Improvements in Magnetic Separators.
Year: 1891

page_text: Date of Application, 3rd Sept., 1891
Complete Specification Left, 31st May, 1892-Accepted, 9th July, 1892
PROVISIONAL SPECIFICATION.
Improvements in Magnetic Separators.
I, THOMAS WILLIAM ARNALL, of 166 Victoria Road Aston near Birmingham
in the County of Warwick Civil Engineer do hereby declare the nature of this
invention to be as follows:-
The object of this invention is to apply to machines used for the purpose of
removing magnetic bodies and particles from other bodies and generally called
"magnetic, separators," the principle of induced magnetism and thereby to increase
the efficiency of the machines by causing the electro-magnets generally used to be
always in action; to avoid the necessity of having to "make and break" the
electric circuit energising them and to simplify and improve generally the electrical
parts of the apparatus.
It is well known that when a piece of soft iron is brought within the influence of
a magnet (which I will call the "inducing magnet") it becomes for the time being
a magnet and capable of attracting magnetic substances and that it loses its
magnetic properties (more or less completely) on being taken away from the
influence of the inducing magnet.
It is pieces of soft iron temporarily magnetized in this way which I use for
actually effecting the separation of magnetic particles from the materials containing
them.
't be "
The invention can be carried out in several ways: for instance :- In a barrel
separator (in which the materials to be separated are passed through a hollow drum
revolving round an inclined axis) I fix outside the drum, but just clear of it, a
series of magnets preferably electro-magnets, extending along the bottom part of
the drum and round on one side thereof to the extent of about one half of the
circumference. These electro magnets may be of any convenient shape but the
poles thereof extend in circumferential lines around part of the drum, the lines
being of north and south polarity alternately each line being either of all north or
all south polarity. The drum revolves just clear of the surfaces of these poles, and
is made of some non-magnetic material such as brass or wood. Inserted in rings
around the drum are a number of pieces of soft iron, the outer ends of these pieces
being on the outer surface. of the drum and carried round by it over the lines of
north and south poles aforementioned and the iuuer ends thereof project through to
the inner surface of the drum. As the drum revolves each of these pieces of iron
becomes a magnet during the time it is being carried over one of the poles or series
of poles of the electro magnets placed outside and is thereby rendered capable of
attracting to itself any pieces of magnetic material it meets with on the inside
of the drum: it continues a magnet until it arrives at or near the top of the cylinder,
where the electro magnets outside cease, it then loses its magnetic properties and the
attracted particles fall off or may be brushed or scraped off into any convenient
receptacle for carrying them away.
11.
111
In order to facilitate the flow of the lines of magnetic force over the interior
surface of the barrel the inner ends of the pieces of soft iron may be furnished with
plates or extensions of iron bringing the respective north and south poles nearer
together on the inside of the barrel than any other parts of the magnetic circuit
may be outside the barrel and so that the magnetic resistance is less through the
interior of the barrel than through any other path. By this device the magnetic
leakage (ie. the lines of force passing from pole to pole without passing into the
interior of the barrel where alone they can do useful work) will be reduced to
a minimum and the efficiency of the machine correspondingly increased.
In order to reduce the tendency of the pieces of soft iron in which the magnetism

