Improvements in and relating to Machines for Pulverizing Ores and other similar Substances.
Year: 1897

page_text: Date of Application, 20th Apr., 1897-Accepted, 22nd May, 1897
COMPLETE SPECIFICATION.
Improvements in and relating to Machines for Pulverizing Ores and
other similar Substances.
We, JACOB JONES STORER of Newton, Middlesex County, Massachusetts,
Loventor, FRANK MARTIN of Medford, Middlesex County, Massachusetts, Mining
Engineer, and GEORGE OSCAR EATON of the City, County and State of New
York, Mining Engineer, all in the United States of America, 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 :-
I
This invention is designed as an improvement on machines for pulverizing ores
and other substances, and its objects are to secure a finer comminution of ores and
other friable substances, to assure a more uniform fineness of the materials
pulverized, to prevent the delivery of coarse material from the machine, and to
more nearly equalize the work done in the separate pulverizing or working
chambers; also to better control the air supply and, in several minor points, to
improve the construction of the machine; all of which will be hereinafter fully
set forth.
The invention consists chiefly in increasing the diameters of the working
chambers and their respective spiders consecutively from the feed end of the
machine to the fan chamber, whereby, with equal axial speeds, the peripheral speed
of each consecutive spider is increased; and it also embraces improved devices for
the introduction and regulation of the air supply.
In the accompanying drawings similar letters of reference indicate corresponding.
parts in all the figures.
Figure 1 is a partly sectional, longitudinal elevation of our improved pulverizer..
Figure 2 is an elevation of the delivery end of the pulverizer cylinder.
Figure 3 is an elevation of the feed end of the pulverizer cylinder with
attachments.
Figure 4 is a sectional elevation of the cylinder on line xx, Figure 1, looking in
the direction of the arrow.
Figure 5 is a plan view on line Y Y, Figure 1.
Figure 6 is a perspective of the cap of the air-supply pipe.
Figure 7 is an elevation showing the clips fixed on the front of the hopper.
In the machine herein shown and described, the cylindrical shell A has its
working chambers B, C, D, of increasing diameters successively from the feed end
of the cylinder to the fan chamber E, as shown in Figure 1, these chambers being
separated from each other and the fan chamber by annular diaphragms a, b, c,
respectively.
The horizontal, revoluble shaft F has fixed upon it a driving pulley and four
spiders, each of which spiders consists of a hub d, having a number of radiating
arms f, secured upon it. Those spiders which revolve in the working chambers.
bave paddles g fastened on the outer extremities of the arms; while on the arms of
the spider revolving in the fan chamber plates h are secured, making it an exhaust
fan, whose function is to draw the dust-laden air through the axial openings in the
diaphragms between the chambers, and deliver or eject it through the peripheral
fan opening or spout G, shown in Figures 2 and 4.

page_text: The operation of the machine is as follows, viz. :
The shaft being put in revolution at a speed that will impart to the outer edges
of the paddles g. in the first chamber, and the fan-plates, in the fan-chamber, a
speed of about two miles a minute, the material to be pulverized is introduced into
the hopper H, whence it is fed by a revoluble feedscrew I into the feed chute K.
From the feed chute it falls through the axial opening i, in the cylinder head into
the first working chamber B, where it is struck by the first set of paddles, which
partly comminute it and, by the centrifugal action of the spider, throw it violently
against the inner periphery of the chamber. The outer edges of the paddles run
about an inch from the smooth concavity of the shell. The inflowing material
quickly fills the space between the paddle edges and the shell, forming a layer of
partly comminuted material which is held against the shell by the air-pressure
created by the rapidly revolving paddles, a pressure estimated to be about one
hundred pounds to the square foot. The belt of material between the paddles and
the shell is kept in grinding motion in the direction of the paddle-revolution by the
rotating air-current produced by the paddles, and by the impact upon and passage
through it of new material constantly fed to the paddles and thrown off from them
tangentially at great velocity. Under the combined influence of bombardment,
disruption and mutual attrition the material of the peripheral belt is rapidly crushed
and abraded, the resulting particles being small and spheroidal.
As the newly added coarser particles thrown off from the spider force their way
through the more comminuted material of the peripheral belt, the finer particles
thereof are forced inward toward the paddles until they are brought within the
influence of the vortices behind the paddles. Into these paddle-created vortices
the finer materials composing the inner face of the belt are drawn, to be whirled
about and still further reduced by mutual attrition until they are fine enough to be
carried by the axial air-current which is continuously drawn through the pulverizer
by the exhaust fan and the spiders revolving in the chambers C, D.
