitably placed at different levels,
for drawing off the caustic alkalies and carbonate of lime respectively.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
"
the said Edward William Parnell in the Great Seal Patent Office on the
7th May 1878.
EDWARD WILLIAM PARNELL, of Liverpool, in the County of Lancaster.
IMPROVEMENTS IN THE MANUFACTURE OF CAUSTIC ALKALIES AND IN APPARA-
TUS OR APPLIANCES USED THEREIN."
The object of my Invention is to reduce the cost of producing caustic soda and
potassa from their carbonates, and to provide apparatus or appliances to be used in
the said production.
In the present mode of manufacturing caustic soda and potassa from their car-
bonates, a solution of alkaline carbonate of a density seldom exceeding 1,110
specific gravity is heated and agitated in an open vessel in the presence of caustic
lime.
When the specific gravity of such solution is materially greater than the
above mentioned, the lime and the carbonate or carbonates will not re-act upon each
other, except to a very limited extent, at any temperature obtainable under ordinary
atmospheric pressure.
Now, my Invention consists essentially in rendering solutions. of alkaline car-
bonates of greater density than those above given, available in the manufacture of
caustic alkalies. For that purpose and in carrying my Invention into practice, I
proceed as follows :-
First. I heat the alkaline carbonate or alkaline carbonates, mixed with caustic
lime, under a pressure greater than the ordinary atmospheric pressure, so as to
obtain a sufficiently high temperature to cause the alkaline carbonate or carbonates
and the caustic lime to re-act upon each other. Thus it is possible under a pressure
of 50 lbs. per square inch to effect the re-action with a solution of 1,200 specific
gravity, or over.
Second. I agitate the mixed alkaline carbonate or alkaline carbonates and lime
during treatment in the manner above described, in order to facilitate the re-action
and hasten its completion.
Third. After the re-action has taken place, I maintain the pressure upon the
products and keep the temperature constant until I have separated the caustic soda
or potassa, or both, from the carbonate of lime produced, in order that the re-action
may not be reversed by a reduction of temperature taking place whilst the caustic
alkali or alkalies and the carbonate of lime are in contact.
Fourth. As means for carrying my improved manufacture into effect, I employ a
vessel into which the materials to be treated are placed, and I obtain the requisite
temperature and pressure by means of steam admitted from a boiler or generator
connected by a pipe or pipes into the said vessel.
Fifth. I apply within the vessel described under the above fourth head, an agitator
or agitators, or give motion to the said vessel.
Sixth. I fit the said vessel with cocks or valves, suitably placed at different levels
for drawing off the caustic alkalies and carbonate of lime respectively.
.Seventh. A vessel constructed and operated as above is formed or fitted with
a door through which the materials to be treated are fed, or the draw-off cocks or
valves with which it is provided may be made to serve for this purpose.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a sectional side elevation, and Fig. 2 a sectional end elevation of appara-
tus or appliances, constructed in accordance with the fourth, fifth, and sixth heads
of my Invention, and is the apparatus or appliances which I prefer to use,
although many modifications of apparatus or appliances may be made to answer the
purposes.
a, boiler or vessel of wrought iron, supported on brickwork b; other means of
support may be used. c, door through which a solution of carbonate of soda or

page_text: potassa, or both, of comparatively high density, and caustic lime are fed to the said
boiler or vessel. More than one door may be used if desired. The said door c is
shown held to its seat by a cottar or wedge, although a screw or other appliance
may be used. d, cage in which the pieces of caustic lime fed through the door c are
held in suspension, and prevented as well as stones or other foreign objects from
falling to the bottom of the vessel, and mixing with the carbonate of lime precipi-
tate formed during the re-action. e, agitators, fixed or secured to the shaft f, and
caused to rotate by the gearing g; h, pipe and valve, through which steam is
admitted from a generator to act on the materials on the interior of the vessel;
i, cock, through which the caustic soda and potassa solution is drawn off; the said
cock is fitted with the pipe j, hinged at k, and fitted at its upper end with the float
1, so as to be free to rise and fall with the rise and fall of the liquid in a; m, cocks,
through which the carbonate of lime precipitate produced is removed; n, cleaning
doors; o, vacuum valve.
The operation is as follows:-The desired quantity of the alkaline carbonate
solutions and caustic lime having been filled into the vessel a, the door c is closed,
steam at a high temperature and pressure admitted through the valve h to act on
the contents of a, and the agitators e are caused to rotate. As soon as a sufficiently
high temperature has been attained, the caustic lime and alkaline carbonates re-act on
each other, and caustic soda or potassa, or both, in solution, and carbonate of lime pre-
cipitate are produced: The solution of caustic soda or potassa or both is or are now
drawn off through the cock i; the steam being allowed to act so as to maintain the
necessary temperature and pressure to prevent the reversal of the re action which
would take place if the temperature were lowered whilst the carbonate of lime and
caustic alkaline solutions were in contact: After all the caustic soda and potassa
solution has been drawn off, the carbonate of lime precipitate is removed through
the cocks m, and the vessel is ready for recharging.
It will be obvious that the vessel might be made to revolve whilst the agitators
remain stationary, and that various other modifications may be made in the appara-
tus or appliances without departing from my Invention.
Having now described the nature of the said Invention in such manner that others
will be enabled to carry my improvements into effect, I claim,-
First. Manufacturing caustic alkalies under pressure and temperature, substan-
tially in the manner herein set forth.
Second. The apparatus herein described for the purposes set forth.
In witness whereof, I, the said Edward William Parnell, have hereunto set my
hand and seal, the Sixth day of May, in the year of our Lord One
thousand eight hundred and seventy-eight.
E. W. PARNELL. (L.S.)