Improvements in the Production of Nitrogen Compounds, and in Apparatus Employed therein.
Year: 1895

page_text: Date claimed for Patent under Sect. 103: of Act,
being date of first Foreign Application (in 15th Apr., 1895
United States of America),
Date of Application (in United Kingdom), 15th Nov., 1895
Complete Specification Left, 14th Aug., 1896-Accepted, 19th Sept., 1896
Improvements in the Production of Nitrogen Compounds, and in
Apparatus Employed therein.
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 nitrogen compounds of metals or
metalloids, and as a further step the production of ammoniacal compounds or
cyanides therefrom.
My improved process consists in bringing nitrogen into contact with a compound
of a metal or metalloid in the presence of carbonaceous matter while subjected to
the extreme heat produced in an electric furnace, whereby the compound is
reduced, and the metal or metalloid forms a new compound with the nitrogen or
with the nitrogen and carbon. The metallic nitride or cyanide thus produced may
then be subjected to further treatment for the production of ammonia or other
nitrogen compounds.
As a type of the metals whose compounds may be thus treated with nitrogen,
I will mention magnesium. A suitable compound of magnesium for the purposes
of my invention is magnesia, MgO. In practising my invention for the simul-
taneous reduction of this oxide and the production of a nitrogen compound with
the magnesium I proceed as follows
In a suitable electric furnace, preferably au aro furnace, I introduce magnesia.
and carbon or any carbonaceous material. Granulated coke or coal dust is
suitable. The carbon should be in sufficient proportion to combine with the
oxygen of the magnesia. Ou forming the electric arc in the furnace, the magnesia
is simultaneously fused and reduced. By suitable means 1 cause a stream of
nitrogen gas to pass into the highly heated mass, whereby the nitrogen is caused to
combine with the magnesium, forming magnesium nitride, Mg,N,. The reaction
Fe believed to ha
3 MgO+ 3C + 2 N
=
Mga N, +3 CO.
The magnesium nitride thus produced is stable at the high temperature of the
electric furnace, but on exposure to air containing moisture, or on treatment with
water, it decomposes into magnesium hydrate and ammonia, according to the
following reaction:
-

page_text: In practising the process above. described; I resort to the atmosphere as 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 CO,, 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.
The carbon monoxide or dioxide does not interfere with the production of the
nitride, but if considered objectionable it might be first 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 1 employ 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 thus eliminated by conversion chiefly into
carbon monoxide, and the mixture of this gas and nitrogen passes out through 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 pipe may enter the masonry of the furnace and extend as
a passage or tuyere through the carbon hearth of the furnace opening upwardly
at the bottom of this hearth. A charge of the magnesia and carbon being placed
in the furnace, and the fuel in the converter having been brought to incandescence,
air is pumped through by the pump until the mixture of nitrogen and carbon
monoxide begins to come off freely through the blow-hole 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 magnesium nitride. Provision may be made for rendering the
process continuous by arranging for the stoking of the furnace from time to time
with the mixture of magnesia and carbon, and for tapping off from time to time the
accumulated magnesium nitride.
According to one construction of the furnace, the gases are introduced through
an iron or graphite pipe connected by a hose with the pipe from the dust separator,
the said iron or graphite pipe being introduced through a hole in, the side of the
furnace, so that it may be thrust in or withdrawn as desired. Or the iron or
graphite pipe may be introduced through the top plate. In either of these
cases the iron pipe may be utilized as a stirrer for the mass to facilitate the.
operation.
According to another construction, the gas may be introduced by making the
'carbon pencil hollow, and connecting its upper end with the flexible pipe
or hose.
My invention may be applied for the production of other nitrogen compounds
than nitrides. For example, the metallio compound to be treated may be calcium
oxide, which being reduced in the electric furnace with carbonaceous matter, is
converted into calcium carbide. Simultanecusly with this reduction, by forcing a
stream of nitrogen into the heated-mass, calcium cyanide is formed according to the
equation:

