Improvements in the Fixation of Nitrogen and the Production of Cyanides.
Year: 1895

page_text: Date of Application, 11th May, 1895
Complete Specification Left, 11th Feb., 1896-Accepted, 21st Mar., 1896
PROVISIONAL SPECIFICATION..
Improvements in the Fixation of Nitrogen and the Production of
Cyanides.
:
I, THOMAS TWYNAM of Elmhurst, Egham IIill Egham, in the County of Surrey
Analytical Chemist do hereby declare the nature of this invention to be as
follows
-
:
Whon a cront of nitrogen gas is passed over a mixture of carbon and a
carbonate of the alkalies or alkaline caiths at a red heat the nitrogen 18 paitly
fixed & forms a cyanide of the alkaline base employed
Hitherto this method of producing cyanide has failed in practice owing to the
difficulty in obtaining on a large scalo n suitably heated current of nitrogen free
from oxygen, & also to the heavy wear & tear of the plaut employed, due to the
necessity for external heating.
As a source of hot gaseous nitrogen I propose to make use of the waste gases
passing off from a Bessemer couverter during the conversion of a charge of pig iron
into steel, and also the hot gas passing off to the stack in open-hearth furnaces.
The gas is practically free from uncombined oxygen, and (in the case of the
Bessemer waste gases) is at a very high temperature.
>
The gaseous current is caused to pass, by means of an exhaust or otherwise, over
lumps of coke saturated with carbonate of potash or soda, or over a mixture of
carbonate of baryta & coke. No extraneous heat is employed as the coke is
quickly heated up. by the heat carried off in the gases. Combination takes place
between the hot nitrogen and the alkaline base, & a cyanide of the base is formed.
The coke is subsequently treated with water which dissolves out the cyanide,
the latter being obtained by crystallization from the solution. Or in presence of
steam & air the cyanide in the coke may be converted into ammonia in situ, the
alkaline base remaining in the coke suitable for leuse.
1005
Improvements in the Flxation of Nitrogen and the Production of
Cyanides.
I, THOMAS TWYNAM of Elmhurst Egham, in the County of Surrey, Analytical
Chemist 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
-
When & current of nitrogen gas is passed over a mixture of carbon and a
carbonate or hydrate of the alkalies o alkaline earths at a red heat or over, the
mitrogen is partly fixed and forms a cyanide of the alkaline base employed.
Hitherto this method of producing a cyanide has usually tailed in practical
working owing to the difficulty in obtaining ou a large scale a suitably heated
current of nitrogen nearly free from oxygen, and also to the heavy wear and tear
of the plant employed due to the necessity for external heating

page_text: As a convenient source of hot gaseous nitrogen I propose to make use of the
waste gases passing off from a Bessemer converter during the conversion of a
charge of pig i ou into steel. The current of gas is practically free from uncombined
oxygen and is at a very high temperature.
No
The gascous current 18 caused to pass by means of an exhaust or otherwise into
a refractory lined chamber or shaft, preferably basic lined, in which lumps of coke
saturated with carbonate of potash or soda have been loosely stacked.
extraneous heat is employed, as the coke is quickly heated up by the heat of the
current of gas. Combination takes place between the hot nitrogen and the alkaline
base, and a cyanide of the base is formed.
The gas from several consecutive blows may be passed over the same charge of
alkalized coke, until a sufficient amount of cyanide is formed in it.
The coke is subsequently treated with water, which dissolves out the cyanide, the
latter being afterwards obtained by evaporation from the solution. Or by the
action of steam and air on the coke, the cyanide in it may be converted into
ammonia in situ: the ammonia being recovered from the excess of steam by
condenantion. In this latter case the alkaline base remains largely in the coke,
Buitable for reuse.
The chamber in which the cyanide is formed should be connected with a suitable
condensing arrangement so that any volatilized cyanide may be recovered.
I profer to begin to pass the gaseous products from the converter into the
cyanide chamber soon after the commencement of the carbon period, and to stop
the gaseous products entering shortly before the drop of the flame. In basic steel
making however the gases may pass in until about the middle of the afterblow.
Having now particularly described and ascertained the nature of my said inven-
tion & in what manner the same is to be performed, I declare that what 1
claim is :-
The horcinbefore described improvement in the fixation of nitrogen and the
production of cyanides which consists in utilizing as a source of hot nitrogen gas
the hot gases passing off from a charge in a Bessemer converter.
Dated this 10th day of February 1896.
T. TWYNAM.