IMPROVED PROCESSES FOR OBTAINING ALUMINIUM FROM ITS ORE OR FROM OTHER SUBSTANCES
Year: 1883

page_text: LETTERS PATENT to Henry Arthur Gadsden of Australian Avenue in the City
"
of London. for an Invention of "IMPROVED PROCESSES FOR OBTAINING
ALUMINIUM FROM ITS ORE OR FROM OTHER SUBSTANCES communicated to
him from abroad by Emerson Foote of the City and State of New York,
United States of America
PROVISIONAL SPECIFICATION left by the said Henry Arthur Gadsden at
the Office of the Commissioners of Patents on the 19th April 1883..
HENRY ARTHUR GADSDEN, of Australian Avenue in the City of London
"IMPROVED PROCESSES FOR OBTAINING ALUMINIUM FROM ITS ORE OR FROM OTHER
SUBSTANCES" [A communication to him from abroad by Emerson Foote of the
City and State of New York, United States of America]
My invention relates to improved processes or methods of obtaining the metal
aluminium from its ore or from other materials containing the said metal.
Heretofore the practised method of extracting aluminium from its ore or from
other substances containing the said metal has been to first change the aluminium
into the chloride of aluminium, and then separate the metal therefrom by the use
of metallic sodium as a re-agent.
My processes or methods differ materially from this as will appear from the
following description.
According to one process or method I form the chloride of aluminium and then
produce the metal therefrom by the action of sodium gas or vapor generated by
heating a mixture of carbonate of soda with charcoal; such gas or vapor being.
brought into immediate contact with the chloride, and thus dispensing altogether
with the use of metallic sodium.
In practising this part of my said invention, I take the required amount of
corundum, bauxite, or other substance containing aluminium, and mix therewith,
say ten per cent of fluoride of soda or potash, and if found desirable about an equal
amount of fluor spar. This mixture may be placed in crucibles or upon the hearth
of a furnace where it is heated to the calcining point, and when properly calcined

page_text: is removed from the furnace and ground to a powder. At the time of this
grinding about ten percent of charcoal or an equivalent amount of some other
carbonaceous substance—such for example as starch or oil, is added to the calcined
material, the whole being thoroughly mixed together, and made up into balls or
other forms, with or without the aid of water, when it is placed in a muffle or
retort in which it is baked and converted into a spongy mass.
The mass having been treated as above described, or substantially so, is to be
taken from the muffle or retort and placed in another retort which may be placed
either vertically or horizontally, and a stream of chlorine gas is made to pass
through it for the purpose of converting it into chloride of aluminium which is
distilled over into a separator or reservoir, the heat applied to the retort being
sufficient to pass the chloride over as fast as it is formed into the reservoir where
the chloride is collected. This chloride of aluminium may then be taken, and
placed in another retort, in which it is converted into aluminium, or it may be
passed in its gaseous form through a vessel or chamber containing iron turnings or
other pieces of iron, and into a vessel prepared for its reception, and it is solidified
and formed into crystals; the object of passing it over the iron turnings being to
extract from the cloride any iron that it may contain.
In reducing the chloride to the metal I employ a furnace having in it a retort
made of fire-clay or other refractory substance, and of such dimensions as may be
required and in it place such an amount of the chloride as it is desirable to treat at
one time, said furnace or retort being connected with another of similar con-
struction by a pipe through which is caused to pass a current of gas generated by
placing in a proper retort or furnace say twenty parts by weight of carbonate of
soda, sixteen by weight of charcoal or an equivalent amount of other carbonaceous
substance, and five parts by weight of chalk or lime-well mixed together and
dried, and then put into bags or packages of asbestos, strong paper, or other
substance that will retain the package in form while being heated.
When the chloride is in its retort heat is applied to it, and to the one in which
the material to be gasified is placed the temperature of the last named one being
raised to such a degree as to cause sodium vapor to be produced in it, and to pass
from it into the retort containing the chloride, the effect of which is to cause a
separation of metallic aluminium from the earthy matter with which it is
associated, to take place, the metal being deposited upon the hearth of the retort
from which it may be drawn and cast into ingots.
I am aware of an article on the metal aluminium published in Watts Dictionary
of Chemistry, Volume I, Page 150, in which there is described a method of
separating aluminium from its chloride by the use of a vapor generated from
metallic sodium, such vapor being conducted into a vessel, in which the chloride
is thrown from time to time.
