Improvements in the Extraction of Cyanogen from Coal Gas.
Year: 1898

page_text: Improvements in the Extraction of Cyanogen from Coal Gas.
I, JULIUS BUEB, Ph.D., of 11, Kaiserstrasse, Dessau, in the Empire of Germany,
Chemist, do hereby declare the nature of this invention to be as follows:
This invention relates to the extraction of cyanogen from coal gas by reactions
already known and described for example in the Specification of Letters Patent
No. 15164 of 1887 granted to Oscar Knublauch, according to which the cyanogen
is separated from coal gas in the form of a double salt by means of alkalies and
iron.
Hitherto endeavours to carry out these reactions have been directed to obtain-
ing the salts in the form of a solution because otherwise the purifying apparatus
would become clogged which would interfere considerably with the practical
working. In dealing with the salts in the form of a solution however with a
view to their ultimate utilization the process was not satisfactory owing to the
large quantities of liquid to be dealt with.
The object of the present invention is to overcome the aforesaid objections by
conducting the process so that insoluble products are formed and separate from
the gas before it passes to the ammonia scrubbers. To effect this there is
arranged between the cooler or tar separator and the ammonia scrubber a chamber
containing a highly concentrated solution of an iron salt. The highly con-
centrated iron-salt solution, with the assistance of the ammonia which, at this
stage, is present in the gas. compels the whole of the cyanogen contained in the
gas to separate in the form of an insoluble precipitate. This chamber practically
acts as a filter by which the insoluble salts formed are separated so that they do
not pass to the scrubbers.
By using a solution of the soluble salt of iron of sufficient concentration practi-
If the
cally all of the cyanogen present will be obtained in the precipitate.
soluble salt of iron be not of such concentration as to cause the whole of the
cyanogen to he obtained in the precipitate any double salt of cyanogen which
may still be left in the dissolved condition may, if desired, be brought to the
insoluble state simply by boiling and without any further addition of chemicals.
The degree of concentration of the iron salt solution employed may vary within
wide limits, but should under no circumstances be so low as to yield the double
salt or the main part thereof in a dissolved form.
In carrying out this process in practice a solution of a concentration of from
10 to 20 per cent has given satisfactory results.
The ammonia which has not entered into reaction passes off with the gas into
the ammonia scrubbers proper, and any chemical combination tending to the
formation of mud and the clogging of the scrubbers is avoided. In practice it is
preferred to employ two or more chambers or preliminary purifiers containing
the iron-salt solution so that by means of suitably disposed valves and connecting
pipes either can, according to requirements, be connected with. or disconnected
from, the system and when a certain quantity of mud has settled down in one
chamber such chamber can be disconnected from the system while another

page_text: chamber charged with iron-salt solution is connected therewith. The contents
of the disconnected chamber after being discharged therefrom may be boiled
and then the dissolved part be separated from the undissolved part and market-
able ammonia-salt may be extracted from the former direct.
Although salts of iron have alone been referred to above other metal salts may,
if desired, be used but I consider only the salts of iron to be, at present, of any
value economically, and although I have described the use of a separate chamber
for the reception of the soluble salts of iron it will be evident that the first com-
partment or first two or more compartments of the scrubber can be used in place
of such separate chamber where the scrubber is of a nature to render this practi-
cable for example the horizontal scrubbers with rotating bodies alternately
dipping into liquid and presenting their, wetted surfaces to the gas. In this
case the first one, two or more of the compartments will contain the soluble salts
of iron in place of water. In this case care must be taken that the solution of
salts of iron is kept separate from the water in the ammonia separating part of
the scrubber.
Dated this 10th dav
J
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.. Agents.
improvements in the Extraction or Cyanogen from Coal Gas.
I, JULIUS BOEB, Ph.D., of 11, Kaiserstrasse, Dessau. in the Empire of Germany,
Chemist, 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 the extraction of cyanogen from coal gas hy reactions
already known and described, for example, in the Specification of Letters Patent
No. 15164 of 1887 granted to Oscar Knublauch, and also in the Specification of
the Patent for the United States of America No. 465600 granted to William L.
Rowland according to which the cyanogen is separated from coal gas in the form
of a double salt, or compound. by means of iron, and of alkalies, or of the
ammonia contained in the gas itself.
The compounds of ferrocyanogen and ammonia exist in two forms; viz.; as
soluble compounds, and as insoluble compounds, the latter differing from the
former in that iron is substituted in them for part of the ammonia, (see the
German periodical "Journal für Gasbeleuchtung," 1888 p. 542), as these insoluble
compounds form, where in the production of the salt, or compound, the quantity
of iron present is greater than that required for obtaining the soluble salt.
Hitherto endeavours to carry out these reactions have been directed to obtain-
ing the double salt, or compound. in the form of a solution, because any insoluble
product that might occur would cause clogging of the purifying apparatus which
would interfere considerably with the practical working at gas works. It was
therefore considered necessary to deal with the salts, or compounds, in the form
of a solution with a view to their ultimate utilization, and the process was not
satisfactory, owing to the large quantities of dilute solution to be dealt with.
The object of the present invention is to overcome the aforesaid objections by
conducting the process so that insoluble products are formed and separate from.
the gas before it passes to the ammonia scrubbers. My invention differs from
methods hitherto proposed in, that it does not hinder the formation of undissolved.
products the production of such undissolved products being its main object. To

