Improvements in Methods of and Apparatus for Melting, Refining, and Casting Metals and other Substances by Electricity.
Year: 1890

page_text: Date of Application, 20th May, 1890-Accepted, 12th July, 18°0
COMPLETE SPECIFICATION.
[Communicated from abroad by EDWARD ALLEN COLBY, of 645, High Street,
Newark, New Jersey, United States of America, Electrician.]
Improvements in Methods of and Apparatus for Melting, Refining,
and Casting Metals and other Substances by Electricity.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Palent 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 :-
This invential relates to a method of and apparatus for melting, refining and
casting metals as well as certain non-metallic substances.
The object of the invention is primarily to melt, refine or cast certain substances
by electricity, and secondly, to accomplish this under conditions which prevent
deterioration of the metals while in a state of fusion, as by carrying on the process
in a rarefied or artificial atmosphere.
The invential is of especial value in refining and casting various metals, in order
that they may be free from blisters, pin-holes and occluded gases, for which latter
many of the metals have a high absorptive capacity. This affinity is especially
manifested at elevated temperatures and between the more refractory metals, such as
platinum and hydrogen, for upon solidification from the molten state, while a portion
of the gases occluded by the metal is retained, the larger proportion is expelled,
violently, if the metal cools rapidly, and sometimes ejecting molten particles, and
creates in its exit minute fissures termed pin-holes or blisters throughout the mass.
Castings made in the ordinary manner are therefore unhomogeneous in structure.
This defect may be greatly magnified in castings of platinum and its allied refractory
metals, which are melted with the oxy-hydrogen flame, because it being impracticable
to supply the compound gases of the flame in the exact proportion of their affinitive
volumes an excess of hydrogen is generally present, free to be absorbed by the
molten metals. An unhomogeneous structure, while perhaps of slight importance
in any metallic mass, may entail serious consequences when, as for example, the
metal is drawn into a fine wire, as any defect in structure then becomes a hidden
source of trouble. This is especially true where, as in the manufacture of incandescent
electric lamps it is of the utmost importance that the platinum sealed in the glass
should be of uniform density. In this case the slightest fissure in the platinum
wires serves as a reservoir and possibly as a channel for the entrance of gases capable
of destructive union with the carbon filaments.
Many experiments have been made to produce a high grade of metallic castings for
such specific uses, but the beneficial results attained have involved methods too
expensive for commercial adoption. This invention consists in heating metals and
refining them by means of the inductive action of electric currents in air or in a
gas exhausted containing vessel, and in casting them while so heated and deprived
of occluded gases into ingots.
The invention will be described in connection with the accompanying drawings,
in which
Figure 1 is a vertical transverse section and
Figure 2 a plan view of a devico adapted to the purpose of the invention.
Referring to the Figures, A represents a suitable stand upon which the furnace B
is supported. This furnace may be carried upon trunnions a. It consists in this
instance, of an outer casing containing an induction device presently to be
described. The case b¹ may be provided with a cover 2 which may be fastened down
by bolts and rest upon cushion B. The cover and case thus form an air-tight
chamber. Within this chamber there is placed the induction device, and this

page_text: comprises a primary coil P a core F and a secondary conductor. The coil P is
designed to be included in the circuit of a generator K delivering alternating, inter-
mittent or pulsatory electric currents. This coil consists of suitable conducting wire
insulated with fire proof material, such for instance as asbestos. It is wound upon a
spool c, which is preferably of refractory insulating material, such for instance as
slate. Within the coil P there is placed an annular block E of nonconducting
material, such for instance as fire clay or lime, capable of withstanding great heat.
This may be separated from the coil P and iron core F by air spaces d. The block E
contains an annular groove e which is designed to receive the material to be heated
or melted, or otherwise operated upon. Such materials may be various chemical
substances, organic or inorganic, having no chemical affinity for the containing
receptacle.
When the material to be treated is a conductor of electricity, it acts itself as
the closed secondary of the induction device and the currents are developed in it
by induction. But when a non-conducting or poorly conducting substance, is to be
treated, a trough S of refractory metal is placed in the groove e and constitutes partly
or entirely, the secondary of the induction device.
To increase the intensity of the magnetic field in which the secondary S is
contained, a core F is employed. This may consist of soft iron wires or plates, which
are insulated from each other to a greater or less extent.
is
These wires extend through the centre of the block E and across the bottom of the
coil P, thence around the sides and across the top as shown. The top of the core
removable, on the lines a where the insulated iron plates dovetail with one another and
when it is in position it serves to complete the magnet circuit through the core F.
It is designed that the primary coil P shall be connected in an electric circuit
by means of conductors Land 12 leading from the generator K or other suitable
source of alternating, intermittent or pulsatory currents. Currents will thus be
induced in the secondary circuit formed by the annular trough or receptacle S, or
by the material under treatment.
Such current will cause this trough or material to be heated, and thus any
material, such as metals alloys and non-conducting chemical substances or liquids,
placed in the trough, as indicated at S will be raised to the desired temperature.
As there is but a single turn of the secondary circuit, the current will be of low
potential but of great quantity, and thus the temperature may be raised to any
required degree. Complete control of the temperature is secured by any of the
usual devices for regulating the current in the primary circuit. Usually it is
necessary that the volume of the substance contained in the receptacle S should be
such that when heated or fused it shall exceed the capacity of that receptacle, so
that no injury will come to it from overheating.
This device is especially useful in melting non-conductors of electricity but it
may also be employed in connection with conducting materials. When the metals
themselves are to serve as the secondary circuit, the trough S may be dispensed with
in some instances, and the currents induced directly in the metals.
The cover may be applied to the case after the substance is in position and,
if it is desired to treat the substance in a rarefied atmosphere, the air may be
exhausted by means of a vacuum pump applied to a tube N leading through the
cover. After the natural air has been exhausted, together with the gas which comes
from the substance when heated, additional gas may be forced by a pump into the
chamber through the inlet N'; preferably leading into the lower portion of the
containing vessel S and thus up through the melted substances. Gases may be
employed which have a chemical affinity for the impurities contained in the substance
being operated upon, or which form, with the substance under treatment, definite
desired compounds. The resultant gaseous products are then removed from the
chamber by the vacuum pump.
When the substance has been sufficiently treated, the entire furnace may be turned
upon the trunnion a by means of a handle or lever H, and if desired, the vacuum
pump may still be in operation. The substance will then be caused to flow into a

