Improvements in the Manufacture of Alumina and Aluminous Compounds and Metallic Aluminium or Alloys of Aluminium, and Obtaining Chlorine, Hydrochloric Acid, Carbonate of Soda, and other Bye-products Resulting from this Manu- facture.
Year: 1893

page_text: Date claimed for Patent under Sect. 103 of Act,
being date of first Foreign Application (in 5th Apr., 1893
France),
Date of Application (in United Kingdom), 31st Oct., 1893
Complete Specification Left, 6th July, 1894-Accepted, 18th Aug., 1894
France),
Date of Application (in United Kingdom), 31st Oct., 1893
Complete Specification Left, 6th July, 1894-Accepted, 18th Aug.,
1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Alumina and Aluminous
Compounds and Metallic Aluminium or Alloys of Aluminium,
and Obtaining Chlorine, Hydrochloric Acid, Carbonate of
Soda, and other Bye-products Resulting from this Manu-
facture.
I, DIMITRY ALEXANDROWITCH PENIAKOFF, of 21 Boulevard Poissonniere,
Paris, in the Republic of France Gentleman do hereby declare the nature of this
invention to be as follows:-
This invention relates to a process for the manufacture of aluminium consisting
in extracting aluminium from bauxite or other aluminous ores or minerals, con-
verting this alumina into sulphuret of aluminium and obtaining metallic aluminium
or its alloys by a process of reduction or electrolysis of the said sulphuret of
aluminium.
This improved process admits of a constant recuperation or regeneration of the
chemical reagents employed as well as of obtaining as bye products, chlorine or
hydrochloric acid carbonate of soda and other materials whence results a considerable
economy in the cost of these products.
In order to obtain pure alumina it is preferable to employ bauxite which is
composed of hydrate of alumina mixed with bydrate of iron almost without silica
and silicates. The bauxite is melted with alkalies or with their carbonates
(carbonate of soda) and the alkaline (sodic) aluminate soluble in water is thus
obtained. This soluble aluminate remains in solution whilst the iron is precipitated.
When this precipitate is separated the solution of aluminate is treated with
carbonic acid which regenerates the carbonate of soda and precipitates the alumina.
The alkaline aluminate can be obtained by the aid of a more 'economical process by
employing sodic sulphate in place of the carbonate of soda.
The alumina Al2O3 (bauxite) is treated with sodic sulphate Na'SO at a very
high temperature. The product melts forming sodic aluminate; (Al2O3 + Na³SO*
=2 AlNaO2 + SO2 + 0) and generates the gases SO, and O.
The principal advantage resulting from the employment of sodic sulphate in
place of carbonate of soda is that it is possible not only to regenerate the sulphate
of soda but this reaction also produces a mixture of sulphurous acid and oxygen
which can be readily utilised for obtaining chlorine or hydrochloric acid..
In fact the mixture SO and O readily decomposes well dried marine or bay salt
at a slightly elevated temperature (under 500 degrees centigrade). This reaction
is represented by the following formula; 2 NaCl + SO +20=Na 2 SO' + 2 Cl.
The gases.
SO and O mixed with a proportionate quantity of hot air
(0 + 4 N\\ containing very little nitrogen that is to say are very slightly diluted

page_text: TO+NaS +3 Na SO₁ = 8 NaAIO3 + 4 SO³.
It is advantageous to replace the sulphate of sodium by pyrites which produce a
still stronger reaction. The theoretical proportion is one part of pyrites to 6
or 7 parts of sodic sulphate. The sulphur in the pyrites is likewise burned in the
form of SO2 which gives an increase of 36 per cent. in the production of sulphurous
acid. This excess of sulphurous acid can be utilized for manufacturing sulphuric
acid.
If in place of producing sulphuric acid it is preferred to utilize (for obtaining
chlorine) the sulphurous acid resulting from the reaction of pyrites or of
sulphuret of sodium mixed with sulphate of soda and bauxite it is sufficient to
cause this sulphurous acid to pass over-marine or bay salt, and in order to
supply it with the necessary quantity of oxygen, oxidising materials (such as
bioxide of barium, mangarrite of calcium, plumbite of calcium, sulphate of copper etc.)

