New Process for Manufacturing Alkaline or Alkaline-earth Cyanides through Atmospheric Nitrogen, and the Application of the same to the Production of Ammonia.
Year: 1890

page_text: Date of Application, 9th Oct., 1890-Accepted, 14th Feb.,
1891
COMPLETE SPECIFICATION.
New Process for Manufacturing Alkaline or Alkaline-earth
Cyanides through Atmospheric Nitrogen, and the Application
of the same to the Production of Ammonia.
I, REGINALD HADDAN, of the firm of Herbert & Co., Patent Agents, of
18, Buckingham Street, Strand, W.C., London, Civil Engineer, do hereby declare
the nature of this invention, a communication to me from abroad by the
Viscount de Lambilly, of Boulevard Henri IV., Paris, in the Republic of France,
Chemist, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
Nitrogen in free state, does not combine, or at least combines to such a slight
extent with hydrogen, even when latter is in nascent state, that hitherto it has not
been practicable to apply such process to produce ammonia gas direct. To combine
with hydrogen, nitrogen requires to be itself in nascent state; consequently it
is necessary to fix it previously in some combination from which it can be easily
disengaged.
Certain compounds of cyanogen are eminently suitable to produce by their
decomposition nitrogen in a free state, and among them the cyanides of the alkaline
metals or alkaline earth metals are the most efficient. These cyanides can
relatively be easily obtained. Free nitrogen and carbon which compose cyanogen
do not combine if they are alone in presence of each other, but if at the same time
they are in presence of some alkalis or alkaline earth suitable to combine easily
with cyanogen and if a high temperature prevails, a cyanide of the alkaline or
alkaline-earth metal used is then produced. It has been known for a long time
that if an intimate mixture is made of powdered charcoal with an oxyde, or with
an alkaline or alkaline-earth carbonate, and a current of nitrogen is passed over
said mixture at a high temperature, a cyanide is then produced. Oxydes and
carbonates of potassium, sodium and barium are the most easily transformed into
cyanides. It is known besides that, when put into water, the cyanides so formed
get slowly decomposed in the cold state, or rather rapidly with the assistance of
heat. The oxygen of water combines with the carbon and metal of the cyanide
to produce a formic-salt, whilst the hydrogen of the same and the nitrogen of the
eyanide both freed in the nascent state, combine to produce ammonia gas.
Consequently by finding an easy way of producing alkaline or alkaline-earth
cyanides, an easy way of producing ammonia gas is at the same time realized.
Numerous trials have been made to produce ammonia by means of cyanides
produced from nitrogen taken from atmosphere. All the inventors in that branch
have operated according to the same system which consists in making an intimate
mixture of charcoal and alkali, and bringing nitrogen in contact with such mixture
at a very high temperature, said nitrogen being taken from atmosphere, being most
generally a current of air deoxidated by passage over glowing charcoal viz. a
current of nitrogen mixed with oxyde of carbon.
In the various methods derived from this system, nitrogen is brought only in
contact with solid carbon, or a gaseous compound of carbon reducible with the
greatest difficulty into its elements. The result being that in order to realise the
production of cyanides in notable quantities a very great temperature was required
which the apparatus used even if made with the best refractory earth could not
stand for a long time.
To use a volatile compound of carbon liable to resolve itself by heat into its
elements, to put the same into the presence of pure nitrogen and of an easily
cyanurable alkali, to decompose the same at a high temperature in order to reduce

page_text: its carbon into nascent state, such is the way by which I resolve the problem of an
easy and abundant production of alkaline and alkaline-earth cyanides and also, as
a consequence, the problem of an easy and abundant production of ammonia by
decomposing such cyanides through water and heat.
The improved method consists principally in the decomposition of lighting gas in
an atmosphere of nitrogen and in presence of a cyanurable substance.
Lighting gas is mainly a mixture of pure hydrogen which exists therein in
variable proportion according to the manner in which the distillation of coal was
carried out, and of three hydrocarbons which according to the grade of their
quantitative importance are:
1st. Formen or hydrogen once carbonated which represents the greatest part of
the same and which has, as a formula, (H' representing one volume of carbon
against four of hydrogen.
2nd. Ethylen or hydrogen twice carbonated having as a formula C H³, viz. two
volumes of carbon against four of hydrogen..
3rd. Acetylen a gas still more carburetted than the two previous ones, the
formula of which is C H viz. two volumes of carbon against two of hydrogen.
These three carburets are decomposed by heat and the ultimate results of such
decomposition are carbon and hydrogen.
Thus, acetylen the most carburetted and most stable of the three is decomposed
by heat approaching white heat, and as it is composed with equal volumes of carbon
and hydrogen it must be necessarily resolved into its elements.
Ethylen is decomposed at an inferior heat, at the red heat, into acetylen and
hydrogen.
CAH* - C* H° + H.
Formen is decomposed also at the red heat, and according to its grade and the
time during which it remains under the influence of heat it gives either ethylen and
hydrogen or acetylen and hydrogen or a complex mixture of these three gases.
It results from these facts that under the influence of a convenient red heat,
lighting gas can be decomposed into a mixture of higher carburetted gases and of
hydrogen, and that, should the latter be eliminated as it gets separated, a gas will
be finally obtained composed for the greatest part of acetylen which can he
decomposed in its turn into its elements, by elevating the temperature in order to
obtain nascent carbon, after having been put in presence of nitrogen and a
cyanurable alkali. The gas will be thus eminently suitable for the production of
cyanides.
The operations of the process are five in number:
I. PREPARATION OF ATMOSPHERIC NITROGEN.
Nitrogen is to be obtained by separating the same from the oxygen with which it
is mixed in the air. All the industrial processes by which the oxygen of the air
can be removed are suitable for such preparation. But I preferably use the process
of copper which consists in heating copper to a red heat in a cylinder, and in letting
a current of air pass over it. Oxyde of copper is then produced and nitrogen
remains which I collect in a gasometer. The oxyde of copper can he employed for
a further operation, which is the reason for preferring this process.
II. PRODUCTION OF LIGHTING GAS.