page_text: mould A which is fastened to the casing and held with its naring mouth in position
to receive the contents of the groove or receptacle e.
A peep hole closed by a glass disc, may be formed in the cover at a suitable point
for observing the operation.
This process and apparatus are well adapted to obtaining pure and homogeneous
castings of all kinds of metals and alloys." The apparatus may be constructed in
different ways, but that shown is both convenient and effective.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent I declare that what 1 claim is :-
First. The herein before described process of electrically melting and refining
metals and other substances which consists in heating the entire mass of the substance
in a retaining receptacle, by inductively establishing electrical currents in the sub-
stance or the receptacle, and thus heating the substances to, and retaining them at the
desired temperature.
Second. The hereinbefore described process of electrically melting and refining
conducting substances, which consists in establishing electric currents within the
same, by inductive action, until the metal is brought to a molten condition and then
casting the same.
Tbird. The hereinbefore described process of melting electric conducting substances,
which consists in creating a rarefied or equivalent atmosphere in a closed chamber,
heating the entire mass of the substance to the point of fusion in such atmosphere, by
inductively establishing electrical currents therein, and casting or operating upon the
substances in such atmosphere.
• Fourth. The combination with a primary circuit and means for supplying electric
currents thereto, of a refractory conducting receptacle constituting a closed secondary
circuit and adapted to receive the substance to be operated upon and placed in
inductive relation to the primary circuit, whereby electric currents may be induced
therein by the action of currents in the primary circuit.
Fifth. The combination with a primary circuit and refractory insulating material
covering the same, of a core of soft iron under the inductive influence thereof, a
mould of refractory conducting material surrounding a portion of the core and
adapted to receive the substance to be operated upon, said mould constituting a
secondary electric circuit.
Sixth. The combination with the primary coil of an electric converter, of electric
conducting material adapted to contain metallic or non-metallic substances to he
heated or refined, said electric conducting material constituting the secondary circuit
of the converter.
Seventh. The combination with the primary coil of an electric converter, of
conducting material adapted to contain metallic or non-metallic substances to be
refined, said conducting material constituting the secondary circuit of the converter,
and an air-tight enclosing case containing the same.
Eighth. The combination with an air-tight enclosing case, of an electric conducting
receptacle for the substance to be operated upon by heat, contained within said air-
tight case, a core of soft iron extending through said receptacle, and an insulated
conductor disposed about said core.
Ninth. The combination with the primary circuit of an electric converter or
induction coil, of a soft iron core applied thereto, an electric conducting receptacle for
refining having an opening for containing the substances to be refined, said receptacle
being placed in inductive relation to said core and forming the secondary circuit in
whole or part.
Tenth. The combination with a primary circuit and means for supplying electric
currents thereto and controlling the same, of a refractory mass adapted to contain
metal to constitute a secondary circuit and adapted to place such metal in inductive
relation to the primary circuit whereby electric currents may be induced therein by
the action of electric currents in the primary circuit.

page_text: Eleventh. The combination with a primary coil of wire and refractory insulating
material covering the same, of a core of soft iron under the inductive influence
thereof, and a mould of refractory material surrounding a portion of the core and
adapted to receive metal to constitute a secondary circuit, substantially as described.
Dated this 20th day of May 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.