Improvements in the Manufacture of Cyanides and other Cyanogen Compounds.
Year: 1895

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 11 of the Patents, &c., Act, 1883), as required by
the decision of the Comptroller General of the 2nd day of July 1896.
Date of Application, 27th May, 1895
Complete Specification Left, 16th Dec., 1895-Accepted, 15th Feb., 1896
PROVISIONAL
UN.
[Communicated from abroad by JOHN FINLAY and EDWIN WILLIAM DERRY,
both of Johannesburg, in the South African Republic.]
Improvements in the Manufacture of Cyanides and other Cyanogen
Compounds.
1, WILLIAM PHILLIPS THOMPSON, F.C.S, M.I.M.E., of The Agency for
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the
County of Lancaster, and Lower Temple Street, Birmingham, in the County
of Warwick, Civil Engineer, do hereby declare the nature of this invention to be
as follows:-
The following is a description of the invention as communicated to me by my
foreign correspondents.
In carrying out the invention a mixture is made of about equal parts of carbon,
alkali, alkaline oxide or carbonate or alkaline earth, preferably barium carbonate
but the quantities may be varied. This mixture is heated in suitable vessels to
about 1,000 degrees Centigrade (but this may vary) and a current of sulphur
dioxide with air deprived of its free and combined oxygen passed over it until the
mixture is converted into sulpho-cyanide of barium.
The vessel is emptied and the contents lixiviated with water when the sulpho-
cyanide comes into solution a little dilute solution of nitric acid or other oxidising
agent is added and a current of carbonic acid gas passed through, preferably at a
boiling temperature and under atmospheric pressure when hydrocyanic acid passes
over and is condensed, (and barium carbonate precipitated) and added to a strong
solution of caustic soda which is contained in a jacket pan, the outside vessel
containing a strong solution of sodium chloride.
Crystals of sodium cyanide then deposit out.
The carbonic acid for the displacement of the H.C.N. is obtained by the com-
bustion of carbon with the atmosphere, whereupon the nitrogen passes on to the
retort to form cyanide with a fresh quantity of the mixture.
The sulphur dioxide is in the first operation derived from any sulphide or from
sulphur. In after operations it is driven from the solution and passes on to the
retorts with the nitrogen to form a fresh quantity of sulphocyanide and cyanide, of
baruum.
This treatment of the gases serves three purposes:-first, the deoxidation of the
air for the retort, second, the displacement of the H.C.N. third, the regeneration
of the alkali

page_text: The precipitate of barium carbonate obtained by the decomposition of the
sulphocyanide is mixed with carbon, dried, and used in a fresh operation.
Dated this 27th day of May 1895.
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicant.
Improvements in the Manufacture of Cyanides and other Cyanogen
Compounds.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 31, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the
County of Lancaster, and Lower Temple Street, Birmingham, in the County of
Warwick, Civil 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:-
This invention relates to improvements in the manufacture of cyanides
and other cyanogen compounds, and in carrying out this invention a mixture
is made of about equal parts of carbou, alkali, alkaline oxide or carbonate,
or alkaline earths, preferably barium carbonate, but the quantities may be
varied.
This mixture is heated in suitable vessels to about 1000 degrees Centigrade (but
this may vary) and a current of air deprived of its free and combined oxygen with
a current of sulphur dioxide, passed over it until the mixture is more or less
converted into cyanide and sulphocyanide of barium.
The vessel is emptied and its contents lixiviated with water when the cyanide,
sulpho-cyanide and oxide of barium come into solution. A small quantity of a
solution of an oxidising agent such as a chlorate or permanganate is then added
(if necessary) until a trace of the added reagent remains in solution unaltered and a
current of deoxidised air passed through preferably at a boiling temperature and
atmospheric pressure but any temperature or pressure may be used. The air
in the deoxidised state consists of free nitrogen and carbon di-oxide (carbonic
acid gas).
The carbon di-oxide in passing through the solution precipitates all the barium
from its various compounds in the form of barium carbonate, the hydrocyanic acid
is liberated and carried over in the gaseous state by the free nitrogen into a
condenser and ultimately in the liquid state passing into a strong solution of caustic
soda, when crystals of sodium cyanide separate out. (The temperature of the
caustic soda must be 40 degrees F.) The sulpho-cyanide is at the same time
decomposed into hydro-cyanic acid and sulphur di-oxide.
The two gases pass over with the nitrogen, but after the condensation of the
hydro-cyanic acid, the free nitrogen and sulphur di-oxide pass on to the vessel in
which the cyanide is formed to form a fresh quantity. This treatment of the gases
serves three purposes :-
(1) The precipitation of the barium carbonate.
(2) The removal of the carbon dioxide from the gases leaving free nitrogen to
pass on to the furnace.
(3) The distillation of the hydrocyanic acid into caustic soda.
The precipitate of barium carbonate is dried, mixed with carbon and used in a
fresh operation.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, as communicated to me

page_text: by my foreign correspondents, I wish it to be understood that I am aware of the
Specification of Gilmour's Patent No. 24,116 A.D. 1892, and I make no claim to
anything described and claimed therein, but I declare that what I claim is :-
1. The use of sulphur dioxide to prevent the formation of cyanates.
2. The formation of sodium cyanide crystals without the use of alcohol.
Dated this 16th day of December 1895.
:-
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicant.