Improvements in the Production of Metallic Cyanides and other Nitrogen Compounds.
Year: 1895

page_text: Date claimed for Patent under Sect. 103 of Act,
being date of first Foreign Application (in 19th Apr., 1895
United States of America),
Date of Application (in United Kingdom), 19th Nov., 1895
Complete Specification Left, 14th Aug., 1896-Accepted, 3rd Oct., 1898
PROVISIONAL SPECIFICATION.
Improvements in the Production of Metallic Cyanides and other
Nitrogen Compounds.
1, THOMAS LEOPOLD WILLSON of No. 19 West Thirty-eighth Street in the
City of New York, United States of America, Electrical Engineer do hereby
declare the nature of this invention to be as follows:-
This invention relates to the production of cyanides or other nitrogen compounds
of metals or metalloids and as a further step the production of aminoniacal
compounds or other cyanides or other nitrogen compounds therefrom.
My improved process consists in bringing nitrogen into contact with a carbide of
a metal or metalloid, either at the instant of the formation of the carbide by
electric smelting or otherwise, or subsequently to its formation, and while it is still
at or has been raised to a suitably high temperature. There is thus produced
a cyanide of the metal or metalloid or some more complicated nitrogen compound.
As an example of the application of my present invention I will mention the treat-
ment of calcium carbide with nitrogen. Calcium carbide is made in the electric furnace
by beating together calcium oxide (or other suitable compound, as the carbonate)
and carbonaceous matter, the resulting calcium carbide fusing under the heat of
the furnace as it is produced. The nitrogen may be injected immediately into this
fused bath while it remains in the furnace, or the molten carbide may be tapped
out of the furnace into a suitable receiver, and the nitrogen then forced into it. The
nitrogen enters into combination with the carbide to form a cyanide of the metal.
The following is believed to be the reaction :-
Ca(CN), + 3H,O = 2 NHa + CaO + 2 CO.
Or other metallic cyanides can be made from it as for example potassium
cyanide, by a double decomposition with potassium chloride according to the
formula

page_text: The
source of nitrogen, first eliminating the free oxygen by converting it into carbon
monoxide or dioxide. This is readily done by passing the air into contact with
incandescent carbon whereby a mixture of nitrogen with CO or CO2, or with both
in varying proportions, is produced, and this mixture is then forced into the electric
furnace to bring the gases into contact with the heated mass under treatment.
carbon monoxide or dioxide does not interfere with the production of the cyanide,
but if considered objectionable it might first be separated by treating with
incandescent carbon under such conditions as to effect a complete combustion, and
then passing the gases through lime water to separate out the carbon dioxide,
thereby leaving the nitrogen practically pure.
The apparatus I employ in the production of calcium cyanide comprises a pump
or air compresser by which air is pumped through a pipe into the bottom of
a closed cupola or converter constructed with a metal shell and refractory fire-
brick lining, and having in its upper part a feeding hopper and valve or slide for
controlling the admission of fuel, and at its lower part an ash door. The air
which is pumped through the mass of incandescent fuel in this converter has its
oxygen eliminated by conversion chiefly into carbon monoxide and the mixture of
this gas
and nitrogen passes out from a pipe and into a dust separator, the function
of which is to separate any ash or dust that may have been carried over from the
fuel. From this separator the gas is passed by a pipe to the electric furnace.
This furnace is of usual construction, having a carbon hearth or crucible and a
carbon pencil connected to opposite poles of a dynamo for generating the requisite
electric currents. The furnace has a refractory cover and is made nearly air-
tight by a luting of fire-clay or other suitable material. The carbon pencil may
be made hollow with a bore or passage through it which communicates through a
hose with the pipe from the dust separator, so that by opening a valve the nitrogen
or mixture of nitrogen and carbon monoxide may be caused to flow into the electric
furnace.
