Improvements in the Manufacture of Ferro Cyanide of Potassium or of Sodium from Sulpho Cyanide.
Year: 1894

page_text: Date of Application, 20th Mar., 1894
Complete Specification Left, 18th Dec., 1894-Accepted, 19th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Ferro Cyanide of Potassium
or of Sodium from Sulpho Cyanide.
We, ALBERT EDWARD HETHERINGTON Ph.D., of Central Laboratory,
Widnes in the County of Lancaster, Analytical Chemist and EDMUND KNOWLES
MUSPRATT of Seaforth Hall, Liverpool in the said County, a Director of The United
Alkali Company Limited do hereby declare the nature of our invention to be as
follows:-
:-
Sulpho cyanides of potassium or sodium are usually converted into ferro cyanides
by means of metallic iron.
Hitherto this operation has not been very successful owing to great loss of
cyanogen compounds partly through oxidation or decomposition and partly through
volatilization.
Our invention has for its object to greatly lessen these losses and thus to largely
increase the yield of ferro cyanide from a given amount of sulpho cyanide.
For this purpose we employ metallic iron, preferably in a divided state such as
filings, borings, scrap or spongy iron, and we treat or mix this iron with fusible
carbonaceous matter such as pitch in a molten condition, and we heat this mixture
to a high temperature so as to reduce any oxide of iron which may be present and
so that the surface of the iron by being covered with the carbonaceous material is
protected from subsequent oxidation. To this metallic iron so treated and in
conjunction with the requisite amount of pitch or fusible carbonaceous material and
whilst at the requisite temperature we add the necessary quantity of sulpho-cyanide
of potassium or of sodium (we will presume it to be potassium in the following
description) in a fused condition. The materials should contain no water.
keep this mixture at the requisite temperature, about 700° to 800° Fahrenheit until
the sulpho cyanide is completely converted into ferro cyanide or nearly so, which
may be ascertained by testing a sample.
We
We find that good results are obtained by using about 70 to 80 parts by weight
of iron prepared as described and 20 to 40 parts by weight of pitch for every
100 parts by weight of sulpho cyanide of potassium.
We heat this mixture in a retort or suitable vessel provided with an aperture or
apertures capable of being closed, through which the metallic iron, the pitch and
the sulpho cyanide may be introduced and the finished charges withdrawn. It is
The vessel or retort can be
useful to agitate the mixture from time to time.
heated by being set in a furnace, and may be connected by a pipe to a scrubber, so
that any sulpho cyanide carried away by gases evolved, or volatilized may be
recovered.
The vessel or retort may be a revolving cylinder so that agitation is continuous,
or it may be provided with a suitable stirrer. If this stirrer be made of material
likely to be injured by the materials the parts should be so arranged that they can
be readily removed and replaced.
When the reaction is finished, the mass is withdrawn. It consists of ferro cyanide
and sulphide of potassium, sulphide of iron, small quantities of sulpho cyanide and
the remains of the reducing agent or pitch.
We extract the soluble salts with hot water and filter the solution.
Through the solution which contains the ferro cyanide sulphide and small traces

