Improvements in Electric Smelting and in Furnaces therefor.
Year: 1892

page_text: Date of Application, 24th Dec., 1892
Complete Specification Left, 23rd Oct., 1893-Accepted, 23rd Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Electric Smelting and in Furnaces therefor.
I REGINA NIEWERTH of Luther Strasse, Berlin, Prussia, no occupation, do
hereby declare the nature of this invention to be as follows:-
The furnace consists of fire bricks enclosed in metal, the top of the furnace is
loose and sealed by water or other suitable joint. A pipe is connected to furnace
to introduce gas and a second to withdraw it. The furnace may be of conductive
material to enable it to conduct the current from one pole. If the furnace is non-
conductive a conductive bottom is provided. Current is conducted to this in any
suitable manner and the other current through the top by carbon conductors
arranged to have an up and down movement; on top of furnace is a suitable hopper
to hold supply of material to be fed to furnace through suitable inlet without
letting in air; the top of this cover is also sealed by water or other hermetically
tight joint.
Assuming copper is to be smelted. After the furnace is charged the lid is closed,
illuminating gas, carbon mon-oxide, or other non-oxydising gas is passed through
one tube into furnace to drive out all the atmospheric air, the gas, and air passing
out through other tube. Then the circuit is completed and the arc or arcs
established between the top carbon conductors and conductive bottom. When the
furnace is full of molten metal it is tapped through an aperture provided for this
purpose and a fresh supply introduced from hopper. If the metal to be smelted
contains oxide of the same metal as an impurity or other impurities that require to
be eliminated, it is advantageous to fill the furnace with a gas capable of reducing
the metallic oxide or forms any such combination as may be easily separated from
the metal by other means. If for instance aluminium is combined with carbon in
which form it is absolutely useless, the carbon can be easily eliminated by the above
process by introducing hydrogen gas into the furnace which combines with the
carbon to form hydrocarbons which escape in gaseous form, the pure aluminium
remaining as a regulus. In like manner carbon may be eliminated more or less
completely from carboniferous iron.
In all electrical smelting processes hitherto it has been necessary to place the
positive pole into the material to be smelted for the following reasons. When the
arc is formed it passes principally from the positive to the negative pole: if
the negative pole were placed in the metal a large amount of air would be driven
to the metal as it is melting which would cause considerable oxydisation. In this
way electric smelting becomes too expensive to be commercially successful. For
this reason the positive pole has always been laid in the material which causes loss,
by metal being thrown out by the current.
According to this invention these disadvantages are obviated. The negative
pole is placed in the metal and the melting is effected quietly and without any of
the metal becoming oxydised as no oxygen is present in the furnace. Furthermore
this arrangement of the current favourably affects the melting as the particles of
gas surrounding the current-whether neutral or conductive-are raised to a high
temperature and rapidly impelled upon and into the metal by the direction of the
current, which causes the smelting to be effected much more rapidly than usual
with a considerable saving of fuel.
Dated this 24th day of December 1892.
FREDERIC PRINCE,
Agent for Applicant,

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Smelting and in Furnaces therefor.
I, REGINA NIEWERTH, of Luther Strasse, Berlin, Prussia, no occupation, 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 invention will be best understood by describing the same with aid of the
accompanying drawings, which is a sectional elevation of a furnace constructed
according to this invention.
a firebrick side and bottom, secured in a metal casing ; a¹ roof having a hanging
metal top e to dip into a water trough d to seal the closing. Instead of water sand
or other form of joint may be used, that will make a hermetically tight joint. e is a
pipe for admitting gas into furnace, and a pipe for the withdrawal of same.
ga material capable of conducting electricity such as carbon, to which the current
from one pole is passed being introduced through the leads h: The current from
the other pole is introduced through the carbon rods; these rods pass through
suitable insulating stuffing boxes, and arranged to be lifted or lowered at will.
A is a metal or other hopper having its cover also fitted with a water or other seal.
The bottom of hopper is formed as a slide 1, for the purpose of letting material
into the furnace, without opening same. The furnace is provided with peep-holes
and draw off' tap hole of the usual kind. Assuming that copper is to be smelted,
the interior of the furnace is supplied with a charge, and a further quantity filled
into hopper, and cover properly secured then through tube e carbon monoxide or
other non-oxydising gas is admitted into the furnace to drive out all atmospheric
air through pipe f when the latter is closed. The circuit of the current is then
completed and the arc or arcs produced between the bottom g and the carbon
points . The melting of the copper rapidly proceeds without any oxydation or
loss, as no oxygen is present. When the molten metal is ready for tapping it is
drawn off, and a fresh supply is introduced from the hopper k.
If the metal to be smelted contains the oxyde of the same metal as an impurity,
or contains other impurities to be eliminated, it is advantageous to fill the furnace
with a gas capable of reducing the metallic oxyde, or forms any such combinations
as may be easily separated from the metal by other means. If for instance
aluminium is combined with carbon, in which form it is absolutely useless, the
carbon can be easily eliminated by the above process by introducing hydrogen gas
into the furnace. The carbon from the aluminium then combines with the hydrogen
to form hydrocarbons which escape in the gaseous form, pure aluminium remains
behind as a regulus. In like manner carbon may be eliminated more or less from
carboniferous iron.
In all smelting processes hitherto effected by electricity it has been necessary to
place the positive pole into the material to be melted and this for the following
reasons:- When the electric arc is formed it passes principally from the positive to
the negative pole, now if the negative pole were placed in the metal, a large amount
of air would be driven rapidly to the metal whose temperature is rising and which
is melting, thus a large portion of the metal becomes oxydised. With this method
for the reason stated, the smelting becomes too expensive. Therefore the positive
pole has always been laid in the metal to be treated whenever smelting was effected
by electricity, which caused the disadvantage and loss of much metal being thrown
out of the smelting apparatus by the current. In my apparatus these disadvantages
are obviated. I place the negative pole in contact with the metal and then the
melting is effected quietly, and not even the smallest quantity of the metal becomes
oxydised, as no oxygen is present in the furnace. Furthermore this arrangement
of the current favourably effects the smelting inasmuch as the particles of gas
surrounding the current, (whether neutral, partly, or wholly conductive) which are

page_text: raised to a high temperature, are rapidly impelled upon and into the metal &c. by
the direction of the current. Thus much more rapid melting is effected and a
considerable saving in coal results.
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. In electric heating or smelting metal. The use in combination with an air
tight furnace of gases non-injurious to metals introduced into furnace first to expel
the air and then to assist in the smelting, substantially as described.
2. The arrangement of means herein before described to enable the negative pole
to be placed in the material to be smelted without waste or damage to the molten
metal.
3. The means and process hereinbefore described for eliminating impurities from
molten metals.
4. In the process above described, the employment of a gas or mixture of gases
capable of conducting electricity.
5. The construction of furnaces for electric smelting hereinbefore described and
illustrated by the accompanying drawings.
6. The combination of the process and means hereinbefore described for the
electric smelting of metals and other substances.
Dated this 23rd day of October 1893.
FREDERIC PRINCE,
37, Cursitor Street, Chancery Lane, W.C., Agent for Applicant.