The charge of the lime or other calcium compound and carbon or other
carbonaceous matter, being placed in the furnace, and fuel having been introduced
into the converter and brought to incandescence, air is pumped through by the
pump until the mixture of nitrogen and carbon monoxide comes off freely through
the blowhole of the furnace. The electric current is then passed through the
furnace while coutinuing the flow of the gases, the pencil being raised sufficiently
to strike an arc, and the operation proceeds until the entire contents of the furnace,
or as much as is practicable, have been converted into calcium cyanide. The first
effect of the electric heat is believed to be to reluce the calcium oxide and convert
it into calcium carbide, and this in turn in its highly heated state combines with
the nitrogen present to form calcium cyanide. The contents of the furnace
may be tapped off from time to time through an outlet into a receiver or sunken
hearth.
Instead of introducing the nitrogen into the furnace through the hollow carbon
pencil, the pencil may be made solid, and the nitrogen be introduced through a
pipe or passage which may be formed in the health of the furnace, terminating in
a tuyere opening upwardly into the crucible.
By a modification of the process the calcium carbide can be first produced in
the electric furnace without the introduction of nitrogen thereto, and then the
nitrogen can be subsequently injected into the furnace to convert the calcium
carbide into calcium cyanide. Or after forming the calcium carbide it may be
tapped off from the furnace into the receiver, and there converted into cyanide by
forcing the nitrogen into it through an iron or graphite tube which is connected by
a flexible hose and valve with the pipe from the dust separator. The said iron or
graphite tube can be used for stirring the molten carbide simultaneously with the
introduction of the nitrogen thereinto.
It is not essential to my invention that the conversion of the carbide into cyanide
be effected as a part of the operation of producing the carbide. The carbide may be
produced in the ordinary manner and permitted to cool, and may subsequently

page_text: be fused and the nitrogen forced into the molten bath of carbide, thereby
converting it into cyanide. This, however, will be uneconomical, because it would
require the expenditure of additional heat to re-melt the carbide, which being
highly refractory requires practically to be melted in an electric furnace. With
other carbides however having lower melting points, this process might in some
cases be advantageous.
My invention may be practised with barium carbide by fusing it or otherwise
highly heating it, and introducing nitrogen into contact with it, thereby producing
barium cyanide.
My invention is generally applicable with all those substances which upon
reduction with carbon are capable of forming carbides. My present invention
does not apply to the treatment in the electric furnace with carbon and nitrogen,
of those substances which when so treated form nitrides.
My invention is applicable with metalloids instead of metals, as for example in
the reduction of silica with carbon to form silicon carbide, which by combining
with nitrogen forms a nitrogen compound of silicon.
Dated this 19th day of November 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.
Improvements in the Production of Metallic Cyanides and other
Nitrogen Compounds.
I, THOMAS LEOPOLD WILLSON, of No. 19 West Thirty-eighth Street in the
City of New York, United States of America, Electrical Engineer, do hereby
declare the nature of the said 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 production of cyanides or other nitrogen compounds
of metals or metalloids and as a further step the production of ammoniacal
compounds or other cyanides or other nitrogen compounds therefrom.
My improved process consists in bringing nitrogen into contact with a carbide of
a metal or metalloid, either at the instant of the formation of the carbide by
electric smelung or otherwise, or subsequently to its formation, and while it is still
at or has been raised to a suitably high temperature. There is thus produced a
cyanide of the metal or metalloid or some more complicated nitrogen compound.
As an example of the application of my present invention I will mention the
treatment of calcium carbide with nitrogen. Calcium carbide is made in the
electric furnace by heating together calcium oxide (or other suitable compound, as
the carbonate) and carbonaceous matter, the resulting calcium carbide fusing under
the heat of the furnace as it is produced. The nitrogen may be injected
immediately into this fused bath while it remains in the furnace, or the molten
carbide may be tapped out of the furnace into a suitable receiver, and the
nitrogen then forced into it. The nitrogen enters into combination with the
carbide to form a cyanide of the metal. The following is believed to be

page_text: into the fused bath of this carbide, or nitrogen may subsequently be brought in
contact with the barium carbide. The reaction is believed to be
Barium cyanide is believed to be stable at high temperatures, probably even at the
temperature of the electric furnace.
