Improvements relating to the Application and Utilization of Magnetism or Electro-magnetism for the Separation of Metals and for other Purposes, and to Apparatus therefor.
Year: 1886

page_text: Date of Application, 5th Apr., 1886.
Complete Left, 4th Feb 1887
Complete Accepted, 1st Apr., 1887.
Improvements relating to the Application and Utilization of
Magnetism or Electro-magnetism for the Separation of Metals
and for other Purposes, and to Apparatus therefor.
I, HIRAM STEVENS MAXIM, of 57" Hatton Garden, in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to the utilization of magnetic force for separating diamagnetic
and paramagnetic from non-magnetic materials or from materials of feebler dia-
magnetism, and for assaying, analysing and other purposes, and to apparatus therefor.
I have discovered that, when diamagnetic materials are placed in a magnetic field
in which there are many changes of polarity or intensity and which is rapidly moved
in any direction, such materials are impelled or deflected in the same direction. For
instance, assuming that two series of magnets are so relatively arranged as to produce
between them a magnetic field having many changes of polarity, or a series of
magnetic fields, and are caused to rapidly rotate in the same direction, if particles or
pieces of diamagnetic material are permitted to fall, or are suspended, between these
series of magnets, the said particles or pieces will, by the action thereon of the
magnetic force or induction, be impelled or deflected in the direction of rotation of
the said magnets. The amount of force whereby they are thus impelled or deflected
will depend partly upon the degree of their conductivity and the strength or intensity
of the magnetic field, and partly upon the rapidity with which the changes of polarity
or intensity follow each other.
Under the term diamagnetic materials, I include gold, silver, copper and other
substances such, for example, as have been enumerated by Faraday and by Sylvanus
P. Thompson.
One object of my said invention is to utilize this action of rapidly succeeding
changes in a magnetic field or of rapidly moving magnetic fields upon diamagnetic
substances for the separation of the precious metals or of copper from ores containing

page_text: the same, or for assaying or similar purposes. But my invention is also advantageously
applicable for the separation of paramagnetic materials from non-magnetic materials
and for other purposes.
In carrying my invention into practice, I prefer to use two circular series of electro-
magnets so arranged that the magnets of one series are opposite those of the other
series. If desired, however, I may use permanent magnets instead of electro-magnets.
These magnets are so arranged that unlike poles face each other.
It is important that air currents produced by the rotation of the magnets or in any
other manner should be carefully excluded from the space through which the substances
to be operated upon are permitted to fall or in which they are suspended. For this
purpose I prefer to enclose the mechanism in a suitable casing which revolves with
the magnets, and to place stationary diaphragms of parchment or drum-head or other
suitable material between each series of magnets and the said space.
If the apparatus is designed for separating precious metals from ores containing the
same, or for similar purposes, I provide moans whereby the ores or other substances
to be treated can be permitted to fall in a continuous stream into and through the
space between the two series of magnets. I also provide one or more inclined plates
or chutes upon which the substance deflected by the inagnets will fall, and down which
the said substance may descend into suitable receptacles.
When the apparatus is to be used for assaying or analysing, I provide suitable
means for suspending the materials to be operated upon in the space between the two
series of magnets and for indicating the deflection thereof by the said magnets, or for
weighing the said materials in, and out of, the said space.
A convenient form of apparatus for the treatment of gold-bearing sand and similar
materials is constructed as hereinafter described, that is to say-Two circular series
of electro-magnets are mounted on a shaft which is carried in suitable bearings in the
frame of the machine. At the top of the machine there is a hopper, and beneath this
hopper is arranged a shaking or vibrating tray or chute for feeding the substances to
be treated from the said hopper into the machine. A spout or chute is provided at
the bottom of the machine for the discharge of the sand or other non-magnetic material
after the gold has been separated therefrom. Spouts or chutes are also provided for
receiving the gold and conducting the same into suitable receptacles. Deflectors or
deflecting plates are arranged in proper relation to the magnets to prevent the rotation
of the particles of gold with the said magnets. A ring or annular piece is attached to,
but insulated from, each series of magnets. The coils of the magnets are connected
with these rings or annular pieces; and contact springs or brushes, connected with
an electric generator, are arranged to bear one on each of the said rings. The
diaphragms which cover the poles of the magnets are stretched, or otherwise mounted,
upon stationary frames.