page_text: capable of being easily regenerated by heat may be added to the bay salt. If
preferred this addition of oxidising materials may be effected at the commencement
with the mixture of bauxite and sulphate of soda or with the mixture of bauxite,
sulphate of soda and sulphuret, destined to produce the aluminate.
The sulphate of alumina derived from the alumina thus obtained is employed as
hereinafter described in the manufacture of metallic aluminium and of its alloys
by the aid of sulphuret of aluminium. The sulphuret of aluminium has been
partially obtained by Mr. Freny by the action of sulphuret of carbon upon
alumina (Al2O3) at a temperature of white incandescence.
This process is improved by replacing the alumina by anhydrous sulphate of
alumina Al' (SO) this substitution presents the following advantages.
1. The temperature of the reaction is. lowered to nascent red, whence results. not
only an economy in the combustible employed, but also the preservation of the
materials of the furnaces, which do not deteriorate under the action of sulphuret of
carbon, except at very high temperatures..
2. The whole of the sulphur contained in the sulphuret of carbon employed in
the operation is completely regenerated. In fact the formula expressing this
reaction is the following Al (SO¹)³ + 6 CS² = Al² S³ + 6 CO² +.12.$.
The sulphuret of carbon proceeding exclusively from the sulphur which has
passed over incandescent carbon the total mass of the regenerated sulphur can be
employed for the total regeneration of the sulphuret of carbon necessary for the
operation and at the end it is only the coal or carbon that has been consumed.
With a view to obviating the treatment of sulphate of alumina with sulphate of
carbon the sulphurets of some metals such as sodium are employed in a mixture
with the sulphate of alumina or in some cases with the alumina itself. This mixture
is heated in vapours of sulphur. The function of the sulphurets of the metals
consists simply in transferring sulphur to the alumina and taking from it the oxygen
by way of double exchange thus:-
(1) 3 Na² S + Al² (SO4)3 = 3 Na² SO₁ + Al² S³.
(2) 3 Na2SO4 + 6 S = 3 Na' S + 6 SO².
This reaction is produced partially the sulphur present destroys the sodic
sulphate formed each time by reconverting it into sulphuret of sodium (2) which
again admits of the double exchange with the sulphate of alumina.
As another example may be mentioned, the mixture of sulphuret of barium, of
sulphates of alumina and the vapours of sulphur, and also the sulphuret of lead
with sulphate of alumina and sulphur.
The sulphuret of calcium (Cas) admits in presence of vapours of sulphur and
out of contact with the air of the employment of alumina itself in place of the
sulphate of alumina.
The oxide of calcium (CaO) is converted in the presence of vapours of
sulphur (2a) into sulphuret of calcium which again admits of the double exchange
with the alumina.
Sulphurous acid is given off and this fact evidently proves the transformation of
the oxide of aluminium into sulphuret of aluminium there being no other oxygen
present except that resulting from the decomposition of the alumina which can
combine with the sulphur assuming that all air has been excluded during the
operation.
In the preceding reactions it will be observed that the function of the sulphuret

page_text: .
(of sodium, barium, calcium &c.) employed consists solely in transferring the
sulphur in vapour to the alumina at the same time depriving the latter of its oxygen.
The sulphur thus simply acts as a vehicle between the sulphur and the alumina, or
its sulphate. It is consequently evident that an extremely small quantity of
sulphuret is sufficient to sulphurate considerable quantities of alumina or of sulphate
of alumina. The process of obtaining the sulphuret of aluminium is consequently
considerably facilitated and simplified.
In order to convert the sulphuret of aluminium into metallic" aluminium the most
simple method is to proceed by way of reduction with the aid of reducing metals
(such as lead, iron, copper, tin, or sodium for example).