Such cyanides may be utilized in various ways, as for example the production of
ammonia by decomposing the cyanide with superheated steam at a temperature of
for example 300 degrees C. according to the reaction
temperature of the electric furnace,
Such cyanides may be utilized in various ways, as for example the production of
ammonia by decomposing the cyanide with superheated steam at a temperature of
for example 300 degrees C. according to the reaction
Ba(CN), +3 H₂O
===
2NH, + BaO + 2 CO.
according to the formula
2 KCl + Ba(CN),
=
BaCl, + 2 KCN.
Or the like reaction can be effected with a sodium salt. Or various other metallic
cyanides can be readily prepared from the cyanide of (for instance) barium.
In practising the process above described I resort to the atmosphere as the
source of nitrogen, first eliminating the free oxygen by some known means, as by
converting it into carbon monoxide or dioxide. This is readily done by passing
the air into contact with incandescent carbon whereby a mixture of nitrogen with
CO or CO2, or with both in varying proportions, is produced, and this mixture is
then brought into contact with the heated mass under treatment. The carbon
monoxide or dioxide does not interfere with the production of some cyanides, but
if considered objectionable it might first be separated by treating with incandescent
carbon under such conditions as to effect a complete combustion, and then passing
the gases through lime water to separate out the carbon dioxide, thereby leaving
the nitrogen practically pure. Or, pure nitrogen may be obtained by passing the
air over heated copper or other oxidizable substance, to fix the oxygen.
The apparatus I employ in the production of calcium or barium cyanide comprises
a pump or air compressor by which air is pumped through a pipe into the bottom
of a closed cupola or converter constructed with a metal shell and refractory
firebrick lining, and having in its upper part a feeding hopper and valve or slide
for controlling the admission of fuel, and at its lower part an ash door. The air
which is pumped through the mass of incandescent fuel in this converter has its
oxygen eliminated by conversion chiefly into carbon monoxide and the mixture of
this gas and nitrogen passes out from a pipe and into a dust separator, the function
of which is to separate any ash or dust that may have been carried over from the
fuel. From this separator the gas is passed by a pipe to the electric furnace.
This furnace is of usual construction, having a carbon hearth or crucible and a
carbon pencil connected to opposite poles of a dynamo for generating the requisite
electric currents. The furnace has a refractory cover and is made nearly air-tight
by a luting of fireclay or other suitable material. The carbon pencil may be made
hollow with a bore or passage through it which communicates through a hose with
the pipe from the nitrogen apparatus, so that by opening a valve the nitrogen or
mixture of nitrogen and carbon monoxide may be caused to flow into the electric
furnace.
The accompanying drawing shows one suitable form of apparatus, the view being
partly in elevation and partly in vertical mid-section.
A is a suitable pump or air compressor forcing air through a pipe a into a
converter B, whereof C is a feeding hopper, b the slide closing it, and c the lower
opening or ash door. From the converter, the air deprived of oxygen passes by a
pipe d into a dust separator D, wherein the dust or ashes carried over are
precipitated. From this it passes by a pipe e to the electric furnace E. This

page_text: 9.
furnace is shown as having a hollow hearth of carbon or graphite resting on a
plate 9 of iron, to which is connected one terminal of the circuit leading from the
dynamo F, the other terminal of which is connected to the carbon pencil The
furnace is closed by a cover h, made tight by a luting i, and formed with a blow-
hole k, and with a hole for the passage of the carbon pencil. The latter is shown
hollow, with its bore conneted with the gas-pipe e by a flexible hose j, a valve e¹
controlling the flow.