page_text: of sulpho cyanide we force carbonic acid gas (from any convenient source, such as a
lime kiln) so as to convert the sulphide into the corresponding carbonate. We then
separate the salts by crystallization.
Dated the 20th day of March 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, Agents.
Improvements in the Manufacture of Ferro Cyanide of Potassium
or of Sodium from Sulpho Cyanide.
We, ALBERT EDWARD HETHERINGTON, Ph.D. of Central Laboratory,
Widnes, in the County of Lancaster, Analytical Chemist and EDMUND KNOWLES
MUSPRATT of Seaforth Hall Liverpool in the said County a Director of The United
Alkali Company Limited, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
Sulpho-cyanide of potassium or of sodium are usually converted into ferro-
cyanides by means of metallic iron.
Hitherto this operation has not been very successful owing to great loss of
cyanogen compounds partly through oxidation, or decomposition, and partly through
volatilisation. This invention has for its object to greatly lessen this loss and thus
to largely increase the yield of ferro-cyanide from a given amount of sulpho-
cyanide.
For this purpose we employ metallic iron, preferably in a finely divided state,
such as filings, borings, scrap or spongy, iron and we treat, or mix, this iron with
fusible carbonaceous matter, such as pitch in a molten condition, and we heat this
mixture to a high temperature so as to reduce any oxide of iron which may be
present, and so that the surface of the iron, by being covered with the carbonaceous
material, is protected from subsequent oxidation.
To this metallic iron so treated and in conjunction with the requisite amount of
pitch or other fusible carbonaceous material, and whilst at the requisite temperature,
we add the necessary quantity of sulpho-cyanide of potassium, or of sodium, (we
will presume it to be potassium in the following description) in a fused condition.
The materials should contain no water, otherwise some of the sulpho-cyanide will
become decomposed and the yield will be lessened. We keep this mixture at the
requisite temperature (about 700° or 800° Fahrenheit) until the sulpho-cyanide is
entirely, or almost entirely converted into ferro-cyanide, which may be ascertained
by testing an aqueous extract of a sample.
We find that good results may be obtained by using for every 100 parts by
weight of sulpho-cyanide of potassium, 20 to 40 parts by weight of pitch and so
much of the iron prepared as described as will correspond to 70 or 80 parts by
weight of metallic iron.
We heat this mixture in a retort or other suitable vessel provided with an
aperture or apertures, capable of being closed, through which the metallic iron, the
pitch and the sulpho-cyanide is introduced and the finished charges withdrawn.
It is advisable to employ the materials in a heated condition so as to avoid the
presence of any moisture; for this reason we prefer to mix the materials only within
the apparatus in which the process is to be carried out, though if the materials be
thoroughly dry, they may be mixed before charging them into the apparatus. It is
useful to agitate the mixture for which purpose the retort, or vessel, can be provided
with any suitable agitator, or the retort, or vessel, may be in the form of a cylinder
or vessel which is rotated. If the stirrer be made of material likely to be injured

page_text: by the materials of the charge the parts should be so arranged that they can readily
be removed, or replaced. The vessel, or retort, can be heated by being set in a
furnace, or by other suitable means, and may be connected by a pipe to a scrubber
so that any sulpho-cyanide carried away by gases evolved, or volatilised, may be
recovered.
When the reaction is finished the mass is withdrawn and extracted with hot
water, the solution is filtered from the residue which contains the remains of the
iron and pitch as well as iron sulphide.
The filtered solution contains ferro-cyanide of potassium, potassium sulphide and
small traces of sulpho-cyanide of potassium.
Through the solution of potassium ferro-cyanide so obtained, we force carbonic
acid gas (from any convenient source such as a limekiln) so as to decompose the
sulphide and form potassium carbonate; we then separate the ferro-cyanide from
the carbonate by crystallisation.
In the case of sodium ferro-cyanide solution made by this process we find it better
to separate the ferro-cyanide from the solution before passing carbonic acid through
and to convert the sulphide of sodium into the carbonate only after the separation
of the ferro-cyanide.
The carbonates of potassium or sodium thus obtained contain traces of sulpho-
cyanides and may contain some ferro-cyanide. They may be usefully employed in
the manufacture of sulpho-cyanides of these bases, by double decomposition with
calcium sulpho-cyanides.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :-
1. The manufacture of ferro-cyanide of potassium, or of sodium, from sulpho-
cyanide by the operations and in the manner herein before described.
2. In the manufacture of ferro-cyanide of potassium, or of sodium, from sulpho-
cyanide the employment of a mixture of pitch, or other fusible carbonaceous
material, with metallic iron free from oxides; substantially as, and for the purposes,
hereinbefore described.
3. In the manufacture of ferro-cyanides of potassium, or of sodium, from sulpho-
cyanides the use of iron which has been purified from oxide, or protected from
subsequent oxidation, or both, by the use of pitch, or other fusible carbonaceous
material; substantially as and for the purposes hereinbefore described.
Dated this 18th day of December 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.