IMPROVEMENTS IN OBTAINING CARBONATE OF POTASH BY THE LEBLANC PROCESS
Year: 1885

page_text: Leblanc Process.
I HEINRICH PRECHT, Factory Manager and Doctor of Philosophy of Neu-
Stassfurt near Stassfurt, Prussia, German Empire do hereby declare the nature
of said invention for IMPROVEMENTS IN OBTAINING CARBONATE OF POTASH BY
THE LEBLANC PROCESS to be as follows:-
"
"
Carbonate of potash has heretofore by the Leblanc process, been produced only
by smelting of sulphate of potash with coal and limestone. The sinelting of the
crude potash in this process requires great skill on the part of the workman, and
also entails considerable losses of carbonate of potash, which partly evaporates.
and partly is contained in an insoluble condition as silicate of potash or as
carbonate of potash and of lime in the smelted material.
The present invention removes these defects and also materially facilitates the
formation of the carbonate of potash in general.
According to this invention an addition of such an amount of magnesia or
magnesia salts is made to the mixture of sulphate of potash, carbonate of lime
and coal produced in the usual manner for the manufacture of potash as shall
prevent the smelting of the saline mixture by red heat to a porridge like "con-
sistency. By the addition of magnesia or magnesia salts it is rendered possible
to produce carbonate of potash by simple burning at a dull red heat without
smelting of the salt mixture, while on the other hand it is impossible to do so
without such addition. The quantity of magnesia required may be modified
according to the temperature of the red hot mass. If a bright red heat is used
the mixture should contain about 1 molecule of magnesia for 1 molecule of sulphate
of potash, or about 23 parts of magnesia for 100 parts of sulphate of potash. If
dull red heat is used an addition of 12 parts of magnesia for 100 parts of sulphate
of potash suffice for preventing the smelting of the salt mixture,

page_text: When sulphate of magnesia or sulphate of potash and of magnesium is used
instead of magnesia such an amount of coal and of carbonate of lime is added
that the sulphate of magnesium is reduced according to the formula
Mg SO* + Ca CO³ + 2 C = Mg O + Ca S + 3 CO³,
and magnesia formed. In practice it is necessary not to work with more coal and
carbonate of lime than theoretically needed, and it is therefore preferable to mix
the materials in the following proportions.
Sulphate of potash
Sulphate of magnesium 18.4
Carbonate of lime
26-6 parts }
"
Coal
36
19
= 45 parts of sulphate of potash
and of magnesium.
In this mixture there are 23 parts of magnesia per 100 parts of sulphate of
potash. It is not necessary to retain these proportions under all circumstances,
for the proportions stated may be varied without materially impairing the process.
The materials are ground fine, intimately mixed and burnt or roasted in a
furnace so as to reduce them. The burning of one charge takes about 40 minutes.
The crude potash, which must be cooled while the air is excluded, is in the form
of a loose or friable mass which can easily be lixiviated. The lixiviation of the
carbonate of potash and the treatment of the lyes are performed in the heretofore
usual manner.

page_text: Improvements in Obtaining Carbonate of Potash by the
Leblanc Process.
I HEINRICH PRECHT Factory Manager and Doctor of Philosophy of Neu
Stassfurt near Stassfurt, Prussia, German Empire 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 :-
Carbonate of potash has heretofore by the Leblanc process been produced only
by smelting of sulphate of potash with coal and limestone. The smelting of the
crude potash in this process requires great skill on the part of the workman, and
also entails considerable losses of carbonate of potash which partly evaporates
and partly is contained in an insoluble condition as silicate of potash or as
carbonate of potash and of lime in the smelted material.
The present Invention removes these defects and also materially facilitates the
formation of the carbonate of potash in general.
According to this Invention an addition of such an amount of magnesia or
magnesia salts is made to the mixture of sulphate of potash, carbonate of lime
and coal produced in the usual manner for the manufacture of potash, as shall
prevent the smelting of the saline mixture by red heat to à porridge like con-
sistency. By the addition of magnesia or magnesia salts it is rendered. possible
to produce carbonate of potash by simple burning at a dull red heat without
smelting of the salt mixture, while on the other hand it is impossible to do so
without such addition. The quantity of magnesia required may be modified
according to the temperature of the red hot mass. If a bright red heat is used,
the mixture should contain about 1 molecule of magnesia for 1 molecule of sulphate
of potash or about 23 parts of magnesia for 100 parts of sulphate of potash. If
dull red heat is used an addition of 12 parts of magnesia for 100 parts of sulphate
of potash suffice for preventing the smelting of the salt mixture.
When sulphate of magnesia or sulphate of potash and of magnesium is used
instead of magnesia such an amount of coal and of carbonate of lime is added
that the sulphate of magnesium is reduced according to the formula
Mg SO+ Ca CO³ + 2 C = Mg O + Ca S + 3 CO³,
and magnesia formed. In practice it is necessary not to work with more coal and
carbonate of lime than theoretically needed, and it is therefore preferable to mix
the materials in the following proportions:
+
Sulphate of potash
28.6 parts] = 45 parts of sulphate of potash
Sulphate of magnesium 18.4
Carbonate of lime
Coal
36
19
and of magnesium.
In this mixture there are 23 parts of magnesia per 100 parts of sulphate of
potash. It is not necessary to retain these proportions under all circumstances,
for the proportions stated may be varied without materially impairing the process.
The materials are ground fine, intimately mixed and burnt or roasted in a
furnace so as to reduce them. The burning of one charge takes about 40 minutes.

page_text: The crude potash, which must be cooled while the air is excluded, is in the form of
loose or friable mass which can easily be lixiviated. The lixiviation of the
carbonate of potash and the treatment of the lyes are performed in the heretofore
usual manner.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what
I claim is
.
1. The manufacture of carbonate of potash according to the Le Blanc process
without smelting the saline mixture by the addition of magnesia or carbonate of
magnesium to the mixture consisting of sulphate of potash, carbonate of lime and
coal as set forth.
2. The process of manufacture of carbonate of potash according to the Le Blanc
process without. smelting the saline mixture by furnacing or firing sulphate of
potash and of magnesium or a mixture of sulphate of potash and sulphate of
magnesium with carbonate of lime and coal as set forth.