Improvements in Processes for the Extraction and Electro Deposition of Aluminium and Aluminium Alloys.
Year: 1888

page_text: Date of Application, 8th Oct., 1888
Complete Specification Left, 8th July, 1889-Accepted, 7th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in Processes for the Extraction and Electro Deposition
of Aluminium and Aluminium Alloys.
I, PASCAL MARINO, of Boulevard Henri IV., Paris, in the Republic of France,
Chemist, do hereby declare the nature of this invention to be as follows:-
This invention has for its object improved processes for the extraction of metallic
aluminium from aluminous clays or from compounds of aluminium such as chlorides
fluorides fluo silicates nitrates acetates suphates or sulphurets either in a pure state or
alloyed; and for its deposition upon all metallic objects as well as upon substances not
conductors of electricity and for producing it in a solid and compact state.
In the baths for the electric decomposition of oxide and salts of aluminium, salts of
ammonium and salts of aluminium are simultaneously decomposed acid and oxygen
appearing at the positive pole, hydrogen and the aluminium base in a brilliantly
metallic state.
1st. A bath of fluoraluminiate of ammonium, consisting of a solution of double
fluoride of aluminium and ammonium. Hydro fluo silicic acid is employed to
dissolve calcined alumina and hydrated silicate of alumina; the treatment is prolonged
until the decomposition of the fluoride of silicium, and hydrated fluoride of aluminium
i then formed.
2nd. A bath of Sulpho-aluminiate of ammonium, consisting of a solution of double
sulphuret of aluminium and ammonium.
The sulphuret of aluminium is obtained from cryolite which being a very soluble
body by a long boiling in water gives sulphuret of aluminium which is calcined
with sulphuret of calcium.
3rd. A bath of nitro-aluminiate of ammonium, a solution of double nitrate of
alumina and ammonia. To obtain the hydrated alumina the solution of this salt is
effected at 140 degrees of heat, Centigrade.
4th. A bath of sulpho-aluminiate of ammonium, a solution of double sulphate of
alumina and ammonia. Ammoniacal alum is not however employed although it is
a double salt of ammonia and alumina.
5th. A bath of aceto aluminiate of ammonium, a solution of double acetate of
aluminium and ammonium.
6th. A bath formed by taking hydrated alumina obtained from aluminous minerals,
or nitrates, sulphates, or acetates of alumina, and treating it by double decom-
position between sulphate of alumina and chloride of barium in solution. I then
evaporate this solution in the air or by moderate heat. To form the bath I dissolve
equal parts of this salt and of chlorhydrate of ammonia.
SECTION 2. COMPOSITION OF A BATH FOR THE ELECTRICAL DECOMPOSITION
OXIDE AND SALTS OF ALUMINIUM BY MEANS OF SODIUM.
OF
I dissolve chloride or cyanide of sodium in the proportion of ¡00 grammes to
7 grammes of metallic aluminium present in the solution, and of 9 to 12 grammes to
a litre of distilled water and I boil the mixture: 1st. with caleined alumina obtained
either from aluminous minerals or from sulphates nitrates or acetates of alumina, and,
2nd, with salts of aluminium obtained from the above named substance and always.in
the proportions already given, finally I filter the solution- and I place it in a vessel
suitable for the process of electro-decomposition.

