Fluxes and Apparatus therefor.
Year: 1888

page_text: Fluxes and Apparatus therefor.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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 :-
The object of this invention is, first to obtain the oxide of aluminium, either by
itself or combined with the oxide of another metal; second to obtain aluminium in
a metallic state, and third to obtain aluminium alloyed with one or more metals.
Great difficulty has been experienced in the reduction of aluminium from ores or
clays containing silica or other similar bases, because of the difficulty of separating
the silica from the alumina.
I overcome this difficulty by mixing with the aluminous earth or silicate ores a
flux and usually a deoxodizing agent, such as finely divided carbon and then heating
the mixture in a furnace or chamber raising the heat high enough to carry off the
alumina in a finely divided state, with the fluxes and passing the vapors through con-
densers or cooling chambers, where the atoms of metal are deposited in the form of
oxides. More or less of the silica will be carried off with the alumina but as it
solidifies at much higher degree of heat than alumina it will leave the alumina and its
fluxes and be mostly deposited first, thus effecting a practical separation of the

page_text: alumina from the silica. Much of the silica is left behind in the furnace as slag.
Various fluxes may be employed for mixing with the ore or clay. I generally use
two an alkaline flux such as common salt, carbonate of potassium, saltpetre,
carbonate of soda or salamonia; and a metallic flux, zinc being preferred.
In order to illustrate the best mode of carrying out the process of producing the
oxide of aluminium, one form of furnace is shown in the accompanying drawings in
which,
Figure 1 is a longitudinal vertical section of a furnace and cooling chamber.
Figure 2 is a front elevation of the same.
1 represents the furnace and 2 a cluster of gas pipes for heating the furnace.
In Figure 2 five clusters are shown leading into the same furnace. 3 represents
a flue leading into a chamber 5. 14 represents a partition separating chamber 5
from a second dome shaped chamber 6." 10 represents a flue pipe leading from
chamber 6 to a series of cooling chambers or condensers 11 which are preferably made
of metal, any desired number of which may be employed. 15 represents a damper in
the flue pipe 12 for regulating the draught. 13 represents an uptake flue. 18 repre-
sent a pipe depending down over the condensers 11 provided with jet orifices.
These pipes are for the purpose of applying a cooling medium, such as water, on the
outsides of the condensers to hasten the cooling of the vapors inside the said condensers.
4 represents a pipe for supplying pipe 17. 8 represents a branch pipe tapping the
dome of chamber for introducing steam or water into chamber 6. 16 represents a
tank. 19 a feeding pipe and 20 a T pipe pierced with orifices for the injection of
any desired cooling agents, such as hydrate of ammonia, to assist in cooling the atoms
of metal in chamber 6. Ammonia will serve as a flux to gather the particles of
alumina together.
The preferred form of carrying out the process of producing the oxides is as
follows: Take clay kaolin or bauxite high in alumina and low in silica-(Irish,
bauxite from near Dublin, Ireland, is a good ore for such treatment). Pulverize the
ore and mix with it about ten per cent. of zinc, either the oxide of zinc or zinc ore may
be employed, one to three parts of carbonate of potassium or other alkaline flux;
and about five parts of finely pulverized coke or charcoal. The carbon may be
one-half by weight of the silica in the ore. Thoroughly mix these ingredients together
and introduce them into the furnace. Gas is preferred as fuel: The furnace should
be raised to about two thousand five hundred degrees Fahrenheit. At this tempe-
rature the zinc is volatilized and oxidized; the aluminium is set free and the heat
and draught of the furnace carries these metals off through the chambers and con-
densers. Some of the silica will be carried forward but most of it will be deposited
in the first chamber any excess which is carried further forward will not interfere
with the future use of the metallic oxides which finely settle in the cooling chambers.
To assist in cooling and collecting the oxides of aluminium, water may be applied to
the outside of the condensers 11. The cooling capacity should be such as to bring
the vapors passing into the flue 13 to about one-hundred degrees Fahrenheit.
Instead of zinc any metal whose atomic weight is greater than that of aluminium
and with which it alloys may be used. Copper while it volatilizes slowly will assist
in bringing down the atoms of alumina in the cooling chambers. It is also useful
in reducing the oxide of alumina deposited in the cooling apartments when such
oxides are to be alloyed with copper. The presence of zinc or tin as oxides in the
oxides of aluminium will not materially interfere with the production of pure alumina
from the oxides.
When any metal is mixed with bauxite or ore it is better to have it finely divided
and mixed therewith. The use of direct heat applied to the ore in the furnace, is the
best form of applying the heat but an air blast is desirable to produce a reducing and
oxidizing flame and hasten the operation. The amount of metal or metallic oxides
mixed with the aluminous ores may be greatly varied without affecting the general
result. So also, a deoxidizing flame may be employed without the addition of
pulverized carbon but the use of carbon is very beneficial.
The oxides of aluminium obtained by the within described process may be readily

