Improvements in Mills for Pulverizing, Crushing, and Grinding Ores, Hard Cements, and other Substances.
Year: 1898

page_text: Improvements in Mills for Pulverizing, Crushing, and Grinding
Ores, Hard Cements, and other Substances.
JOHN FREDERICK CREASE C.B., a Major General in the Army (retired) of Sion, near
Stourbridge, in the County of Worcestershire do hereby declare the nature of this
invention to be as follows:-
My invention relates to an improved mill in which the reducing action is obtained
by means of balls or their equivalent in a disc shaped mill rotating on an axle and
so constructed as to overcome the objectionable slowness of action which exists in
the rotating drum and cylindrical ball mills of ordinary type and small diameter such
as have heretofore been in use. The object of iny invention is to construct a mill
in which this objection is removed and which I accomplish by making the mill
itself in the shape of a narrow disc by this means concentrating the whole weight of
the grinding balls when the mill is being rotated with the narrow space between the
converging sides of the mill near to its circumference the crushing and pulverising
action of the halls when so placed being intensified by the fact that the outer
ones are thrown inwards by the converging sides of the mill towards its central
plane across the path of the inner central balls, which falling directly downwards
produce in combination with the others an amount of concentrated pulverising
and crushing power upon the material to be ground between then attainable by
no other method. The two sides of the mill, from 5 to 6 feet across, are hung
on an axle 2 to 3 inches in diameter one side being permanently fixed to it,
the other side so fitted as to be capable of being slid along it backwards and
forwards on a key projecting from the axle, so that when the axle rotates the
mill fixed on it rotates also. The sides of the mill when fixed in position are parallel
to each other for about 18 to 24 inches from the centre thence they taper to about
3 inches or less apart at the circumference terminating in a rounded edge
from which projects a flange 3 or more inches in depth perforated with a certain
number of bolt holes through which the two sides are bolted together by means
of bolts and nuts. Between the flanges and before they are bolted together I place
3 or 4 sections each consisting or 3 or more curved steel bars from 5 to 4 feet in.
length, of an inch in width, and 1 inch in depth which are riveted together side by
side with tapered steel wedges between them so as to have a space between their
inner edges of 3 or more of an inch and or more of an inch between their outer
edges. These groups of bars made as described are of such length as when butted
together will go completely round the circumference of the mill between the flanges,
and have when in that position their interior surfaces flush with the bottom of the
mill whilst their outer edges rest on the bolts which passing through. the flanges hold
the two sides of the mill together and which when screwed up fix these sections and
the sides of the mill firmly in position. These bar sections so placed thus form a sort
of grid attached to the circumference of the mill, through the openings in which
the material which is ground and pulverised in the mill find its way out of it.
Along the whole of the outer circumference of the mill, outside the grids, as
described, and on projections made for the purpose I fix 3 or more seives on whose

page_text: interior surfaces as the mill rotates the material being ground in it, falls, the
seives being so arranged that the coarser portions of the ground material which
do not pass through their meshes on to a collector beneath, settles towards their ends
each seive being provided at those points with a pipe or other suitable arrangement
fixed outside the mill through which the coarse material tumbles back into the feeder
which placed outside the mill feeds it through holes in the side of the mill made
close to the axle for the purpose. In order to strengthen the sides of the mill in the
vicinity of the axle which are weakened by the formation of these holes I have cast
on their interior surfaces and projecting 2 or 3 feet from the centre, ribs, of such
proportions as considered necessary. The mill is actuated by a cogged wheel or a
pulley cast on the moveable side of the mill or fixed on the axle separate from it as
found to be most expedient.
In some cases instead of allowing the coarser ground material which does not pass
through the seives to drop back into the mill feeder by means of the pipes outside
the mill I prefer to let it fall back into the mill itself between the butts of the grills
which in that case I space 6 inches or more apart and fix into the intervals between
them hollow bottomless iron boxes fitted with sloping caps over them which project
inside the mill in such a way that when the mill is rotated the balls and the material
being ground pass over them and also so that the coarse material collected in the
ends of the seives may tumble back through them direct into the mill.