page_text: The compound of aluminium with iron is of the colour required for arms, whilst
that of aluminium with nickel is an inoxidisable and unalterable silver-white with
more durability solidity and beauty than ordinary nickel plate.
SECTION 8. DESCRIPTION OF THE PROCESS.
After having carefully cleaned washed and afterwards dried and treated with nitrate
of mercury the articles which are to be coated with aluminium either pure or in
combination with other metals, they are placed in the bath in contact with the
negative pole of an electro dynamo machine in the way ordinarily used in electro
plating. The deposit of aluminium is like that ordinarily produced of silver or nickel,
that is to say absolutely without oxide or precipitated metal. Its adhesion upon the
other metals is perfect, so that the coating takes a very fine polish without shewing
any sign of rubbing off. In order that the metallic coat may resist wear for a longer
time it is only necessary to prolong the electro-plating process and the corresponding
thickness of the deposit. The same process may be applied to animal vegetable or
mineral substances which can be rendered conductors of electricity by plumbago or
metallic powders or by solutions such as phosphorus in sulphuret of carbon, nitrate of
silver dissolved in ammonia, gallic, acid, caustic lime, etc. or by the other known means
employed in electrotyping.
I have also applied the process directly to glass which having been first thoroughly
cleaned with acid, soda, and alcohol, is then surrounded with a band of copper and is
submitted to the electro-plating process as if it were of metal, when by degrees, and
at length almost entirely, the glass becomes covered with a layer of aluminium.
By the same processes a thick layer of aluminium or its alloy may be deposited
either upon a metal which melts at a lower or higher temperature than that of the
aluminium or alloy or upon an electrode of hard carbon or of coke.. I thus obtain
solid and massive aluminium either pure or alloyed which can be brought into a
compact mass. Or I obtain an alloy of aluminium in a compact state by depositing
it in the same way upon a plate of the metal with which it is to be alloyed; the relative
weights of the two metals being so proportioned that when afterwards melted together
they form the desired alloy.
Renewal and restoration of the baths. I renew and restore the baths when
necessary either by repeating the process required for each bath or by means of a
soluble plate connected with the positive pole which will keep the metallic solution of
the bath in a constant state of concentration, or by adding the same oxides and the
same metallic salts already dissolved in the bath, in the following manner; I enclose
the oxides or salts in a cloth which I hang in the bath, or I put them into a sheet of
platinum or aluminium in the form of a funnel or cylinder pierced with small holes
which I connect with the positive pole.
My invention embraces all the electro-decompositions, compounds, and chemical
products and their equivalents named above, also the chemical products and their'
equivalents of the metals necessary to obtain the different alloys, amongst others,
acetate, chloride, cyanide, fluoride, nitrate, sulphate, and sulphide, of aluminium,
alumina, silver, gold, copper, iron, tin, nickel, potassium, sodium, zinc, and antimony,
also the composition and method of preparing the baths, described in sections 1, 2, 3, 4, 5,
and 6, as well as the substances and their equivalents, which enter into the composition
of all these baths, also all the processes and applications pointed out in section 7 with
regard to alloys.

page_text: of ammonium and salts of aluminium are simultaneously decomposed acid and oxygen
appearing at the positive pole, hydrogen and the aluminium base in a brilliantly metallic
state at the negative pole.
In each of the following baths the ammonium is obtained by the use of chlorhydrate 1
of ammonia in the proportions given.
1st. A bath of fluoraluminate of ammonium, consisting of a solution of double
fluoride of aluminium and ammonium, obtained as follows:-
Fluoride of Aluminium
Chlorhydrate of Ammonia -
Distilled Water
50 parts.
20 parts.
1000 parts.
Into the solution thus formed ammonia is introduced in the proportion of 15 cubic
centimetres to each 50 grammes. of fluoride of aluminium.
To form the fluoride of aluminium hydrofluo silicic acid is employed to dissolve
calcined alumina and hydrated silicate of alumina; the treatment is prolonged until 2
the decomposition of the fluoride of silicium, and hydrated fluoride of aluminium is
then formed.
2nd. A bath of sulpho-aluminiate of ammonium, consisting of a solution of double
sulphuret of aluminium and ammonium, obtained as follows
Sulphuret of Aluminium
Chlorhydrate of Ammonia
Distilled Water
-
50 parts.
20 parts.
1000 parts.
To this solution 20 Cubic centimêtres of ammonia are added to each 50 grammes
of sulphuret of aluminium.
3rd. A bath of nitro-aluminiate of ammonium, a solution of double nitrate of 3
alumina and ammonia, obtained as follows:-
50 parts of Nitrate of Alumina are placed in distilled water at a temperature
of 140 degrees and maintained at this temperature until hydrated alumina is obtained
(Al² 0³, 6 HO). With this residue are mixed 20 parts of Chlorhydrate of Ammonia
and the whole is dissolved in 1000 parts of water. To this solution is added 20 cubic
centimetres of ammonia to each 50 grammes of Nitrate of Alumina.
To obtain the hydrated alumina the solution of this salt is effected at 140 degrees of
heat, Centigrade.
4th. A bath of sulphoaluminiate of ammonium, a solution of double sulphate of
alumina and ammonia, obtained as follows :-
-
Sulphate of Alumina
Chlorhydrate of Ammonia
100 grammes.
40 grammes.

