Improvements relating to the Application and Utilization of Electro- magnetism for the Separation of Metals and Magnetic Substances from Sand and other Material, and to Apparatus therefor.
Year: 1889

page_text: Date of Application, 17th Sept., 1889
Complete Specification Left, 18th Dec., 1889-Accepted, 25th Jan., 1890
Improvements relating to the Application and Utilization of Electro-
magnetism for the Separation of Metals and Magnetic Substances
from Sand and other Material, and to Apparatus therefor.
I RICHARD R. MOFFATT of 120, Broadway, New York, United States of America,
Electrician do hereby declare the nature of this invention to be as follows:—
This invention relates to a novel method of separating associated substances, such as
metallic from non-metallic materials, and also the magnetic from the non-magnetic
metal particles, and is especially applicable to the separation from earth and sand of
particles of gold and other metals..
The chief peculiarity of my invention consists in the employment of electro-magnets,
energized by means of alternating or intermittent currents of electricity thus causing
rapid reversals of magnetic polarity or pulsations of magnetism, the effect of which
upon particles of metal coming within the influence of the magnetic field will be to
attract the magnetic, and at the same time repel or deflect the non-magnetic metal
particles, while the non-metallic material is in no way affected or acted upon by the
magnetic forces, suitable means being applied to conduct the separated metals into
proper receivers, while the nonmetallic substance falls by its own gravity through the
magnetic field into its own receptacle.
It is well known that non-magnetic metals such as gold, silver, copper &c., which
are good conductors when subjected to the influence of a rapidly alternating or
changing polarity in a strong magnetic field, become electrically charged by induc-
tion and are effected in such a manner as to be impelled or deflected, if free to move
transversely across the magnetic lines of force, and it is the utilization of this principle
in a system of electro-magnetic separation of ores, metals, etc., that constitutes the
chief feature of my invention.
The mechanism which I employ in effecting the separation of metals according to
my invention, admits of various modifications the principle of construction will how-
ever remain unchanged.
Thus for example I amploy a fixed bar electromagnet, made preferably of iron
wire. or thin sheets of iron insulated from each other to facilitate rapid magnetization
and demagnetization, and to avoid the formation of Foucault currents. This magnet is
carried horizontally by a fixed transverse shaft supported in a suitable frame or box,
and it is enclosed in a rotary drum or case of thin sheet iron, mounted loosely upon
the fixed transverse shaft and having a layer of soft iron, wire wound around its
periphery. Situate above this drum is a hopper for the reception and delivery onto
the drum of the pulverized material to be sorted.
The material fed from the hopper, will fall on the upper side of the
rotary drum, and will be carried round with the drum. On arriving opposite
the end of the magnet, which is to be excited from any suitable generator.
the non magnetic, metal particles will become inductively electrified and will
he repelled from the drum and caused to fall into a receptacle provided at the
bottom of the case to receive them. The non metallic matters such as sand, will fall
perpendicularly by the action, of gravity into a second receptacle, whilst the magnetic
particles adhering to the drum will be carried round by it to the neutral point on the
under side of the drum where meeting with a rotary brush they will be swept off into
a third receptacle.
As a modification of this apparatus I may duplicate the same by arranging two or
more magnets with their rotary drums side by side or in different planes and instead of
coating the enclosing drum with soft. wire Ï may fit its periphery with longitudinal

page_text: The drums may also be mounted so as to rotate in a horizontal instead of a vertical
plane and horse shoe magnets may be used in place of bar magnets.
I also propose in applying my system of electro magnetic separator, to use in com-
bination with a stationary electro magnet energized by an alternating current, a
rapidly rotating or moving armature or armatures arranged in such a manner with
respect to the poles of the magnet as to produce strong contracted magnetic fields,
while the rapid rotation of the armature, causes a continuous advance of the magnetic
lines of force within the fields in the direction of the armature's rotation, which advance
acts upon the non-magnetic particles in their passage through the field in a manner
thai impels or deflects them in their course, forcing them out of the magnetic field, in
the direction of rotation, thus causing them to fall into a receiver apart from those in
which the non metallic and the magnetic substances fall.