In other cases where space is limited I do away with the external seive altogether
and let the ground material fall direct into an accumulator beneath the mill whence
I lift it by elevaters into a circular seive enclosed in a box, and placed in any
convenient position above the mill, it being so arranged that the coarse material
which does not pass through the seive is passed back through a wooden shoot into
the mill feeder and the finely ground powder which does come through the seive is
conveyed by another wooden shoot to be bagged off or dealt with in any other
way as thought desirable.
Dated this Eighteenth devre of Innil 1800
Improvements in Mills for Pulverizing, Crushing, and Grinding
Ores, Hard Cements, and other Substances.
I, JOHN FREDERICK CREASE, C.B., a Major-General in the Army (retired) of Sion,
near Stourbridge, in the County of Worcester, 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 an improved mill in which the reducing action is obtained,
by means of balls or their equivalent, in a disc shaped mill rotating on a shaft and
so constructed, as to overcome the objectionable slowness of action which exists in
the rotating drum and cylindrical ball mills of ordinary type and small diameter,
such as have heretofore been in use. The object of my invention is to construct a mill,
in which this objection is removed, by making the mill itself in the shape of a narrow
disc, by this means concentrating the whole weight of the grinding and crushing
balls, when the mill is being rotated, into the narrow space between the converging
sides of the mill near to its circumference, the crushing and pulverising action of the
balls, when so placed, being intensified by the fact, that the outer ones are thrown
inwards, by the converging sides of the mill, towards it central plane across the path
of the inner central balls, which falling directly downwards, produce in combination
with the others, an amount of concentrated pulverizing and crushing power, upon

page_text: the material to be ground between them, attainable by no other method. The two
sides of the mill are hung on a shaft one side being fixed, and the other
moveable along it, and the two sides are secured together by means of nuts and bolts
which pass through a flange, at the outer circumference of each side and which bolts
support on them, three curved grids made of steel bars riveted together and which,
when the mill is set up and bolted together, are in such position, that whilst their
inner surfaces coincide with the bottom of the mill, their outer surfaces rest on the
bolts, which passing through the flanges, hold the sides of the mill together. Between
the grids, whose ends butt on them, are placed three bottomless cast metal boxes,
fixed in position by means of bolts passing through the rear part of each and the
flanges of the mill to which they are attached, these boxes are so constructed, that
whilst all ground material can be made to pass inwards through them into the
mill, whilst it is in motion, from its outside, no material can pass outwards through
them from the interior of the mill, to the seives outside it. Bolted to the flanges
of the mill, along the whole of its outer circumference, are fixed three seive frames,
containing seives and constructed so as to receive all the ground material, which fall's
on to them from between the bars of the grids when the mill is in motion. The
seives are so arranged that they collect those coarse portions of ground material, not
sufficiently fine to pass through the seives themselves, on spots immediately opposite
to the bottomless boxes, through which, as the mill rotates, they fall back by the
action of gravity into the mill itself, to be further ground to the fineness
required.
In order that my said invention may be fully understood I proceed more
particularly to describe the same and for that purpose shall refer to the several figures
on the annexed sheets of drawings the same letters of reference indicating
corresponding parts in all the figures.
Section through centre of shaft.
SHEET 1.

page_text: pieces, bolted together, by means of bolts and nuts 1, l, l, to a flange at f.
