IMPROVEMENTS IN THE MANUFACTURE OF FERROCYANIDES
Year: 1883

page_text: LETTERS PATENT to Georges De Vigne of Lille in the Republic of France,
temporarily of Clements Lane in the City of London, Engineer for an
PROVISIONAL SPECIFICATION left by the said Georges De Vigne at the
Office of the Commissioners of Patents on the 1st March 1883.
GEORGES DE VIGNE of Lille in the Republic of France temporarily of Clement's
Lane in the City of London, Engineer "IMPROVEMENTS IN THE MANUFACTURE
OF FERROCYANIDES."
The object of the present invention is to extract from coal gas or smoke or from
any other kind of gas or smoke which may contain them the cyanogen and
hydrocyanic acid, and at the same time to convert these substances into ferro-
cyanides.
The invention consists in subjecting the gas or smoke after they have been cooled
and deprived of the tarry products, to the action of a mixture of iron filings or
oxide, sulphide, carbonate or other suitable salt of iron with an alkaline or earthy
alkaline oxide, hydrate or carbonate.
In carrying out this invention as applied to the extraction of cyanogen and
hydrocyanic acid from coal gas I take, say crystallised carbonate of soda and reduce
it to powder, and I mix it with, say, half its volume of iron filings. The filings
which I prefer to use are those obtained from working what is known as "grey
cast iron" which contains in combination the greatest possible proportion of carbon,
sulphur, phosphorus and selenium.
Filings obtained from other kinds of iron may also be used, but in this case
I prefer first to mix therewith about five per cent of sulphur, phosphorus or
selenium.
The iron in the form of filings may also be entirely replaced by the sulphide of
iron, the protoxyde carbonate or other suitable salt of iron.
The mixture thus formed is placed in a suitable vessel, and the gas which as
before remarked, has been cooled and deprived of its tarry products, and in addition
Price 4d]

page_text: may also have been submitted to the washing or scrubbing operation, is passed
through it.
The hydrocyanic acid which is contained in the gas combines with the carburets,
phosphurets and sulphurets of iron and forms cyanide of iron which in the
presence of the carbonate of soda is transformed immediately into ferro-cyanide of
sodium,
The cyanogen contained in the gas combines with the carbonate of soda and forms
cyanate and cyanide of sodium, and the last named in the presence of the iron also
gives ferro-cyanide of sodium.
It is the hydrocyanic acid which causes the most sensible reaction, and I
therefore prefer to treat the gas after the scrubbing operation, because during that
operation most of the cyanogen is converted into ammonia and hydrocyanic acid,
the acid remaining in suspension in the gas.
I prefer to use carbonate of soda because of the quantity of water of crystallization
it contains, as I find I obtain better results if the mixture be kept in a state of
humidity than if it be dry.
In order to render the mixture more permeable to the gas I may add to it a
small proportion of coke dust, saw dust, or other suitable material.
The mixture may be contained in a separate vessel or it may be used in the
purifiers in alternate layers with the ordinary purifying agent.
The gas is exposed to the mixture for a period varying according to the amount
of cyanogen and hydrocyanic acid it contains, to ascertain which, the gas is tested
in any convenient manner.
The mixture is afterwards washed and the solution obtained, on being evaporated,
gives by crystallization ferro cyanide of sodium, which may be treated in any well
known manner to obtain other ferro cyanides.
The process as applied to the treatment of smoke and fumes from the com-
bustion of coal, turf, and similar materials, is analogous to that above described.
The smoke is first cooled and then washed to remove as fully as possibly the
tarry products, and it is then passed through the mixture of carbonate of soda and
iron filings.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Georges De Vigne in the Great Seal Patent Office on the
1st September 1883.
GEORGES DE VIGNE of Lille in the Republic of France, temporarily of Clements
Lane in the City of London, Engineer IMPROVEMENTS IN THE MANUFACTURE
OF FERRO-CYANIDES
"
"
The object of the present invention is to extract from coal gas or smoke, or from
any other kind of gas or smoke which may contain them, the cyanogen and
hydrocyanic acid, and at the same time to convert these substances into ferro-
cyanides.
The invention consists in subjecting the gas or smoke, after they have been
cooled and deprived, as far as possible, of the tarry products, to the action of a
mixture composed of iron filings or oxide, sulphide, carbonate, or other suitable
salt of iron, and an alkaline or earthy alkaline oxide, hydrate, or carbonate.
The
In carrying out this invention as applied to the extraction of cyanogen and
hydrocyanic acid from coal gas, I take, say, crystallized carbonate of soda, and
reduce it to powder, and I mix it with, say, half its volume of- iron filings.
filings which I prefer to use are those obtained from working what is known as
grey cast iron," which contains, in combination, the greatest proportion of
impurities in the form of carbon, sulphur, phosphorus and selenium, and which
have the property of fixing the hydrocyanic acid.
44
Filings obtained from other and purer kinds of iron may however also be used,
but in this case I find it desirable to mix therewith, before use, from one to five
per cent, or in some cases even more, of either sulphur, phosphorus, or selenium.
The iron filings may also be partially or entirely replaced by the sulphide of
iron, the protoxyde, carbonate or other suitable salt of iron.
The mixture thus formed is placed in a suitable vessel, and the gas, which, as
before remarked, has been cooled and deprived of its tarry products, and in
addition has by preference been submitted to the washing or scrubbing operation,
is passed through it.
The hydrocyanic acid which is contained in the gas combines with the carburets,
phosphurets, and sulphurets of iron, and forms cyanide of iron, which in the presence
of the carbonate of soda, is transformed into ferro-cyanide of sodium.
The cyanogen contained in the gas combines with the carbonate of soda, and
forms cyanate and cyanide of sodium, and the last-named, in the presence of the
iron, also gives ferro-cyanide of sodium.
Hydrocyanic acid causes the most sensible reaction, and I therefore prefer to
treat the gas after the scrubbing operation, because during that operation nearly
all the cyanogen in presence of the water used in the washing is converted into
ammonia and hydrocyanic acid, the acid remaining in suspension in the gas.
It will be evident however that the gas may be treated at any time during the
manufacture without departing from my Invention, but I have found the best
results are obtained after scrubbing, as above explained.
In like manner I prefer to use crystallized carbonate of soda in carrying out my
Invention as this salt contains a larger quantity of water of crystallization than
most other alkaline substances, and better results are obtained, if the mixture be
kept in a state of humidity, than when dry; I may however use other alkaline or
earthy alkaline carbonates, oxydes, hydrates or salts, so long as the mixture shall
be kept by appropriate means in a sufficiently humid state, having regard to the
nature of the carbonate, oxyde, hydrate or other salt employed.