The operation of this machine is as follows, viz:-A suitable current of electricity
is taken in through one of the contact springs or brushes and out through the other
spring or brush; and the magnets of each series are thereby excited, thus producing
between the two diaphragms a very powerful magnetic field in which there are many
changes of polarity.
The shaft and the two series of magnets are now rotated at a high speed, and the
material to be operated upon is placed in the hopper, and fed forward so that it falls
in a continuous stream into the space between the two diaphragms. The material
which is affected by the magnetic force or induction will be powerfully impelled or
deflected in the direction of rotation and thrown into the chutes provided for its
reception. The material which is not acted upon by the magnetic force or induction,
or which is very slightly acted upon thereby, falls directly into, and through, the
bottom chute and is discharged from the machine.
The poles of the magnets are sometimes made in the form of a chisel-edge, that is
to say, V-shaped in transverse section, and the said magnet poles are arranged radially.
The limbs of the magnets are secured to soft iron discs or plates and are parallel with
the shaft; each magnet is provided with a polar extension, or with a series of polar
extensions like saw-teeth, or with a series of fine needle points, which points are

page_text: arranged in rows or in circles, or in the form of a volute; or the said magnets are
made with ordinary flat poles.
To intensify the magnetic fields and increase their action upon very fine particles,
I prefer to arrange the magnets of each series in pairs and to provide them with pole-
picces so 'formed and arranged that the pole-pieces of each pair extend towards each
other, and, when the two series of magnets are placed in position on the shaft, the
pairs of pole-pieces of one series coincide or correspond with those of the other series.
The pole-pieces are, therefore, arranged in groups of four, and are not equidistant, the
distance between the pole-pieces of one group and those of an adjacent group being
greater than the distance between the pole-pieces of either group. By these means
I provide for ensuring an abrupt or sudden transition from one polarity to the other
between the magnets forming each group, that.is.to say, the lines of magnetic force
of one polarity are in close proximity to those of the opposite polarity; the neutral
axis between the four magnetic poles is, in this case, sharply defined and has the form
of the letter X.
When the apparatus is to be used for assaying or analysing, I sometimes provide a
standard or upright which is secured to the top of the frame or casing of the machine
and is provided with a hook, pin or other device to which a silk or other thread may
be attached. I also form on, or attach to, the upper side of the casing a graduated
scale. In assaying, the piece or package of ore or other material is suspended in the
space between the diaphragms by means of a silk or other thread attached to the said
pin, hook or the like. The greater the quantity of gold or other metallic substance
present in the ore or other material, the greater will be the deflection thereof. The
amount of this deflection will be indicated upon the said graduated scale. If the
material operated upon is all earthy or non-metallic matter, there will be no deflection
thereof. Or I provide means for weighing the picce or package of ore or other
material in and out of the space between the diaphragmns.
In testing the quantity of salts, saccharine matter or acids in a solution, the latter
is put into a bottle which is suspended, as above described, between the said
diaphragms. The larger the quantity of salts or acids present in the solution, the
greater will be the deflection-thereof."
If desired, the two series of magnets are provided with means for producing rapid
reversals of the current therein; the said magnets can then be rotated at a slower
speed than when a continuous current is used.
I sometimes use two series of stationary magnets and provide means for rotating
the material to be operated upon in the space between them, but better results can be
obtained by the arrangement herein-before described.
KILJ of Anvil 1886
HASELTINE, LAKE & Co.,
Agents for the Applicant.

page_text: Improvements relating to the Application and Utilization of
Magnetism or Electro-magnetism for the Separation of Metals
and for other Purposes, and to Apparatus therefor.
I, HIRAM STEVENS MAXIM of 57D Hatton Garden in the County of Middlesex
Mechanical Engineer 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 :-
My invention relates to a novel method of employing magnetism or electro-
magnetism for the separation of associated materials and for other purposes hereinafter
indicated, and it comprises improved apparatus hereinafter described.
The chief peculiarity of my said invention consists in the employment of moving
magnetic fields as hereinafter specified for the separation of gold, silver, copper and
other metals which are commonly known as non-magnetic (but some of which have
been classified by Faraday and other writers as diamagnetic metals) from non-metallic
substances or bodies.