It should be understood that I do not limit myself. to the use of alternating electric
currents, as the intermittent or pulsating electric current causes a similar effect i.e.
producing rapid changes of magnetism in the field of force, and thereby setting up an
induced electric state within metal particles moving in the magnetic field, and
the consequent impelling or deflecting of said particles when nonmagnetic as
described.
Dated this 17th day of September 1880
NEWTON & SON,
Agents for the Applicant.
-
COMPLETE SPECIFICATION.
Improvements relating to the Application and Utilization of Electro-
magnetism for the Separation of Metals and Magnetic Substances
from Sand and other Material, and to Apparatus therefor.
I RICHARD R. MOFFATT of 120, Broadway, New York, United States of America,
Electrician, 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 hy
the following statement:-
My invention appertains to a novel method of separating associated pulverized
substances, such as metallic from non-metallic materials, and also the magnetic from
non-magnetic metal particles, aud is especially applicable to the separation from earth
and sand, of particles of gold and other metals.
The chief peculiarity of my invention consists in the employment of electro magnets.
energized by means of alternating or intermittent currents of electricity, thus causing
rapid reversals of magnetic polarity, or pulsations of magnetism, the effect of which.
upon particles of metal coming within the influence of the changing magnetic field, is
to attract the magnetic, and at the same time repel or deflect the non-magnetic metal
particles, while the non-metallic particles of the material under treatment, are in no
way affected or acted upon by the magnetic forces, suitable means being applied to
conduct the separated metals into proper receivers. while the non-metallic substance
falls by its own gravity through the magnetic field into its receptacle without
deflecting.
It is well known that non-magnetic metals, such as gold, silver, copper, etc., which
are good conductors, when subjected to the influence of a rapidly alternating or
changing polarity in a strong metallic field, become electrically charged by induction.
and are affected in such a manner as to be impelled or deflected (if free to move)
transversely across the magnetic lines of force, and it is the utilization of this novel
action, in a system of electro-magnetic separation of ores, metals &c., that constitutes
the chief feature of my invention.
In the accompanying drawings, I show various devices for the carrying out of my
invention.
Fig. 1 is a vertical central section of an apparatus especially applicable for treating
substances in which the magnetic material predominates.

page_text: Fig. 2 is a similar view, illustrating the grouping in series of my apparatus (two
or more) for acting successively upon the material under treatment, to insure a more
perfect separation of its component parts.
Figs. 3 and 4 shew in vertical section.further modifications of my improved apparatus,
Fig. 5 is a plan, and
Fig. 6a vertical section, of a further modification of my invention.
Figs. 7 and 8 are views illustrating a special magnetic cylinder or drum.
Fig. 9 is a vertical section of another apparatus, in which a deflecting armature is
used.
Fig. 10 is a plan of Fig. 9.
Similar letters in each figure represent like or corresponding parts.
A represents an electro-magnet, the core of which is preferably made of soft iron
wire, or thin sheets of soft iron, each lamina being insulated in order to prevent the
formation of Foucault currents therein, also to facilitate the rapid magnetization and
demagnetization of the core. In Figs. 1, 2, and 3, the magnets A are fixed in a
horizontal position within a rotating drum B, and in the plane of its axis. The drum.
which receives rotation in any convenient manner, is fitted with central hubs e, which
turn upon fixed hollow trunnions e, secured to, or forming part of the magnet. A, and
carried in the main framing. The cylindrical portion of the drum B is preferably
made of thin sheet iron, or of some other suitable material, having a layer of wrought
iron wire circumferentially wound upon its periphery.