In that process the heat used in reducing the chloride to the metal is obtained,
by the burning of the vapor itself within the vessel in which the action of
separating the metal takes place. This differs essentially from my process, in that
I apply the necessary heat externally to the vessel containing the chloride, such
heat resulting from the burning of the coal or other ordinary fuel, by which means
a great reduction in the cost, and increase of yield, are obtained.
According to another part of my invention I first convert the material into
fluoride of aluminium and then produce the metal direct therefrom by the action
of sodium vapour or gas generated by heating a mixture of carbonate of soda, or an
equivalent thereof, with charcoal and chalk or lime, said gas or vapor being brought
into immediate contact with the fluoride. In practising this process I take equal
parts by weight of corundum, bauxite, or other materials containing aluminium,
and of fluor spar, and place them in a furnace or retort having a suitable bottom
upon which to put the material to be treated, or the material may be put in
crucibles placed in the furnace. The object of this step of my process being to
expel all moisture from the material and to properly calcine it, which will be done
by heating the furnace to a bright red heat. When the calcining of the material

page_text: has been effected the mass is withdrawn from the retort and, when cold, is
pulverized or broken into small pieces. With each one hundred pounds of the
pulverized material, there is to be mixed say thirty pounds of fluoride of soda. This
mixture is then placed in a furnace or in crucibles and melted into a mass, which
converts it into fluoride of aluminium and fluoride of sodium. This compound
fluoride is then ground to a powder or reduced to very small pieces and mixed
with one fourth of its weight of powdered charcoal, or with other carbonaceous
substances; the different kinds of oil being well adapted to be used for this
purpose.
To each one hundred pounds of this powdered substance twenty five pounds of
chloride of potassium, and ten pounds of chloride of sodium, are to be added and
thoroughly mixed together and made into cakes or balls with the aid of water, if
necessary; the two last named ingredients being melted together before mixing them
with the others; other forms of flux may be used at this point, but I prefer that
above described.
When the ingredients have been treated as above indicated, the whole mass is
placed in a suitable oven and its moisture is expelled by heat.
In carrying forward the next step of this process, the dried material is placed in
a retort provided with a false bottom or perforated diaphragm upon which the
material is placed, it being some distance above the bottom of the retort or
furnace. This last named retort is connected with another in which there is put,
say twenty parts by weight of calcined soda ash or carbonate of soda, ten parts of
powdered charcoal, and five parts of chalk, lime, or its carbonate.
This compound when well mixed together is placed in a retort which is
connected with the one in which the fluoride under treatment is placed so that
the gas generated in the former may pass freely into the latter. As a matter of
convenience I prefer to put the compound from which the gas or vapor is derived
into tubes made of asbestos or some other material that will preserve the form of
the package while heat is being applied to it, but it may be placed upon the
bottom of the retort without materially affecting the results.
At this point in the process, external heat is applied to both of the last named
retorts, and the one in which the material to be gasified placed is gradually
heated up to nearly a white heat, the effect of which is to cause sodium vapor to
be produced from the soda and charcoal and which passes into the retort having
the perforated diaphragm and comes into contact with the material placed therein,
thus causing a chemical reaction upon it the result of which is to precipitate upon
the bottom of the retort the metal contained in it.
I desire it to be understood that in. giving proportions of materials used in
carrying out my processes or methods I do not intend to confine myself to the
exact quantity there named, as experience has demonstrated that they may be
varied to some extent without materially changing the results. I have named
such quantities as I have found to produce satisfactory results.
It will be seen that in these processes the production of sodium vapor is going
on simultaneously with its action as a reducing agent upon the aluminium
compound.
Moreover equivalents for the substances bere named may be employed, and
some of the substances named may be omitted without destroying all useful
results.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
.
by the said Henry Arthur Gadsden in the Great Seal Patent Office on the
18th October 1883.
HENRY ARTHUR GADSDEN, of Australian Avenue, in the City of London.
"IMPROVED PROCESSES FOR OBTAINING ALUMINIUM FROM ITS ORE OR FROM OTHER
SUBSTANCES," A communication to me from abroad by Emerson Foote of the
City and State of New York, United States of America.
"
This invention relates. to improved processes or methods for obtaining. the
metal aluminium from its ore or from other materials such as corundum or
bauxite.
Heretofore the usual method of effecting this result has been to first prepare
from the ore or raw material chloride of aluminium and then separate the metal
from the latter by the use of metallic sodium as a re-agent.