It is well known that gold, silver, copper and other metals, which are ordinarily
considered non-magnetic, and which in their normal condition are not susceptible, or
are but very slightly susceptible of magnetization, can yet by electro-magnetic or
magneto-electric induction have temporarily imparted to them a condition resembling
that of ordinary magnetic bodies.
I have discovered that, when particles or pieces of the herein-mentioned and other
metals pass through a series of group of magnetic fields, in which there are many
alternations or reversals of polarity and the magnets of which rapidly move or change
their position relatively to such particles or pieces, the latter though not in contact
with the magnet-poles, will be impelled or deflected in the direction of movement of
the magnetic fields. For example, assuming that two series or groups of magnets are
so relatively arranged that the magnet-poles of one group are opposite those of the
other group, unlike poles facing each other, so that magnetic fields are produced
between them; if these opposite series or groups of magnets are simultaneously
rotated in the same direction, particles or pieces of metal permitted to fall through, or
suspended in, the space between them, will, by the action of the magnets, be impelled
or deflected in the direction of rotation of the magnets, and if free will be thrown
tangentially away from the circular path of the said magnets. The magnitude of the
force by which they are thrown out depends partly upon the relative conductivity of
the metals, and partly upon the strength or intensity of the magnetic fields and the
frequency of the changes or reversals thereof.
The separative action or effect, however, is not dependent upon the existence in the
metals of any inherent or normal condition or property such as that by virtue of which
a piece iron in the presence of a magnet, when both are at rest, is magnetised in the
direction of the field or lines of force. And the separation, instead of being the result

page_text: of the approximation of the metals to the magnet-poles, is caused by forces which
move the particles transversely across the field or space between the magnets.
According to one part of my said invention, I utilize this action of rapidly moving
series or groups of magnetic fields for the separation of the precious metals or of
copper from ores containing the same, or for assaying or analysing ores and other
substances, or for similar purposes.
I can utilize moving magnetic fields in the manner herein specified for the separation
of iron from non-metallic materials, or for the assay or analysis of substances
containing iron. My invention is, however, more advantageous for the treatment of
non-magnetic or diamagnetic metals, or those which are but slightly magnetic than for
the treatment of iron, because iron, having a tendency to approach and adhere to the
magnet-poles, cannot be thrown outward unless the tangential or centrifugal force due
to the rotation of the magnets is sufficient to overcome such tendency.
In order that the efficient working of the apparatus shall not be affected or impaired
by air-currents produced by the rotation of the magnets or in any other manner, it is
important that such air-currents should be carefully excluded from the space through
which the substances to be operated upon are permitted to fall, or in which they are
suspended. For this purpose I prefer to enclose each series or group of magnets in a
casing which revolves therewith, and to place stationary diaphragms of parchment or
other suitable material between the said series or groups of magnets so as to leave a
space between the said diaphragms in which the air will be unaffected by the
movement of the magnets. In some instances, I also enclose the two series or
groups of magnets in a stationary box or casing.
If the apparatus is to be used for separating precious metals from their ores, or
for similar purposes, I provide means whereby the ores or other substances to be
treated can be caused to fall or pass in a continuous stream into and through the
space between the two opposite series or groups of magnets. I also provide one or
more inclined plates or chutes upon which the metals or other materials deflected by
the magnets will fall, and down which the said materials may descend into suitable
receptacles.
When the apparatus is to be used for assaying or analysing, provide suitable
means for suspending, in the space between the two series or groups of magnets, the
materials to be examined, and for indicating the degree of movement or deflection
thereof by the said magnet; or I provide for weighing such materials in and out of
the said space.
In the accompanying drawings, I have illustrated a convenient form of apparatus
for the treatment of gold-bearing sand and similar materials according to my present
invention.
Figure 1 is a vertical central section of the said apparatus.
Figure 2 is a vertical section on the line a, a, Figure 1.
Figure 3 is a longitudinal central section through one of the series or groups of
magnets and a casing enclosing the same.
Figure 4 is an end elevation, partly in vertical section, of the apparatus illustrated
in Figure 3, some of the parts being removed.
