A Process of Manufacture of Aluminium-and-Magnesium Alloys.
Year: 1899

page_text: Date of Application, 10th July, 1899-Accepted, 23rd Sept., 1899
COMPLETE SPECIFICATION.
A Process of Manufacture of Aluminium-and-Magnesium Alloys.
A communication from abroad by PAUL AULICI, of Berlin, in, the Empire of
Germany.
I, ALFRED GEORGE BROOKES, of 55 and 56, Chancery Lane, in the County of
London, Chartered Patent Agent, 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:-
Owing to the successful labours of Dr. Ludwig Mach, of Jena, whose inventions
are the subjects of Applications for Patents Nos. 24878 dated November 25 1898
and 5225 dated March 9, 1899, whose object was to render aluminium capable of
industrial treatment by the addition thereto of magnesium, aluminium-and-
magnesium alloys have of late come into the foreground among the discoverios
of interest in connection with the aluminium question. Hitherto these alloys
have mostly been obtained by fusing the metals together under a suitable pro-
tective covering (as of chloride of an alkali, asbestos-cardboard &c.): This
method may, indeed, be carried out, without any material difficulty; where, how-
ever, manufacture on a large scale and, more particularly the production of an
inexpensive article, are the objects contemplated, the process hereinafter
described is to be preferred; the essential feature of such process being that the
alloy is separated or extracted direct from certain aluminium-and-magnesium.com-
pounds, suited to the purpose, by the employment either of proper chemical
reducing agents or of electrical current. Apart from the simplicity of the
process, and the saving in the cost of production consequent thereon, this plan of
obtaining the alloys direct further affords a number of advantages which, in the
several forms in which the novel process may be carried out, manifest themselves
in various directions.
The following is a description of the three typical modes of performance of
this invention, illustrated by a number of examples
A. Mixtures of suitable aluminium-and-magnesium compounds (say, aluminium-
sodium-chloride and magnesium chloride) are submitted to the action of one or
more reducing media (sucli as sodium or potassium) at the proper temperature,
whereby aluminium and magnesium are separated simultaneously, both metals
at the same time, combining into an alloy.
This method as compared for example with the separate production, or extrac-
tion, of magnesium from its chloride and the subsequent alloying of the same
with aluminium, also obtained separately, offers the following advantages;
Firstly magnesium (by reason of the very high catorio "tone" of its compounds)
shows a very marked tendency to re unite with the electro negative component
which, during its separation has become free, or bound to an alkali, with the
result that, in practice, the amount of magnesiuin obtained is considerably less
than that which sliould be obtained theoretically. Secondly, magnesium is

page_text: lighter, or at all events, not appreciably heavier, than the compounds employed
in its preparation; hence it readily rises to the surface (indeed mere circulation
will induce it to do so) and is there burnt, a result which even protective cover-
ings are not altogether adequate to prevent, more particularly where a process of
this description is continued for a lengthy period of time; and thirdly, and
lastly, the magnesium is very apt to evaporate at the temperatures employed in
its production which affords a further cause of losses.
These three drawbacks which must needs be taken into account wherever
manufacture on a large scale is intended, are more or less completely obviated
by the novel process, according to the nature of the compounds and reducing-
agents used; for in the first place, the affinity of magnesium for the electro-nega-
tive components becomes less owing to its immediate combination, or in other
words, to its becoming directly alloyed, with the aluminium, secondly, the ten-
dency of the magnesium to rise to the surface either entirely disappears under
the influence of the heavier aluminium, or is at any rate considerably checked,
or reduced where comparatively heavy aluminium-and-magnesium compounds are
used; and thirdly, the magnesium, in alloys in which aluminium preponderates,
exhibits no marked tendency to evaporate, so that this cause of loss is also
removed by the present process.
The foregoing remarks apply not only to the simultaneous separation of alumi-
nium and magnesium from their chlorides by means of the metals of the alkalies,
but also in a greater, or less degree, to all other methods, such, for example, as
the separation from the oxides, fluorides, sulphides, or their double compounds;
to the various electrolytic methods (as Heroult's process) in which either aqueous
solutions are used, or fusion is resorted to; and to the application of the electric
are (after Cowles). All these processes need not be specified in detail here inas-
much as they are sufficiently well known in practice, and are for the most part
applicable to this invention without any material modification; for instead of
using a given aluminium compound or a given magnesium compound (as the case
may be) by itself, a suitable mixture of both may be submitted to the action of
the reducing medium, that is to say an aluminium-producing and a magnesium-
producing process may be combined, or in other words made to coincide both as
to time and space. Nor is it by any means necessary, in order to attain this end,
that the two processes to be combined should in all cases be analogous, as is the
case in the example above given.
Thus, production of aluminium from fluoride might be combined with the
production of magnesium from chloride, by reducing a fused mixture of cryolito
and chloride of magnesium by means of the metals of the alkalies or by an
electric current.
B. A further typical form in which this process may be carried out would be
applicable to cases where aluminium is first obtained by itself, by any suitable
method, and is then, in the course of the magnesium-producing process, added
to the given magnesium compound; or where (as in the electrolytic processes) it
serves as a cathode, so that the magnesium, as soon as separated, is absorbed by
the aluminium. Where this method is adopted in forming the alloy, the same
advantages may be derived from the invention as in the case described in para-
graph A, the magnesium being, in this instance, likewise prevented by the
aluminium from re-uniting with the electro negative constituent, and also from
rising to the surface and evaporating. This mode of procedure may be illus-
trated by the following examples: Aluminium may be added to fused chloride
of magnesium and after the fusion of the same sodium be superadded for the
purpose of separating the magnesium; or the bottom of the crucible may be con-
nected with the negative pole of a source of electricity, the aluminium forming
the cathode. Again double salts or mixtures of magnesium chloride with the
chloride of an alkali or the chloride of an alkaline earth may be used in the
same manner.
C. Lastly, as the third typical method of operation, the converse case may be