page_text: carry out my invention there is arranged between the cooler, or tar separator,
and the ammonia scrubber, a chamber containing a highly concentrated solution
of an iron salt such as ferrous chloride and ferric sulphate for example. The
ammonia scrubber is fed with water, or dilute gas liquor, in the usual way. The
highly concentrated iron-salt solution, with the assistance of the ammonia which,
at the stage at which the gas comes into contact with the said iron salt, is
present in the gas, compels the whole of the cyanogen contained in the gas to
separate in the form of an insoluble precipitate. The said chamber therefore
acts practically as a filter by which the insoluble salts, or compounds, formed, are
separated so that they do not pass to the scrubbers. By using a solution of the
soluble salt of iron of sufficient concentration, practically all of the cyanogen
present will be obtained in the precipitate. If the soluble salt of iron be not of
such concentration as to cause the whole of the cyanogen to be obtained in the
precipitate, any double salt of cyanogen which may still be left in the dissolved
condition may, if desired, be brought to the insoluble state simply by boiling the
solution without any further addition of chemicals. The degree of concentration
of the iron salt solution employed may vary within wide limits, but should,
under no circumstances, be so low as to yield the double salt, or the main part
thereof, in a dissolved formi.
In carrying out this process in practice solutions of a concentration of from 10 to
20 per cent. and upwards having given satisfactory results, but a solution of even
as low a concentration as 3 per cent. will be serviceable.
The ammonia which has not entered into reaction passes off with the gas into
the ammonia scrubber proper and is separated in the ordinary, or any suitable,
way, any chemical combination tending to the formation of mud and the clogging
of the scrubbers being avoided by the process according to this invention.
By energetically boiling, (without the addition of any substances exercising
a chemical action), the muddy matter obtained, and separating, by mechanical
means, any solution therefrom, a product is obtained which can very readily he
converted into marketable cyanogen compounds.
The dissolved ammonia salts remaining in the separated solution can be
liberated by evaporation.
In practice it is preferred to employ two, or more, chambers, containing the
iron-salt solution, so that, by means of suitably disposed valves and connecting
pipes, either chamber can, according to requirements, be connected with, or dis-
connected from, the system and when a certain quantity of mud has settled down
in one chamber such chamber can be disconnected from the system while another
chamber, charged with iron-salt solution, is connected therewith.
Although I have only referred to salts of iron other similarly acting metallic
salts may, if desired, be used; but I consider the salts of iron only to be at
present, of any value economically; and although I have described the use of a
separate chamber, (or chambers), for the reception of the soluble salts of iron it
will be evident that the first compartment, or first two, or more compart-
ments, of the scrubber can be used in place of such separate chamber, where the
scrubber is of a nature to render this practicable; for example, the horizontal
scrubbers with rotating bodies alternately dipping into liquid and presenting
their wetted surfaces to the gas. In this case the first one, two, or more, of the
compartments will contain the soluble salts of iron in place of water. In this
case care must be taken that the solution of salts of iron is kept separate from
the water in the ammonia separating part of the scrubber.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. The separation of cyanogen from coal gas by subjecting the said gas to
treatment by a concentrated solution of an iron salt before it passes to the
ammonia scrubbers so as to form a precipitate, or sediment, which is retained.

page_text: whilst the gas passes on, to the ammonia scrubbers; substantially as, and for
the purposes, herein before described.
2. In obtaining cyanogen from coal gas the boiling of the precipitate, on
sediment, (obtained according to the preceding claiming clause), without the
addition of any substance exercising a chemical action, so as to obtain a product
to be worked into cyanogen compounds.
Dated this 19th day of January 1899
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.