page_text: reduced to a metallic state. These oxides are of themselves suitable for a great
number of uses in metallurgical operations. When they are reduced to the metallic
state directly, the following is one form of reduction: Take the oxides gathered from
the condensers mix with them about two per cent. of pulverized charcoal, and place
them in a crucible or retort. Then add a flux, either a metal or alkaline flux or both.
For this purpose aluminium itself may be used alone and its presence will hasten the
reduction; close the crucible and introduce it into a furnace and subject the charge
to a high degree of heat. The higher the heat the quicker will be the reduction,
but about the melting point of Bessemer steel will be sufficient. Continue this heat
until the oxides are reduced to a metallic state. The addition of aluminium or zinc
or other similar metal will hasten the gathering of the fine particles of aluminium
together as they are fused. When the oxides contain zinc or zine is introduced into
the crucible to assist in the reduction, it can be readily driven off in the form of vapor
or they may be separated by the difference of the gravity which will cause the
aluminium to rise above the zinc, so it can be drawn off in a separate tap hole. So
also, other metals can be separated from the aluminium alloy, reduced from the oxides
when it is desired to obtain alumina without the alloy. When it is desired to make
aluminium bronze or an alloy of copper and aluminium, the presence of copper is
beneficial to easy reduction of the oxides which readily enters into the alloy.
In reducing the oxides of alumina either with or without the presence of other
metals, such as zinc, copper or tin, it is better to introduce an alkaline flux into the
crucible; for this purpose several kinds may be employed, such as borax, carbonate
of soda, nitrate of ammonia, nitrate of soda or potassium, and other fluxes in common
use in metallurgical reductions.
A flux composed of ten parts of phosphorous to ninety parts of flour spar well
pulverized and mixed is a very useful flux for treating copper and alloying it with
aluminium, improving the quality of the metal and assisting in the alloying and
reduction of the oxides. Many clays contain iron which will be carried over with the
oxide of aluminium to some extent. This is not objectionable when the oxide of
aluminium is to be alloyed with copper, as the iron will be separated from the copper
and aluminium as slag. The use of zinc or tin as a flux in producing the oxides
assist in separating the iron from the other metals, and renders the production of
pure aluminium easy. The iron can be separated from the alumina by various other
means common in metallurgical operations. When the oxides of aluminium gathered
from the condensers are to be used for the alloying of irons and steel, the presence
of the oxide of iron with the oxide of aluminium is beneficial and not objectionable.
The oxides of alumina may be reduced to aluminium by the use of sodium, but the
process is more expensive and the use of aluminium as a gathering agent to collect
the fused particles of alumina is preferred.
When the aluminous ores are to be reduced to oxides without bringing the ores
into direct contact with the products of combustion, more flux and a higher degree of
heat will materially hasten the operation.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is :-
First The process of separating alumina from aluminous earths in the form of an
oxide by the means substantially as herein specified.
Second The process of separating alumina from aluminous earths and its silicious
associates, and gathering it in the form of an oxide and then reducing the said oxides
to a metallic state.
Third-The reducing furnace and series of cooling and condensing chambers
arranged to catch the oxides of alumina.
Fourth-The process of obtaining aluminium from aluminous ores by first driving
off the alumina in a finely divided form and depositing it in a form of oxides, and
then reducing the oxides to a metallic state by a deoxodizing agent and a flux.

page_text: Fifth A flux composed of feldspar and phosphorus mixed and applied to the
metals or oxides during the process of fusing.
Sixth The process of separating alumina from silicious associates by means of a
metallic flux mixed with the ore which is treated in the furnace and reduced to oxides
and then gathered and further treated.
Seventh The process of reducing aluminium from aluminous earths by mixing
with an ore deoxodizing agent and a flux and then separating the alumina by heat,
which is deposited in cooling chambers, then gathered for further treatment.
Dated this 1st day of May 1888
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.