Figure 5 is a projection of portions of two series of groups or magnets (that is to
say, a view illustrating portions of the peripheries of the said series or groups developed
or projected upon a plane) shewing the relative arrangement of the magnet-poles
polar extensions, some of the parts being shewn in section.
ог
Figure 6 is a face view, and Figure 7 an end view of a peculiarly shaped pole-piece
hereinafter described.
Like letters indicate corresponding parts throughout the drawings.
A is a table or platform mounted upon standards A¹. B is a box or casing supported
upon, and firmly secured to, the said table or platform, and enclosing parts of the
mechanism. C, C are plates or discs of soft iron, which are fixed upon a shaft D
carried in bearings B' secured in the sides of the box or casing B. E, E are electro-
magnets, the cores E¹ of which are firmly secured to the plates C, so that the said
plates serve to connect the cores of each magnet. F is a sleeve or distance-piece which

page_text: is placed upon the shaft D between the two plates C. These plates and the said sleeve
or distance-piece are firmly clamped between a collar D' formed or fixed on the shaft D
and a nut D screwed upon the said shaft.
G, G¹ are metal rings which are firmly attached to, but insulated from, the plates (),
and which are connected, by means of binding screws G2, one with each end of the
wire forming the magnet-coils. H, H are contact springs or brushes, which are
connected with the poles of an electric generator, and which bear against the
rings G, G¹.
The magnet-coils of one series or group are electrically connected with those of the
other series or group through the shaft D or the sleeve F, or in any other convenient
manner. If desired the magnets of each series or group may be connected with the
electric generator by separate contact springs or brushes.
I is a pulley which is fixed upon the shaft D and is connected, by means of a rope
or belt I, with another pulley J fixed upon a shaft J¹ carried in bearings in the
standards A¹. A pulley J is also fixed upon the shaft J¹ and is to be connected, by
means of a rope or belt, with a steam-engine or other suitable motor.
K, K are casings of wood or other suitable material, one of which is placed over
each series or group of magnets and is secured to the corresponding plate C. These
casings assist in preventing any disturbance of the air in the space around the said
magnets by the rotation of the latter. The magnet-poles or polar extensions E
extend through apertures in these casings.
L, L are diaphragms of parchment or other suitable material, which are stretched or
otherwise mounted upon frames L¹ firmly secured within the box B, and which are
arranged between the two series or groups of magnets in such a manner as to leave a
space between them wherein the air will be undisturbed by the rotation of the magnets.
M is a hopper, which is suitably supported above the box or casing B. Beneath
this hopper is arranged a shaking or vibrating tray or chute N for feeding the
substances to be treated from the said hopper into the machine.
This chute is operated in a well-known manner by means of a shaft N¹ connected, by
means of the rope or belt N2 and pulleys N³, N, with the shaft D. O is a spout or chute for
the discharge of the sand or other materials after the gold has been separated therefrom.
This chute is arranged beneath the space between the diaphragms L. P, P¹ are
spouts or chutes for conducting the gold deflected by the magnets into the
receptacles Q, Q. Deflectors or deflecting plates, such as that shown at R, Figure 1,
are, if necessary, arranged in proper relation to the magnets to prevent the carrying
of the particles of gold around with the said magnets.
The operation of this machine is as follows, that is to say :-A suitable current of
electricity is passed into the magnet-coils through one of the contact springs or
brushes H, Hand out through the other of the said contact springs or brushes; the
magnets of both series or groups are thereby excited, thus producing between the two
diaphragmns L a series or group of very powerful magnetic fields, the magnets being so
wound that unlike poles face each other. The shaft D and the two series or groups of
magnets are then rotated at a high speed, and the material to be operated upon is
placed in the hopper M whence it falls into the tray or chute N. By the vibration of
this tray or chute, the said material is fed forward so that it falls in a continuous
stream into the space between the diaphragms L. The material which is affected by
the magnets is powerfully impelled or deflected in the direction of rotation and thrown
into one or the other of the chutes P P¹. The material which is not affected by the
magnets or which is very slightly affected thereby falls directly into and through the
chute O and is discharged from the machine.
