IMPROVEMENTS IN THE MANUFACTURE OF ALUMINIUM, SODIUM, AND OTHER KINDRED METALS, AND IN APPARATUS APPLICABLE THEREFOR"
Year: 1879

page_text: PROVISIONAL, SPECIFICATION left by William Phillips Thompson at the
Office of the Commissioners of Patents on the 27th May 1879.
WILLIAM PHILLIPS THOMPSON, Civil Engineer, of Tranmere, in the County of
Chester. 66
IMPROVEMENTS IN THE MANUFACTURE OF ALUMINIUM, SODIUM, AND
OTHER KINDRED METALS, AND IN APPARATUS APPLICABLE THEREFOR"
This Invention has for its object the manufacture of certain metals having a
great affinity for oxygen, more especially of sodium, potassium, and aluminium, in
a cheaper manner than hitherto, and without forming the black detonating com-
pound so liable to form in the ordinary process of manufacturing potassium. It
consists mainly in the use of fluid iron, or a fluid alloy of iron, as a reducing agent,
or as an assistant to the actual reducing agent, hydrogen or carbon. The reduction
takes plates in a converter somewhat resembling the Bessemer steel converter. As
arranged for making aluminium direct the form of converter I prefer to adopt is a
chamber on trunnions with a single orifice, but divided below into two lobes, each
capable of containing a heavy charge. The chimney and the entrance to a chamber
hereafter described are so arranged that when one lobe is bottom the orifice opens
into the chimney, and when the other lobe is bottom the orifice opens into the
chamber. A projecting shield on the converter or otherwise closes the mouth of
the chamber when the orifice of the converter is directed to the chimney. At the
bottom of the lobe, which is lowest when the orifice of the converter faces the
chimney, is the ordinary air blast. At or near the bottom of the other lobe are two
tuyeres or sets of tuyeres, arranged so that their streams shall tend to quickly
intermingle. One of these is for hydrogen or hydrocarbon gas, the other for the
chloride or fluoride of the metal to be reduced, or the double chloride or fluoride of
it and another metal.
Each lobe is capable of containing the entire charge, and arranged at such an
angle that the contents can be poured from one lobe entirely into the other. Iron
or an alloy of iron being poured into the air lobe a blow commences, and when it is
a little heated the contents are poured into the second lobe; and in the case of
aluminium manufacture, hydrogen or a hydrocarbon, and the chloride or fluoride
of aluminium, or double chloride or fluoride of aluminiuin and sodium are forced in,
preferably in the melted or gaseous state. The hydrogen takes the chlorine or
fluorine, and gives it up to the iron. The hydrogen and chloride or fluoride of iron
escape into the chamber, where the latter is condensed, and the former is drawn off
for re-use. The carbon of the hydrocarbon and the aluminium remain behind.

page_text: When the mixture begins to cool it is turned into the blowing chamber, and the
carbon oxidised. It is then turned back, and the reducing proceeded with. When
most of the iron is used up pure hydrogen only is used for reducing, and after all
the carbon is burnt off and the iron is nearly used up, a portion of the alloy of iron
and aluminium is poured off into 'a ladle, and a fresh charge of cast iron poured in.
The entire contents could be changed, but as the alloy of iron and aluminium is
fusible at a lower temperature than cast iron I think it will be found best always
to keep some aluminium in the converter. For the lining of the converter a mixture
of lime, magnesia, and alumina will probably be found best.
For sodium manufacture the apparatus is much simplified; no hydrogen is used,
and only enough carbonaceous matter is forced into the iron as is required to act
as fuel in reheating. Iron being poured into the converter, as before, caustic soda
is forced in. The carbon in the iron takes up the oxygen, and the sodium escapes
and is condensed in the chamber. When all the carbon is burnt off the iron can be
made into Bessemer steel, and a fresh charge inserted; or it can be re-carbonised
by a strong Bunsen blast, with excess of carbon in the air chamber, or, if desirable,
can be oxidised away.
If potassium be required a waste of iron is necessary, as pure iron only can be
used, or an alloy of iron with some difficultly oxidisable metal. Great waste will
in any case occur, as iron and potassium form an alloy, and this process is conse-
quently not so well adapted for potassium as sodium.
If very pure aluminium be required sodium must be manufactured, as above, and
the chloride or fluoride of aluminium placed in the chamber. The chamber must
be kept at such a temperature that the flux of chloride or fluoride of sodium remains
very liquid. A stirring apparatus can also be employed to gently stir the mass so
as to let the shots of aluminium agglomerate. When a sufficient quantity is col-
lected the aluminium and slag can be partially tapped out. The chamber must be
lined with calcined alumina or other basic or neutral material, and should have at
one end a raised bed, flat or slightly sloping, into which the aluminium salt is thrown
from a double valve hole in the top (arranged so that no air can get in). As the
aluminium and slag are formed they run off the shelf into the well. Arrangements
can be made for the aluminous salt to be introduced in regulated fine streams to
more perfectly combine with the sodium vapour.
The aluminium formed in this way will be nearly pure; that formed in the con-
verter will require purifying from iron by means of nitre.
A modification of this process, especially the indirect one, in which sodium or
potassium is first formed, will I believe be found suitable for the manufacture of
calcium, magnesium, strontium, and barium, the salts of these metals being used
respectively in place of those of aluminium.
It will also be seen at once that supporting the furnace on trunions is a mere
mechanical detail not absolutely necessary to the process, as it, like the Bessemer
process, could be conducted in a stationary hearth, and a stationary hearth may
eventually be found the most convenient apparatus to work it in. In such case the
metal is tapped out instead of poured out, and the air and gases, or some of them,
can be heated in regenerating or other stoves.