My processes or methods differ materially from that heretofore employed, as will
appear from the following description.
According to one process or method I form the chloride of aluminium and then
regain or recover the metal therefrom by the action of sodium gas or vapor
generated by heating a mixture of carbonate of soda with charcoal; the said gas
or vapor being brought into immediate contact with the chloride. I thus dispense
with the use of metallic sodium.
In practising this part of the said invention, I take the required amount of
corundum, bauxite, or other substance containing aluminium and mix therewith
Bay ten per cent. of fluoride of soda or potash and, if desirable, about an equal
amount of fluor spar. This mixture may be placed in crucibles or upon the hearth
of a furnace, where it is heated to the calcining point, and when properly calcined
it is removed from the furnace and ground to a powder. At the time of this
grinding about ten per cent, of charcoal or an equivalent amount of some other
carbonaceous substance such, for example, as starch or oil, is added to the calcined
material, the whole being thoroughly mixed and made up into balls or lumps, with
or without the aid of water. It is then placed in a muffle or retort in which it is
baked and converted into a spongy mass.
८
The mass, having been treated substantially as above described, is taken from the
muffle or retort and put in another retort which may be placed either vertically
or horizontally. A stream of chlorine gas is made to pass through it, for the
purpose of converting it into chloride of aluminium, which is distilled over into a
separator or reservoir, the heat applied to the retort being sufficient to pass the
chloride over, as fast as it is formed, into the reservoir where the chloride is
collected. This chloride of aluminium is then either placed in another retort in
which it is converted into aluminium, or it is conducted in its gaseous form through
a vessel or chamber containing iron turnings, or other small pieces of iron, and into
a vessel prepared for its reception; wherein it is solidified and formed into
crystals; the object of passing it over the iron turnings or pieces is to extract
from the chloride any iron that it may contain.
In reducing the chloride to the metal, I employ a furnace having in it a retort
made of fire-clay or other refractory substance, and of such dimensions as may be
required. In this retort I place such an amount of the chloride as may be con-
veniently treated at one time, the said furnace or retort being connected with
another or similar apparatus by a pipe, through which is caused to pass a current
of gas generated by placing in a proper retort or furnace say twenty parts by
weight of carbonate of soda or other suitable compound of soda, sixteen parts
weight of charcoal or an equivalent quantity of other carbonaceous substance, and
five parts by weight of chalk or lime, well mixed together and dried and then put
into bags or packages of asbestos, strong paper, or other material that will properly
retain these substances while being heated.
When the chloride is in its retort, heat is applied thereto and to the retort in

page_text: which the material to be gasified is placed, the temperature of the last named retort
being raised to such a degree as to cause sodium vapor to be produced therein and
to pass therefrom into the retort containing the chloride. The effect of this
operation is to cause a separation of metallic aluminium from the eartly matter
with which it is associated, the metal being deposited upon the hearth of the retort
from which it may be drawn and cast into ingots.
According to another part of the said invention I first convert the raw material
into fluoride of aluminium and then regain or recover the metal directly therefrom
by the action of sodium gas or vapor generated by heating a mixture of carbonate
of soda or an equivalent thereof with charcoal and chalk or lime, the said gas or
vapor being brought into immediate contact with the fluoride.
.
In carrying this process into effect I take equal parts by weight of corundum,
bauxite, or other material containing aluminium, and of fluor spar, and place them
in a furnace or retort having a suitable bottom upon which to put the material to
be treated, or the material may be contained in crucibles placed in the furnace.
The object of this part of the said process is to expel the moisture from the raw
material and to properly calcine the latter, which will be done by heating the
furnace to a bright red heat. When the calcining of the material has been effected,
the mass is withdrawn from the retort and, when cold, is pulverized or broken into
small pieces. With each one hundred pounds of the pulverized material are mixed
about thirty pounds of fluoride of soda. This mixture is placed in a furnace or in
crucibles and melted into a mass, being thus converted into fluoride of aluminium
and fluoride of sodium. This compound fluoride is then ground to a powder or
reduced to very small pieces and mixed with about one fourth of its weight of
powdered charcoal or with other carbonaceous substances; oil being well adapted
to be used for this purpose.
To each one hundred pounds of this powdered substance twenty five pounds of
chloride of potassium and ten pounds of chloride of sodium are added, and the
whole is thoroughly mixed and made into cakes or balls, with the aid of water if
necessary, the two last named ingredients being melted together before mixing
them with the other ingredients. Other forms of flux may be used at this point,
but I prefer that above described.
