AN IMPROVED METHOD OF OR PROCESS FOR EXTRACTING PROVISIONAL SPECIFICATION
Year: 1883

page_text: LETTERS PATENT. to Dr Hugo Kunheim of Berlin, Prussia, German Empire,
and Heinrich Zimmermann, Manufacturer, of Wesseling, near Cologne °/Rhinė
for an Invention of "AN IMPROVED METHOD OF OR PROCESS FOR EXTRACTING
PROVISIONAL SPECIFICATION left by the said Dr Hugo Kunheim and
Heinrich Zimmermann at the Office of the Commissioners of Patents on the
5th July 1883.
'
Dr HUGO KUNHEIM of Berlin, Prussia, German Empire,' and HEINRICH
ZIMMERMANN, Manufacturer, of Wesseling, near Cologne °/Rhine
" AN IMPROVED
METHOD OF OR PROCESS FOR EXTRACTING FERROCYANIDES FROM SUBSTANCES
CONTAINING THE SAME.
This invention relates to a method of or process for extracting ferrocyanides
from the refuse or waste products of gasworks or from other substances containing
ferrocyanides.
Heretofore, the process for the extraction of ferrocyanides from the refuse of
gasworks has been based upon the treatment of these waste products by milk of
lime or alkaline lyes, this treatment requiring a washing with water in order to
extract the soluble salts of Ainmonia present in the said refuse, and requiring also,
in many cases, the extraction of sulphurets by means of sulphide of carbon, heavy
coal oils or other solvents.
Experience has proved that this process for extracting ferrocyanides by treating
with or without heat, the refuse as above stated, with milk of lime is not
satisfactory. When lyes of caustic alkalies are used, solutions of the said ferro-
cyanides can also be obtained, but in this case such a quantity of solvents is
required that the process becomes impracticable on account of the expense
attending the same.
According to this invention I extract nearly all the ferrocyanides present in the
said refuse in the following manner that is to say ;-I desulphurize the refuse in

page_text: the ordinary manner and also free the same from its soluble ammoniacal salts by
means of a washing with water.
The extraction of the sulphurets is not indispensable in this process, I extract
them however in order to prevent the formation of sulphur of lime which would be
highly objectionable. The remaining mass still contains a certain amount of
ammonia which is in combination in an insoluble form with the ferrocyanides.
This mass is subsequently mixed with pulverized caustic lime which is desiccated
or it may be prepared from pulverized burnt lime, which causes the insoluble ferro-
cyanides to appear.
It is sufficient for this purpose to use a quantity of lime equal to that of the
mass of refuse, and the said materials must be thoroughly well mixed, the
surrounding atmosphere being carefully. desiccated. This mixing may be effected
by hand, I prefer however to employ machinery such as disintegrators, mixing,
drums, rakes, or rollers.
The materials having been well mixed, I proceed in one of two different manners
that is to say, I place the desiccated mixture in a closed apparatus submitted to
continuous agitation and heated to from 40° to 100° Celsius in order to partly
expel the Ammonia from its insoluble combinations, this ammonia which thus
escapes being condensed in the ordinary manner. The mass is then subjected to a
methodical washing with water whereby a lye containing ferrocyanide of calcium
is obtained; or I first subject the mass to a washing with water when a lye
containing ammoniacal ferrocyanide of calcium is produced which has naturally a
strongly alkaline reaction. This lye is carefully neutralized and heated to boiling
point, which causes a soluble ferrocyanide to precipitate which is not easily soluble
and is mainly a ferrocyanide of calcium and Ammonium Ca (NH 4), Fe Cy.:
Lyes obtained by methods heretofore used may be treated in the same manner,
a ferrocyanide of calcium and ammonium being obtained by precipitation subsequent
to neutralization and heating.
By treating this ferrocyanide of calcium and ammonium with caustic line, the
same is decomposed, the ammonia freed being secured and a clean lye obtained
containing ferrocyanide of calcium. The neutralization and precipitation by
heating to boiling point may also be applied to the modification of my process
which is first herein before described. The lyes containing ferrocyanide of calcium
may be treated in the ordinary manner by precipitation with proto-salts of iron
and subsequent oxydation with Prussian blue. When it is required to obtain
yellow prussiate of potash from the said lyes, the latter are evaporated by steam
and mixed with as much chloride of potassium as is required for the formation of
ferrocyanide of calcium and potassium Ca Ka, Fe Cy. This double ferrocyanide
separated either in a cold state or by means of heat is filtered, freed from the
lyes by washing, and boiled with carbonate of potash, the said double ferrocyanide
being consequently transferred into yellow prussiate of potash.
In this operation only one half of the carbonate of potassium is necessary for
the formation of the yellow prussiate of potash, whereas chloride of potassium
which is much cheaper takes the place of the other half. Instead of carbonate of
potash carbonate of soda may be used for the decomposition of the ferrocyanide
of calcium and potassium; in this case the resulting product is composed of -ferro-
cyanides of sodium and potassium.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said D Hugo Kunheim and Heinrich Zimmermann in .the Patent Office
on the 4th January 1884.
Dr HUGO KUNHEIM, of Berlin, Prussia, German Empire, and HEINRICH
ZIMMERMANN, Manufacturer, of Wesseling, near Cologne, o/Rhine, "AN IMPROVED
METHOD OF OR PROCESS FOR EXTRACTING FERROCYANIDES FROM SUBSTANCES
CONTAINING THE SAME'
"
This invention relates to an improved method or process for extracting ferro-
cyanides from the refuse or waste products in the manufacture of gas, or from
other substances containing ferrocyanides.
The processes heretofore employed for the extraction of ferrocyanides from the
said refuse or waste products are based upon the treatment of these waste products
with milk of lime or alkaline lyes, which treatment necessitates previous washing
with water in order to extract the soluble salts of ammonia present in the said
waste products, and also, in many cases, the extraction of sulphur by means of
sulphide of carbon, heavy coal oils or other solvents.
Experience has proved that these processes for extracting ferrocyanides, by
treating the waste products with milk of lime as above stated (with or without
the aid of heat) are far from being satisfactory. When lyes or solutions of caustic
alkalies are used, solutions of the said ferrocyanides can also be obtained, but in
this case so large a quantity of the solvent is required that the process becomes
impracticable by reason of its cost.
According to the present invention, we extract nearly all the ferrocyanides present
in the said waste products in the following manner, that is to say;-We
desulphurate the said waste products in the ordinary manner and free the same
from soluble ammoniacal salts by washing with water.
We extract
The extraction of the sulphur is not indispensable in this process.
them, however, in order to prevent the formation of sulphuret of lime which
would be highly objectionable. The mass still contains a certain amount of
ammonia which is in combination, in an insoluble form, with the ferrocyanides.
This mass is subsequently mixed in a dry state with dry pulverized caustic lime,
which causes the insoluble ferrocyanides to appear. It is sufficient for this purpose
to use a quantity of lime (which may be slaked in any manner or may be obtained
by disintegrating calcined lime) equivalent to that of the said mass, and the
materials must be intimately mixed in a dried atmosphere. This mixing may be
effected by hand, we prefer however to employ machinery such as disintegrators,
mixing mills, drums or rakes,
The materials having been well mixed, we proceed in one of the two following
manners, that is to say-We place the desiccated mixture in a closed apparatus,
where it is subjected to continuous agitation and is heated to from 40° to 100°
Celsius in order to partly expel the ammonia from its insoluble combinations, the
The mass
ammonia which thus escapes being condensed in the ordinary manner.
is then properly washed with water, whereby a lye containing ferrocyanide of
calcium is obtained. Or we first wash the mass with water and thus form a lye
containing ammoniacal ferrocyanide of calcium which has naturally a strongly
alkaline reaction. This lye is carefully neutralized and heated to boiling point,
which causes the precipitation of a ferrocyanide not easily soluble and consisting
mainly of a ferrocyanide of calcium and ammonium Ca (N H.), Fe Cy...
Lyes obtained by methods heretofore employed may be treated in the same
manner, ferrocyanide of calcium and ammonium being obtained by precipitation
.