Sheet 3 Fig. 6 hung on a shaft b one side c being permanently fixed to it by means
of a key e the other side c¹ being so fitted as to be capable by means of a feather e¹ of
being slid backwards and forwards along it, whenever necessary. When fixed in
position these sides are parrallel to each other for a foot from the centre of the mill,
this distance varying according to the size and the diameter of the mill. From this
point the two sides c, c¹ bend inwards towards each other at an angle of fifteen or
twenty degrees, the circumferences of each one terminating in a rounded edge
from which projects a flange two or more inches in depth; between these flanges
and before the mill is set up, by their being bolted together, are placed three curved
sections of tapered steel bars m, m, m, riveted together at certain points by counter
sunk rivets n, n, n, as shown on Sheet 3 Fig. 4 the tapered steel bars being separated
from each other, at those points, by four tapered 1½ inch long steel wedges o, 0, 0, 0,
of such dimensions as to make the bars, when riveted together, 3½ of an inch apart
on their inner edges and of an inch apart on their outer edges. These sections, so
made, form 3 grids which when placed in position around the circumference of the
mill, rest on the bolts h, k, k, k, which secure its two sides together; the inner sides
of the grids being then flush with the bottom of the mill and their ends m, m, m,
butting on 3 bottomless cast metal boxes p, p, p, Sheet 4 Fig. 7 which are
secured in the position shown on plan, by bolts k, k, k, which pass through the
solid back part of the boxes and the flanges around the circumference of the
mill. These boxes are furnished on their inner side with hollow caps p, p, Sheet 4
Fig. 7 and 8 so arranged that whilst no material can pass out through them from
the inside of the mill, whilst in motion, to its outer side, these boxes yet permit any
unseived portions of matter, which may be collected by the diaphragms in the seives,
to pass freely through them back into the mill. The two sides of the mill c cí
which I form of cast steel or iron are made thicker where they rest on the shaft
so as to secure, at those points, a good bearing for the sides of the mill and these
sides are further stiffened, by having cast on their interior surfaces, 4 ribs h, h, h, h,
Sheet 2 Figs. 2 & 3 which radiate from the central block and taper towards their
points. The moveable side c¹ is provided with a door, closed by a moveable
cover fixed to the side by means of bolts and nuts, and the fixed side c has cast
on it a ring r, Sheet 2 Fig. 3 to which is fixed the sheet iron revolving feed
box s Sheet 1, Fig. 1 from which the material, to be ground, passes into the
mill through the holes in the side j, j, j, Sheet 2 Fig. 3 provided for the
purpose.
On the flanges around the whole of the outer circumference of the mill I fix 3
circular shaped wooden frames y, y, y, Sheet 3 Fig. 4 and bolt them on, by means of
Into the outer circum-
bolts and nuts, to the flanges of the mill Sheet 4 Fig. 8.
ference of these frames are inserted moveable_seives. w, w, w, Sheet 5, Figs. 9,
10 and 11 secured in position by thumbscrews B, B, B, which, passing through the
sides of the seives, screw into metal sockets fixed in the frame beneath. Each of
the circumferential seive frames is provided at a point A, on its inside, with a sloping
worden diaphragm Sheet 2 Fig. 2 and Sheet 4 Fig. 7, which extends across each
seive frame, in such manner as to block each one entirely at that point. These
diaphragms are so placed, that their inner and smaller ends rest on the plates q, I, I,
which are fixed to the grids where they butt on the bottomless boxes on those sides
opposite to their solid ends. The shaft of the mill is supported on two bearings a a
Sheet 1 Fig. 1, placed on the top of two fixed pillars and is actuated by a driving
band on a pully d or by a cogged wheel fixed on the end of the shaft. From the
pillar opposite the fixed side of the mill, projects a sheet iron feed box t, supported
by an iron bracket u. This feed box is so made that its rim projects into the
revolving feed box s fixed on the side of the mill, in such manner that the material
which is passed into the feed box to be ground, will fall from it into the revolving
feed box on mill, without being permitted to escape from it, save through the three
holes in the side of the mill into the interior of the mill itself. The action of this
mill is as follows, a quantity of balls of various sizes from one inch to four inches in
0..:

page_text: diameter, or their equivalent, amounting in a mill of this size to an aggregate weight
of 2 cwts., having been placed in the mill, through the door in its side c', and the
door plate having been bolted on, the mill is set in motion. The material required
to be ground is then fed into the fixed feed box t and thence into the mill, the balls,
or their equivalent, in falling from P to Q. as the mill rotates, are forced in their.
descent, by the sloping sides of the mill, sidewise violently against those balls which
are descending towards its bottom in a line with a plane passing perpendicularly and
longitudinally through the centre of the mill, in this way, the matter which has to be
dealt with, is not only ground and pulverized between the balls, in their descent, and
the sides and the bottom of the mill, but it is also jammed violently between the
balls themselves, as they fall, in which way a crushing pulverizing and grinding
power is exercised far greater than is due to the weight and velocity of an equal
number of balls or their equivalent falling directly downwards in any rotating ⚫
cylinder with vertical sides and under ordinary conditions.
