Improved Process for the Production of Caustic Alkalis and Alkaline Earths, and of Aluminates.
Year: 1899

page_text: Date of Application, 29th Mar., 1899
Complete Specification Left, 25th Nov., 1899-Accepted, 29th Mar., 1900
Improved Process for the Production of Caustic Alkalis and
Alkaline Earths, and of Aluminates.
I, FRITZ PROJAHN, Chemist, of Düsseldorferstrasse 132, Duisburg, in the
Kingdom of Prussia, do hereby declare the nature of this invention to be as
follows:-
The process is based on the chemical effect of pure metals on salts rich in
oxygen, such as sulphates or nitrates, under heat.
The chemical reaction is somewhat as follows:--The metal decomposes the
sulphates, producing metal sulphides and oxides of the metal, and free oxygen,
while the basis of the salt forms a caustic product.
With nitrates the decomposition yields oxides of the metal and the lower
oxidations of nitrogen. Here too, the basis of the salt is precipitated in a
caustic form.
The chemical reactions between metals and sulphates are of special practical
importance. To illustrate a case I will select sulphate of sodium as the repre-
sentative of the sulphates, and iron as representing the metals.
The chemical reaction is probably somewhat as follows:-
=
=
=
Al, Na O +3 FеS + V
n
4
Al, Na, O +3 FeS + 3 Fe 0+0
Al, Na 0+ 3 FeS 3 Fe, 0),
+
Al, 0, +3 Na, SO, + Fe,
2 Al 0, +3 Na, SO, + Fe
2 A 0, +3 Na, SO, + Fe
Inasmuch as, according to the above, the process may be carried out so that
free oxygen is produced, and on the other hand, when nitrates are used, the
lower oxidations of nitrogen are obtained, it becomes probable that both pro-
cesses may be so combined, as to secure the regeneration of the gases for the
purpose of obtaining nitric acid, either by the combination of the corresponding
mixture in one process, or by the union of the gases obtained by the separate
processes.
A partial use of the nitrate process may also greatly advance the sulphate

page_text: The process may also be applied to the salts of alkaline earths.
The process is carried out by heating a mixture of the parts represented in
the above formulae, in a furnace. The molten product is lixiviated with
water, and the lye as well as the residue henceforward are treated by known
processes.
The advantages of the process will be found to lie in the simplicity of the
operation and the usefulness of all the intermediate products. Thus, when
iron is the metal used for the reduction, the lixiviated residue can be used, in
the case where sulphates are employed, for the production of either sulphurous,
or sulphuric acid, the residues from which, may again be used in the furnaces
of a foundry for the purpose of obtaining metallic iron.
The production of powdered raw iron is best carried out in connection with
a foundry, say, by granulation in water followed by a further reduction in
size by passing the material under rollers.
Other metals may be employed in the same manner as iron.
This process may prove to be of importance in the working of bauxites,
especially those, rich in iron, inasmuch as the residue of the aluminate smelt
is, in reality a very good iron ore.
Dated this 2011
1000
BOULT & WADE,
Agents for the Applicant.
Improved Process for the Production of Caustic Alkalis and
Alkaline Earths, and of Aluminates.
I, FRITZ PROJAHN, Chemist, of Düsseldorferstrasse 132, Duisburg, in the
Kingdom of Prussia, 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 :-
Caustic soda is produced not only by the electrolytic decomposition of chloride
of sodium, but also and chiefly from carbonate of soda. Aluminates are also
produced by means of soda or caustic alkali acting upon argillaceous sub-
stances. For instance sodium aluminate can be obtained by dissolving hydrate
of alumina in a caustic soda lye.
According to the present invention the products are obtained directly from
alkali sulphates, thereby avoiding the soda process.
The process is based on the chemical reaction, under heat, of sulphates on
native or pure metals, resulting in the formation of sulphide and oxide of the
metal. The basis of the salt is obtained as an oxide.
As an example I will take sulphate of sodium as representing the sulphates,
and iron as representing the metals.
As far back as 1863, James Bowron and George Robinson endeavoured to
substitute, as indicated by their English Specification No. 2422 of 1863, for the
old process for the production of soda from sulphate chalk and carbon--a
process according to which sodium sulphate and molten iron were mixed
together and the mixture heated in the presence of atmospheric air: soda,
oxide of iron, and sulphurous acid gas being indicated as products thereof.
Inasmuch as the term "atmospheric air" can only mean oxygen_contain-
ing much carbonic acid gas, it quite possible that carbonate of sodium was
indeed obtained, provided that during the roasting of the transitorily formed
sulphide of iron no recombination of the latter occurred to form sulphates.

page_text: In the latter case the process must have proved a failure. The said specifica-
tion, moreover, does not contain any reference to fixed proportions of the raw
materials used.
The present process differs from it, in that it works without the co-operation
of atmospheric air, and the sulphur permanently combines with the iron, from
which it is separated after the separation of he caustic soda from the residue,
by roasting it for the purpose of recovering the former. In short: the fusing
involved in this process is really a reducing process while that of the English
process is an oxidising process.
Another important feature of the present invention is that the raw materials
employed are made to react on each other in certain definite quantities.
When iron and sulphate of sodium are fused together in arbitrary quanti-
ties and at determined temperatures, the products resulting are caustic soda,
iron-sodium sulphide, iron sulphide, and ferric and ferrous oxides in vary-
ing relative quantities.
The lyes resulting from such operations are useless on account of their high
percentage of sulphur and iron. When however, the quantities of the raw
materials are fixed according to the following equations, and the necessary tem-
perature is provided, almost pure caustic soda Iyes are obtained.
The chemical reaction is probably represented by the following equations:
n
Fe
2 Al, 0, +3 Na, SO, +9 Fe = Al, Na. O + 3 Fе S + 3 Fe̟ O̟.
Q
Of course, the proportions of the raw material are not restricted to these
formulae, but may vary according to the quality of the raw materials, and re-
quirements as indicated by experience.
This process may also be applied to the salts of the alkaline earths. The lye
is separated in the same way as the lyes of the caustic alkalis.
The process, for instance in the case of the production of caustic soda, is
practically carried out by heating a mixture of sodium sulphate and powdered
iron in a suitable furnace. The reaction starts at dark red heat and is quickly
finished, much heat being evolved. The fused product is lixiviated with water,
after which both lye and residue are treated according to known processes.
The advantages of the process will be found in the simplicity of the opera-
tion and the usefulness of all intermediate products. Thus when iron is used
for the reduction in combination with sulphates, the lixiviated residue may be
used for the production of either sulphurous or sulphuric acid the residue from
which may again be converted into metallic iron, preferably in the form of
spongy iron,
Other metals capable of forming sulphides, soluble in water, may be em
ployed in the same manner as iron.
This process will prove of importance in the working of bauxites, especially
those rich in iron, inasmuch as the residue of the aluminate smelt is, in reality,
a very good iron ore.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. A process for the production of caustic alkalis, alkaline earths and alu-
minates, in which sulphates are transformed into the caustic state by metals,
without the employment of carbon for reduction, the sulphur of the sulphate
combining (without necessitating the presence of a third substance such, for

page_text: instance as lime) with the metal, to form a sulphide, and in the event of
argillaceous substances being added, aluminates being formed, substantially as
described.
2. In a process for the production of caustic soda, heating together a mixture
of sodium sulphate and powdered iron, and lixiviating the fused product with 5
water, substantially as described.
Dated this 24th day of November 1899.
BOULT, WADE & KILBURN.
Agents for the Applicant.