Improvements in Crushing and Grinding Mills.
Year: 1895

page_text: Date of Application, 30th Nov., 1895
Complete Specification Left, 28th Aug., 1896-Accepted, 24th Oct., 1896
Improvements in Crushing and Grinding Mills.
I, WILLIAM HENRY COWARD, of Hastings Villa, Bexley Road, Erith, in the
County of Kent, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in the crushing or pulverizing mill known
as the Niagara Mill, which consists of a drum revolving on a horizontal axis and
having an edge runner rolling therein. Heretofore the motion of the edge runner
has been derived from the rotation of the drum with which it was in mere rolling
contact, the roller and drum having the same surface speed.
It has also
The present invention has for its object to produce a grinding or rubbing action
as well as a crushing action by causing the roller and drum to revolve at different
surface speeds, and to enable their relative surface speeds and the distance between
their acting surfaces to be varied to suit the material operated on.
for object to increase the efficiency of the grinding surfaces; to provide improved
means of conveying the material to, and repeatedly passing it beneath, the crushing
roller; to increase the area of the gauge plate used when the crushed ore is to be
concentrated; and to ensure the return to the drum of the grosser particles which
may be carried off with the blast when the gauge plate is not used.
To impart different surface speeds to the drum and roller, so as to produce a
grinding action, both the drum and roller are driven positively and are geared
together through gearing so proportioned that the surface speed of the drum will
differ considerably from that of the roller, being either greater or smaller according
to circumstances, the variation of the relative speed of the roller and drum being
provided for by means of change wheels.
The grinding drum has hollow trunnions of large diameter at each side which
rest on two sets of supporting rollers mounted on the drum driving shafts which are
supported in bearings situated between the two sets of supporting rollers. The one
set of rollers has gear wheels combined with them which mesh with a ring of teeth
on the trunnion, and the shafts are driven from the shaft of the grinding roller
through gear wheels, which may be changed to vary the relative speeds of the
drum and roller. The shaft of the grinding roller is mounted near its outer end in
a sleeve supported in a ball and socket bearing so as to accommodate the angular
rising and falling motion of the shaft under the variations of work, the shaft being
provided at its outer end with a driving pulley and being loaded at a point near
the grinding roller by a spring whose stress is regulated by means of adjusting
screws. The spring bears on a die-block bearing which is movable in vertical
guides and rests on a stop adjustable by means of a screw and nut-operating worm
gear whereby contact of the roller with the drum is prevented, and the distance
between them regulated. The periphery of the grinding and crushing roller is
formed with circumferential V-shaped ribs or corrugations so as to increase the
area of the grinding surface and improve the grinding action by the obliquity of
the surfaces, and the grinding surface of the drum is similarly ribbed or
corrugated to correspond.
The grinding roller is constructed of a corrugated rim cast in one piece and of
two cheek-plates, one of which is formed on a hub, the plates having bevelled edges
received in corresponding seats in the rim and united by bolts. The grinding
surface of the drum is formed by a lining made in segments and held between

page_text: dove-tailed gib-flanges formed in the drum, a gate being formed at one point by a
segment of the gib-flange at one side being removable so as to admit of the sections
of the lining being introduced and then slid round into position between the gibs,
the last segment of the lining introduced being fixed circumferentially by set
screws passed through the removable segment, thus preventing a circumferential
movement of the entire lining relatively to the drum, the removable side cover of
the drum serving to hold the gate segment in place laterally.
