IMPROVEMENTS IN THE PROCESS OF RENDERINO ALKALIES CAUSTIC, AND APPARATUS FOR THAT PURPOSE
Year: 1874

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lanc, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THE PROCESS OF RENDERINO ALKALIES CAUSTIC, AND
APPARATUS FOR THAT PURPOSE."- -A communication from abroad by
Hermann Kühne, of Magdeburg, in the German Empire.
Scaled the 11th December 1874, and dated the 29th June 1874.
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
29th June 1874.
I, JOHN IMRAY, of No. 20, Southampton Buildings, Ohancery Lane,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IUPROVEMENTS IN THE PROCESS OF RENDERING ALKALIES CAUSTIC,
AND APPARATUS FOR THAT PURPOSE," to be as follows:-
In order to render the alkalies, potash, and soda caustic it is usual to
beat a solution of the carbonates of those alkalies with quicklime,

page_text: which becomes precipitated as carbonate of lime, having taken the
carbonic acid from the alkaline carbonates and left them in solution in
their caustic condition. In this operation great care is needed as to the
strength of the solution and the proportions of limo to be added, and
the lime after precipitation retains a large per-centage of the alkali
which can only be recovered by numerous successive washings, involving
great expenditure of time and labour and of fuel for concentrating, by
evaporation, the solutions of the recovered alkali.
The present Invention relates to a method of conducting this process
by means of suitably arranged apparatus so as to render it more con-
tinuous and less costly than when it is conducted in the usual way, and
to obtain alkaline solutions less varied in their strength. For this pur-
pose a set of tanks or vessels are arranged at a high level and another
set at a lower level, there being several of the latter to each one of tho
former, so that each upper vessel serves to charge a number of the lower
vessels in rotation by means of a pipe provided with a stop-cock having
branches or capable of being altered in direction to command the several
lower vessels. The upper vessels are charged with the solution of the
alkaline carbonate, and with the required proportion of quicklime,
and the mixture is heated and agitated by blowing through it steam
from a pipe immersed in the mixture and perforated with numerous
small holes. Each of the lower vessels has at its bottom a pipe, tho
mouth of which can be closed by a flap valve, such valve having on
it a pipe of smaller size provided with a stop-cock. Over the opening
of the pipe at the bottom of the vessel is placed a conical sieve or
strainer, and above this is placed a layer of gravel, and on it a layer of
sand, the whole covered by a plate which can be removed by means of
a chain or chains to which it is hung. When the mixture in one of the
upper vessels has been for some time heated and agitated by blowing
steam through it, the cock at its bottom is opened and the mixture is
allowed to run into one of the lower vessels, the sand therein being pre-
vented from being displaced by the plate lying upon it, and the valve
and cock on its discharge pipe being closed. When the lower vessel has
thus been charged the plate is removed and the cock on the discharge
pipe is opened, whereupon the solution of caustic alkali filters through
the sand and gravel and flows into a vessel below provided for its recep-
tion, the carbonate of lime being left as a thick layer upon the sand.

page_text: Should any particles of the alkali have escaped being rendered caustic
in the upper vessel, they will in filtering through this layer of lime be
sure to meet with caustic particles therein, which will effect their
conversion. When the alkali has filtered through, a quantity of water
is run into the vessel in order by its pressure to force out the residue of
alkali still held by the carbonate of lime, and thus the whole or nearly
the whole of the alkali is recovered without boing diluted as in the
process usually employed. The water together with the carbonate of
lime is then run off from the vessel, the conical filter being for this
purpose pulled up by a chain and the discharge valve opened, whereby
also the discharge pipe thereon is diverted from the recipient containing
the alkali. The vessel being cleared of its contents the filter can be
reinstated for a fresh operation.
When the contents of the upper vessel has been run into one of the
lower vessels a fresh charge is prepared in the former, and is then run
into another of the lower vessels, and thus each of the lower vessels is
charged in rotation, so that by the time the process of filtration lias
been completed in the first lower vessel, each of the other vessels has
received its charge, and the upper vessel is in readiness to charge the
first vessel again, and thus the process is rendered continuous.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Imray in the Great Seal Patent Office
on the 21th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
IMRAY, of No. 20, Southampton Buildings, Ohancery Lanc, in tho
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Leiters Patent, bearing date the Twenty-ninth day of June, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty.
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Imray, Her special licenso
that I, the said John Imray, my executors, administrators, and
assigns, or such others as I, the said John Imray, my executors