Of course some fine dust is produced by the first fracture of the entering material
when struck by the paddles in the first chamber; and these dust atoms, being too
light to be much affected by the centrifugal throw of the paddles, escape the rotary
air-current and are at once taken up and borne onward by the axial air-current.
Speaking generally, the primary comminution or reduction of the materials is
effected by impact and attrition in the space between the shell and the paddle
edges; the final and ultimate reduction is effected by attrition in the vortices
behind the paddles.
By the continuous axial air-current (the volume and force of which may be
regulated at will by the adjustment of the air-supply register L, and the counter
current register M), the finer particles of material are drawn away from the action
and influence of the paddles in the first working chamber, into the second chamber C,
by the action of whose higher speed paddles they are further comminuted; thence
they are carried by the axial air-current into the succeeding chamber D, where
pulverization to an almost impalpable powder is completed before the material is
drawn into the fan chamber to be expelled from the machine through its peripheral
exit pipe G.
Although all the air enters and leaves the working chambers axially, a portion
of it is diverted constantly, though temporarily, and is given a centrifugal motion
by the revolving paddles; so that it may be said that there are two constant air
currents in each chamber, the axial and the centrifugal; and while the actual force
of the former most affects the quality of the yield of material and the actual force
of the latter the quantity of the yield, it is upon their relative values that the
efficiency of the machine greatly depends.
In a machine wherein the working chambers are of equal diameters, and the
spiders therein are also of like diameters, the paddle-created air-currents are of
equal force or power in each chamber, and together form the centrifugal air-
current.
It will be seen then, that if there were, as in such a machine, three working

page_text: chambers, the axial air-current on issuing from the first and second chambers
successively, would have only to counteract and overcome the influence of a
constantly diminishing centrifugal air-power or current and consequently become
relatively stronger as it approaches the fan chamber.
For this reason a pulverizer having ali its working chambers of the same diameter
would he defective in operation. The centrifugal force of each set of paddles
would be the same; and the axial current, which would draw particles of a given
size from the first working chamber, would draw them more readily and quickly
from each succeeding chamber; so that they could not. remain under the influence
of the second and third sets of paddles for a sufficient time. As a consequence
many particles would be drawn into and discharged from the fan chamber of a size
and shape (not spheroidal) which would show that they had been only, or but
briefly, under the influence of the first set of paddles, and either escaped the others,
or remained for too short a time subject to their action.
י
:
In our improved pulverizers we make the first working chamber and the: fan
chamber of like diameter, as in the machine above referred to; but the diameters
of the second and third working chambers and their respective spiders are increased :
so that with the same axial speed (for instance, a speed that will give to the outer
edges of the first chamber paddles a peripheral velocity of about two miles a
minute) the paddle edges in the second and third chambers will, in the same time,
respectively move about one thousand and two thousand feet faster, and create in
their respective chambers proportionally increased air-pressure and vortical actions.
They will also give increased initial velocities to the particles of material thrown
off from them; and (the power of the exhaust-fan being equal in both cases), the
paddles will hold the particles of material under their comminuting influence for a
longer time, or until they are more finely pulverized.
It will be observed that as the working chambers successively increase in
diameter the chamber-separating diaphragms, including the diaphragm separating
the last working chamber from the fan chamber, relatively increase in depth
toward the discharge end of the cylinder; that the axial openings in the first two
diaphragms are of the same area though the second diaphragm is deeper, and that
the axial opening in the third diaphragm-which separates the last working
chamber from the fan chamber-is much smaller than the preceding one.
construction tends greatly to prevent the escape of any but the finest particles
from the third chamber.
This
The air that is permitted to enter the machine axially through the air-supply
register is violently drawn in by the combined centrifugal action of the three sets
of working paddles and the fan; but it is expelled, together with the pulverized
material, by the action of the fan aloue. The action of the fan and the three sets
of working paddles together, in sucking air through the supply register, must
obviously be greater than the exhaust action of the fan and two sets of paddles,
which combine to draw air and partly pulverized material from the first working
chamber; in like manner the velocity of the axial current must diminish on leaving
the second chamber, and still more after the centrifugal force of the third set of
paddles has ceased to effect it. Hence it will be seen that the force of the axial
current diminishes from the feed-end of the machine to the fan chamber, although
the centrifugal action of each succeeding set of working paddles increases; also
that while the pulverizing action increases in each successive working chamber: the
force of the exhaust therefrom decreases, conditions which are the reverse of
those obtaining in the hypothetical machine above referred to. By virtue of the
improved action in our new machine, the material acted upon must become more
finely reduced in each succeeding working chamber before it can be exhausted
therefrom, since it is longer subjected to the abrading forces and the forces are
more powerful.