When the ingredients have been treated as above indicated, the whole mass is
placed in a suitable oven and its moisture is expelled by heat.
In the next stage of this process, the dried material is placed in a retort provided
with a false bottom or perforated diaphragm, upon which the material is placed,
the said diaphragm being some distance above the bottom of the retort or furnace.
This last named retort is connected with another retort into which I put say twenty
parts by weight of calcined soda ash or carbonate of soda, ten parts of powdered
charcoal, and five parts of lime or its carbonate.
This compound, when well mixed, is placed.in a retort connected with the retort
containing the fluoride under treatment, so that the gas generated in the former
may pass freely into the latter. As a matter of convenience, I prefer to make a
package of the compound from which the gas or vapor is derived and put the same
into tubes made of asbestos or other material that will preserve the form of
the package while heat is applied thereto, but the said compound may be placed
upon the bottom of the retort without materially affecting the result.
At this stage of the process, external heat is applied to both of the last named
retorts, and that containing the material to be gasified is gradually heated to nearly
a white heat, the result of this operation is the production of sodium vapor from
the soda and charcoal; this vapor passes into the retort having the perforated
diaphragm and comes into contact with the material placed therein, thus causing a
chemical reaction, the result of which is to precipitate the metal upon the bottom
of the retort.
It will be seen that in these processes the production of sodium vapor is going
on simultaneously with its action as a reducing agent upon the aluminium
compound,

page_text: .
Having thus fully described the said invention as communicated to me by my
foreign Correspondent and the manner of performing the same I desire it to be
understood that in giving proportions of materials used in carrying out my
processes or methods I do not intend to confine myself to the exact quantities
named, as experience has demonstrated that they may be varied to some extent
without materially changing the results. I have named such quantities as I have
found to produce satisfactory results.
Moreover I wish it understood that equivalents for the substances herein
named may be employed and some of the substances named may be omitted without
destroying all useful results.
I further wish it understood that I am aware of an article on the metal
aluminium published in Watts' Dictionary of Chemistry Volume 1, Page 150, in
which there is described a method of separating aluminium from its chloride by the
use of a vapor generated from metallic sodium, such vapor being conducted into a
vessel in which the chloride is thrown down from time to time. In that process,
the heat used in reducing the chloride to the metal is obtained by the burning of
the vapor within the vessel in which the separation of the metal takes place. This
differs essentially from my process, in which I apply the necessary heat externally
to the vessel containing the chloride, such heat resulting from the burning of coal
or other ordinary fuel, and I thus effect a great reduction in the cost and obtain an
increased production of the metal. And I claim
First. The above described process consisting in first calcining and roasting the
ore or compound together with fluor spar, fluoride of soda, or other material con-
taining fluorine, then converting the fluoride of aluminium thus produced into
chloride of aluminium and then subjecting the chloride to the action of sodium
vapor obtained by heating a mixture of carbonate of soda, or other suitable compound
of soda, with charcoal or other carbonaceous substance, substantially as, and for the
purpose, set forth.
Second. The above described process of extracting the metal aluminium from its
chloride, by subjecting the chloride to the action of sodium vapor obtained by
heating a mixture of carbonate of soda, or other suitable compound of soda, with
charcoal or other carbonaceous substance, substantially as set forth,
Third. The above described process consisting in subjecting the fluoride of
aluminium, at a high temperature, to the action of sodium vapor produced simulta-
neously from a mixture of a sodium salt with a reducing agent, substantially as
described for the purpose specified.
Fourth. The above described process consisting in subjecting the mixed fluorides
of aluminium and sodium or potassium, at a high temperature, to the action of
sodium vapor simultaneously produced from a mixture of a sodium salt or other
suitable compound with a carbonaceous substance or reducing agent, substantially
as described for the purpose specified.
Fifth. The above described process consisting in subjecting a compound containing
aluminium, at a high temperature maintained by an independent or external com-
bustion, to the action of sodium vapor produced simultaneously from a mixture of
a compound containing sodium with a carbonaceous substance or reducing agent,
substantially as described for the purpose specified.
In witness whereof I the said Henry Arthur Gadsden have hereunto set my
hand and seal this Seventeenth day of October in the year of our Lord One thousand
eight hundred and eighty three.