page_text: subsequent to neutralization and heating. By treating this ferrocyanide of calcium
and ammonium with caustic lime, it is decomposed; the liberated ammonia is
collected and a clean lye is obtained containing ferrocyanide of calcium. The
neutralization and precipitation by heating to boiling point may also be applied to
the modification of the present improved process which is first herein before
described. The lyes containing ferrocyanide of calcium may be treated in the
ordinary manner by precipitation with protoxide of iron and subsequent oxidation
with Prussian blue. When it is required to obtain ferrocyanide of calcium and
potassium from the ferrocyanide of calcium lyes, the latter are evaporated by steam
and mixed with as much chloride of potassium as is required for the formation of
ferrocyanide of calcium and potassium Ca K, Fe Cyc. This double ferrocyanide,
separated either, in a cold state or by the aid of heat, is filtered and freed from the
lyes by washing. By boiling this ferrocyanide with carbonate of potash, the said
double ferrocyanide is converted into yellow prussiate of potash or ferrocyanide of
potassium. In this operation only one half of the carbonate of potassium is
necessary for the formation of the yellow prussiate of potash, whilst the other half
thereof may be replaced by chloride of potassium which is much cheaper. Instead
of carbonate of potash, carbonate of soda may be used for the decomposition of
the ferrocyanide of calcium and potassium, whereby ferrocyanides of sodium and
potassium are obtained.
The process above described is not only applicable to the refuse or waste
products in the manufacture of gas, but also to other, substances containing
ferrocyanides.
-
Having thus fully described our said invention and the manner of performing
the same we wish it understood that we Claim ;-
First The extraction of ferrocyanide of calcium and ammonium by boiling and
neutralizing the lyes containing ammoniacal ferrocyanide of calcium which result
from the treatment of the mass containing ferrocyanide with 'caustic lime or with
milk of lime.
Second. The extraction of ferrocyanide of calcium and potassium by precipitation
in ferrocyanide of calcium lyes by means of chloride of potassium.
In witness whereof we the said Hugo Kunheim, and Heinrich Zimmermann
have hereunto set our hands and seals this Twenty eighth day of December in
the year of our Lord One thousand eight hundred and eighty three.