page_text: chloride can be converted into potassium cyanide, or the same operation may be
performed with a sodium salt, or it may be otherwise utilized for the production of
ammoniacal substances or cyanides. This process of making calcium cyanide is
included generically within my present invention.
It appears that whether a nitride or cyanide is produced by means of the
process constituting my present invention, depends upon whether the metal whose
compound is reduced is capable of combining with carbon to form a carbide. If it
is so capable of forming a carbide, then the addition of nitrogen produces a
cyanide if the metal is not so capable of forming a carbide, then the nitrogen
combines directly with the reduced metal to form a nitride. Any metal or
metalloid which when treated in the manner described produces either a nitride or
a cyanide is within my invention.
.
Dated this 14th day of November 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.
CODIT ULD DEVITTUATION
Improvements in the Production of Nitrogen Compounds, and in
Apparatus Employed therein.
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 nitrogen compounds of metals or
metalloids, and as a further step the production of ammoniacal compounds or
cyanides therefrom.
"
My improved process consists in bringing nitrogen into contact with a compound
of a metal cr metalloid in the presence of carbonaceous matter while subjected to
the extreme heat produced in an electric furnace, whereby the compound is reduced,
and the metal or metalloid forms a new compound with the nitrogen or with the
nitrogen and carbon. The metallic nitride or cyanide thus produced may then be
subjected to further treatment for the production of ammonia or other nitrogen
compounds.
As a type of the metals whose compounds may be thus treated with nitrogen,
I will mention magnesium. A suitable compound of magnesium for the purposes
of iny invention is magnesia, MgO. In practising my invention for the simul-
taneous reduction of this oxide and the production of a nitrogen compound with
the magnesium I proceed as follows:-
In a suitable electric furnace, preferably an are furnace, I introduce magnesia
and carbon or any carbonaceous material. Granulated coke or coal dust is
suitable. The carbon should be in sufficient proportion to combine with the
oxygen of the magnesia. On forming the electric are in the furnace, the magnesia
is simultaneously fused and reduced. By suitable means I cause a stream of
nitrogen gas to pass into the highly heated mass, whereby the uitrogen is caused to
combine with the magnesium, forming magnesium nitride, Mg,N,. The reaction
is believed to be

page_text: "
j
!
:
Mg,N, + 6 H₂O
=
3 Mg(OH), +2 NH,.
Hence to generate ammonia according to my invention the magnesium nitride is
brought into contact with water, and the gas which is given off is collected in a
suitable vessel.
'In practising the process above described, I resort to the atmosphere as the
source of nitrogen, first eliminating the free oxygen by any known process. Thus
it may be readily. converted into carbon monoxide or dioxide by passing the air
into contact with incandescent carbon, whereby a mixture of nitrogen with CO. or
CO, 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. The carbon monoxide or dioxide do not interfere with the
production of the nitride, but if considered objectionable they 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, the
oxygen may be removed by passing the air over red hot copper, whereby the
nitrogen is obtained free from CO or CO,.
The apparatus I employ is shown in the accompanying drawings, wherein
Fig. 1 is a sectional elevation of the entire apparatus in its preferred form;
Figs. 2 and 3 are sections of the electric furnace showing different modes of
introducing the nitrogen into the mass under treatment;
Fig. 4 is a sectional elevation of a modified construction of carbon pencil for the
furnace.
Referring to Fig. 1, A designates a pump or air compressor by which air ia
pumped through a pipe a into the bottom of a closed cupola or converter B, con-
structed with a metal shell and refractory firebrick lining, and having in its upper
part a feeding hopper C and valve or slide 6 for controlling the admission of fuel,
and at its lower part au ash door c. The air which is pumped through the mass of
incandescent fuel in this couverter, has its oxygen thus eliminated by conversion
chiefly into carbon monoxide, and the mixture of this gas and nitrogen passes out
from a pipe d and into a dust separator D, the function of wbich is to separate any
ash or dust that may have becu carried over from the fuel. From this separator the
gas is passed by a pipe e to the clectric furnace E. This furnace is of usual
construction, having a carbon hearth or crucible f, and a carbon pencil g connected
to opposite poles of a dynamo F for generating the requisite electric currents. The
furnace has a refractory cover h, and is made nearly airtight by a luting i of fire-
clay or other suitable material. The pipe e is shown in Fig. I as-ontering the
masonry of the furnace and extending as a passage or tuyere through the carbon
Ihearth of the furnace, opening upwardly at the bottom of this hearth. A charge
of the oxide to be reduced and carbon being placed in the furnace, and the fuel in
the converter B having been brought to incandescence, air is pumped through by
the pump A until the mixture of nitrogen and carbon monoxide begins to come off
freely through the blow-hole j of the furnace. The electric current is then passed
through the furnace while continuing the flow of the gases, the pencil g 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 a
nitride of the metal or metalloid whose oxide was used. Provision may be made
for rendering the process continuous by arranging for the stoking of the furnace
from time to time with the mixture of oxide and carbon, and for tapping off from
time to time the accumulated nitride.
i
In the construction of furuace shown in Fig. 2, the gases are introduced through
an iron or graphite pipo G, connected by a lose with the pipe e Fig. 1, the
pipe G being introduced through a hole in the side of the furnace so that it may
be thrust in or withdrawn as desired. In Fig. 3, a similar, arrangement is shown,