page_text: To this solution are added 20 cubic centimêtres of ammonia.
Ammoniacal alum is not however to be employed although it is a double salt of
ammonia and alumina.
5th. A bath of aceto aluminiate of ammonium, a solution of double acetate of
aluminium and ammonium, obtained as follows:-—
Acetate of Alumina
Chlorhydrate of Ammonia
Distilled Water
-
-
100 grammes.
10 grammes.
2000 grammes.
To this solution are added, by slow degrees and with continual agitation to prevent
it from becoming. gelatinous, 10 cubic centimêtres of ammonia which should be
sufficient for the preparation.
It should be observed that in the five baths described, the solutions are reheated up
to boiling and are then allowed to cool to a gentle temperature in order to expel the
ammonia.
SECTION 2. COMPOSITION OF A BATH FOR THE ELECTRICAL DECOMPOSITION OF
OXIDE AND SALTS OF ALUMINIUM BY MEANS OF SODIUM.
I dissolve chloride or cyanide of sodium in the proportion of 100 grammes
to 7 grammes of metallic aluminium present in the solution, and of 9 to 12 grammes
to a litre of distilled water and I boil the mixture: 1st with calcined alumina obtained
either from aluminous minerals or from sulphates nitrates or acetates of alumina, and,
2nd, with salts of aluminium obtained from the above named substance and always in
the proportions already given, finally I filter the solution and I place it in a vessel
suitable for the process of electro-decomposition.
Amongst the aluminous clays I prefer the mineral known as Beauxite from which.
oxide of aluminium can be economically obtained purer than from any other source.
This oxide costs one-fourth of that extracted from alum.
Among the many methods of precipitating the oxide of aluminium I may mention
the use of zinc and platinum in an aqueous solution of alumina.
I refer to this process as one of the least costly.

page_text: SECTION 6.
In another composition of bath I dissolve 1 kilogramme of citric acid in two and
a half litres of distilled water, and I then add 470 grammes of quick-lime, and I mix
with it a solution of citrate of magnesia previously prepared (citrate of magnesia
500 grammes and distilled water 1400 grammes). I filter and add 500 grammes of
soluble salt of aluminium dissolved in 8 to 10 litres of distilled water, with 60 grammes
of grape sugar. I then boil the whole for half an hour or more, and, finally when
cold, I add ammonia in the same condition and manner as in the bath described in
section 5..
SECTION 7. ALLOYS.
In one of the baths the composition of which has been indicated above I place
either the oxide, salt, or a soluble plate of the metal which it is intended to deposit
simultaneously with the aluminium. I place such metal, which may be gold, silver,
copper, tin, nickel, iron, antimony, etc.-according to the alloy which is to be produced,
in connection with the positive pole of the electro-dynamo machine, and its
decomposition takes place simultaneously with that of the aluminium.
The compound of aluminium and tin is capable of a very high polish of which tiń
alone is incapable.
Among its many useful applications cooking utensils may be especially mentioned,
as the salts of aluminium are absolutely harmless being without action upon organic
bodies, and the absolute harmlessness of the metal to the health being due to its
resistance to most agents and to nitric sulphuric, acetic, and tartaric acids."
The compound of aluminium with iron is of the colour required for arms, whilst
that of aluminium with nickel is an inoxidizable and unalterable silver-white with
more durability solidity and beauty than ordinary nickel plate.
SECTION 8.
DESCRIPTION OF THE PROCESS.
After having carefully cleaned washed and afterwards dried and treated with
nitrate of mercury the articles which are to be coated with aluminium either pure or
in combination with other metals, they are placed in the bath in contact with the
negative pole of an electro dynamo machine in the way ordinarily used in electro
plating. The deposit of aluminium is like that ordinarily produced of silver or nickel,
that is to say absolutely without oxide or precipitated metal. Its adhesion, upon the
other metals is perfect, so that the coating takes a very fine polish without shewing
any sign of rubbing off. In order that the metallic coat may resist wear for a longer
time it is only necessary to prolong the electro-plating process and the corresponding
thickness of the deposit. The same process may be applied to animal vegetable or
mineral substances which can be rendered conductors of electricity by plumbago or
metallic powders or by solutions such as phosphorous in sulphuret of carbon, nitrate
of silver dissolved in ammonia, gallic acid, caustic lime, etc. or by the other known
means employed in electro-plating.
I have also applied the process directly to glass which having been first thoroughly
cleaned with acid, soda, and alcohol, is then surrounded with a band of copper and is
submitted to the electro-plating process as if it were of metal, when by degrees, and
at length almost entirely, the glass becomes covered with a layer of aluminium.
By the same processes a thick layer of aluminium or its alloy may be deposited
either upon a metal which melts at a lower or higher temperature than that of the
aluminium or alloy or upon an electrode of hard carbon or of coke. I thus obtain
solid and massive aluminium either pure or alloyed which can be brought into a
compact mass. Or obtain an alloy of aluminium in a compact state by depositing.
it in the same way upon a plate of the metal with which it is to be alloyed, the
relative weights of the two metals being so proportioned that when afterwards melted
together they form the desired alloy.

