Improvements in the Process of Manufacturing Carbonic Acid and in the Production of Bye Products such as Sodium Sulphate and Magnesium Sulphate.
Year: 1894

page_text: Date of Application, 24th July, 1894-Accepted, 25th Aug., 1894
COMPLETE SPECIFICATION.
Improvements in the Process of Manufacturing Carbonic Acid and
in the Production of Bye Products such as Sodium Sulphate
and Magnesium Sulphate.
I ERIK WILLIAM ENEQUIST of No. 82 Nassau Street in the City, County and
State of New York United States of America, Chemist do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
My invention consists of a process in which I employ an alkaline acid-sulphate
or nitre cake dissolved in water to any suitable strength and allow the hot solution
to come in contact with a large excess of magnesium carbonate or magnesite
instead of ordinary sulphuric acid and marble dust or magnèsite as now used,
thereby producing carbonic acid in a uniform and advantageous manner and
obtaining it at less expense, the acid sulphate or nitre-cake being of comparatively
little value. Through the elimination of the sulphuric acid therefrom in the
process, the value of the resultant alkaline sulphate is considerably increased.
Nitre-cake or sodium acid-sulphate is obtained very extensively as a bi-product
and in many instances thrown away as valueless. It generally contains 20 to
30 per cent. of free sulphuric acid which cannot be separated from the sodium
sulphate without considerable expense, but then the free acid is invariably
sacrificed. In my process I not only save the sacrifice of the sulphuric acid, but I
utilize the same to the fullest extent of its value.
Carbonic acid is produced in many different ways, but the purest gas is obtained by
the acid process or in the treatment of magnesite or marble dust with sulphuric
acid. In my process the carbonic acid is obtained equally pure but at much less
Carbonic acid may also be obtained in the acid process by the treatment of
nitre-cake with marble dust, lime stone or chalk, but the sulphuric acid is wasted
in the shape of calcium sulphate.
cost.
The sodium sulphate solution is mixed with a large amount of the same and an
excess of calcium carbonate, from which it will be inconvenient to separate the said
solution. There are other methods in existence for eliminating the injurious
sulphuric acid from nitre-cake, for instance by roasting in a furnace etc., but I am
not aware of any method, in which the sulphuric acid is allowed to perform work in
competition with the pure acid and instead of being detrimental becomes as valuable
as the same.
In carrying out my process about 9300 pounds of nitre-cake containing
about 25 per cent. of free sulpburic acid, or a corresponding quantity of another
acid sulphate, is dissolved in about 18000 pounds, more or less, of hot water and
brought in contact with magnesite, of which about 2000 pounds will be dissolved
by the acid solution. As the mass becomes heated, carbonic acid gas escapes in a
uniform manner. It is collected, washed and compressed or otherwise utilized,
about 1000 pounds of gas being obtained.
When the production of gas has come to an end, and the solution has been
heated to boiling, it has an alkaline reaction, and iron, aluminous and silicious
matters and other impurities are precipitated in consequence. The colorless
solution which contains sodium and magnesium sulphates and registers about
35°-38° Bé is settled and drawn into crystalizing tanks, where sodium sulphate or
Glauber's salts crystalize; about 9000 pounds being obtained. The process is so
regulated that the remaining salts are present in equivalent quantities for forming
a double salt of sodium and magnesíum sulphates. By employing a nitre-cake
containing more or less acid and regulating the strength of the solution thereof

page_text: care is taken that the excessive Glauber's salts crystalize in the first operation.
The solution containing the double salts, which crystalizes with 55% of water, is
evaporated until it registers 42°-45°Bé, when a double salt of sodium and magnesium
sulphates will crystalize; about 10000 pounds being obtained.
An equivalent quantity of an alkaline chloride may be added at the first stage of
the process or later on, by means of which the magnesium sulphate that is formed will
bé decomposed into magnesium chloride, when more sodium sulphate is obtained, if
sodium chloride was employed.
The sodium sulphate or Glauber salts that are obtained in this process are
perfectly pure except containing magnesium sulphate which may be eliminated
through re-crystalizing or precipitation by lime etc.
The double salt of magnesium and alkaline sulphates may be decomposed by an
alkaline hydrate or carbonate, in which case, magnesium hyurate or carbonate and
an alkaline sulphate is obtained. Or the double salts may be decomposed by a
soluble alkaline earth hydrate in which case magnesium hydrate, sodium sulphate
and an alkaline earth sulphate are formed. The various products are then separated
in any well known and suitable manner.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :
1. The process of treating a solution of nitre-cake or another acid sulphate with
magnesite substantially as described.
2. The process of producing carbonic acid and pure alkaline sulphate and
magnesium sulphate by treating a solution of an alkaline acid sulphate with
magnesium carbonate or magnesite, thereby evolving carbonic acid gas and causing
an alkaline reaction, thus precipitating iron, aluminous and silicious matters and
other impurities substantially as described.
3. The process of treating a hot solution of nitre-cake with magnesite and
separating the excess of Glauber's salts by means of crystalization, then purifying
the same substantially as described.
4. The process of treating a solution of an alkaline acid sulphate with magnesite
and a corresponding alkaline chloride, forming carbonic acid, an alkaline sulphate
and magnesium chloride substantially as described.
5. The process of treating a solution of an alkaline acid sulphate with magnesite,
producing carbonic acid, and alkaline sulphate and a mother liquor containing an
alkaline sulphate and magnesium sulphate, and decomposing the same with a
corresponding alkaline hydrate or carbonate, forming magnesium hydrate or
carbonate and a corresponding alkaline sulphate.
6. The process of treating a solution of nitre-cake with magnesite forming
carbonic acid, Glauber salts and a solution containing sulphates of sodium and
magnesium decomposing the same with a soluble alkaline earth bydrate forming
sodium sulphate, magnesium hydrate and an alkaline earth sulphate and separating
the same.
Dated this 22nd day of June 1894.
PHILIP M. JUSTICE,
Chartered Patent Agent, London,
For the Applicant.