For this purpose lead is preferably employed as a reducing metal for the
sulphuret of aluminium considering that lead does not form alloys with metallic
aluminium. Lead reduces the metallic aluminium from the sulphuret of aluminium
and the reaction is the following: Al'S³ + 3 Pb = 2 Al + 3 PbS.
The sulphuret of lead admits of easy regeneration of the metallic lead.
Iron is also a very good reducing agent for metallic aluminium especially when
the reaction takes place at very moderate temperatures. By employing iron in
different quantities the metallic aluminium can be obtained pure or in the form of
alloys of this metal with the iron in the desired proportions.
In regenerating the sulphurets of lead or iron the gas SO2 can be utilized for
obtaining sulphuric acid.
With the same object metallic sodium can be utilized which ignites on coming in
contact with the sulphuret of aluminium and gives as residue pure metallic
aluminium or alloys of aluminium and sodium if it has been employed in excess of
this latter metal. The sulphuret of aluminium in fusion (either alone or mixed
with other metals) can be easily reduced into metallic aluminium by electrolysis.
The employment of sulphate of alumina presents notable advantages in
comparison with the electrolytic reduction of the chlorides and fluorides of
aluminium as now practised because the sulphuret of aluminium is more rich in
pure metal than. chlorides, fluorides and the like. (The chlorides and fluorides
contain in fact from 10 to 13 per cent. of pure aluminium whereas the sulphurets.
contain about 35 per cent.)
The sulphuret of aluminium in fusion easily dissolves considerable quantities of
alumina and this mixture is electrolysed as easily as the sulphuret alone which
renders it possible to directly electrolyse aluminas this being a process altogether
unknown heretofore. The electrolysis proper may here find powerful aid in the
chemical reaction 2 Al2O3 + A12S³ = 6 A1 + 3 SO³.
Dated the 21st do of the 1000
1
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Alumina and Aluminous
Compounds and Metallic Aluminium or Alloys of Aluminium,
and Obtaining Chlorine, Hydrochloric Acid, Carbonate of
Soda, and other Bye-products Resulting from this Manu-
facture.
I, DIMITRY ALEXANDROWITCH PENIAKOFF of 21 Boulevard Poissonniere
Paris in the Republic of France Gentleman do hereby declare the nature cf'my
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 a process for the manufacture of aluminium consisting
in extracting alumina from bauxite or other aluminous ores or minerals, converting
this alumina into sulphuret of aluminium and obtaining metallic aluminium or

page_text: its alloys by a process of reduction or electrolysis of the said sulphuret of
aluminium.
:
This improved process admits of a constant recuperation or regeneration of the
chemical reagents employed as well as of obtaining as bye products, chlorine or
hydrochloric acid carbonate of soda and..other materials whence results a
considerable economy in the cost of these products.
In order to obtain pure alumina it is preferable to employ bauxite which is
composed of hydrate of alumina mixed with hydrate of iron almost. without
silica and silicates. The bauxite is melted with alkalies or with their carbonates
(carbonate of soda): and the alkaline (sodic) aluminate soluble in water is thus
obtained. This soluble aluminate remains. in solution whilst the iron is precipitated.
When this precipitate is separated the solution of aluminate is treated with
carbonic acid which regenerates the carbonate of soda and precipitates the
alumina. The alkaline aluminate can be obtained by the aid of a more economical
process by employing sodic sulphate in place of the carbonate of soda.
The alumina APO³ (bauxite) is, treated with sodic sulphate Na2SO at a very
high temperature. The product melts forming sodic aluminate; (Al2O3 + Na2SO4
=2 AINaO+SO2 + 0) and generates the gases SO² and O.
The principal advantage resulting from the employment of sodic sulphate in
place of carbonate of soda is that it is possible not only to regenerate the
sulphate of soda. but this reaction also produces a mixture of sulphurous acid. and
oxygen which can be readily utilized for obtaining chlorine or hydrochloric acid.
In fact the mixture SO2 and O readily decomposes well dried marine or bay salt
at a slightly elevated temperature (under 500 degrees centigrade). This reaction
is represented by the following formula; 2 NaCl + SO2+20= Na 2 SO +2 Cl.