•
These novel conditions are of vital importance in a pulverizer designed for the
most minute and uniform pulverization of material, and in which the reduction
must be effected chiefly by the action of air currents.

page_text: In our improved machine the axially entering air immediately impinges centrally
against the first spider-hub, by whose rapid rotation, aided by the centrifugal
throw of the paddles, it is distributed with the entering material evenly around
the inner periphery of the first working chamber in such a way that neither in
the first nor the subsequent chambers is the axial current at any point locally
intensified, or greater in volume or more forcible than at all other points.
With a direct axial air-feed and a gradually diminishing axial exhaust current,
our improved machine produces results superior to those of any pulverizer with
which we are acquainted. The superior centrifugal force of the air current in the
second working chamber holds there for further reduction most of the particles
withdrawn from the first working chamber by the axial current proper; and the
still superior force in the third working chamber holds there for yet finer reduction
much of what the axial current draws from the second chamber; in fact the
material in the third chamber is there retained until the particles become so fine
and light that they are no longer affected by the centrifugal force, and submit
to and become part of the constant dust-laden axial current flowing into the fan
chamber.
It is obvious that these most important and desirable conditions cannot obtain
in a machine of this type whose working chambers are all of equal diameter, or
in which the pulverizing chambers and their spiders do not successively increase in
diameter from the feed end of the machine to the fan chamber.
It is obvious too that while the exhausting force of the fan in our machine
relatively decreases in comparison with the successively increasing centrifugal
forces in the working chambers (so that comparatively coarse particles cannot be
carried into the fan chamber by the axial current), the superior centrifugal forces
of the second and third chambers, in combination with the axial current, must
constantly draw from the first chamber, for finer pulverization, much material that
is only partially reduced, thus unremittingly making room in that chamber for a
larger constant supply of material, thus relieving the first set of paddles from
excessive work and giving the other sets more to do, thereby equalizing the work
of all the chambers.
We do not confine ourselves to three working chambers, but may employ two or
more without departing from the principles involved in our invention.
Another improvement relates to the air supply.
We apply a hood or cover N, extending from the feed-hopper H, to the further
upper edge of the feed chute or box K, covering that part of the feed screw I
which extends beyond the hopper and the chute K, making an air-tight covered
way over them.
In the top of this cover is an opening in which is fitted a vertical
pipe Q, having on its top a removable cap Q³, in which is a register L, by
adjustment of which (best shown in Figure 6) the amount of air entering the axial
opening in the head of the pulverizer through the feed-box may be readily and
absolutely regulated and coutrolled, and always supplied in quantity properly
proportional to the amount of material fed into the machine.
As the amount of air entering the machine with the material to be pulverized
controls in the greatest measure the fineness of the product, this improved
construction will be seen to be of vital importance.
In the sloping part of the hood N is another opening through which the operator
may examine at will the action or working of the screw I, and the clips Q. This
opening is at all other times kept closed by a hinged cover Q, as shown in
Figures 1, and 5.
The feed screw and its attachments are shown at 1, and comprise the tapering
screw itself which, arranged in the bottom of the hopper H, normally has its
larger end slightly projected out of the opening in the hopper front about which
the clips are arranged. The screw shank is extended rearward through the
back of the hopper and through suitable bearings, and its extreme end is passed
through a slot (not shown) in a vertical lever whose lower end is pivoted to

page_text: a horizontal rod which is secured to, and projects from, the hopper standard as
shown.
To the standard supporting the screw shaft bearings is pivoted a slotted bar
through the slot of which a thumb nut is passed into the said vertical lever, so that.
by tightening said nut, said lever may be held firmly in desired position, while on
loosening said nut the lever may be adjusted at any desired angle, whereby the
feed screw may be drawn entirely within the hopper for the purpose of expelling,
when revolving, the maximum quantity of material therefrom, or may be projected
entirely forward out of the hopper, with only the screw shank therein, whereby the
delivery of material from the hopper will cease though the screw may continue to
revolve; and any adjustment of the feed screw may be made between these two.
extremes, so that the amount of material delivered from the hopper may be regulated.
as desired.
The feed screw shank is provided with a horizontal key or spline (not shown),
which engages in a corresponding key way (not shown), in the pulley which is fixed
on said shank between the bearings, so that the said screw may be adjusted at will
while revolving. A nut on the rear end of the shank prevents the accidental
disengagement therefrom of the vertical lever.