The charge of the lime or other calcium compound or baryta or other barium
compound, and carbon or other carbonaceous matter, being placed in the furnace,
and fuel having been introduced into the converter and brought to incandescence,
air is pumped through by the pump until the mixture of nitrogen and carbon
monoxide comes off freely through the blowhole of the furnace. The electric
current is then passed through the furnace while continuing the flow of the gases,
the pencil being raised sufficiently to strike an arc, and the operation proceeds
until the entire contents of the furnace, or as much as is practicable, have been
converted into calcium cyanide or barium cyanide, as the case may be. The first
effect of the electric heat is believed to be to reduce the calcium (or barium) oxide
and convert it into calcium (or barium) carbide. The contents of the furnace may
be tapped off from time to time through an outlet into a receiver or sunken
hearth.
Instead of introducing the nitrogen into the furnace through the hollow carbon
pencil, the pencil may be made solid, and the nitrogen be introduced through a pipe
or passage which may be formed in the hearth of the furnace, terminating in a
tuyere opening upwardly into the crucible. This pipe or passage is indicated by
dotted lines at n, being connected by a pipe (flexible or rigid) communicating with
the pipe e.
By a modification of the process the calcium (or barium) carbide can be first
produced in the electric furnace without the introduction of nitrogen thereto, and
then the nitrogen can be subsequently injected into the furnace to convert the
carbide into calcium (or barium) cyanide. Or after forming the carbide it may
be tapped off or removed from the furnace into a receiver, and there converted
into cyanide by forcing the nitrogen into contact with it, as for example through
an iron or graphite tube which is connected by a flexible hose and valve with the
pipe from the nitrogen apparatus. The said iron or graphite tube can be used
for stirring the molten carbide simultaneously with the introduction of the nitrogen
thereinto.
In the drawing the iron or graphite tube is shown at H, G being the molten
carbide which has been tapped off from the furnace by a tap-hole m. Gas is
admitted from the pipe e to the tube H by a flexible hose p, the flow being
controlled by a valve p².
It is not essential to my invention that the conversion of the carbide into
cyanide be effected as a part of the operation of producing the carbide. The
carbide may be produced in the ordinary manner and permitted to cool, and may
subsequently be heated or fused and the nitrogen forced into contact with it,
thereby converting it into cyanide. This, however, will be uneconomical, because
it would require the expenditure of additional heat to reheat the carbide. With
some carbides however, this process might in some cases be advantageous, especially
in the case of carbides whose cyanides are volatile at the high temperature of the
electric furnace, or at white heat, in which case it is preferable to treat them with
nitrogen at a lower temperature, as at red heat.
My invention is generally applicable with all those substances which upon
reduction with carbon are capable of forming carbides whenever such carbides in
contact with free nitrogen at a sufficiently high temperature produce cyanides. My
invention is applicable to carbides of metals of the alkaline earths (as calcium-
barium, strontium) and of the alkaline metals (as potassium, sodium) and to
carbides of other metals. It is applicable to such carbides singly or in combination
or mixture.

page_text: My invention is applicable with metalloids instead of metals, as for example in
the reduction of silica with carbon to form silicon carbide, which by combining
with nitrogen forms a nitrogen compound of silicon.
My present specification does not apply to the treatment in the electric
furnace with carbon and nitrogen, of those substances which when so treated form
nitrides.
Having thus particularly described and ascertained the nature of my said inveu-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The manufacture of cyanides by means of carbides, substantially as specified.
2. The manufacture of cyanides by bringing nitrogen into contact with a heated
carbide, in substantially the manner specified.
3. The manufacture of cyanides by treating an oxygen compound of a metal or
metalloid with carbon in the electric furnace to produce a carbide, and bringing
a stream of nitrogen into contact with the heated carbide, substantially as set
forth.
4. The described manufacture of cyanide of calcium from calcium carbide,
substantially as specified.
5. The described manufacture of cyanide of barium from barium carbide,
substantially as specified.
6. The described manufacture of ammonia by bringing nitrogen into contact
with a heated carbide to form a cyanide and decomposing the cyanide with
superheated steam.
7. The described manufacture of a cyanide of an alkali metal, by bringing
nitrogen into contact with a heated carbide to form a cyanide and decomposing
such cyanide with a chloride of the alkali metal.
Dated this 14th day of August 1896.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.