Improvements in and connected with the Separation, or Production, of Hydrocyanic Acid from Gases containing such Acid, or Cyanogen.
Year: 1898

page_text: Date of Application, 12th Dec., 1898
Complete Specification Left, 1st Aug., 1899-Accepted, 30th Sept., 1899
PROVISIONAL SPECIFICATION.
Improvements in and connected with the Separation, or Production,
of Hydrocyanic Acid from Gases containing such Acid, or
Cyanogen.
I, JULIUS BUEB, of Dessau, in the German Empire, Ph.D., do hereby declare
the nature of this invention to be as follows:-
This invention relates to the production of hydrocyanic acid from gases (other
than coal gas), containing cyanogen, such, for example, as the gases obtained by
the dry distillation of molasses, or residues resulting from sugar making.
The invention is also applicable to the separation of synthetically formed
hydrocyanic acid from other gases combined therewith.
In dealing with such gases, various difficulties have hitherto been encountered in
separating from them the hydrocyanic acid as such, more particularly in effecting
its separation from carbonic acid and hitherto it has been necessary, in order
to extract hydrocyanic acid from the gases in question, to adopt the same
course, as that which has to be followed in obtaining cyanogen from coal-gas,
the cyanogen being first separated in the form of a double ferro-cyanogen salt
and then converted into the required alkaline compound of cyanogen.
The present invention supersedes this indirect process by providing a process
permitting the said gases to be freed from their hydrocyanic acid direct, such
acid being then, when required, converted into the alkaline compound by another
direct operation.
In carrying out this invention the gases to be treated are cooled and, if they
contain ammonia, they are conducted through diluted sulphuric acid, (say at
20 per cent.), which will absorb the ammonia. The sulphate of ammonia lye
thus obtained, which by the gradual addition of concentrated sulphuric acid
may be made to contain as much as from 28 to 30 per cent. of (NH) 2 SO, is then
evaporated to convert it into solid sulphate of ammonia.
The gases freed from ammonia are conducted through a tower, or vessel, in
contact with a current of high-grade alcohol the gases and alcohol passing in reverse
directions. The alcohol exercises its selective action upon the hydrocyanogen con-
tained in the gases, and separates such acid from the gases and dissolves it,
so that an alcoholic solution of hydrocyanic acid is discharged from the bottom
of the tower. The solution of hydrocyanic acid, thus obtained, is subjected
to fractional distillation, and the hydrocyanic vapours are condensed. This is
preferably accomplished by conducting the alcohol and hydrocyanic acid vapour,
which has been distilled off, through chambers containing alcoholic caustic
alkali.
When the hydrocyanic acid and caustic alkali meet, the cyanogen alkali,
scarcely soluble in alcohol, becomes precipitated in the form of a white powder.
The alcohol, which distils through and is free from hydrocyanic acid, is condensed,
and can be again utilized in the tower for the purpose of absorbing hydrocyanic
acid
'