The cores E of the magnets are arranged radially upon the plates C. The pole-
pieces or polar extensions may be made in the form of a chisel edge, that is to say,
V-shaped in transverse section. Or each magnet may be provided with a series of
polar-extensions like saw-teeth, or with a series of fine needle-points, which points are
arranged in rows or in circles, or in the form of a volute; or the said magnets may be
made with ordinary flat poles, or otherwise.
I prefer, however, to form and arrange the pole pieces or polar extensions as shown

page_text: in the drawings, in order to intensify the magnetic fields and ensure the proper action of
the magnets upon very fine particles, or pieces of metal. By referring to Figures 5, 6
and 7, it will be seen that the pole-pieces E are so shaped that, when they are secured
in their proper positions upon the magnet-cores, the pole-pieces of each magnet are
inclined towards each other. Moreover when the two series or groups of magnets
are placed in their proper relative positions on the shaft D, the pairs of pole-pieces of
one series or group coincide or correspond with those of the other series or group.
The pole-pieces of the two series or groups of magnets are, therefore, arranged in sets
of four, and are not equidistant, that is to say, although the four pole-pieces of each
set are equidistant or approximately equidistant from each other, the distance between
the pole-pieces of one set and those of an adjacent set is greater than the distance
between the pole-pieces of either set. By this peculiar arrangement of the magnet-
poles or polar extensions, I provide for ensuring an abrupt or sudden reversal of
polarity or transition from one polarity to the other between the four pole-pieces
forming each set, the lines of magnetic force of one polarity being in close proximity
to those of the opposite polarity, and the neutral lines or axes between the four
magnetic poles being sharply defined and forming together a cross like the letter X.
The result is that the magnets, when rotated as above described, will affect very
minute particles of metal.
Although I have shown electro-magnets in the accompanying drawings, yet it is
obvious that permanent magnets are applicable for the purposes of my invention.
Moreover, in some instances, I can use the magnet-coils without the cores.
When the apparatus is to be used for assaying or analysing, I sometimes provide a
standard or upright which is secured to the top of the box or casing B and is provided
with a hook, pin, or other device to which a silk or other cord or thread may be
attached. I also form on, or attach to, the upper side of the said casing a graduated
scale. In assaying, the piece or package of ore or other material to be operated upon
is suspended in the spaco between the diaphragms L by means of the said cord or
thread, and the magnets are then rotated; if gold or other metallic substance is
present in the material being operated upon, it will be more or less deflected according
to the quantity of gold or other metallic substance which it contains. The amount of
this deflection will he indicated by the said cord or thread upon the graduated scale.
In some cases, I provide means for weighing the piece or package of ore or other
material in and out of the space between the diaphragms.
In testing the quantity of salts, saccharine matter or acids in a solution, the latter
is put into a bottle which is suspended, as above described, between the said diaphragms.
On rotating the magnets, the said bottle will be deflected, and the larger the quantity
of salts or acids present in the solution, the greater will be the deflection thereof.
According to a modification of my invention, I provide the series or groups of
magnets or solenoids with any well-known or suitable means for producing rapid
reversals of the electric current therein; the said magnets can then be rotated at a
slower speed than when a continuous current is used."
Instead of permitting the materials which are to be operated upon to fall into and
through the space between the two opposite series or groups of magnets, I may force
or draw the said materials into and through the said space by means of a current of
air or otherwise. In this case, I might so arrange the magnets that no movement need
be imparted to them, suitable means being provided for producing rapid reversals or
alternations of the current in the magnet-coils.
It is obvious that the construction of my apparatus may be considerably modified
without departing from the nature of my invention. For instance, I sometimes
employ more than two series or groups of magnets fixed upon a common shaft con-
centrically therewith in such a manner that one or more magnet-poles of one group
are at all times opposite a corresponding number of those of an adjacent group. I may,
if desired, employ endless bands or belts of magnets so arranged that the poles of the
magnets of one band or belt are opposite those of an adjacent band or belt, suitable
means being provided for simultaneously moving the said bands or belts in the same
direction for the purposes above specified.

page_text: In some instances, instead of arranging the circular series or groups of magnets
around the common axis as shewn in the drawings, I arrange them to rotate upon or
about separate axes, one of the said axes being a short distance above or at one side of
the other axis, and the magnets of each series or group being arranged with their axes
either parallel to that upon or about which they rotate, or extending radially therefrom.
