Process for the Production of Caustic Lyes of the Alkalies.
Year: 1895

page_text: Date of Application, 18th Feb., 1895
Complete Specification Left, 14th Nov., 1895-Accepted, 14th Dec., 1895
[Communicated from abroad by THE CHEMISCHE FABRIK RHENANIA, of
Aachen, in the German Empire.]
Process for the Production of Caustic Lyes of the Alkalies.
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
In rendering potash and soda lyes caustic, by means of caustic lime, an excess
of lime is employed in order to entirely convert the carbonate salts in the solutions
into caustic alkali. The process has however the disadvantage that not the whole
of the caustic lime is utilised, and that the precipitate is with difficulty removed by
washing, so that considerable quantities of soda and potash remain in the lime
sludge.
Also in the process described in Lunges work on the soda industry, according to
which for rendering the solution caustic, a second operation is carried on in the
same pan, without removing the lime sludge of the first operation, the whole
of the caustic lime is not utilised as the resulting main product, the lime sludge,
always contains a mixture of caustic lime which cannot be washed out and which is
calcium carbonate.
For this
The present invention has for its object to obviate these defects.
in the first instance render the fresh lye only partially caustic by a
purpose
mixture of calcium carbonate and caustic lime.
The caustic lime is by this means entirely utilised and converted into calcium
carbonate, so that the precipitate almost entirely consists of the latter. The
imperfectly caustic lye thus obtained, is converted by means of an excess of fresh
lime into lye which is almost entirely free from alkali carbonates being nearly all
caustic potash or caustic soda. A complete conversion only succeeds in solutions
that are so dilute that it would not be practically useful owing to the high cost of
evaporation.
For rendering the process readily understood I will give a practical example of
the way of carrying it out.
The apparatus employed for this example consists by preference of wrought iron
vessels which are about 190 cm. deep, and have a diameter of about 357 cm., and
consequently contain about 19000 litres.
Steam is introduced from the bottom of these vessels.
At top they are provided with iron gratings to prevent accidents which gratings
have a central opening for the introduction of a perforated or sieve-like vessel
containing the lime, which vessel is about 70 cm. high and the same diameter, and
is suspended from suitable raising and lowering tackle.
I. At the commencement of the operation crude lye is introduced into the vessel
which is diluted to about 17° Bé. by means of the washing water used for treating
the lime sludge from a previous operation. Steam is then blown into the vessel
until the temperature of the liquid has risen to about 70° C. while at the same time
the specific gravity sinks to 14° Bé.
About 900 kilos. of lime are then added, which rapidly passes from the basket
into the liquid, the stony particles being retained. Lastly, the steam supply is
stopped and the liquid, which together with the lime now has a volume of about

page_text: 18,000 litres, is allowed to stand. After the precipitate has settled down, the
liquid above it is drawn off, and the lye is then treated for the production of solid
caustic soda.
II. After the drawing off of the caustic lye, fresh lye, in the same quantity as
before, is added and is boiled together with remaining sludge of the first operation,
consisting of calcium carbonate and lime.
The residue is thus entirely converted into calcium carbonate, while the lye
contains sodium carbonate, and is therefore imperfectly caustic.
first removed from the vessel and then the residue.
The lye is then
The imperfectly caustic lye is then treated with fresh lime as described in I,
whereby the soda salts are converted into caustic soda, resulting in a liquid that
can be converted into solid caustic soda. The sludge produced again contains
calcium carbonate and lime, nixed, and is converted into calcium carbonate as
above described.
There is consequently obtained by this process the great advantage not only of
effecting a great saving in fresh caustic lime, but also of enabling the alkalies
to be better extracted by washing from the precipitated calcium carbonate,
than was possible with the mixture of lime and calcium carbonate hitherto
obtained.
Dated this 18th day of February 1895
ABEL & IMRAY,
Agents for the Applicant.
Process for the Production of Caustic Lyes of the Alkalies.
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
In rendering potash and soda lyes caustic, by means of caustic lime, an excess
of lime is employed in order to entirely convert the carbonate salts in the solutions
into caustic alkali. The process has however the disadvantage that not the whole
of the caustic lime is utilised, and that the precipitate is with difficulty removed
by washing, so that considerable quantities of soda and potash remain in the lime
sludge.
Also in the process described in Lunges work on the soda industry, according to
which for rendering the solution caustic, a second operation is carried on in the
same pan, without removing the lime sludge of the first operation, the whole of the
caustic lime is not utilised as the resulting main product, the lime sludge, always
contains a mixture of caustic lime which is not easily washed out.
purpose
The present invention has for its object to obviate these defects. For this
I in the first instance render the fresh lye only partially caustic by a
mixture of calcium carbonate and caustic lime. The caustic lime is by this means
entirely utilised and converted into calcium carbonate, so that the precipitate
almost entirely consists of the latter. The imperfectly caustic lye thus obtained,
is converted by means of an excess of fresh lime into lye which is almost entirely
free from alkali carbonates being nearly all caustic potash or
A complete conversion only succeeds in solutions that are so dilute that it would
caustic soda.
not be practically useful owing to the high cost of evaporation.
For rendering the process readily understood, I will give a practical example of
the way of carrying it out.
Vessels are provided into which steam is introduced from the bottom and at
the top they are provided with iron gratings to prevent accidents which gratings

page_text: have a central opening for the introduction of a perforated or sieve-like vessel
containing the lime, which vessel is about 70 cm. high and the same diameter,
and is suspended from suitable raising and lowering tackle.
The following an example of the process.
I. At the commencement of the operation crude lye is introduced into the vessel
which is diluted to about 17° Bé. by means of the washing water used for treating
the lime sludge from a previous operation. Steam is then blown into the vessel
until the temperature of the liquid has risen to about 70° C. while at the same time
the specific gravity sinks to 14° Bé.
Lime is then added, which rapidly passes from the basket into the liquid, the
stoney particles being retained. Lastly, the steam supply is stopped and the liquid,
is allowed to stand. After the precipitate has settled down, the liquid above it is
drawn off, and the lye is then treated for the production of solid caustic soda.
II. After the drawing off of the caustic lye, fresh lye, in the same quantity as
before, is added and is boiled together with the remaining sludge of the first
operation, consisting of calcium carbonate and lime.
The residue is thus entirely converted into calcium carbonate, while the lye
contains sodium carbonate, and is therefore imperfectly caustic. The lye is then
removed from the vessel and afterwards the residue.
The imperfectly caustic lye is then treated with fresh lime as described in 1,
whereby the soda salts are converted into caustic soda, resulting in a liquid that can
be converted into solid caustic soda. The sludge produced again, contains calcium
carbonate and lime, mixed, and is converted into calcium carbonate as above
described.
There is consequently obtained by this process the great advantage not only of
effecting a great saving in fresh caustic lime, but also of enabling the alkalies to
be better extracted by washing froin the precipitated calcium carbonate, than was
possible with the mixture of lime and calcium carbonate hitherto obtained.
Having now particularly described and ascertained the nature of this inven⚫
tion and in what manner the same is to be performed, I declare that what I
claim is :-
The herein described process for producing caustic alkalies from their carbonates
by first treating carbonate lye with a mixture of calcium carbonate and caustic
lime, thus rendering the lye imperfectly caustic, then separating this lye from the
sludge and adding fresh lime to it thus rendering it completely caustic.
Dated this 14th day of November 1895.
ABEL & IMRAY,
Agents for the Applicant.