page_text: instanced, where magnesium is first produced by itself (as aluminium was before),
and is added to the given aluminium compound in the course of the subsequent
production of aluminium, so that, during the reduction of such aluminium com-
pound, it at once forms an alloy with the separated aluminium. While this
method is not so advantageous in practice as either of those described above, yet
it may prove applicable to those cases where it is desired to shorten the time
taken up by the production of the aluminium-and-magnesium alloy.
To this end magnesium, and in addition to this, sodium, for example, may be
mixed with melted cryolite. Preferably however, other metals should be added
to the magnesium, either before or after its introduction into the aluminium
compound as will be presently explained.
Now the following remarks apply to each of the three methods, A, B and C
described above.
The process should preferably be so conducted that the alloy obtained shall
contain from to 40 parts of magnesium for every 100 parts of aluminium; for
which purpose the aluminium-and-magnesium compounds in the case A, the
aluminium metal and magnesium compounds in the case B, and the magnesium
and the aluminium compounds in the case C, should be proportioned in accord-
ance with the result which it is sought to attain.
Alloys may however be prepared which contain less than part or more than
40 parts (per cent.) of magnesium and the proportion of magnesium contained in
these alloys, may be subsequently adjusted so as to meet the requirements of
practice by fusing them together with other alloys either richer or poorer in
magnesium.
Besides the aluminium-and-magnesium alloy may, as soon as formed, be
alloyed with other metals; or if required, the composition of the alloy may be
altered by the addition of metalloids (such as phosphorus, for example) among the
possible metallic additions we may here mention, by way of example, iron,
nickel, cobalt, uranium, cadmium, zinc, tin, lend, copper, silver, arsenic,
manganese, bismuth, wolfram, molybdenum, chrome; but what deserves par-
ticular notice in this connection, is antimony. These metals may, in the case A,
be added to the mixture of aluminium and magnesium compounds at the very
outset or at any time during the course of the process; either in the melted con-
dition, or under certain circumstances, in the solid state, and in the case of elec-
tric methods of separation or decomposition especially in the first stage thereof,
they should form the cathode.
In the case B, the metals already named, or other metals, may be introduced
into the process at the same time as (or if preferred after) the aluminium; or
better still; they might be alloyed with the aluminium previously, the mode of
operation is the same in the case C, the proper metals being added either at the
beginning or in the course of the process, or alloyed with the magnesium before
hand.
With regard to antimony the case is somewhat different from that of the other
metals mentioned: The experiments of Dr. L. Mach of Jena, to which reference
has been made in the introductory part of this specification, have shown that this
metal very considerably raises the point of fusibility of aluminium-and-mag-
nesium alloys, and hinders their evaporation even at a white heat. Now it is
precisely for this reason that antimony in conjunction with aluminium, is better
fitted, than any other agent to overcome all those obstacles which otherwise render
the separation of magnesium more difficult and more expensive. One way of
carrying out the process in this last mentioned form is as follows:
Dehydrated magnesium chloride or a dehydrated double salt of the same with
the chloride of an alkali or the chloride of an alkaline earth is melted in a
crucible, and an alloy consisting of 100 parts of aluminium and say from 5 to
50 parts of antimony is added to the contents of the crucible. After fusion this
alloy is utilized as the cathode for the separation of the magnesium by means of
electrical current.

page_text: of the said
Having now particularly described and ascertained the nature
invention, and in what manner the same is to be performed I declare that what
I claim is:
1. A process for the production of aluminium-and-magnesium alloys the main
feature of such process being that the said alloys are separated direct from
aluminium and magnesium compounds suitable for the purpose, proper chemical
reducing agents or electrical current being used at the same tinie.
2. The process as claimed in the first claim the main feature thereof being that
aluminium produced separately is added to the given magnesium compound in
the course of the production of magnesium or forms the cathode in the electro-
lytic process.
3. The process as claimed in the first claim its main feature being that magne-
sium produced separately is added to the given aluminium compound in the
course of the production of aluminium or forins the cathode in the electrolytic
process.
4. The process as claimed in the second claim its main feature being that
antimony is added to the aluminium either before or after its addition to the
magnesium compound to be decomposed for the purpose of preventing the rising
of the magnesium its evaporation and its re-union with the electro negative
constituent.
101
1
12 T 1
1000
WM. BROOKES & SON,,
55/56, Chancery Lane, London, Agents for the Applicant.