This iron should not be of sufficient mass to absorb and act as a conductor for all
the magnetic lines of force passing from one pole of the magnet to the other, but is
intended to operate with sufficient induced magnetic power to firmly hold the
particles of magnetic matter that are attracted to the periphery of the drum by the
magnet A. so as to carry them out of the field of force, as the drum is rotated, to a
point that is neutral, or nearly neutral, where it is caused, by brushes, to pass into a
suitable receptacle c. The electric current conductors, extending from the electric
source to the helix wire of the magnet A. pass through the hollow trunnions e'. A
hopper C (or other suitable device) is arranged above the drum B. to receive the
material to be treated. This material will pass, by gravity, onto the drum B. which,
rotating, conveys the same into the magnetic field of force, where it is acted upon by
the rapidly changing or alternating magnetic polarity of the magnet, the effect of
which is to induce an electric state in the non-magnetic metal particles, causing them
to be repelled or deflected in a direction transverse to the lines of magnetic force, and
causing them to fall into a receiver a, while those metal particles that are magnetic in
their nature are strongly attracted towards the drum B. adhere to it, and are, by its
rotation, conveyed to the brushes D. which. rotating in contact with the drum, free
the magnetic particles from the drum, and allow them to fall into the receiver c.
non metallic substances discharged onto the drum will. as it rotates, fall in સી
perpendicular line from the field, being in no-wise affected by it, into a receiver b. If
desired, the thin iron shell forming the periphery of the drum. may be provided with
longitudinal radial ribs or projections, as shewn in Figs. 7 and 8, which will prevent
the non-metallic particles from being thrown out from the drum B as they are
conveyed from the hopper to the field. In this case, the drum's circumferential
surface need not be of magnetic material.
The
By arranging a pair of magnets and drums as shown in Fig. 3, the magnetic fields
of force at the poles N and S are more powerful, the two magnets A A operating as a
single straight bar electro magnet, both poles (N and S) of which can be utilized, a
shown, by simply rotating the drums B B in opposite directions, as indicated by the
arrows.
In Fig. 4. A is an electro-magnet of well known form, having a connecting
piece A, and the poles N and S located as slown.-B represents an endless apron of
thin strips of magnetic metal, arranged in such a manner that it can move in the
direction indicated by the arrows. By the plan shown in this device, the material.. in
falling from the hopper, is acted upon successively by the two magnetic poles N and S.
as will be understood.

page_text: In the arrangement shown in Figs. 5 and 6, ilie magnet A and drum Bare
mounted in a vertical position, the latter being arranged to turn in a horizontal
direction. By this arrangement, the material is subjected to the alternating action of
the magnetic field for a longer period of time than when operated upon in the
arrangement shown in Figs. 1, 2 or 3; moreover, both poles of the magnet are
utilized at the same time.
Another novel and valuable element in my system of electro magnetic separation.
is the combination with a stationary electro magnet, energized by an alternating
current, producing rapid changes of magnetic polarity, of a rapidly rotating or moving
armature or armatures, arranged in such a manner with respect to the poles of the
magnet, as to produce strong contracted magnetic fields, while the rapid rotation of
the armature causes a continuous advance of the magnetic lines of force within the
flelds in the direction of the armature's rotation, which advance acts upon the non-
magnetic metallic particles in their passage through the field, in a manner that impels
or deflects then in their course, forcing them out of the magnetic field in the direction
of rotation, thus causing them to fall into a receiver apart from that in which the
non-metallic and the magnetic substances fall.
A is
In Figs. 9 and. 10 is shown a plan embodying this moving armature feature.
the field magnet of the apparatus, having its helix coils so wound as to produce con-
sequent poles, marked N and S. As will be understood, m is an armature having
radial arms or branches extending from a hub centre. This armature is arranged in any
desired manner, to rotate in a vertical position. There is an open space between the
ends of the armature arms and the magnetic poles, which constitute the magnetic
fields of force.
+
In these open spaces, the material to be treated is allowed to pass from hoppers or
any desired feeding device. B is a cylindrical magnetic conveyor screen arranged
for the purpose of preventing the disturbance of the air in the magnetic field by the
rapid rotation of the armature, and C Care the hoppers for feeding the material to
be treated onto the conveyor screen. If desired. the screen B may be arranged to
move in the direction shewn by the arrows. This device is intended especially for
treating material in which the nonmagnetic metals predominate, or with material that
has been subjected to the operation of a device like that shown in Fig. 1, the magnetic
particles having, in whole or in part, been separated therefrom before being submitted
to the action of this apparatus.