The sides of the drum are provided with the usual cups by which the material
that has passed beneath the roller is lifted for the purpose of being repeatedly
subjected to the crushing and grinding action. The material to be ground is fed
to the machine in the first instance by a screw-conveyor which may be driven from
the grinding roller shaft by an endless chain. This screw conveyor works in a
trough that passes through a stationary disc cover by which the trunnion at that
side of the drum is closed, the trough projecting completely across the drum and
having an outlet situated over the grinding roller towards the ingoing or front side
thereof. The trough is V-shaped and of considerable breadth so as to admit of
the material being readily shovelled or dumped into that part of the trough which
is outside of the cover, one side of the trough being extended upwards so as to
form within the drum a shoot on to which the material that is raised by the cups
falls in order that it shall be conveyed over the grinding roller to the front side
thereof to be again subjected to the grinding action. A supplementary shoot
supported at a certain distance below this part of the trough and extending
upwards between the two series of cups nearly to the periphery of the drum,
catches the material that first falls from the cups and delivers it on to the top of
the grinding roller which by its rotation carries the material over to the front side
thereof. By this means the material raised by the cups which would fall and
accumulate behind the grinding roller, is at once carried over the latter to the feed
or ingoing side so that the whole of the material is continually subjected over and
over again to the grinding action, which therefore takes effect in a uniformly
progressive manner upon the whole contents of the drum. The cups at the one
side of the drum are attached directly thereto, whilst the cups at the opposite side
are held at a certain distance from the side of the drum by tubular distance pieces
through which the fastening bolts pass, this side of the drum being made slightly
conical for a purpose hereafter mentioned. The drum is provided with a conical
outlet tube leading to the inlet of an exhaust fan by which a blast is drawn through
the drum to carry off from the falling shower of material the particles which have
been ground to a sufficient degree of fineness. The conicity of this outlet tube is
such that any of the grosser particles which may be carried off and fall out of the
blast before reaching the fan will run back down the outlet tube and be returned to
the drum.
The cups are made without backs and a loose annular backing plate is applied,
when the crushed and ground material is to pass directly to the fan without being
concentrated. When, however, the ore is to be concentrated this back is removed
and a perforated gauge plate introduced in its place. This perforated gauge plate
which covers the entire outlet from the drum, is only intended to be used when
the material is to pass at once to a concentrator which takes the place of the cone.
The gauge plate is clamped between the periphery and side of the drum and the
coned form of the side of the drum is intended to afford clearance behind the gauge
plate which forms the backing for the cups and thus has an area corresponding to
the full internal diameter of the drum. The fan receives motion through a
countershaft driven from a cone of pulleys on the shaft of the grinding roller
whereby its speed may be varied to suit the work.
The bearing of the roller shaft is a long sleeve, and in order to prevent leakage
of oil and clogging with dust, the bearing is continued through the cover nearly up
to the roller and a gasket packing is applied round the shaft between the end of
the bearing and the roller and is enclosed by a collar bolted to the latter. To.
prevent dust collecting in the trunnion and escaping at the aperture in the cover, a

page_text: dust guard is fixed to the inside of the cover, the upper part of the guard being
sloped so as to throw the dust inwards and the lower part which is close up to the
roller being apertured to allow of the passage and up and down play of the shaft
and bearing, the space between the dust guard and cover being loosely filled with
packing to prevent the escape of dust without impeding the play of the shaft. The
stationary cover has a flange fitting within the trunnion and together with the feed
trough is supported by the frame.
Dated this 30th day of November 1895.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
Improvements in Crushing and Grinding Mills.
I, WILLIAM HENRY COWARD of Hastings Villa, Bexley Road, Erith, in the
County of Kent, 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 :-
This invention relates to improvements in the crushing or pulverising mill known
as the Niagara Mill, which consists of a drum revolving on a horizontal axis and
having an edge runner rolling therein. Heretofore the motion of the edge runner
has been derived from the rotation of the drum with which it was in mere rolling
contact, the roller and drum having the same surface speed.
The present invention has for its object to produce a grinding or rubbing action
as well as a crushing action by causing the roller and drum to revolve at different
surface speeds, and to enable their relative surface speeds and the distance between
their acting surfaces to be varied to suit the material operated on. It has also for
object to increase the efficiency of the grinding surfaces; to provide improved
means of conveying the material to, and repeatedly passing it beneath, the crushing
roller; to increase the area of the gauge plate used when the crushed ore is to be
concentrated; and to ensure the return to the drum of the grosser particles which
may be carried off with the blast when the gauge plate is not used.
To impart, different surface speeds to the drum and roller, so as to produce a
grinding action, both the drum and roller are driven positively and are geared
together through gearing so proportioned that the surface speed of the drum will
differ considerably from that of the roller, being either greater or smaller according
to circumstances, the variation of the relative speed of the roller and drum being
provided for by means of change wheels.
Reference is to be had to the accompanying drawings, forming part of this
specification, wherein
Figure 1 represents a longitudinal sectional elevation of the improved crushing
and grinding mill, and
Figures 2 and 3 cross-sections on lines 2-2 and 3-3 respectively.
Figure 4 is a detail section shewing a few of the cups and the perforated gauge
plate which is used when the ore is to be concentrated.
Figure 5 is an axial section of the grinding and crushing roller shewing its
construction, and
Figure 6 is a detail face view (partly sectional) of the drum shewing the mode
of inserting and fixing the lining.
The same letters of reference denote like parts in all the figures.
The grinding drum A has hollow trunnions A' A³ of large diameter at each side
which rest on two sets of supporting rollers B B¹ mounted on the drum driving
shafts C which are supported in bearings D situated between the two sets of
supporting rollers B B₁. The one set of, rollers B¹, has gear wheels B* combined

page_text: with them which mesh with a ring of teeth E on the trunnion, and the shafts C
are driven from the shaft F of the grinding roller through gear wheels C¹, F¹,
which may be changed to vary the relative speeds of the drum and roller. The
shaft F of the grinding roller G is mounted near its outer end in a sleeve
supported in a ball and socket bearing F2, so as to accommodate the angular rising
and falling motion of the shaft F under the variations of work, the shaft being
provided at its outer end with a driving pulley H and being loaded at a point near
the grinding roller G by a spring I whose stress is regulated by means of adjusting
screws. The spring bears on a die-block bearing J which is movable in vertical
guides K and rests on a stop L adjustable by means of screw land nut-operating
worm gear M, whereby contact of the roller with the drum is prevented and the
distance between them regulated. The periphery of the grinding and crushing
roller G is formed with circumferential V-shaped ribs or corrugations so as to
increase the area of the grinding surface and improve the grinding action by the
obliquity of the surfaces; and the grinding surface of the drum is similarly ribbed
or corrugated to correspond.
The grinding roller G is constructed, as shewn in Figure 5, of the corrugated
rim g cast in one piece and of two cheek plates gl, one of which is formed on a
hub, the plates having bevelled edges received in corresponding seats in the rim
and united by bolts g³.
The grinding surface of the drum A is formed by a lining N made in segments
and held between dove-tailed gib-flanges n formed in the drum, a gate being formed
at one point by a segment n¹ of the gib-flange at one side being removable so as to
admit of the sections of the lining being introduced and then slid round into position
between the gibs, the last segment N' of the lining introduced being fixed
circumferentially by set screws n2 passed through the removable segment n' thus
preventing circumferential movement of the entire lining N relatively to the
drum A, the removable side cover N2 of the drum serving to hold the gate
segment n² in place laterally.
The sides of the drum A are provided with the usual cups 00', by which the
material that has passed beneath the roller G is lifted for the purpose of being
repeatedly subjected to the crushing and grinding action. The material to be
ground is fed to the machine in.the first instance by a screw conveyor P which
may be driven from the grinding roller shaft by an endless chain pas shewn. This
screw conveyor works in a trough Q that passes through a stationary disc cover R
by which the trunnion at that side of the drum is closed, the trough Q projecting
completely across the drum and having an outlet 9 situated over the grinding
roller G towards the ingoing or front side thereof. The trough Q is V-shaped
and of considerable breadth so as to admit of the material being readily shovelled
or dumped into that part of the trough which is outside of the cover R, one side
of the trough being extended upwards so as to form within the drum a shoot q' on
to which the material that is raised by the cups O O₁ falls in order that it shall be
conveyed over the grinding roller G to the front side thereof to be again subjected
to the grinding action. A supplementary shoot S supported at a certain distance
below this part of the trough Q and extending upwards between the two series of
cups OO¹ nearly to the periphery of the drum, catches the material that first falls
from the cups and delivers it on to the top of the grinding rolier G which by its
rotation carries the material over to the front side thereof. By this means the
material raised by the cups O O' which would fall and accumulate behind the
grinding roller, is at once carried over the latter to the feed or ingoing side so that
the whole of the material is continually subjected over and over again to the
grinding action, which therefore takes effect in a uniformly progressive manner.