page_text: This operation is made in retorts or cylinders which are filled with the mixture
to be cyanurated, and in which equal volumes of nitrogen and lighting gas deprived
of hydrogen are made to pass simultaneously. The mixture is composed of powdered
charcoal or equivalent carbon and alkali infimately mixed. The alkali is preferably
an oxyde or a carbonate of potassium, sodium, barium or a mixture of these different
alkalis. A high temperature is necessary, not however amounting to white heat in
order to decompose the gas speedily and to produce cyanuration.
An improvement is here introduced over what has been practised by the previous
inventors. Formerly the current of nitrogen more or less pure is made to pass as
soon as the temperature appeared sufficiently high; but such current became diluted
at its entrance into the mixture to be cyanurated by a considerable quantity of
oxyde of carbon coming from dissociation of alkali,and which prevented the intimate
contact of the nitrogen with the cyanurable substance. The unavoidable result
was a slackening and a decrease in cyanuration which the operators tried to correct
by an elevation of temperature which became excessive. Making an application
of the laws of dissociation established by Mr. Ste. Claire Deville, I find it advan-
tageous, before passing nitrogen and gas intended to produce cyanogen, to stir up
the dissociation of alkali as soon as it begins, and it begins at a temperature some-
what moderate, by drawing off and eliminating according to its production the oxyde
of carbon, which is generated by the same.
Drawing off the oxyde of carbon, I collect it as a combustible gas to heat the
cyanurating furnace. This oxyde represents the carbon of the carbonate, and the
coal spent during the process of decarbonating and of deoxidating the alkali.
When it is thought by the volume of oxyde of carbon so extracted that the alkali
is sufficiently reduced, the current of nitrogen and of mixed gases to cyanurate
alkali is then passed through. This improvement permits a second improvement to
be realised.
As there is no more inconvenience from the presence of an excess of oxyde of
carbon, I may, instead of making gases merely pass, keep the same under light
pressure, viz. give the overflow of gases a suitably confined discharge instead of a
discharge completely free. The surplus gases are composed of some oxyde of
carbon and principally with hydrogen coming from the decomposition of carburet.
These gases being combustible are used also for the heating of the stove.
pressure provides a more intimate contact of the elements intended to react one
upon each other, and helps the cyanuration.
This
Finally I introduce advantageously into the mixture to be cyanurated some
small iron shot which can be easily extracted after the operation by means of a
magnet. The utility of the iron lies in the fact that it gets heated more rapidly
than coal and alkali and by giving up its heat to the particles with which it is in
contact accelerates the combination of cyanide.
It is customary, in the mixture to be cyanurated, to introduce a certain quantity
of lime. Such introduction is useful: 1) it contributes to maintain the porosity of
the mixture; 2) it helps the dissociation of alkaline carbonates.

page_text: This apparatus must be so constructed that steam may get condensed and fall
back into the distilling boiler. All the nitrogen of the cyanide is disengaged in the
state of ammonia gas which can be collected at once in an acid.
The heating is preferably operated only from twenty four to forty eight hours
after the wetting; by doing so, the decomposition of cyanide becomes quicker.
When such operation is over, the substance is sufficiently dried to be again
introduced in the cyanurating apparatus after having been mixed with powdered
charcoal or the like to make up for that, which has been speut in the reduction of
alkali.
•
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1.) The process of preparation of alkaline and alkaline earth cyanides, which
consists in decomposing lighting gas by heat in presence of nitrogen and of an oxyde
or of a carbonate either of an alkali, or alkaline earth.
2.) In the process of manufacturing cyanides with lighting gas the method of
preparing the lighting gas to remove free hydrogen by making it pass over oxyde
of copper at a red heat, and by which method the copper is regenerated at the
same time.
3.) In the process of manufacturing cyanides the method of hastening the dis-
sociation of the alkaline or alkaline earth composed by drawing off and eliminating
the gases which are the product of this dissociation said gases being used to heat
the cyanurating furnace."
4.) In the process of manufacturing cyanides the method which consists in
passing the gases intended to produce cyanide by keeping them under a slight
pressure.
5.) In the process of manufacturing cyanides the method which consists in
introducing small iron shot in the mixture to be cyanurated in order to help and
accelerate the action of heat.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.