Improvements in the Production of Aluminium and Aluminium-bronze.
Year: 1885

page_text: Improvements in the Production of Aluminium and
Aluminium-bronze.
I, RICHARD GRÄTZEL, doctor of philosophy, residing in Bremen, German Empire,
do hereby declare the nature of this invention to be as follows:-
My invention relates to the production of aluminium from the compound fluoride
of aluminium and of an alkali-metal, and it consists in decomposing the aluminium
fluoride of the said compound, when being in melted condition, by means of mag-
nesium, which may be employed in prepared state as metal, or forined in the bath
of the melted fluoride by the electric decomposition of magnesium chloride. If
the electric current is called into aid, the said magnesium chloride may be replaced
by chloride of calcium, baryum or strontium. The invention also comprises the
production of aluminium-bronze by the introduction of copper into the melted bath
from which the aluminium is obtained.
If the compound fluoride of aluminium and of an alkali-metal (especially of
potassium or sodium) is melted and exposed to the action of magnesium, fluoride
of magnesium is formed and aluminium separates out in metallic state.
The magnesium may be employed in solid or fused condition or in the form of
vapour. In case it is produced in the melted fluoride by electric decomposition
of chloride of magnesium, it acts in nascent state on the fluoride of aluminium.
In like manner as by magnesium the fluoride of aluminium may be decomposed by
calcium, baryum and strontium, but these metals appear to be practically available
in nascent state only, i.e. when being, produced by electrolysis from their chlorides
in the fused fluoride.
If, in addition to magnesium, copper is introduced into the melted fluoride,
the same combines with the aluminium and forms therewith aluminium-bronze.
In the electrolytic process a negative electrode of copper may be used for this
purpose.

page_text: Aluminium-bronze..
I, RICHARD GRÄTZEL, doctor of philosophy, residing in Breinen, 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
This invention relates to the production of aluminium from the compound fluoride
of aluminium and of an alkali-metal, and it consists in decomposing the aluminium-
fluoride of the said compound when being in melted condition, by means of mag-
'nesium, which may be employed in prepared state as metal, or formed in the bath
of the melted fluoride by the electric decomposition of magnesium chloride. If
the electric current is called into aid, the said magnesium-chloride may be replaced
by chloride of calcium, baryum or strontium. The invention also comprises the
production of aluminium-bronze by the introduction of copper into the melted
bath from which the aluminium is obtained.
If the compound fluoride of aluminium and of an alkali-metal (especially of
potassium or sodium) is melted and exposed to the action of magnesium, fluoride
of magnesium is formed and aluminium separates out in metallic state.
The simplest mode of proceeding is to add magnesium in solid or fused condition
to the melted fluoric compound. At the beginning of the operation it is advan-
tageous in such case to promote the mixture of the magnesium with the melted
salt by stirring. But the magnesium may also first be evaporated in a closed
vessel, the vapour produced being conducted through a tube into the melted
.fluoric salt.
The third manner of carrying out the invention consists in producing the mag-
.nesium during the process by electrolysis of chloride of magnesium. As is well
known, this salt may be decomposed in fused state by the electric current, chlorine
being evolved at the positive pole, while the metal is deposited at the negative pole,
Now, if the compound Huoride of aluminium and of an alkali-metal is melted
together with chloride of magnesium (preferably in the proportion of three equiva
lents of the chloride to one equivalent of fluoride of aluminium contained in the
fluoric salt), and if an electric current of sufficient strength is conducted through
the molten mass, the said current decomposes the chloride of magnesium, chlorine
is evolved, the magnesium combines in nascent state with the fluorine of the
aluminium fluoride, and metallic aluminium separates out.
6
As fluoric compounds of aluminium may be used native cryolite (Al, F, + 6 Na F)
or an artificial compound fluoride of aluminium and of an alkali-metal. Moreover,
it is to be observed that, instead of simple chloride of magnesium, the compound
chloride of magnesium and potassium or sodium, for instance carnallite, or a
mixture of magnesic and potassic or sodic chlorides may be employed with
advantage, in as much as the fused mass will thereby become more fluid.
In comparison with the direct production of aluminium from the melted fluoride
of aluminium by electrolysis, to which relate my German patent No. 26962 and

page_text: the British patent No. 5509. A.D. 1882, or from the double fluoride of aluminium
and of an alkali-metal, the process described in the foregoing presents the advan-
tages that it may be carried out with an electric current of lower tension, and that
the crucibles employed in the operation are not, or but very little corroded
(especially in the presence of chloride of potassium or sodium) by the fluoride of
magnesium, or of magnesium and an alkali-metal, formed in the process; whereas
the fluorine or comparatively pure fluoride of potassium or sodium produced by
the former method, acts in a high degree destructively on the crucibles. The latter
advantage is also of importance in respect to the employment of metallic mag-
nesium as compared with the decomposition of fluoride of aluminium by means
of sodium.
In like manner as by magnesium the decomposition of fluoride of aluminium
may be brought about by means of calcium, baryum, and strontium; but on account
of the great difficulties which the production of these metals presents, their employ-
ment in reguline state would, for the present at least, not be adapted to make the
process remunerative. The chloride of calcium, baryum, and strontium may,
however, be used instead of chloride of magnesium for decomposing the fluoride of
aluminium with the assistance of electricity.
If, in addition to magnesium, copper is introduced into the melted compound
fluoride, the same combines with the aluminium as it separates out, and forms
therewith aluminium-bronze. In the electrolytic process a negative electrode
consisting of copper may be used for this purpose.
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 process of producing aluminium from the compound fluoride of aluminium
and of an alkali-metal by melting the same and by causing, magnesium to act
thereon, for the purpose of decomposing the aluminium fluoride, substantially as
herein before described.
2. The process of producing aluminium from the compound fluoride of aluminium
and of an alkali-metal by melting the same and by causing magnesium, or one of
its described equivalents (calcium, baryum, strontium) produced in the melted
fluoride by electrolysis of chloride of magnesium or of one of the said equivalents,
to act in nascent state on the said fluoride, for the purpose of decomposing the
aluminium fluoride, substantially as hereinbefore specified.
3. In the process of producing aluminium from the compound fluoride of alumi-
nium and of an alkali-metal by melting the same and causing magnesium to act
thereon, the introduction of copper into the melted fluoride, for the purpose of
obtaining aluminium-bronze, substantially as described.
4. In the process of producing aluminium from the compound fluoride of alumi-
nium and of an alkali-metal by melting the same and causing magnesium, or one
of its described equivalents (calcium, baryum, or strontium), produced in the melted
fluoride by electrolysis of chloride of magnesium or of one of the said equivalents,
to act in nascent state on the said fluoride, the introduction of copper into the
melted fluoride, for the purpose of obtaining aluminium-bronze, substantially as
hereinbefore set forth.