A Process for the Manufacture of Cyanides.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
A Process for the Manufacture of Cyanides.
I, JOHANNES PFLEGER, of Kaiserslautern, in the Empire of Germany,
Chemical Engineer, do hereby declare the nature of this invention to be as
follows:-
Cyanides, as is well known, can be produced by treating heated alkali, to which
a certain quantity of charcoal has been added, with ammonia. This is accom-
plished either by first converting the mixture of alkali and charcoal into cyanate,
by adding ammonia to it, and then forming cyanide by heating the cyanate con-
taining an excess of charcoal to a higher temperature (Siepermann's process); or
by liquefying the fused alkali in the presence of charcoal and then straining the
same through sieves in an atmosphere of ammonia (Beilby's process).
There are, however, drawbacks attached to both of these processes. With
Siepermann's method it is extremely difficult to convert the whole of the cyanate
formed into cyanide even when excessively large quantities of charcoal are used.
Under the most favourable conditions a product is obtained that contains from 50
to 60 per cent. only of cyanide, which can only be freed from the impurities--
amounting to 40 or 50 per cent.-by a laborious process of lixiviation.
In the case of Beilby's method, the evolution of cyanide, it is true, is accom-
plished in one operation and that without there being any necessity for gradually
increasing the temperature, but the proposed straining through wire sieves is, from
a technical point of view, altogether impracticable, since the sieve soon becomes
choked up and the process must of necessity be interrupted. Neither does this
process supply a marketable article, for charcoal has, also in this case, to be used
in excessively large quantities, the result being a product containing a considerable
percentage of cyanate and charcoal.
The invention hereinafter described is based on the well-known reaction of
ammonia on heated alkali mixed with charcoal, but it has none of the drawbacks
above referred to, the result of the process being a pure cyanide that can at once
be placed on the market. The process is based on observations made by the
inventor which went to show that the detrimental primary formation of cyanate was
due to the fact that the ammonia was allowed to act on the mixture of alkali and
charcoal at too early a stage, when the mixture was not sufficiently heated and to
the fact that the temperature was still further prevented from reaching a degree
required for the chemical reaction by reason of the excessive quantity of charcoal
added in the first instance.
Taking this circumstance into account, the inventor allows the action of the
ammonia to take place only when the temperature of the mixture of alkali and
charcoal has risen to 900° C.; moreover, the mixture thus treated contains initially
only a small percentage of charcoal, the remaining quantity of charcoal required
being added by degrees whilst the reaction takes place.
The reaction occurring both in Siepermann's and in Beilby's process is as
Follows:-