The gases SO2 and 0 mixed with a proportionate quantity of hot air
(0+4+N) which contain very little nitrogen that is to say are very slightly
air
diluted act without difficulty upon dry calcined bay salt heated to a temperature of
about 500 degrees centigrade forming. sulphate of soda NO'SO* and evolving
chlorine mixed with the excess of nitrogen.
By means of a methodical or regular action it would be possible to allow.only
the chlorine and nitrogen to escape from the apparatus or in other words to use up
the whole of the sulphurous gas. This action of the sulphurous gas (SO3 mixed
with air and nitrogen) upon the bay salt has already been applied by
Mr. Hargreaves but the gases (from pyrite furnaces) did not act upon bay salt
except in the presence of superheated steam and yielded diluted hydrochloric
acid as the result whereas in the present case the chlorine is separated very
readily.
The gases from the pyrites employed by Mr. Hargreaves contain at a minimum
22 volumes of nitrogen to one-volume of SO2 (sulphurous acid) and one volume
22 volumes nitrogen
of oxygen which amounts to
.
=
22 11 volumes of
1 volume SO + 1 volume O
2
inert gas to one volume of active gas.
1 volume SO +2 volumes oxygen
.4.5
3
= 15 volume, of inert gas
Whereas in the mixture employed according to this invention the gases contain
4 volumes of nitrogen to one volume of S02+2 volumes of oxygen being
4.5 volumes nitrogen
equivalent to
to 1 volume of active gas.
By heating bay salt to the above mentioned temperature and causing the mixed
gases to pass at the temperature at which they leave the furnace the reaction is
rendered self supporting and does not require continual heating even when cold
salts are added. The whole of the sulphate of soda previously employed and the
chlorine [or hydrochloric acid (CIH) when operating with superheated steam] is
thus obtained.
The operation is a very simple one from a technical point of view.. The bauxite

page_text: =
is melted in a suitable furnace with the sulphate of soda (Al'O³ + Na³SO*
2 AINaO2 + SO2 + 0) and the sulphurous acid and the oxygen generated are
conducted with a proportionate quantity of hot air into retorts filled with bay salt
(well dried beforehand by incandescence).
It is evident that the sodic aluminate obtained by the above process can be a
converted into alumina and into carbonate of soda by the aid of carbonic acid as
herein before described. With regard to the alumina it can be converted into
sulphate of aluminium by known processes.
The formation of the sodic aluminate is more advantageously effected, when the
sodic sulphate is mixed with one fifth of its weight of sulphuret of sodium. This
latter reaction is expressed by the following formula:
4 Al²O³ + Na²S + 3 Na²SO* = 8 NaAlO² + 4 SO³
It is advantageous to replace the sulphate of sodium by pyrites (or sulphuret of
sodium) which produce a still stronger reaction. The theoretical proportion is one
part of pyrites to 6 or 7 parts of sodic sulphate. The sulphur in the pyrites is
likewise burned in the form of SO2 which gives an increase of 36 per cent. in the
production of sulphurous acid. This excess of sulphurous acid can be utilised for
manufacturing sulphuric acid.
If in place of producing sulphuric acid, it is preferred to utilise (for obtaining
chlorine) the sulphurous acid resulting from the reaction of pyrites or of sulphuret
of sodium mixed with sulphate of soda and bauxite it is sufficient to cause this
sulphurous acid to pass over marine or bay salt and in order to supply it with the
necessary quantity of oxygen, oxidizing materials (such as bioxide of barium,
manganite of calcium, plumbite of calcium, sulphate of copper and the like) capable
of being easily regenerated may be employed.
.
Sulphate of alumina derived from alumina is employed as hereinafter described
in the manufacture of metallic aluminium and of its alloys by the aid of sulphuret
of aluminium. The sulphuret of aluminium has been partially obtained by
Mr. Freny by the action of sulphuret of carbon upon alumina (Al³0³) at a
temperature of white incandescence.