The material when ground or pulverized in the manner described, to a sufficient
fineness, falls, as the mill rotates, through the grids m m m on to the wire seives zzz
outside the mill. That portion of the ground material, which is sufficiently fine, then
falls through the seives into an accumulator beneath the mill and those coarser portions
which will not do so, roll along the interiors of the seives, as the mill rotates, until
brought up by the diaphragms in the seives and collected at the points A A A.* Still
falling as the rotary motion of the mill is continued, these coarser atoms fall into the
bottomless boxes ppp and thence through their inner openings back into the mill,
again to be reground and reseived until fine enough for the purposes required.
In some cases, according to my invention instead of making the sides C C¹ of cast
steel or iron I prefer to form each one of them of two or more inch steel plates
Sheet 6 Figs. 14 and 15 having brought (using on each side 2 plates) the edges of
these 2 plates together I fix them in that position by means of a steel butt strap D
which I place evenly over the joint between each of the two plates, and then rivet
these straps firmly to the plates in question at points E E E the two sides, so forined,
I then bolt on to a cast steel centre piece H at points G G G by bolts and nuts, the
steel centres being recessed on their interior sides at H H for the purpose of receiving
the plates in question. The feed box, which rotates with the mill, I fasten to it by
means of the angle lugs F F F F which are fixed at suitable points to the side of the
mill to receive it, in all other respects I make this mill simarly to that one already
described. In some cases, according to my invention, I prefer to dispense altogether
with the use of the bottomless boxes for passing back into the mill, from the circum-
ferential seives, the coarser material which will not pass through them.
In this case
I lengthen the 3 grids so as to allow their ends when in position, to butt together
instead of against the bottomless boxes and provide each seive, at the point where the
> coarser unseived material is collected by the diaphragmns A A A with a suitable metal
or wooden shoot which I lead from each of the 3 points A A A ont through the seive
frame and down the exterior side of the mill, in such manner, that the unseived
matter may fall through them direct into the fixed feed box outside the mill.
According to my invention, in some cases, I prefer, where space is limited, to do away
5 with the seives 2, w, yz, w, yz,, y altogether, allowing the ground material to pass
through the grids directly into an accumulator beneath the mill, whence I lift it by
an elevator, into a circular seive placed in a closed box at any convenient point above
the mill from this seive I lead the insufficiently ground material, which will not
pass through it, by means of a shoot back into the inill feed below, the finely ground
portions, which do pass through the seive I convey away by similar means to any con-
venient spot to be dealt with as deemed desirable.
Having now particularly ascertained and described the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
1. A narrow disc shaped mill rotating on a shaft in which the pulverizing grinding

page_text: converging sides of the mill, when in motion, are thrown violently inwards against
each other in their descent, thus causing and exercising a lateral as well as downward
pressure on the material being pulverized ground and crushed between them, and
between them and the sides and bottom of the mill.
2. In a narrow disc shaped mill, in which the pulverizing grinding and crushing
power is obtained by means of balls, or their equivalents, on the mill being rotated,
grids fixed round its circumference, whose ends butt on bottomless metal boxes,
together with circumferential seives arranged outside the mill, in such manner as to
cause the unseived material, remaining froin that delivered into the seives from the
mill through the grids, and which will not pass through the seives, to be returned
through the bottomless boxes, by gravity, back into the mill, to be again
ground.
3. The arrangements and combination of parts constituting narrow disc shaped
mills for pulverizing grinding and crushing ores hard cements and other substances
placed in them substantially as herein before described and illustrated in Sheet 1
Fig. Number 1. Sheet 2 Fig. Number 2 and Fig. Number 3. Sheet 3 Fig. Number 4
Fig. Number 5 and Fig. Number 6. Sheet 4 Fig. Number 7 and Fig. Number 8
Sheet 5 Fig. Number 9 Fig. Number 10 and Fig. Number 11 or modified mill as
described with regard to Sheet 6 Fig. Number 14 and Fig. Number 15.
Dated this Sixth day of January 1899
J. FRED. CREASE.