Improvements in Magnetic Separators for Ore and similar material.
Year: 1892

page_text: Date of Application, 8th Mar., 1892-Accepted, 23rd Apr., 1892
COMPLETE SPECIFICATION.
Improvements in Magnetic Separators for Ore and similar
material.
We, CHARLES TROTTER THOMPSON, Mechanical Engineer, residing at
2116, Spruce Street, in the City of Philadelphia and State of Pennsylvania,
United States of America, and RICHARD HAWES SANDERS, Mining Engineer,
residing at 1225 Locust Street, in the said City of Philadelphia, do hereby
declare the nature of this invention and in what manner the saine is to be
performed, to be particularly described and ascertained in and by the following
statement :-
Broadly speaking, our invention consists in the following combination of devices:
A hollow rotating drum is provided with stationary exterior magnets whose poles
envelop a portion of the exterior periphery thereof, the wall or shell of the drum
being of such character, and the magnet of such energy, as to ensure the formation
of a magnetic field throughout a portion of the interior of the drum. A stationary
discharge chute is arranged within the drum beneath the upper limit of the
magnetic field, and leads therefrom to a point exterior to the drum. The material
to be treated is fed in at one end of the drum and caused to travel, preferably by
gravity, towards the other end as the drum rotates. During such travel, those
portions of the ore or other material which are susceptible to magnetic action are
attracted outwards towards the magnetic poles and are thereby held against the
inner surface of the drum, rising with it in rotation until they reach the upper
limit of the magnetic field which overhangs the chute. As soon as that portion of
the drum against which they have been held moves past said limit, they drop off
from the inner surface of the shell into the chute and are removed, preferably by
gravity, to any desired receptacles.
Other features of our invention relate to means whereby differences of energy
may be produced in different parts of the magnetic field for the purpose of effecting
a graded separation of the material.
In the accompanying drawings,
Figs. 1, 2 and 3, represent a simple type of the apparatus embodying our
invention Fig. 1 being a side view thereof; Fig. 2 an end view thereof, and
Fig. 3 a vertical longitudinal section on a plane passing through the centre of the
drum.
Figs. 4, 5, 6 and 7 represent a more highly organized type of apparatus,
operating upon the same general principle as the simpler one, but admitting of a
greater range of variation in the magnetic energy at different parts of the field.
Fig. 4 represents a side view of such modified apparatus; Fig. 5 is an end view
thereof; Fig. 6 is a longitudinal vertical section on a plane passing through the
centre of the drum, and Fig. 7 is a detail view in diagrammatic form, illustrating the
system of circuits which we employ to obtain the desired range of variation in
the magnetic field.
Referring now to the simple form of apparatus which is shown in Figs. 1, 2 and 3,
we will proceed to describe the same in detail.
Referring to the drawings, A represents a rectangular open frame-work, which
is preferably tilted or inclined, as a whole, upon its supports B. Within said
frame is mounted the separating drum, which in the present instance is a hollow
cylinder C, supported and driven as follows:
Around its periphery at one end is a projecting annular flange, D, provided with
half-shrouded gear teeth, d, which engage with the similarly half-shrouded teeth of
a pinion, D', mounted upon a driving shaft, F. Guide rollers, E and E¹, mounted
upon the frame A, and having peripheral grooves adapted to receive the projecting

page_text: portions of the teeth d, receive and support the flange D. At the other end of the
cylinder an annular flange, «, extends around the periphery, and is received and
guided by flanged rollers E, E and E. The cylinder is thus freely supported for
rotation, but endwise movement is prevented by the engagement of the flanges D
and c with their respective guiding rollers.