From the foregoing, it will be evident that my invention can be embodied in
various arrangements, and the principle utilized in many ways, without departing
from its nature. I therefore do not wish to limit myself simply to the apparatus
herein described, and I wish it fully understood, that I do not confine my invention
to the use of electromagnets energized by alternating electric currents, as the inter-
mittent or pulsating electric current causes a similar effect to the rapid changes of
magnetic polarity in the field of force, thereby setting up an induced electric state
within the metal particles moving in the magnetic field, and the consequent impelling
or deflecting of said particles when non-magnetic, as described.
It is well known that an electro magnet energized by means of a continuous
current, requires power, proportioned to the resistance of the lielix coils; also, that
when the same magnet is energized by means of an alternating current of electricity,
the counter electro-motive force produced in the helix wire, due to the magnetization
and de-magnetization of the iron core, is sufficient to aid the current against the
resistance of the helix wire, to such a degree, that little or less power is required.
I am aware that electro magnetic separators are known, in which groups of electro
magnets are arranged to produce fields of force, which magnets, being rotated at a
high speed, will act inductively upon slow moving particles of metal passing through
them producing an electric state therein, thus causing the non-magnetic melal
particles to be deflected, and thereby separated from the magnetic and non-metallic
inatier. But in these cases a continuous electric current is used, and the rapil
changes of polarity in the magnetic field are produced by rotating the electro-magnets.
This system I disclaim, as being radically different from my invention.
·

page_text: Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is-
1. The method above described of separating the mingled particles of conductors
and non-conductors of electricity, consisting in causing them to pass in minute
particles together through a magnetic field whose lines of force are alternating or
Changing, whereby an electrical state is induced in the conductors, which will cause
the non magnetic to be deflected, and the magnetic attracted, and conveyed each
in separate receptacles from the non-metallic substance.
2. In an apparatus for separating metals from non-metallic substances, an electro-
magnet energized by means of an electric current of such a mature as will produce
rapid changes of magnetic polarity, and thereby induce an electric state in metallic
particles passing through the field of force, and cause the non magnetic metal
particles to be deflected, substantially as specified. .
3. In an apparatus for separating metallic from nou metallic substances, a stationary
electro magnet energized by means of an electric current of such a nature as will pro-
duce rapid changes of magnetic polarity in the field of force, thereby inducing such
an electric condition of the metallic particles passing through the field of force, that
the nou-magnetic particles of metals will be elected or repelled, and the magnetic
particles attracted, substantially as specified.
4. In an apparatus for separating mingled particles of metallic and non-metallic
substances, the combination of a stationary magnet, energized by an alternating
current of electricity, with a rotating or moving magnetic conveyor, whereby the
metallic particles are magnetically or electrically charged inductively, causing a
separation one from the other, and also from the nonmetallic substances, substan
tially as herein specified.
5. In an apparatus for separating mingled metallic and non metallic particles, the
combination of a stationary electro magnet, energized by means of an electric
current of such a nature as to cause rapid changes of polarity therein, a movable
magnetic screen or carrier, and a rapidly rotating or moving armature, whereby
an electric and magnetic state will be induced in the metallic particles, as they
pass through the rapidly changing magnetic field or lines of force, thus causing
the magnetic metal particles to be attracted, and the non-magnetic incial particles
to be deflected. separating the one from the other, while the non-magnetic particles
not being influenced in their passage through the changing magnetic field or lines
of force, simply pass by their own gravity in a different direction, thereby producing
a thorough separation of the particles, substantially as set forth.
6. In an apparatus for separating mingled non-metallic and metallic particles, an
electro magnet located within a rotating drum or conveyor, said drum or conveyor
being provided with projecting ribs extending longitudinally upon its periphery at
suitable intervals, and a rotating brush located at or near the neutral line, substan-
tially as specified.
7. In an apparatus for separating metallic and non-metallic substances by electro
magnetic induction, the combination of a stationary electro-magnet energized by an
electric current of such a nature as will produce rapid changes of polarity in its
field, or lines of force, with a rapidly moving armature or armatures, and a slow
moving conveyor screen. operating between the armature and the magnetic poles, in
such a manner as to prevent a disturbance of the air within the field by the rapid.
movement of the armature or armatures, and also act to convey the magnetic particles
towards the neutral point, substantially as set forth.
11 1 11 1011 1
1000