page_text: The proportions above indicated for the mixture of iron filings and carbonate of
soda I have found to answer well the object I have in view, but they may be
varied according to circumstances, and according to the proportions of cyanogen
and hydrocyanic acid contained in the gas, which will be ascertained by testing in
any convenient manner.
In order to render the mixture more permeable to the gas, I may add to it a
small proportion of coke dust, saw dust, or other suitable inert material.
The mixture may be contained in a separate vessel, or it make be used in the
purifiers in alternate layers with the ordinary purifying agent.
The gas is allowed to remain in contact with the mixture for a period varying
according to the amount of cyanogen and hydrocyanic acid contained in the gas.
The mixture is afterwards washed with hot or cold water, and the solution
obtained, on being evaporated, gives, by crystallization, ferro-cyanide of sodium,
which may be treated in any well known manner to obtain other ferro cyanides.
The process, as applied to the treatment of any smoke and fumes from the
combustion or imperfect distillation of coal, turf, and similar materials, is analogous
to that above described. The smoke is first cooled, and then washed, to remove as
fully as possible the tarry products, and it is then passed through the mixture of
carbonate of soda and iron filings, or an equivalent mixture which is afterwards
washed and the solution is evaporated as before mentioned.
Having now described my Invention and explained the manner of carrying the
same into effect, I claim :
First The process for obtaining Ferrocyanides from coal gas or other gas
containing cyanogen or hydrocyanic acid in greater or less proportions, consisting
in submitting the gas, which has first been cooled and deprived of its tarry
products, to the action of a mixture of iron filings or a salt of iron and an alkaline
salt, either after or before or during the operations of scrubbing or purifying,
subsequently washing the mixture, and evaporating the solution so obtained,
substantially as herein described and for the purpose set forth.
Second: The process for obtaining Ferrocyanides from the smoke arising from
the combustion of coal and other fuel, and consisting in submitting the smoke, after
being cooled and deprived of its tarry products, to the action of a mixture of iron
filings or a salt of iron and an alkaline salt, subsequently washing the mixture, and
evaporating the solution substantially as herein described.
Third: The mixture consisting of iron filings or a salt of iron alone or in
combination, and with or without the addition of sulphur, phosphorus or selenium,
and an alkaline or earthy alkaline oxyde, hydrate, carbonate, or other salt,
substantially in the proportions herein specified, and for the purpose set forth.
In witness whereof I the said Georges De Vigne have hereunto set my hand and
seal the twenty-third day of August in the year of our Lord One thousand eight
hundred and eighty three.
HAR