page_text: The chambers, containing the alcoholic caustic alkaline lye, are disconnected
after the lye has been used up and discharged upon a strainer, having first, if
necessary, been allowed to cool. After straining some cyanogen alkali remains
upon the strainer, and this, on being dried will be found to contain from
96 to 98 per cent. of pure cyanogen salt. The alkali lye, running off from the
strainer, containing from 2 to 4 per cent. of cyanogen alkali, is placed in a
saturator, in front of the alcohol tower, and the gases, passing through it, pre-
cipitate the alkali in the form of an alkaline carbonate, while the alcohol becomes
saturated with hydrocyanic acid. The carbonate of alkali precipitated, after
having been strained and dried, will contain 99 per cent. of carbonate. The
alcohol containing hydrocyanic acid, is treated in the manner hereinbefore
described.
The process according to this invention may be used in all cases to which, from
its nature, it is applicable, and where the object is to separate hydrocyanic acid,
as such, from gas, or gas mixtures containing cyanogen.
Dotad th 19th day of Dasambar 180º
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.
Improvements in and connected with the Separation, or Production
of Hydrocyanic Acid from Gases containing such Acid, or
Cyanogen.
1, JULIUS BOEB, of Dessau, in the German Empire, Ph.D., do hereby declare
the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to the production of hydrocyanic acid from gases (other
than coal gas) containing cyanogen, such, for example, as the gases obtained by
the dry distillation of molasses, or residues resulting from sugar making.
The invention is also applicable to the separation of synthetically formed
hydrocyanic acid from other gases combined therewith.
In dealing with such gases, various difficulties have hitherto been encountered in
separating from them the hydrocyanic acid as such, more particularly in effecting
its separation from carbonic acid and hitherto it has been necessary in order
to extract hydrocyanic acid from the gases in question, to adopt the same
course as that which has to be followed in obtaining cyanogen from coal-gas,
the cyanogen being first separated in the form of a double ferro-cyanogen salt
and then converted into the required alkaline compound of cyanogen.
The present invention supersedes this indirect process by providing a process
permitting the said gases to be freed from their hydrocyanic acid direct, such
acid being then, when required, converted into the alkaline compound by another
direct operation.
In carrying out this invention the gases to be treated are cooled and, if they
contain ammonia, they are conducted through diluted sulphuric acid, (say at
20 per cent.), which will absorb the ammonia. The sulphate of ammonia lye
thus obtained, which, by the gradual addition of concentrated sulphuric acid,
may be made to contain as much as from 28 to 30 per cent. of (NH) 2 SO₁, is then
evaporated to convert it into solid sulphate of ammonia.
The gases freed from ammonia are conducted through a tower, or vessel, in

page_text: contact with a current of high-grade alcohol preferably alcohol of a strength of
94 to 98 per cent. the gases and alcohol passing in reverse directions.
The alcohol exercises its selective action upon the hydrocyanogen con-
tained in the gases, and separates, such acid from the gases and dissolves it,
so that an alcoholic solution of hydrocyanic acid is discharged from the bottom
of the tower. The solution of hydrocyanic acid, thus obtained, is subjected
to fractional distillation, and the hydrocyanic acid vapours are condensed. This is
preferably accomplished by conducting the alcohol and hydrocyanic acid vapour,
which has been distilled off, through chambers containing alcoholic caustic
alkali.
When the hydrocyanic acid and caustic alkali meet, the cyanogen alkali,
scarcely soluble in alcohol, becomes precipitated in the form of a white powder.
The alcohol, which distils through and is free from hydrocyanic acid, is condensed,
and can be again utilized in the tower for the purpose of absorbing hydrocyanic
acid.
The chambers, containing the alcoholic caustic alkaline lye, are disconnected
after the lye has been used up and discharged upon a strainer,-having first, if
necessary, been allowed to cool. After straining, some cyanogen alkali remains
upon the strainer and this, on being dried, will be found to contain from
96 to 98 per cent. of pure cyanogen salt. The alkali lye, running off from the
strainer containing from 2 to 4 per cent. of cyanogen alkali, is placed in a
saturator, in front of the alcohol tower, and the gases, passing through it, pre-
cipitate the alkali in the form of an alkaline carbonate, while the alcohol becomes
saturated with hydrocyanic acid. The carbonate of alkali precipitated, after
having been strained and dried, will contain 99 per cent. of carbonate. The
alcohol containing hydrocyanic acid, is treated in the manner hereinbefore
described.
The process according to this invention may be used in all cases to which, from
its nature, it is applicable, and where the object is to separate hydrocyanic acid,
as such, from gas, or gas mixtures containing cyanogen.
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:
-
1. Obtaining hydrocyanic acid, from gases containing cyanogen by first separat-
ing from the said gases any ammonia they may contain and then conducting them
through alcohol of high percentage, and then subjecting the alcoholic solution of
hydrocyanic acid thus obtained to fractional distillation.
2. In the process referred to in the first claim carrying out the fractional
distillation by conducting the vapours of alcoholic and hydrocyanic acid, as they
arise from distillation, through a chamber containing alcoholic caustic alkali,
wherein the hydrocyanic acid will separate from the alcohol in the condition of an
insoluble cyanogen alkali.
3. In the process referred to in the first claim saturating the mother-lye, which
contains the cyanogen, with carbonic acid (preferably the carbonic acid contained
in the gas mixture) whereby the alkali will be precipitated in the condition of
carbonate, while the hydrocyanic acid becomes dissolved in the alcohol and may
be separated therefrom.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.