page_text: except that the pipe G is introduced through the top plate h. In either of these..
cases the iron pipe may be utilized as a stirrer for the mass to facilitate the
operation.
Fig. 4 shows how the gas may be introduced by making the carbon pencil 9
hollow and connecting its upper end with the flexible pipe or hose e'.
In the case of magnesium nitride it is best to pass pure nitrogen through the
electric furnace, as a mixture of nitrogen and CO or CO, would be undesirable,
since magnesium nitride is liable to be decomposed at red heat or higher by contact
with CO or CO₂
My invention may be, applied in connection with other metals or metalloids
than magnesium for the preparation of nitrides. For example titanium nitride
may be produced by beating titanium dioxide (rutile) with carbon in the electric
furnace, in an atmosphere of nitrogen. By a like process I can produce horon.
nitride, silicon nitride, calcium nitride, and otliers.
My invention may be applied for the production of other nitrogen compounds
than nitrides. Thus by treating compounds of the metals of the alkaline earths,
for example, according to my process cyanides of the metals may in some cases, be
formed instead of nitrides. It is known that by heating barium or caustic baryta
with carbon in au atmosphere of nitrogen, barium cyanide is formed. By heating
titanium dioxide and carbon to a white heat with nitrogen, titanium cyano-nitride:
may be formed.
Whether a nitride or a cyanide is formed when an oxygen compound of a metal
or metalloid is heated with carbon and nitrogen in an electric furnace, appears to.
depend upon the degree of affinity of the carbon for the reduced metal or
metalloid; if the carbon after reducing it has but inferior affinity for it. the
nitrogen alone combines with it. to form a nitride; but if the carbon affinity is
strong the product is either a cyanide or a mixture of a carbide and a cyanide.
Thus in the making of barium carbide, the employment of an atmosphere of
nitrogen results in the production of a large proportion of barium cyanide mixed
with the carbide.
As an example of the formation of a nitrogen compound of a metal of the
alkaline earths, the metallic compound to be treated may be calcium oxide, which
being reduced in the, electric furnace with carbonaceous matter, is ordinarily
converted into calcium carbide. But, simultaneously with this reduction, by
forcing a stream of nitrogen into the heated mass, some calcium nitride is formed,
so that the residue consists of a mixture of calcium carbide and calcium nitride.
Theoretically, this process should produce calcium cyanide, according to the
equation:
CaC, + N₂ = Ca(CN).
But my trials thus far have not resulted in the production of recognizable
quantities of this cyanide.
When calcium or other cyanide is produced, it may be decomposed with
superheated steam to make ammonia, or by a double decomposition with potassium
chloride can be converted into potassium cyanide, or the same operation may be
performed with a sodium salt, or it may be otherwise utilized for the production of
ammoniacal substances or cyanides.
I disclaim the production of oyanides of the alkaline metals by the treatment of
carbon and an alkali by electrically-generated heat in the presence of nitrogen.
I also disclaim the production of nitrides by heating a metal or amalgam in free
nitrogen. I further disclaim the production of nitrides or cyanides by other
I
'

page_text: degree of heat is almost unlimited, while the destruction of the crucibles or retorts
by the heat is avoided, and it is practicable to maintain an atmosphere of nitrogen
in effective contact with the nascent reduced metal or metalloid.
Nitrides of magnesium, silicon, boron, aluminium, calcium, titanium, barium, etc.,
may be made by my process from oxides or salts of these elements.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The manufacture of nitrogen compounds of metals or metalloids by exposing
refractory oxygen compounds thereof to the heat of an electric furnace in the
presence of a reducing agent (as carbon) and forcing free nitrogen into contact
therewith, essentially as described, whereby the metal or metalloid is: simultaneously
dissociated from oxygen and combined with nitrogen.
2. The described manufacture of nitrides of metals and metalloids in a closed
electric furnace by forcing free nitrogen into contact with the oxygen compounds
thereof during their reduction by carbon, substantially in the manner specified.
3. The described manufacture of magnesium nitride, by subjecting a compound
of magnesium with a reducing agent to the heat of an electric furnace, and
simultaneously introducing nitrogen into contact therewith.
4. The described manufacture of ammonia by first subjecting an oxygen
compound of a metal or metalloid with a reducing agent to the heat of an electric
furnace, in the presence of nitrogen, to produce a nitride, and subsequently
decomposing such nitride with water to liberato ammonia.
6. The described apparatus for producing metallic nitrides, consisting of a closed
electric arc furnace, having a pipe or passage for introducing nitrogen into the
material under treatment, an apparatus for fixing free atmospheric oxygen, and a
blower for forcing air through said apparatus and thence through said pipe into
the furnace.
Dated the 14th dow of Suavet 1900
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered' Patent Agents.