The wall or shell of the cylinder should of course be of such a character as not
to substantially interfere with the formation of a magnetic field throughout a
portion of its interior by the stationary exterior magnet. When the cylinder wall
is constructed of substantially non-magnetizable material, practically none of the
lines of force which go to make up the magnetic field are cut off by interposition of
the wall. If, on the other hand, the material of the wall be magnetizable, it will
cut off as many lines of force as it is capable of retaining and will thus divert them
from the interior of the cylinder. It is therefore necessary, where a magnetizable
material is used for the wall or shell of the cylinder, to employ a magnet of energy
more than sufficient to magnetically saturate so much of the wall as would
otherwise interfere. In such case the surplus lines of force will be projected into
the interior of the cylinder and will produce the necessary field, the interposed wall
being, when saturated, substantially non-interfering so far as such surplus is
concerned. Hence, while we prefer to use non-magnetizable material, such as
wood or brass, for the wall of the cylinder, (because we thereby are enabled to use
a magnet of less energy), we do not limit ourselves to the employment of such
materials, and when in our claims we use the expression "substantially non-
interfering to describe the nature of the wall, we mean that it is of such a
character with reference to the energy of the exterior magnet as to be incapable of
retaining within itself, or cutting off, the whole of the lines of force which that
magnet is capable of projecting.
"
Adjacent to that side of the cylinder at which the driving shaft is situated, and
which for convenience will be termed the front, is arranged a powerful magnet
which is preferably constructed as follows:
Within a stout frame-work, I, mounted upon the frame, A, is rigidly mounted a
horizontal horse-shoe electro-maguet, J, a portion of whose coils are indicated at G,
the terminals,, ', being connected with a dynamo, or other suitable generator of
electricity. To the ends of the horse-shoe are secured wrought iron plates, H
and H, of arc-shaped section, each one of which envelops substantially a semi-
circle of the cylinder's periphery, the two plates together extending substantially
the whole length of the cylinder, and in close proximity to its exterior. These
plates may be reinforced, if desired, throughout a portion of their are, by means of
short backing plates, h, h', or they may be otherwise stayed or maintained in
position relatively to the cylinder. The plates H and H' thus constitute enlarged
poles of the magnet, closely enveloping substantially one-half of the exterior
periphery of the cylinder and capable of acting through its shell upon magnetizable
substances within it.
An inclined chute, K, runs through the interior of the cylinder beneath the
upper limit of the magnetic field. A diaphragm, K', extends across the chute a
short distance above the bottom (as shown in the sectional view of Fig. 2) and runs
from the discharge end thereof to a point somewhat beyond the line of nearest
approach of the poles H, H, to one another, and a similar but shorter
diaphragm, K, extends across the chute above said first mentioned diaphragm,
running from the discharge end of the chute to a point somewhat short of said line
of approach of the poles. Thus in fact three separate chutes are provided, each of
which receives material from a different longitudinal part of the cylinder and
communicates with a separate receiver, as indicated at k, k, k², respectively.
A delivery chute, M, for the ore, O, leads to the higher end of the cylinder, and
a discharge chute, N, for the refuse leads from the lower end of the cylinder.
The operation of the apparatus is as follows:
The driving shaft, F, being suitably actuated, the cylinder rotates, and the ore
or other material, which is fed in at a proper rate of speed, travels along the inner

page_text: surface. The magnet being energized, the enlarged poles thereof, H, H', create a
strong magnetic field throughout the proximate portion of the interior of the
cylinder, and the richer ores, or portions of material susceptible to magnetic
influence are held, (the refuse dropping to the bottom) until in rotating they reach
the upper limit of the magnetic field, whereupon they fall into the chute K.
The refuse finally works to the lower end of the cylinder and is discharged into
the chute N.
The strongest part of the magnetic field will be a semi-circular band; or belt,
adjacent to the line intermediate between the edges of the two poles, H, H', and
by reason of this increase in the intensity of the field, the portions of the ore least
susceptible to magnetic influence (and therefere presumably less rich) will be
retained there, even though they have previously passed through the less intense
part of the field without detention.
-
The arrangement of the diaphragms, K1, K2, is such that the ore which has been
retained in the central part of the cylinder drops upon the diaphragm, K, and
passes off to a separate trough, k, the second diaphragm, K2, receiving that part
of the ore which is detained in the field beyond the belt of greatest intensity,
and discharging it into a third trough, k, the three troughs leading to distinct
receivers.
We will now proceed to describe the more highly organized form of apparatus,.
shown in Figs. 4, 5, 6 and 7, the letters of reference hereafter mentioned applying
only to those figures and not to Figs. 1, 2 and 3.