page_text: is induced to become permanently magnetized the direction of the current circu-
lating in the coils of the electro magnets may be reversed at intervals, and at each
reversal the direction of the magnetism induced in the pieces of soft iron will be
reversed also and any tendency they, may have to acquire a permanent magnetism
will be checked.
a
Or otherwise the same means may be obtained thus: Beyond the end of each
line of the inducing magnets on the outside of the barrelvL placeta magnetic pole of
the opposite kind i.e. beyond the end of each line of north polar magnetism place
a south pole and beyond the end of each line of south polar magnetism I place
north pole, and so, immediately after each piece of soft iron carried round by the
barrel has passed beyond the place where its induced magnetism should be lost,, for
a short time it comes under the influence of a pole of the opposite kind to that
which previously influenced it and so any tendency it may have to acquiring a
permanent magnetism will be checked seeing that its magnetic state will be reversed
once during every revolution. This "de-magnetizing pole" as it may be termed,
would be made by the same current as that which excites the main electro
magnets.
In cases in which the material from which the iron has to be separated is carried
along by a belt, or made to pass over an inclined plane, or along a trough or shoot,
I fix the revolving drum carrying the pieces of soft iron in which the magnetism is
induced over the belt, inclined plane, trough or shoot, as the case may be, and place
the inducing magnets inside the revolving drum; the magnetic particles in this case
will be attracted to the outside of the drum and collected from the surface thereof
into a trough or other convenient receptacle when removed from the influence of
the inducing magnets. Or otherwise the pieces of soft iron in which the magnetism
is induced may be carried by a band or belt or by a rotating disc, under the inducing
magnets and over the materials in which the magnetic particles are contained, and
being carried along clear of the said materials and beyond the influence of the
inducing magnets may be collected into a convenient receptacle or shoot for
removal.
Dated this 2nd day of September 1891.
THOMAS WILLIAM ARNALL,
Per J. J. Raggett, Agent.
COMPLETE SPECIFICATION.
Improvements in Magnetic Separators.
11..
I, THOMAS WILLIAM ARNALL of 166 Victoria Road, Aston, near Birmingham
in the County of Warwick, Civil 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 and illustrated by the
accompanying drawings :-
The object of this invention is to apply to machines used for the purpose of
removing magnetic bodies and particles from other bodies, and generally called,
"magnetic separators" the principle of induced magnetism and thereby to increase
the efficiency of the machines by causing the electro magnets generally used to be
always in action; to avoid the necessity of having to "make" and "break" the
electric circuit energising them, and to simplify and improve generally the electrical
parts of the apparatus.
It is well known that when a piece of soft iron is brought within the influence
of a magnet (which I will call the "inducing magnet") it becomes for the time
being a magnet and capable of attracting magnetic substances and that it loses its
magnetic properties (more or less completely) on being taken away from the
influence of the inducing magnet. It is pieces of soft iron temporarily magnetised
in this way which I use for actually effecting the separation of magnetic particles
from the materials containing them.

page_text: The invention can be carried out in several ways: for instance :-In a barrel
separator (in which the materials to be separated are passed through a hollow
drum revolving round an inclined axis) I fix outside the drum, but just clear of it,
a series of magnets preferably electro magnets extending along the bottom part
of the drum and round on one side thereof to the extent of about one half of the
circumference. These electro-magnets may be of any convenient shape but the
poles thereof extend in circumferential lines around part of the drum. the lines
being of north and south polarity alternately each line being either of all north or
all south polarity. The drum revolves just clear of the surfaces of these poles, and
Inserted in rings
is made of some non-magnetic material such as brass or wood.
round the drum are a number of pieces of soft iron, the outer ends of these pieces
being on the outer surface of the drum and carried round by it over the lines of
north and south poles aforementioned and the inner ends thereof projecting through
to the inner surface of the drum.
As the drum revolves each of these pieces of iron becomes a magnet during the
time it is being carried over one of the poles or series of poles of the electro magnets
placed outside and is thereby rendered capable of attracting to itself any pieces of
maguetic material it meets with on the inside of the drum, it continues a magnet
until it arrives at or near the top of the cylinder where the electro-magnets outside
cease; it then loses its magnetic properties and the attracted particles fall off or
may be brushed or scraped off into any convenient receptacle for carrying them
away.
In order to facilitate the flow of the lines of magnetic force over the interior
surface of the barrel, the inner ends of the pieces of soft iron may be farnished with,
plates or extensions of iron bringing the respective north and south poles nearer
together on the inside of the barrel than any other parts of the magnetic circuits
may be outside the barrel, and so that the magnetic resistance is less through the
interior of the barrel than through any other path.
By this device the magnetic leakage (i.e. the lines of force passing from pole to
pole without passing into the interior of the barrel where alone they can do useful
work) will be reduced to a minimum and the efficiency of the machine corre-
spondingly increased.
In order to reduce the tendency of the pieces of soft iron, in which the magnetism
is induced, to become permanently magnetised; the direction of the current
circulating in the coils of the electro-magnets may be reversed at intervals and at
each reversal the direction of the magnetism induced in the pieces of soft iron
will be reversed also, and any tendency they may have to acquire a permanent
magnetism will be checked.
Or otherwise the same means may be obtained thus:-Beyond the end of each
line of the inducing magnets on the outside of the barrel I place a magnetic pole
of the opposite kind; i.e. beyond the end of each line of north polar magnetism I
place a south pole and beyond the end of each line of south polar magnetism I place
a north pole and so, immediately after each piece of soft iron carried round by the
barrel has passed beyond the place where its induced magnetism should be lost for
a short time it comes under the influence of a pole of the opposite kind to that which
previously influenced it, and so any tendency it may have to acquiring a permanent
magnetism will be checked seeing that its magnetic state will be reversed once
during every revolution. This "demagnetising pole" as it may be termed would
be made by the same current as that which excites the main electro magnets.
In cases in which the material from which the iron has to be separated is carried
along by a belt, or made to pass over an inclined plane or along a trough or shoot,
I fix the revolving drum carrying the pieces of soft iron in which the magnetism is
induced over the belt, inclined plane trough or shoot as the case may be and place
the inducing magnets inside the revolving drum; the magnetic particles in this
case will be attracted to the outside of the drum, and collected from the surface
thereof into a trough or other convenient receptacle when removed from the
influence of the inducing magnets; or otherwise the pieces of soft iron in which