In such cases the two series or groups of magnets must be so relatively situated that
one or more of the magnet-poles of one group will at all times be opposite a
corresponding number of the magnet-poles of the adjacent group; moreover the said
series or groups of magnets must be arranged to rotate in opposite directions so that
the magnet-poles which are opposite each other will travel in the same direction
relatively to the particles or pieces which are caused to pass or are suspended between
them. The axes upon or about which the magnets rotate may be either horizontal or
vertical.
I sometimes provide for the separation of two or more substances differing in
respect of their conductivity or susceptibility to induction by employing chutes placed
in different positions relatively to the series or groups of magnets, so that the materials
will pass down one or other of the said chutes according to the extent of their deflection
by the magnets.
In all cases, it is necessary according to my invention, that, during the passage of
the materials through or between the series or groups of magnets, the latter by the
motion imparted to them or by other means shall continuously and rapidly reverse
or alternate the polarity of the magnetic fields or lines of force through which the
materials pass.
I am aware that rotating magnets have been employed for separating magnetic from
non-magnetic substances by the adherence of the particles of magnetic material to the
magnet-poles or to a band or belt in contact therewith, for example, as described in
the Specifications of Letters Patent granted to F. J. King and dated 29th July
A.D. 1873, No. 2574 and 11th February A.D. 1880, No. 607; I am also aware that
means have been devised by T. A. Edison for separating magnetic from non-magnetic
substances by employing the attraction of stationary magnets to alter the path of the
magnetic substance and draw it away from the non-magnetic substance, as described
in the Specification of Letters Patent dated 20th October A.D. 1880, No. 4276. In
these cases, however, the separation of the magnetic from the non-magnetic bodies or
particles is effected, or partially effected, by force of attraction, which acts in the line
or direction of the axes of the magnets, and is independent of any movement of the
magnets or magnetic fields; whereas my apparatus is designed to work and works
most efficiently without the adhesion of the metals to the magnet poles; and the
movement or action which effects the separation takes place transversely to the axes of
the magnets and magnetic fields, as above stated.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I wish it understood that I make no
claim either to the devices described in the said former specifications or to any similar
devices, but I claim :-
First. The herein described method or process, wherein I utilize the action of
moving or alternating magnetic fields, for the separation of non-magnetic, diamagnetic
or other metals from non-metallic substances.
Second. The assay or analysis of associated materials by subjecting them to the
action of moving or changing magnetic fields in the manner above specified.
Third. The separation of associated materials by a process or method wherein they
enter or pass through a space in which they are subjected to the action of changing or
alternating magnetic fields in such a manner as to cause a separative movement of the
metal from the other substances transversely to the axes of the magnets.
Fourth. The separation of associated materials by a method or process in which
magnetic and tangential or centrifugal force are utilized as above set forth.
Fifth. The separation of associated materials by means of electro-magnetic or
magneto-electric induction as above set forth.

page_text: as
Sixth. The employment, for the purposes specified, of two or more series or groups
of magnets so arranged that magnetic fields exist in the space between them, and
provided with means for simultaneously rotating or otherwise moving them so
to produce rapid and continual reversals or alternations of polarity as above set forth.
Seventh. The modification of my invention wherein I provide for producing rapid
reversals of the electric current in the magnet-coils or solenoids, for the purposes
above specified.
Eighth. The modification of my invention, substantially as hereinbefore described,
whereby I provide for the separation of two or more substances of different relative
conductivity or susceptibility to induction.
Ninth. The combination, with two or more circular series or groups of magnets
(with or without the casing or casings enclosing them) and means for rotating the said
magnets for the purposes above specified, of diaphragms arranged between the said
series or groups of magnets and having a space between them wherein the air will be
unaffected by the movement of the magnets.
Tenth. The above described improvements relating to the magnet poles or polar
extensions, whereby I provide for intensifying the magnetic lines of force and ensuring
the desired action of the magnets upon very small or minute pieces or particles of the
associated materials.
Eleventh. The apparatus or machine consisting of the parts constructed and
combined substantially as described with reference to the accompanying drawings
and operating as, and for the purposes, specified.
Dated this Inira
ay or rebruary 1004.
HIRAM STEVENS MAXIM.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.