A represents a rectangular frame-work, preferably inclined or tilted as a whole,.
upon its supports B. C represents the separating drum rotatably mounted within
the frame in the following manner:
Around the periphery of the drum at one end is a projecting annular flange, D,
having half-shrouded radial teeth, d, which engage with the similarly half-shrouded
teeth of a pinion, D', mounted upon the driving shaft F. Guide rollers E,
mounted upon the frame, A, and having peripheral grooves adapted to receive the
projecting portions of the teeth, d, are arranged in contact with the flange, D, at
diametrical points, as shown particularly in Fig. 5.
At the other end of the drum
an annular flange, c, extends around the periphery and is received and guided by
means of the flanged rollers, E', E, E. The drum is thus freely supported for
rotation, but endwise movement is prevented by the engagement of the grooved
rollers with the flange, c, and the toothed portion of the flange D. An inlet
chute, M, for the ore or other material leads to the upper or receiving end of the
drum.
Along the side of the drum which is to the right in Fig. 5, and which for
convenience we term the front, are grouped the stationary electro-magnets whose
fields embrace preferably a semicircle of a vertical diameter. These magnets in
the instance shown are three in number, and each of them consists of a pair of
parallel U-shaped plates, with their inner edges facing the exterior of the drum,
their entire outer edge being backed and connected by means of a flat U-shaped
band, so that the cross-section of the plates and the connecting band is also
U-shaped..
In Fig. 6, L represents the backing or connecting band, and T, t, the plates
of the magnet which are nearest to the receiving end of the separator, and
which we term the first magnet.; L' represents the band and T, t, the plates
of the central magnet, and L2, T2 and 3; represent respectively the band and the
plates of the magnet which are nearest to the discharging end, which we term
the last magnet. The three. magnets are held in position by bolts, a', a2 and as,.
which pass through the transverse strips, A', A2 and A³, respectively, and are.
secured to the bands, L, L' and L² of the respective magnets.
"
The energizing coils of these magnets are wrapped around each of the plates.
lengthwise and follow the U-shaped contour thereof, exposing only the inner edge
of the plate. Each magnet is therefore a shallow but very wide horse shoe, whose.

page_text: respective poles are U-shaped, extending the whole length of the inner edge of
cach plate.
:
To permit of variation in the energy of the different magnets, for the purposes
which will be hereafter described, we divide the coils of the first magnet into five
groups, as shown in the diagrammatic view of Fig. 7, where N represents that
group which is nearest to the pole or inner edge of the plate T N', the next
group, N, the third group, N³, the fourth group, and N, the fifth group, or the
one most remote from the pole. The other plate or leg, t, of the magnet is provided
with similar groups, n, n², n², n³ and ', which correspond in position and number of
coils with the respective groups upon the leg T.,
Those upon
The coils upon the central magnet are divided into four groups.
the plate, T, being represented by P, P1, P2 and P3, respectively, whilst those
upon the other plate, &, are represented by p, p', p² and p³, respectively. The last
magnet has its coils divided into three groups. Those of the plate, To, being
indicated by Q, Q', and Q, while the corresponding ones upon the plate, ², are
indicated by q, q' and q².
The groups upon each magnet are, in the instance shown, connected in series,
as are also the three electro-magnets themselves; and in order to permit the
throwing into or out of circuit any desired number of the groups upon the respective
magnets, independent terminal wires lead to the main wire at points intermediate
between the several groups. These intermediate terminals for the coils of the first.
magnet are indicated by u, u³, u² and u³, whilst the main terminals thereof are
indicated by U and U
By means of a switch, O, adapted to connect with any one of the respective
terminal wires of the first magnet, the circuit can be limited to any desired number
of the groups upon the said magnet, since the group or groups beyond the contact
point to which the switch is, applied are of course cut out. The main terminals of
the central magnet are indicated by V, VI, the intermediate terminals by u, v, 2
and the switch by O'. The main terminals of the third or last magnet are indicated
by W, W', the intermediate ones by w, w', and the switch by 02.
The source of electricity is indicated at 0. The current may be either direct
or alternating. The circuit wires are respectively indicated at 03 and 05.
The capacity for variation of magnetic energy is greatest in the first magnet, and
least in the last magnet, the capacity of the central magnet for variation being
intermediate between the two.