upon the whole contents of the drum. The cups O at the one side of the drum
are attached directly thereto, whilst the cups O at the opposite side are held at a
certain distance from the side of the drum by tubular distance pieces through which
the fastening bolts pass, this side of the drum being made slightly conical, as
shewn, for a purpose hereafter mentioned. The drum is provided with a conical

page_text: outlet tube U leading to the inlet of an exhaust fan V by which a blast is drawn.
through the drum to carry off from the falling shower of material the particles
which have been ground to a sufficient degree of fineness. The conicity of this
outlet tube is such that any of the grosser particles which may be carried off and
fall out of the blast before reaching the fan will run back down the outlet tube U
and be returned to the drum.
The cups O are made without backs and a loose annular backing plate o is
applied, as shewn in Figure 1, when the crushed and ground material is to piss
directly to the fan without being concentrated. When, however, the ore is to be
concentrated this back o is removed and a perforated gauge plate T introduced in
its place, as shewn in Figure 4. This perforated gauge plate T which covers the
entire outlet from the drum, is only intended to be used when the material is to
pass at once to a concentrator which takes the place of the cone U. The gauge-
plate T is clamped between the periphery and side N2 of the drum and the coned
form of the side of the drum is intended to afford clearance behind the gauge plate.
which forms the backing for the cups and thus has an area corresponding to the
full internal diameter of the drum. The fan receives motion through a countershaft
driven from a cone of pulleys W on the shaft F of the grinding roller whereby its.
speed may be varied to suit the work.
The bearing J of the roller shaft F is a long sleeve and in order to prevent.
leakage of oil and clogging with dust the bearing is continued through the cover R
nearly up to the roller G and a gasket packing is applied round the shaft between
the end of the bearing and the roller and is enclosed by a collar bolted to the
latter. To prevent dust collecting in the trunnion and escaping at the aperture in
the cover R, a dust guard r is fixed to the inside of the cover, the upper part of the
guard being sloped so as to throw the dust inwards and the lower part which is
close up to the roller being apertured to allow of the passage and up and down
play of the shaft and bearing, the space between the dust guard r and cover R
being loosely filled with packing to prevent the escape of dust without impeding
the play of the shaft. The stationary cover R has a flange fitting within.
the trunnion A' and together with the feed trough is supported by the frame R¹.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The herein described roller mill consisting of a revolving drum having large
trunnions and lateral lifting cups, and of an edge runner or roller revolving therein,.
the drum being geared with and driven positively from the roller shaft and at a
different surface speed to that of the drum and the roller shaft being mounted in a
ball and socket pivotal bearing and in a vertically sliding spring-loaded bearing
provided with an adjustable stop, the grinding roller having a V-grooved periphery
and the drum having a correspondingly V-grooved internal grinding surface
constructed of segments held between dovetailed gibs, substantially as described.
2. The combination, with the roller mill constructed as described, of a feed
trough and screw-conveyor passing into the drum through the cover thereof, the
trough being formed as described so as to act as a hopper outside the drum and as
a shoot within the drum and of an under shoot attached below the trough and
passing up between the two sets of cups the double shoot thus formed being in
position to receive the material which falls from the cups and return it over the
grinding roller to the front thereof as described.
3. In the herein described roller mill the perforated gauge plate covering the
outlet from the drum and forming the backing of the cups at that side of the drum
with clearance between it and the side of the drum so that the area of the gauge
plate corresponds to the full internal diameter of the drum as specified.
4. In the herein described roller mill the combination of the packed joint for the
roller shaft bearing and of the dust guard preventing the access of dust thereto as
specified.

page_text: 5. In the herein described roller mill, the grinding roller constructed of a
complete annular rim and of two side discs having bevelled edges fitting in corre-
sponding seats in the rim and united by cross bolts so as to clamp the rim firmly
between them substantially as specified.
Dated this 28th day of August 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.