An Improved Process for Recovering Alkali from a Waste Product.
Year: 1893

page_text: Date of Application, 7th Oct., 1893
Complete Specification Left, 4th Aug., 1894-Accepted, 8th Sept., 1894
PROVISIONAL SPECIFICATION.
An Improved Process for Recovering Alkali from a Waste Product.
We, JAMES BAXTER MURRAY, of 28 Herriet Street, Pollokshields, Glasgow,
Manufacturer, and MATTHEW BARR BAIRD, of 59 Waterloo Street, Glasgow,
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to a process for recovering soda from a waste product of
shale oil works known as soda-coke.
The substance is subjected to several treatments.
1st We take a quantity, say 100 parts, of the crude soda coke and crush it
well, we then put it into a crucible or other suitable vessel and burn it thoroughly
with fire until the substance ceases to flame, stirring occasionally.
This treatment consumes all oily and foreign matters at a loss of t, or 25%, of
the original quantity of the crude article.
The crucible or other vessel used for burning the crude article requires to be
strong as the whole becomes red hot and remains so throughout this treatment.
2nd-The burned substance which is now reduced to 75% of the original
quantity is transferred to a suitable pan or open boiler where there is added to it
about twice its bulk of pure water, it is then boiled and the substance well stirred
during the boiling process. The boiling is continued just long enough to liquefy the
particles of soda in the substance and thereby separate them from the coke
which is insoluble. The fire is now drawn and the liquid allowed to stand for a
time until all the particles of coke settle to the bottom and leave the surface
liquid comparatively clear. This liquid is now transferred to another vessel or
open boiler, preferably a copper one. More water is added to the first pan and the
contents boiled again as before. This process is repeated until all traces of soda
have been removed from the coke residue. The presence of soda can at once be
detected by the taste.
This treatment we call washing the coke. There is no apparent loss the result
being about 37% of concentrated soda and a residue of about 37 % of pure
carbonated coke.
3rd-The clear liquid or washings of the coke is now boiled down and
carefully evaporated in a copper pan until it is capable of crystallization on
cooling.
The substance resulting from the 3rd treatment is pure soda crystals.
The coke or carbon residue can be thoroughly dried in a kiln, oven, or the like,
or in other suitable manner. It can then be ground into a fine powder suitable
for making black paint or blacking.
The liquid soda or ley, before crystallization, may be cauterized with lime in the
usual way, i.e., boiled up with lime and then allowed to settle, the clear liquid
being run off into an iron pan and therein sufficiently evaporated, by boiling down,
until it solidifies on cooling. It is then run into sheet iron drums and closed up in
the usual manner.
Dated this 6th day of October 1883.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.

page_text: An Improved Process for Recovering Alkali from a Waste Product..
We, JAMES BAXTER MURRAY, of 28 Herriet Street Pollokshields, Glasgow,
Manufacturer, and MATTHEW BARR BAIRD, of 59 Waterloo Street Glasgow,
Engineer, 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:-
This invention relates to a process for recovering soda from a waste product of
shale oil works known as soda-coke.
The substance is subjected to several treatments.
1st: We take a quantity, say 100 parts, of the crude soda coke and crush it
well, we then put it into a crucible or other suitable vessel and burn it thoroughly
with fire until the substance ceases to flame, stirring occasionally.
This treatment consumes all oily and foreign matters at a loss of a quarter or
25% of the original quantity of the crude article.
The crucible or other vessel used for burning the crude article requires to be
strong as the whole becomes red hot and remains so throughout this treatment.
2nd-The burned substance which is now reduced to 75% of the original
quantity is transferred to a suitable pan or open boiler where there is added to it
about twice its bulk of pure water, it is then boiled and the substance well stirred
during the boiling process. The boiling is continued just long enough to liquefy
the particles of soda in the substance and thereby separate them from the coke
which is insoluble. The fire is now drawn and the liquid allowed to stand for a
time until all the particles of coke settle to the bottom and leave the surface
liquid comparatively clear. This liquid is now transferred to another vessel or
open boiler, preferably a copper one. More water is added to the first pan and
the contents boiled again as before. This process is repeated until all traces of
soda have been removed from the coke residue. The presence of soda can at once
be detected by the taste.
This treatment we call washing the coke. There is no apparent loss the result
being about 37 % of concentrated soda and a residue of about 371 % of pure
carbonated coke.
3rd The clear liquid or washings of the coke is now boiled down and
carefully evaporated in a copper pan until it is capable of crystallization on
cooling.
The substance resulting from the 3rd treatment is pure soda crystals.
The coke or carbon residue can be thoroughly dried in a kiln, oven, or the like,
or in other suitable manner. It can be then ground in oil and the resultant paste
be used for making commercial black paint. or blacking.
The liquid soda or ley before crystallization may be causticized with lime in the
usual way, i.e. boiled up with lime and then allowed to settle, the clear liquid being
run off into an iron pan and therein sufficiently evaporated, by boiling down, until
it solidifies on cooling. It is then run into sheet iron drums and closed up in the
usual manner.
In making caustic soda by steam boiling, 50 lbs. of fresh slaked lime are
required for each 100 lbs. of soda and about 10 to 12 parts of water to each part
of soda.
It is usual to slake the lime with hot water and when the soda and lime, with the
water, have been put into the tank, or vat, the steam is turned on and passes up
through the mixture causing it to boil, it is then allowed to boil for several hours.
The agitation produced by the boiling greatly aids the rapidity of the causticizing
process, by keeping the soda and lime in close contact with each other.

page_text: When the boiling has been sufficient the steam is turned off and the contents of
the tank allowed to repose, so that the carbonate of lime, which is formed, may
subside. The ley is then drawn off and the lime washed several times with fresh
water, the last runnings being used instead of water in future operations.
The caustic liquid thus obtained deposits at a certain concentration all the
foreign salts present in a solid state, so that they can be strained or skimmed off
from the caustic liquid which is then evaporated down by boiling until the liquid is
found to solidify on cooling, this will give the minimum percentage of caustic
soda, and the greatest quantity, but by carrying on the evaporating process the
liquid will become more concentrated until the maximum percentage is reached
which gives the smallest bulk; but the liquid can be allowed to solidify at any
point according to the commercial percentage required.
In order to ascertain if the soda has been properly and fully causticized, a few
drops of hydrochloric acid are added to a small quantity of the liquid, and if
effervescence takes place, it is a sure indication that uncausticized carbonate of
soda is present, in that case the ley must be returned to the lime again if necessary,
until it is perfectly caustic. Another very simple method is to pour a little of the
ley into clear lime water, then, if the mixture assumes a milky appearance, (from
the formation of carbonate of lime) it is proof that uncausticized carbonate of
soda is present.
The tanks for causticizing soda should be made of wrought iron plates rivetted
together, with open steam pipe inside. The evaporating pans could be cast iron
steam jacket pans, or fitted with fire, as may be found most convenient.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner it is to be performed, we declare that what we consider
novel and desire to claim is :-
The process for recovering soda from soda-coke substantially as hereinbefore
described.
Dated this 1st day of August 1894. *
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.