We prefer also that when all three of the magnets are energized to their fullest
extent, the last magnet should be the most powerful, the central magnet next in
power and the first magnet the one of least power.
Within the drum C, are three delivery chutes, K, K and K, arranged at
different levels, but in line with the upper limit of the magnetic field, and leading,
as shown in Fig. 6, from different longitudinal points. The chute K extends from
the receiving end of the drum entirely to the delivery end; the chute K' extends
from a point intermediate between the first and second magnets and leads out to the
delivery end, overhanging of course the corresponding portion of the chute K;
while the chute K³ extends from a point intermediate between the second and third
magnets to the delivery end and overhangs a corresponding portion of the chute K¹.
Thus the ores or other materials which drop from the drum at the upper limit of
the magnetic fields are segregated in accordance with the field from which they
fall, the purpose of such division being to effect a graded separation, capable of
variation through the control established over the respective magnets.
Thus, if the first magnet has one or more of the groups of its coils cut out of
circuit, so as to reduce the energy of its field, only the richest ore will be held
within this field and fall into the chute K. If the central magnet be energized to
a degree intermediate between the first and last magnets, ores of the next degree
of richness (or not sufficiently susceptible to have been arrested by the first magnet)
will be retained in the central portion of the drum and will fall into the chute

page_text: The field of the third magnet, which is energized to the fullest extent, should be
sufficiently powerful to arrest all the remaining poorer portions of the ore and to
ensure their discharge into the chute K*.
Having thus described our invention we wish it to be understood that while we
have specified the use of a single horse shoe magnet as the simplest type of our
invention, and while in some of our claims hereinafter made we employ the word
magnet to indicate the source of magnetic energy, we are not to be understood as
limiting our invention to one such device, but we use the term in a sense broad
enough to include any number of inagnets, and any grouping or arrangement of
their poles relatively to the separating drum which is capable of producing sub-
stantially the results above described. Furthermore, in the system illustrated in
Figs. 4, 5, 6 and 7, we have represented a very complete embodiment of our
invention, in that the coils of each of the three magnets are divided into groups as
above described, so as to present a very wide range of possible variation, but it must
be understood that we do not limit ourselves to the particular arrangement shown,
since other and equivalent methods of varying the energy in the different fields
may be resorted to for the same purpose and with a like result; such for instance,
as employing separate sources of electricity for the magnets respectively, and
varying the currents thereof, or, in fact, employing any of the well known devices
whereby fields of different energy may be produced. Again, whilst we have
indicated the entire frame-work of the apparatus as inclined or tilted, that being
the preferred form, it is obvious that this detail of construction can be varied
without changing the principle of operation, provided the proper means be employed
for causing the gradual travel of the ore or other material through the cylinder as
the latter rotates.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manuer the same is to be performed, we declare that what we
claim is:
1. The combination of a rotatable hollow drum, having a substantially non-
interfering wall, a stationary magnet whose poles closely envelop a portion of the
exterior periphery of said drum, and a chute arranged within the drum, beneath
the upper limit of the magnetic field, substantially as set forth.
2. The combination of a rotatable hollow drum, having a substantially non-
interfering wall, a stationary magnet having enlarged arc-shaped poles which closely
envelop a portion of the exterior periphery of said drum, and chutes arranged
within said drum, beneath the upper limit of the magnetic field and leading from
different points in the length thereof, whereby the ores detained in different parts
of said field may be separately delivered, substantially as set forth.
3. The combination of a rotatable hollow drum, having a substantially non-
interfering wall, and having annular flanges around its ends, one of which flanges is
provided with gear teeth, a driving pinion engaging with said teeth, guide rollers
engaging with said flanges, a stationary magnet whose poles closely envelop a
portion of the exterior periphery of said drum, and a chute arranged within said
drun beneath the upper limit of the magnetic field, substantially as set forth.
4. The combination of a rotatable hollow drum, having a substantially non-
interfering wall, with a plurality of stationary electro-magnets, a plurality of
chutes respectively extending from beneath the upper limits of the several fields to
different delivery points. and means substantially as set forth whereby the energy
of the fields of one or more of the magnets may be varied, as and for the purpose
specified.
Dated this 8th day of March 1992
CARPMAEL & Co.,
Agents for the Applicants