These clips Q, consist of two legs pivoted together at their upper ends on a holt
which holds them to the bopper front. From their opposing edges a semi-circle is
cut out about which is a lip extending forward at right angles. When in place
these clips cover the opening in the hopper frout, which opening is of greater
diameter than the feed screw, and embrace said screw which projects through the
circular opening in them, and the clip spring normally holds said clips about the
screw so that the latter can deliver from the hopper only what material may be.
engaged in the screw grooves.
Should large pieces of material, nuts, bolts, pick points or the like accidentally
get into the hopper and under the action of the feed screw the said screw or the
clips would be thereby broken were the latter held rigidly in place, hence they are
arranged to yield laterally; and were the hopper front opening only of the
diameter of the feed screw, the latter would break or its revolutions be stopped.
were anything to become jammed between it and the sides of said opening, hence
said opening is made larger than said screw.
The plug or stopper R, removably fitted into a corresponding opening in the
bottom of the first working chamber of the pulverizer is opened and closed by a.
compound lever R', the handle of which is fixed within easy reach of the operator.
Said plug being desigued to normally close said opening and to be withdrawn.
therefrom by the operator, through the medium of the said lever, whenever it may
be desired to have ejected from the first working chamber any nuts, bolts or other
interfering articles that may have been accidentally introduced, through the
hopper, into the machine while at work.
The steel plate linings S, of the working chambers are secured in place by the
countersunk screws k, and serve to prevent wear of the cylinder shell. They will
endure through several months of constant use, and when worn may be easily
removed and replaced.
By the addition of a third journal box T, vibration is prevented and a steadier-
running of the machine is assured.
The counter air-register M, in the discharge end of the cylinder, is, in combina-
tion with the air supply register L, an important feature. When it is nearly or
quite open the volume of air entering through it effects, in conjunction with the
partial closing of the register L, a great reduction of the axial current entering
the feed end of the machine. In this way when desirable, as it is when pulverizing
some substances, the entire product of the machine can be made to consist only of
the finest floated powder.
Of course when material is to be reduced to floated powder the quantity fed in
within a given time must be less than when reduction of the normal character is.
required.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
First. A cylindrical ore pulverizer constructed substantially as herein shown
and described, with two or more pulverizing chambers communicating with each
other through axial openings in the separating diaphragms, said chambers being of
increasing diameters from the feed end toward the discharge end of the cylinder,
as set forth.
Second. A horizontal cylindrical ore pulverizer constructed substantially as
herein shown and described, with two or more revoluble pulverizing spiders, the
diameters of which are successively increased from the feed end toward the
discharge end of the cylinder, as set forth.
Third. An ore pulverizer constructed substantially as herein shown and described,
with a horizontal cylinder or shell interiorly divided by annular diaphragins into
two or more working or pulverizing chambers and an exhaust-fan chamber, the
pulverizing chambers being of successively increasing diameters from the feed
toward the discharge end of the cylinder, and all of them being made to com-
municate with each other by means of axial openings through the diaphragms,
said cylinder being provided with a revoluble shaft extending through its axis and
having fixed upon it pulverizing spiders arranged to work in the pulverizing
chambers, and a fan spider to operate in the fan chamber, said pulverizing spiders
being of successively larger diameters, as are the chambers, and being provided
with suitable peripheral working paddles; the fan spider being provided with
suitable fan plates, substantially as set forth.
Fourth. An ore pulverizer constructed substantially as herein shown and
described, with a horizontal fixed cylinder or shell interiorly divided by annular
diaphragms into two or more communicating pulverizing chambers and an exhaust-
fan chamber having a peripheral delivery, the diameter of the first working
chamber and the fan chamber being alike, while the diameters of the other
working chambers increase successively toward the discharge end of the cylinder,
as set forth.
Fifth. In an ore pulverizer constructed substantially as herein shown and
described, provided with an axial feed opening, with two or more pulverizing
chambers and a fan chamber communicating with each other through axial
openings, and an attached feed chute between said axial feed opening and feed
hopper, an air-tight hood or cover covering the opening in the top of said chute
and extending to and covering the discharge opening of the feed hopper, as set
forth, whereby all excess of air is prevented from entering the cylinder along with
the material fed into it.
Sixth. In an ore pulverizer of the character herein shown and described, the
combination with an adjustable air-supply register connected with but beyond
the feed end of the machine, of an adjustable counter-air register in the discharge
end of the machine, as set forth, whereby the volume and force of the air entering
through the axial opening into the machine may be regulated.
1
Dated this Twentieth day of April 1897.
For the Applicants,
GEDGE & FEENY,
60 Queen Victoria Street, London, E.C., Chartered Patent Agents.