page_text: 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 PROCESS OF RENDERING ALKALIES CAUSTIC, AND APPARATUS FOR THAT PURPOSE,"
a communication to me from abroad by Hermann Kühne, of Magdeburg,
in the German Empire, upon the condition (amongst others) that I, tho
said John Imray, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and scals, should 1
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 Scal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, tho said John Imray, do hereby declare 1
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying
Drawing and to the letters marked thereon, that is to say :-
In order to render the alkalics, potash, and soda caustic, it is usual to 2
heat a solution of the carbonates of those alkalies with quicklime
which becomes precipitated as carbonate of lime, having taken the
carbonic acid from the alkalino carbonates and left them in solution in
their caustic condition. In this operation great care is needed as to the
strength of the solution and the proportions of lime to be added, and 2
the lime after precipitation retains a large per-centage of the alkali which
can only be recovered by numerous successive washings, involving great
expenditure of time and labour and of fuel for concentrating by evapo-
ration the solutions of the recovered alkali.
The present Invention relates to a method of conducting this process 3
by means of suitably arranged apparatus, so as to render it more con-
tinuous and less costly than when it is conducted in the usual way, and
to obtain alkaline solutions less varied in their strength.
The arrangement of the apparatus employed for this
in sectional clevation on the accompanying Drawing
purpose is shown

page_text: One or more tanks a are arranged on the upper floor of a building,
and below these are sets of other tanks b, b, there being a number, by
preferenco six, of the lower tanks to cach of the upper ones, so that
cach of the latter serves to charge a number of the former in rotation.
The upper tanks a are charged with the solution of alkalino carbonate
and with tho requisite proportion of quicklime, and the mixture is
heated and agitated by blowing in steam through a perforated pipe .
When by this means the alkali has been rendered caustic and tho
requisite degree of concentration has been obtained, a cock cat tho
bottom of the tank is opened, and the liquid is caused to flow into one
of the tanks b by means of the movcable spout d. Each of these lower
tanks has at its bottom a pipe e closed by a flap valve ƒ having on it a
pipe / provided with a stop-cock g. Over the opening of the pipe at
the bottom of the tank is placed a conical sieve or strainer 1, and abovo
this is placed, firstly, a layer of small pebbles m, and secondly, a layer
of sand, the whole being covered by a plato o which can be removed
by means of a chain, and which serves to prevent the stream of liquid
flowing into the tank 6 from the tank a from disturbing the layer of
sand. When the tank has been filled with the liquid the plate o is
removed and the cock y is opened, whereupon the solution of caustic
alkali filters through the layers of sand and pebbles and flows in a per-
fectly clear condition through the pipes e and h into the receiver i below.
At the same time the carbonate of lime is deposited in a thick layer
upon the sand, serving as a very fine filtering medium for the alkali.
solution and also acting chemically thereon, inasmuch as any particles
of the alkali that have escaped being rendered caustic in the tank a will
in filtering through the lime be sure of meet with caustic particles
therein which will effect their conversion. When the alkali solution
has all filtered through, and the lime begins to get dry, the tank & (which
will be about half full of the lime deposit) is filled with water from
the cock p, the plate o being placed on the top of the lime while the
water is flowing in so as to prevent the lime from being disturbed
thereby. The water by its pressure will force out the residue of caustic
alkali still held by the lime, its place being taken by the water. By
this means the great advantage is attained that the whole of the caustic
alkali prepared in the vessel a is obtained at one and the same degree of
concentration, and without the dilution with water which is necessary
in the process heretofore employed. The whole of the alkali being thus

page_text: discharged the sieve is withdrawn by means of the chain from the
opening of the pipe e, and the flap valve f is opened (the pipe con-
nected thereto being thus diverted from the opening of the recipient i)
whereupon the lime and water will flow out of the tank b into a channel
which conducts it away to wherever required. The tank being cleared t
of its contents, the filter can be reinstated for a fresh operation.
When the contents of the tank a has been run into one of the tanks b
a fresh charge is prepared in the former, and is then run into another of
the tanks b, and thus each of these tanks is filled in rotation, so that by
the time the process of filteration has been completed in the first lower 1
tank cach of the other tanks has received its charge and the tank a
is in readiness to charge the first one again, and thus the process is
rendered continuous, two attendants being sufficient to prepare the
six charges of the tank a in one day, so that all six of the tanks → can
be charged daily.
]
By the above described improved process and apparatus a saving of
over one-third of the quantity of fuel is effected as compared with that
required for the ordinary process, as also a saving of about two-thirds of
the expense of manual labour, inasmuch as the stirring of the mixture
required for the ordinary process is here dispensed with.
Furthermore, a still more important saving is effected in the timo
required for carrying out the process, as by it better results are obtained
in one-tenth of the time heretofore necessary for producing the same
quantity of caustic alkali.
Having thus described the nature of this Invention, and in what
manner the same is to be performed as communicated to me by my
foreign correspondent, what I claim is,-
-
First. The process of rendering alkalies caustic, wherein the mixture
of the alkaline carbonates and quicklime, after preparation in a tank or
vessel where it is subjected to the action of steam is run into other
tanks or vessels where it is caused to filter through a layer of sand and
pebbles, substantially as and for the purpose herein described.
Second. The use of apparatus for rendering alkalies caustic in the
manner above described, such apparatus consisting of one or more tanks
or vessels for preparing the mixture of alkaline carbonato and quicklime,

page_text: under the action of steam heat, in combination with one or moro other
tanks or vessels containing a filter, arranged and operating substantially
as herein described.
In witness whereof, I, the said John Imray, have hereunto set
my hand and seal, this Twenty-fourth day of December, in the
year of our Lord One thousand eight hundred and seventy-
four.