This process is improved by replacing the alumina by anhydrous sulphate of
alumina Al² (SO)³ this substitution presents the following advantages.
1. The temperature of the reaction is lowered to nascent red whence results not
only an economy in the combustible employed but also the preservation of the
materials of the furnaces which do not deteriorate under the action of sulphuret of
carbon except at very high temperatures.
2. The whole of the sulphur contained in the sulphuret of carbon employed in
the operation is completely regenerated. In fact the formula expressing this
reaction is the following Al' (SO)³ + 6 CS² AlS+6 CO² + 12 S.
=
The sulphuret of carbon proceeding exclusively from the sulphur which has
passed over incandescent carbon the total mass of the regenerated sulphur can be
employed for the total regeneration of the sulphuret of carbon necessary for the
operation and at the end it is only the coal or carbon that has been consumed.
With a view to obviating the treatment of sulphate of alumina with sulphuret of
carbon the sulphurets of some metals such as sulphuret of sodium are employed in
a mixture with the sulphate of alumina or in some cases with the alumina itself.
This mixture is heated in vapours of sulphur. The function of the sulphurets of
the metals consists simply in transferring sulphur to the alumina and taking from it
the oxygen by way of double exchange thus.
(1) 3 Na³S + Al² (SO4)3 = 3 Na2SO* + Al³S³.
(2) 3 Na2SO + 6 S = 3 Na³S + 6 SO% ·

page_text: sulphate formed each time by reconverting it into sulphuret of sodium (2) which
again admits of the double exchange with the sulphate of alumina.
As another example may be mentioned the mixture of sulphuret of barium, of
sulphates of alumina and the vapours of sulphur and also the sulphuret of lead
with sulphate of alumina and sulphur.
::
:
The sulphuret of calcium (CaS) admits, in presence of vapours of sulphur and
out of contact with the air of the employment of alumina itself in place of the
sulphate of alumina."
:
The oxide of calcium (CaO) is converted in the presence of vapours of sulphur
(2a) into sulphuret of calcium which again admits of the double exchange with the
alumina.
Sulphurous acid is given off and this fact evidently proves the transformation of
the oxide of aluminium into sulphuret of aluminium there being no other oxygen
present except that resulting from the decomposition of the alumina which can
combine with the sulphur assuming that all air has been excluded during the
operation.
.
:
In the preceding reactions it will be observed that the function of the sulphuret
(of sodium, barium, calcium &c.) employed consists solely in transferring the
sulphur in vapour to the alumina at the same time depriving the latter of its oxygen.
The sulphuret thus simply acts as a vehicle between the sulphur and the alumina
or its sulphate. It is consequently evident that an extremely small quantity of
sulphuret is sufficient to sulphurate considerable quantities of alumina or of sulphate
of alumina. The process of obtaining the sulphuret of aluminium is consequently
considerably facilitated and simplified.
In order to convert the sulphuret of aluminium into metallic aluminium the most
simple method is to proceed by way of reduction with the aid of reducing metals
(such as lead, iron copper tin or sodium for example).
For this purpose lead is preferably employed as a reducing metal for the
sulphuret of aluminium considering that lead does not form alloys with metallic
aluminium. Lead reduces the metallic aluminium from the sulphuret of aluminium
and the reaction is the following :-
-
The sulphuret of lead admits of easy regeneration of the metallic lead..
Iron is also a very good reducing agent for metallic aluminium especially when
the reaction: takes place at very moderate temperatures. By employing iron in
different quantities the metallic aluminium can be obtained pure or in the form, of
alloys of this metal with the iron in the desired proportious..
1
In regenerating the sulphuret of lead or iron the gas SO' can be utilized for
obtaining sulphuric acid.
With the same object metallic sodium can be utilized which ignites on coming in
contact with the sulphuret of aluminium and gives as a residue pure metallic
aluminium or alloys of aluminium and sodium if it has been employed in excess of
this latter metal. The sulphuret of aluminium in fusion (either alone or mixed with
other metals) can be easily reduced into metallic aluminium by electrolysis.
