A NEW METHOD OF RECOVERING THE POTASSIUM OF THE TARTAR IN THE FORM OF HYDRATE OF POTASSA IN THE MANUFACTURE OF TARTARIC ACID
Year: 1878

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company,
Patent Solicitors, at Frankfort on the Main, in the Empire of Germany, for the
Invention of "A NEW METHOD OF RECOVERING THE POTASSIUM OF THE
TARTAR IN THE FORM OF HYDRATE OF POTASSA IN THE MANUFACTURE OF
TARTARIC ACID." A communication from Hermann Goldenberg, Doctor of
Philosophy. of Wiesbaden, in the Empire of Germany.
Sealed the 9th May 1879, and dated the 18th November 1878.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office
of the Commissioners of Patents on the 18th November 1878.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "A NEW METHOD OF RE-
COVERING THE POTASSIUM OF THE TARTAR IN THE FORM OF HYDRATE OF POTASSA
IN THE MANUFACTURE OF TARTARIC ACID." [A communication from Hermann
Goldenberg, Doctor of Philosophy, of Wiesbaden, in the Empire of Germany.]
This Invention has for its object a new method of recovering the potassium of
tartar in the form of hydrate of potassa in the manufacture of tartaric acid.
It consists in heating tartar with a much greater quantity of water and with
caustic lime in a closed vessel under a pressure of some atmospheres, by which the
tartar is transformed into tartrate of lime and into lie of potassa.
The separation of the resulting products is effected by filtration whilst the tempe-
rature in the filter is held at about 100° Celsius.
The same result can be obtained by neutralizing the tartar with chalk or milk of
lime, and by filtering off the tartrate of lime resulting therefrom. The solution of
the neutral tartrate of potassium is thereby run slowly into milk of lime whilst
continuously agitating the same.

page_text: The transformation into tartrate of lime and lie of potassa is a complete one.
However for maintaining the precipitate in a state in which it can be filtered, the
whole mass must be heated under a pressure of about one atmosphere. The product
is cooled, by which the greatest part of the tartrate of lime remains insoluble in the
form of a basic salt and is filtered off. The filtered liquid containing the whole
quantity of potassium in the form of hydrate of potassium is now heated and
filtered for separating the whole quantity of the tartrate of lime which might have
been left dissolved.
The basic salt of lime is used for neutralizing new, quantities of tartrate.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frank Wirth in the Great Seal Patent Office on the 16th May
1879.
25
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort-on-the-Main, in the Empire of Germany. A NEW METHOD OF RE-
COVERING THE POTASSIUM OF THE TARTAR IN THE FORM OF HYDRATE OF POTASSA
IN THE MANUFACTURE OF TARTARIC ACID." A communication from Hermann
Goldenberg, Doctor of Philosophy, of Wiesbaden, in the Empire of Germany.
This Invention has for its object a new method of recovering the potassium of
tartar in the form of hydrate of potassa in the manufacture of tartaric acid.
In the conversion of tartar into tartaric acid lime (tartrate of lime), by the present
well known methods the potassium of the tartar remains behind as a solution of
chloride of potassium, the transformation of which into a solid substance is not
profitable.
If about 188 parts of tartar, and 10 parts water, together with 112 parts of
caustic lime, are heated by steam for several hours in a closed vessel under pressure
of about 3 atmospheres, the tartar is converted into tartrate of lime and into lye of
potassa upon the whole being stirred when cooling. More than 100° C. prevents a
partial reformation of neutral tartrate of potassium, which is not worth naming at
100° C., and disappears completely near 30° C.
By this process the sticky glutinous mass is rendered capable of filtration, or
what is hereinafter termed "filterable," and a separation takes place at a temperature
of about 100° C.
A second method is the following:-Tartar is neutralized with chalk or milk of
lime, and the tartrate of lime formed is filtered off. The solution of neutral tartrate
of potassium is stirred and poured into milk of lime of about 15° Bo, at the
normal temperature, the proportions being as follows:
1 molecular part in weight of neutral tartrate of potassium.
2 molecular parts in weight of hydrate of potash, and 10 times the quantity of
water.
The transformation into tartrate of lime and lye of potassa is complete. To
render the mass "filterable" however the same has to be heated for about 2 hours
in open vessels, or better in closed ones, under a pressure of 1 atmosphere.
The product is cooled down as in the first method, whereby the greater portion
of the tartrate of lime is left as an unsoluble basic salt and is filtered off cold. The
filtered liquid, which contains all the potassium as hydrate of potash, is heated to
about 100° C., at which temperature it is filtered in order to remove any trace of
tartrate of lime which it may still contain.
The basic salt is used to neutralize a fresh quantity of tartar. In this manner
the lime is not lost but is returned into use. In the methods heretofore used a lye
of potassa has been obtained, in which tartrate of lime as a basic salt was gela-
tinously suspended.
In order to render the product of reaction filterable" it has been necessary to boil
the same under pressure, and to cool the mass by reason of the considerable re-
formation which takes place.
Now however a proportion has been discovered which can be worked cold in
open vessels, and yields a directly "filterable mass.
"
If I take 226 parts by weight of neutralized tartrate of potassium, with 8 times
as much water, and 122 parts by weight of quick lime slacked in 16 times the
quantity of water, and pour this solution of neutralized tartrate of potassium into
the above named mixture at a normal temperature while stirring the same, the
greater portion of the tartrate of lime, with two atoms of lime in the molecule, is
precipitated in an unsoluble, powdered, "filterable" mass, and on the other hand the
iye of potassa is formed.

page_text: The lime salts are filtered off, and the small quantity of tartrate of potassium
still in solution can be separated from the lye of potassa in the shape of small flakes
by heat.
The above described operation is very simple, and can be effected in a short time
without the use of complicated apparatus. In carrying this process into effect
success depends chiefly on the quantities employed and in following the order of
operation. In order to insure success, for example, if in place of pouring tartrate
of potassium into lime milk, lime milk is poured into tartrate of potassium a
gelatinous unfilterable product will be the result.
It is most important also to use well burnt lime in this method, as otherwise the
operation must be effected very cold. Moreover by this method alumina, which is
so detrimental in the manufacture of tartaric acid, is removed, the same being held
in solution in the lye of potassa. Tartrate of lime is soluble in cold hydrate of
potash. Only by heat it would be separated as a gelatinous unfilterable product.
The use of the salt, "filterable" and insoluble in cold hydrate of potash (with
two atoms of lime in the molecule), which has been heretofore unknown, permits
the above described process to be carried in practice as described, and this salt
most important in the working of my Invention.
Having thus fully described the said Invention, and the manner in which the
same is to be carried into practice, I wish it understood that I do not limit myself
to the exact proportion mentioned in the above description, and which within
certain limits may be modified without departing from my Invention, and I
claim,―
First. The method of recovering the potassium of tartar in the manufacture of
tartaric acid as hydrate of potash.
Second. The method of obtaining a powdery "filterable" substance by a cold or
warm process.
Third. The method by which the alumina is held in solution and therefore easily
removed, all in the manner and for the purpose specified.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand and
seal, this Tenth day of May, in the year of our Lord One thousand eight
hundred and seventy nine.
FRANK WIRTH. (L.S.)