page_text: In the process herein described the reaction, on the other hand, takes place
according to the following simple equation―
K,CO+4C + 2NH,=2KCN +3 CO +6 H.
The carbonic oxide and hydrogen escape as gases leaving behind pure cyanide.
The practical mode of procedure is as follows:-
A mixture consisting of about 1000 parts of potash and 100 parts of charcoal is
placed in a crucible provided with a tightly fitting cap and an escape-tube. After
closing the crucible the mixture is heated to 900° C. On this temperature being
reached ammonia is introduced in a continuous stream at a pressure of about 5 lbs.
above that of the atmosphere, through a tube inserted in the cap and reaching
right down to the bottom of the crucible. Simultaneously with the ammonia,
charcoal is added. The admixture of ammonia is continued for about two hours,
the operation being discontinued as soon as the escape of carbonic oxide and
hydrogen through the tube above referred to ceases.
The crucible will now be found to contain pure cyanide without any by-products
or impurities whatsoever.
If perchance more charcoal has been added than is required in accordance with
the above formula, the excess can easily be removed by filtering the cyanide while
still in a state of fusion.
Instead of making use of the nascent nitrogen derived from the ammonia,
nitrogen gas may be used, in which case, however, the temperature will have to be
considerably higher. An adequate rise in the temperature can easily be brought
about by introducing air instead of pure nitrogen, the oxygen of the air effecting
the combustion of a portion of the charcoal when coming into contact with the
fused mass.
Instead of introducing the charcoal-the quantity of which must be increased in
the event of air being used-simultaneously with the ammonia, it may be mixed
with the potash in the crucible.
Dated this 10th dex of Anoush 100%
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
I, JOHANNES PFLEGER, of Kaiserslautern, in the Empire of Germany,
Chemical 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 :-
Cyanides, as is well known, can be produced by treating heated alkali, to which
a certain quantity of charcoal has been added, with ammonia. This is accom-
plished either by first converting the mixture of alkali and charcoal into cyanate,
by adding ammonia to it, and then forming cyanide by heating the cyanate con-
taining an excess of charcoal to a higher temperature (Siepermann's process); or
by liquefying the fused alkali in the presence of charcoal and then straining the
same through sieves in an atmosphere of ammonia (Beilby's process).
With
There are, however, drawbacks attached to both these processes.
Siepermann's method it is extremely difficult to convert the whole of the cyanate
formed into cyanide even when excessively large quantities of charcoal are. used.
Under the most favourable conditions a product is obtained that contains from 50
to 60 per cent. only of cyanide, which can only be freed from the impurities-
amounting to 40 or 50 per cent.- by a laborious process of lixiviation.

page_text: In the case of Beilby's method, the evolution of cyanide it is true, is accom-
plished in one operation and that without there being any necessity for gradually
increasing the temperature, but the proposed straining through wire sieves is, from.
a technical point of view, altogether impracticable, since the sieve soon becomes
choked up and the process must of necessity be interrupted. Neither does this
process supply a marketable article, for charcoal has, also in this case, to be used
in excessively large quantities, the result being a product containing a considerable
percentage of cyanate and charcoal.
The invention hereinafter described is based on the well-known reaction of
ammonia on heated alkali mixed with charcoal, but it has none of the drawbacks
above referred to, the result of the process being a pure cyanide that can at once
be placed on the market. The process is based on observations made by the
inventor which goes to show that the detrimental primary formation of cyanate
was due to the fact that the ammonia was allowed to act on the mixture of alkali.
and charcoal at too early a stage, when the mixture was not sufficiently heated andi
to the fact that the temperature was still further prevented from reaching a degree-
required for the chemical reaction by reason of the excessive quantity of charcoal
added in the first instance.
Taking this circumstance into account, the inventor allows the action of the-
ammonia to take place only when the temperature of the mixture of alkali and
charcoal has risen to 900° C.; moreover, the mixture thus treated contains
initially only a small percentage of charcoal, the remaining quantity of charcoal
required being added by degrees whilst the reaction takes place.
The reaction occurring both in Siepermann's and Beilby's process is as follows:

page_text: 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. A process for the direct manufacture of pure marketable cyanide by means of
a heated mixture of alkali and charcoal and nitrogen in such a manner that the
alkali mixed with a small quantity of charcoal put in a crucible, which is closed
by means of a cap fitted with two tubes as herein before described, and on the
mixture being heated to a temperature of 900° C. ammonia is forced in through
the inlet-tube, which reaches to the bottom of the crucible, the remaining quantity
of charcoal required for the reaction being simultaneously and gradually added to
the mixture, which operation is continued until such a time as the escape of
carbonic oxide and hydrogen through the outlet-tube ceases, upon which the
resulting pure cyanide, after freeing it from any charcoal it may still contain, by
means of filtration, is left to cool in the air.
2. The substitution, in the process described in the foregoing claim of nitrogen
gas for ammonia, the reaction taking place at a higher temperature which is
brought about in this way that the nitrogen is introduced in the shape of atmo-
spheric air, the oxygen of the latter effecting a local combustion of a portion of the
charcoal, which is introduced in a correspondingly larger quantity.
Dated this 2nd day of May 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.