The employment of sulphuret of alumina presents notable advantages in; com-
parison with the electrolytic reduction of the chlorides and fluorides of aluminium
as now practised because the sulphuret of aluminium is more rich in pure metal
than chlorides fluorides and the like, (the chlorides and fluorides contain in fact
from 10 to 13 per cent. of pure aluminium whereas the sulphurets contain about
35 per cent.).
 ݂ܕ

page_text: The sulphuret of aluminium in fusion easily dissolves considerable quantities of
alumina and this mixture is electrolysed as easily as the sulphuret alone which
renders it possible to directly electrolyse aluminas this being a process altogether
inknown heretofore. The electrolysis proper may here find powerful aid in the
chemical reaction 2 Al2O3 + AI'S³ = 6 A1 +3 80%.
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 general process of manufacture of aluminium consisting in extracting the
alumina from bauxite or other aluminous ore or mineral, transforming this alumina
into sulphuret of aluminium and obtaining metallic aluminium or its alloys by the
reduction of the sulphuret of aluminium, the said process being characterized
essentially by the constant regeneration of the chemical reagents employed as well
as by the obtaining of bye products such as chlorine, carbonate of soda and other
materials whence there results a considerable economy in the cost of these
products.
2. The process of manufacturing alumina by the aid of bauxite or other
aluminous mineral the said process consisting,
(a) in treating it at an elevated temperature with a sulphate of soda so as to
obtain on the one hand aluminate of soda and on the other hand a mixture
of sulphurous acid gas and oxygen.
() in causing the mixture of gas SO' + O to which about one volume of air
has been added to pass over marine or bay salt at a temperature of
500 degrees at the maximum in such a manner as to regenerate on the one
hand the sulphate of soda employed in the first stage of the process and to
obtain as bye product chlorine or in the presence of steam hydrochloric
acid.
(c) in making a solution of sodic aluminate obtained according to (a) and
separating it from the hydrate of iron which is precipitated then treating
the solution of aluminate with carbonic acid according to known processes
so as to obtain the alumina and as a bye product carbonate of soda.
3. The modification in the stage (a) of the process of manufacturing the alumina
claimed under No. 2 consisting in treating the bauxite with a mixture of sulphate
of soda and sulphuret (sulphuret of sodium or pyrites) in place of sulphate of soda
alone with a view to obtaining on the one hand aluminate of soda and on the other
hand sulphurous acid.
4. The use of oxidising materials capable of being readily regenerated (such as
oxide of barium and the like) with a view to developing the oxygen required to
act at the same time as the sulphurous acid (obtained according to the processes
claimed in Claims 2 (a) and 3) upon marine or bay salt for the manufacture of
chlorine.
:
5. The manufacture of the sulphuret of aluminium by the aid of alumina
consisting in transforming the alumina beforehand into sulphate of alumina and
then causing sulphuret of carbon at a nascent red to act upon this sulphate, this
method having the essential advantages of enabling the operation to be performed
at a relatively low temperature and of regenerating the sulphur from the sulphuret
of carbon.
6. As a modification of Claim 5 the manufacture of sulphuret of aluminium by
the aid of alumina consisting in transforming the alumina beforehand into sulphate
of alumina and causing sulphuret of sodium (or another sulphuret such as sulphuret
of barium or the like) to act upon this sulphate in the presence of vapours of
sulphur the function of these vapours consisting in retransforming into sulphuret
the sulphate of soda (or of barium or the like) as fast as it is formed with the
object. of obtaining large quantities of sulphuret of aluminium with minimum
quantities of sulphuret of sodium (or of barium or the like).

page_text: 7. As a second modification of Claim 5 the manufacture of the sulphuret of
aluminium with the aid of alumina consisting in causing sulphuret of calcium to act
upon this alumina in the presence of vapours of sulphur, the function of these
vapours being the same as that indicated in Claim 6.
Dated this 6th day of July 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, Agents.