page_text: the magnetism is induced may be carried by a band or belt or by a rotating disc
under the inducing magnets and over the materials in which the magnetic particles
are contained, and being carried along clear of the said materials and beyoud the
influence of the inducing maguets may be collected into a convenient receptacle or
shoot for removal.
In order that the invention may be fully understood a magnetic separator of the
revolving barrel type constructed according to the invention is shewn on the
accompanying drawing. Fig. 1 is a transverse section through the machine on
the line A B and Fig. 2 a longitudinal section through the centre line or axis.
. a. a. is the framework of the machine, here shewn as constructed of wood:
bis the "inducing magnet," an iron casting with projecting circular ribs c. c. c.
on the inside, and on which are wound and properly secured the magnetising
coils d. d. d.
.
The direction of the electric current in these coils is so arranged as to make the
ribs c. c. c. present alternately north and south polarity on the inside to the revolving
barrel e.
This is shewn constructed of wood with two angle iron rings f. f. on the outside
the rings act as tyres or hoops to the barrel and they also serve as bearing surfaces
to rest on the rollers g. g. which support the weiglit of the barrel and its contents:"
Other rollers h. h. are fixed at a higher level to afford lateral support to the
barrel. One or both of the roilers g. g. which support the weight may be utilized
to drive the barrel by frictional contact or the barrel may be driven by any other
well known method. The pieces of soft iron which are carried by the barrel and
in which magnetism is induced are shewn at iii; they may conveniently take the
form of ordinary bolts as shewn in the drawing, with the heads outside, and the
screwed parts and nuts inside the barrel. These bolts also fix to the inside of
the barrel the square shaped pieces of ironjjj which serve as polar extension to
the magnetised bolts and facilitate the flow of magnetic lines into the interior of the
barrel. The bolts are fixed in rings round the barrel, and so that as it revolves
each line of bolts will travel over but just clear of one of the circular ribs e of the
inducing magnet. k is an inclined trough or shoot or other device for catching the
magnetic material which has been separated by the machine and conveying it away
to some convenient receptacle l. m is another receptacle into which falls the
material which is non magnetic.
The action of the machine is as follows:-*
}
The material to be separated is fed from the hopper n. into the interior of the
barrel; as, this revolves the material rolls over and over and down the inclined
surface, every part of it coming into contact with one or other of the bolts i. i.'
or their flat polar extensions:jj which on the lower part and on the rising side of
the barrel are in a magnetic condition.
:
.
[
The magnetic bodies or particles adhere to the magnetised bolts or their polar
extensions and are carried up until the heads of the bolts on the outside of the
barrel pass beyond the end of the magnetic rib c. of the inducing magnet and its
magnetising coils here the bolts and their polar extensions lose their magnetism
and the magnetic material that has been adhering to them falls off into the shoot:
or apparatus to be collected in the receptacle 1. In the meantime the non-
magnetic material has been rolling and tumbling over the bottom of the barrel
and finally falls out into the receptacle m.
'
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. In magnetic separating machinery for separating magnetic from non-magnetic
materials. The use of moving masses of soft iron in which magnetism is temporarily
induced by fixed magnets for the purpose of separating the magnetic from the
non-magnetic portions substantially as hereinbefore described and illustrated by the
accompanying drawings.

page_text: 2. A magnetic separator consisting of the parts arranged and combined sub-
stantially as hereinbefore described and illustrated by the accompanying drawings.
Dated this 30th day of May 1892.
THOMAS WILLIAM ARNALL,
Per J. J. Raggett, Agent.