IMPROVE- MENTS IN THE MANUFACTURE OF SODA AND POTASS FROM THE SULPHATES OF SODA AND POTASS, AND IN OBTAINING SULPHUROUS ACIDS THEREFROM
Year: 1878

page_text: LETTERS PATENT to Gerard Wenzeslaus von Nawrocki, of the Firm of J. Brandt
and G. W. von Nawrocki, Civil Engineers and Patent Agents, of No. 2, Koch
Strasse, Berlin, in the German Empire, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF SODA AND POTASS FROM THE SULPHATES OF
SODA AND POTASS, AND IN OBTAINING SULPHUROUS ACIDS THEREFROM."
A communication by Ernst Siermann, of Pommersdorf, near Stettin, in the
German Empire.
PROVISIONAL SPECIFICATION left by the said Gerard Wenzeslaus von
Nawrocki at the Office of the Commissioners of Patents on the 28th January
1878.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W. von
Nawrocki, Civil Engineers and Patent Agents, of No. 2, Koch Strasse, Berlin, in the
German Empire. "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASS
FROM THE SULPHATES OF SODA AND POTASS, AND IN OBTAINING SULPHUROUS ACID
THEREFROM." [A communication by Ernst Siermann, of Pommersdorf, near Stettin,
in the German Empire.]
According to a process proposed by Balard soda is produced by means of bauxite
by heating the latter to a red heat together with sulphate of soda and carbonaceous
material, thereby obtaining aluminate of soda, which is decomposed by carbonic acid.
The iron contained in the mineral gives rise however to the formation of objec-
tionable iron pyrites and sulphide of sodium combinations, no alumina free from iron
being obtained, and the production of the soda being consequently expensive.
The process forming the subject of the present Invention differs from the above
in the employment of pure alumina, and in effecting the reduction of. the sulphate
separate from the formation of the aluminate, thereby enabling the sulphurous acid
to be gained. For this purpose sulphate of soda or sulphate of potash is melted
down together with carbonaceous material in a furnace, thus producing sulphide of
sodium or sulphuret of potassiumn; this is then reduced to small fragments and
D

page_text: mixed intimately with alumina, and the compound is then heated to redness in a
closed chamber with access for air. As soon as the mass is raised to a red heat the
alumina acts on the sulphide or the sulphuret, the sulphur escaping and in burning
formning sulphurous acid fumes which escape through a pipe in the top of the
furnace into the sulphuric acid lead chambers to be there utilised. The remaining 5
aluminate is dissolved in water and decomposed by carbonic acid (furnace gas).
The alumina employed is entirely regained by drawing off the soda or potass
solution by a syphon, the remaining alumina being then dried and used over
again.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gerard Wenzeslaus von Nawrocki in the Great Seal Patent Office
on the 17th July 1878.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W. von
Nawrocki, Civil Engineers and Patent Agents, of No. 2, Koch Strasse, Berlin, in the
German Empire. "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASS
FROM THE SULPHATES OF SODA AND POTASS, AND IN OBTAINING SULPHUROUS ACID
THEREFROM. A communication by Ernst Siermann, of Pommersdorf, near Stettin,
in the German Empire.
"
According to a process proposed by Ballard, soda is produced by means of bauxite
by heating the latter to a red heat together with sulphate of soda and carbonaceous
material, thereby obtaining aluminate of soda, which is decomposed by carbonic acid.
The iron contained in the mineral gives rise however to the formation of objec-
tionable iron pyrites and sulphide of sodium combinations, no alumina free from iron
being obtained, and the production of the soda being consequently expensive.
The process forming the subject of the present Invention differs from the above
in the employment of pure alumina, and in effecting the reduction of the sulphate
separate from the formation of the aluminate, thereby enabling the sulphurous acid
to be gained and reducing the cost and labour of recovering the alkali. For this
purpose the alkaline sulphate is reduced to powder under edge runners, or in a mill
with spherical runners, or by other known pulverising apparatus, and intimately
mixed in the same mill-with dry alumina added in quantity somewhat less than is
necessary to form an aluminate with the quantity of alkali, which is therefore
somewhat in excess. The powdered mixture is then charged into the reducing oven,
which is an iron muffle with a hollow or deepened bottom, having at one end a
working door, and communicating by a pipe with a main pipe leading from a
number of muffles to a lead chamber for receiving the sulphurous acid which comes
off during reduction to be converted into sulphuric acid in the usual way. The
muffle is set in a furnace so as to be quite surrounded by the fire and products of
combustion.
When the muffle has been charged with the mixture of alumina and sulphate,
the door is closed until the mixture becomes heated to a bright red. The door is

page_text: then gradually opened and finally removed, and the heated mass is constantly
rabbled until there is no farther development of sulphurous acid. By the admssion
of the air at a high temperature the alumina acts on the sulphate, whereby themass
is converted into an aluminate of the alkali, while the sulphurous acid generated is
led away by the before-mentioned pipe to the sulphuric acid chamber. The
aluminate is then withdrawn from the muffle, whereupon it can be charged with a
fresh supply.
It is advantageous to work the several muffles communicating with one and the
same sulphuric acid chamber in rotation, so as to keep the supply of sulphurous acid
tolerably uniform. In the mass withdrawn from the muffle there is generally.
present a small quantity of sulpho-salts and of the original sulphate which will
correspond with the excess of sulphate originally mixed with the alumina. The
mass is put into iron tanks and dissolved with water. The solution is drawn off
from the undissolved impurities (such as fragments of coals) and placed in other
iron vessels, where it has carbonic acid blown through it. This gas is conveniently
obtained from the products of the combustion of the reducing furnaces, which are
heated by coke, and it is blown through the solution by a fan, injector, or other
known means. By this action the alumina is separated, leaving as the product of
the process the alkaline carbonate with a small quantity of alkaline sulphate which
is treated in the usual way for the manufacture of soda or potass.
The small quantity of alkaline sulphate could be avoided if in the heating process
an excess of alumina instead of an excess of sulphate were used, but it seems more
important to avoid any waste of alumina for the sake of profitable working, more
particularly as in treating the carbonate of potass for the production of potass,
the sulphate of potass is regained, while with the soda the public are accustomed
to the presence of a small percentage of the sulphate.
The precipitated alumina is dried and used for operating on other quantities of
alkaline sulphate.
Having thus described the nature of the said Invention and in what manner the
same is to be performed, as communicated to me by my correspondent, I claim
obtaining soda or potass, and also sulphurous acid, from sulphates of these alkalies
by heating to redness a mixture of the sulphate with alumina, dissolving the
product in water, and precipitating the alumina by carbonic acid, substantially as
herein described.
"
In witness whereof, I, the said Gerard Wenzeslaus von Nawrocki, have here-
unto set my hand and seal, this Second day of July, in the year of our Lord
One thousand eight hundred and seventy-eight..
GERARD WENZESLAUS v. NAWROCKI (L.S.).