page_text: Renewal and restoration of the baths. I renew and restore the baths when necessary.
either by repeating the process required for each bath or by means of a soluble plate
connected with the positive pole which will keep the metallic solution of the bath in
a constant state of concentration, or by adding the same oxides and the same metallic
salts already dissolved in the bath, in the following manner; I enclose the oxides or
salts in a cloth which I hang in the bath, or I put them into a sheet of platinum
or aluminium in the form of a funnel or cylinder pierced with small holes which
I connect with the positive pole.
SECTION 9.
My invention embraces all the electro-decompositions, compounds, and chemical
products and their equivalents named above, also the chemical products and their
equivalents of the metals necessary to obtain the different alloys, amongst others,
acetate, chloride, cyanide, fluoride, nitrate, sulphate, and sulphide, of aluminium,
alumina, silver, gold, copper, iron, tin, nickel, potassium, sodium, zinc, and antimony, also
the composition and method of preparing the baths, described in sections 1, 2, 3, 4, 5,
and 6, as well as the substances and their equivalents, which enter into the composition
of all these baths, also all the processes and applications pointed out in section 7 with
regard to alloys.
From numerous experiments 1 have proved that different objects in iron, steel,
copper, nickel, zinc, tin, brass, and other metals, can be certainly and perfectly coated
with a variable thickness of aluminium and its alloys, of the character and in the
conditions specified in section 8 of the foregoing specification, so that the coating
resists friction and is capable of taking a very high polish.
It should be noted that for each process and bath the detailed conditions in order to
ensure perfect success will vary more or less, these variations being impossible to
describe in detail as they depend upon practice and personal experience.
The coating of Aluminum and its alloys affected in the way described is
far superior to that of silver nickel, tin, or bronze as ordinarily used. The positive
advantages of my improved process can be easily shewn by taking for example the
return from 1 kilogramme of aluminium. In this calculation I consider principally
the value of the minerals and salts of aluminium, the perfection and composition of
the baths, and the amount of the electro-dynamic force.
Taking as the salt ordinary alum, it contains 94 grammes of alumina per kilogramme
(Potash alum contains 99-40 grammes; Ammonia alum 119 grammes). Alumina is
composed of Aluminium 5327+ Oxygen 46-73=100; 1 kilogramme of ordinary
alumi therefore contains 50-07 grammes of aluminium.
In order to extract the maximum, a perfect composition of bath and an electro
dynamic machine of great power would be necessary. I use therefore the minimum
and I calculate upon one fifth only of the quantity, obtainable by an imperfect bath
and a dynamo machine of moderate force, that is to say 10 grammes of aluminium
from each kilogramme of alum, or for a kilogramme of aluminium 100 kilogrammes
of alum at 0-20 francs per kilogramme=20 francs + 10 for general expenses=30 francs.
It should be noticed that these expenses are calculated upon continuous working and
not upon a mere experiment. The cost of 1 kilogramme of pure aluminium would
therefore be 30 francs, but this amount though very much below the present commercial
price of 150 francs would be still more reduced it (as explained in section 2) instead
of alum the mineral Beauxite be used which gives an oxide of aluminium purer and
of about one fourth the cost of that extracted from alum, and if moreover a sufficiently
strong electro-dynamo machine were used to reduce nearly the whole of the oxide of
aluminium in the mineral.
By my improved process therefore metallic aluminium can be produced at sufficiently
low cost to meet the demands of commerce the metal being at the same time applied
upon the surface of the different objects to be coated.
The great lightness of aluminium renders it of great value for special applications,
thus, to manufacture an article which would require 1 kilogramme of aluminium it

page_text: would be necessary to use 2-619 kilogrammes of zinc 2.847 of tin 3.529 of copper,
4.580 of silver or 7519 of gold. It also possesses the valuable property of being
unaffected by air contaminated with sulphuretted hydrogen whilst it is inoxidizable
even at a red heat and is absolutely harmless and of a beautiful lustre. At the same
time it is one of the most abundant metals forming as it does the base of all clays,
so that there can be little doubt of its great future when produced sufficiently
economically.
if
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is
. 1. The solutions compounds and chemical products and their equivalents substantially
as and for the purposes herein described.
2. The chemical products and their equivalents containing the metals necessary to
obtain the different alloys, as acetate, chloride, cyanide, fluoride, nitrate, sulphate,
sulphuret, of aluminium, alumina, silver, gold, copper, iron, tin, nickel, potassium,
soilium, zinc, antimony, and others substantially as herein described.
3. The methods of making and using the baths substantially as described in
sections 1, 2, 3, 4, 5, and 6.
4. The materials and their equivalents used in the composition of all the baths some
or all of such materials being used, substantially in the manner and for the purpose
herein described.
5. Also the processes and applications in relation to alloys, substantially as described
in section 7 of the above specification.
6. Also the process in all its details described in section 8 of the above
specification.
7. Also the processes for depositing aluminium either pure or alloyed with other
metals, upon other metals and their alloys and upon bodies which are non-conductors
of electricity substantially in the manner and for the purposes described.
Dated this 8th day of July 1880
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Patentee.