Improvements relating to the Pulverization or Reduction of Mineral or other Substances and to Apparatus therefor.
Year: 1887

page_text: Date of Application, 26th Jan., 1887
Complete Left, 6th Oct., 1887
Complete Accepted, 20th Jan., 1888
Improvements relating to the Pulverization
or
Reduction of
Mineral or other Substances and to Apparatus therefor.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents.
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention to be as follows:-
This invention relates to the pulverization or reduction of minerals and other
substances, and to apparatus therefor.
The said invention consists partly in an improved method of using air in such
pulverization.
Hitherto in pulverizing by means of air it has been usual to force fresh air into the
machine and to free the air which is drawn from the machine from the particles of
dust which it carries, by means of settling chambers, subsequently permitting this air
to pass off. A certain amount of material is wasted in this way, being carried off by
the escaping air, and this system is subject to further disadvantages which will here-
inafter be explained at length. The improved method contemplates the continuous
and repeated use of the same body of air so that all waste of material, as well as the
other disadvantages above referred to are thus obviated.
The invention further partly consists in certain features and details of construction
of the machine and its attachments, as hereinafter fully described.
In the drawings annexed forming a part of this specification.
Figure 1 is a side elevation of my improved pulverizer, a part of the top being
represented as broken off and shown on the left hand of the main part of the
figure.
Fig. 2 is a plan view, partly in section, through line 2—2, Fig. 1.
Fig. 3 is an end view of the pulverizer as it appears when viewed from the position
ted her arrow 3 Five 1

page_text: Crtical Cross section of the machine.
Fig. 5 is a vertical longitudinal section of the machine.
Fig. 6 represents the separating chamber as it appears when seen from the side
opposite to that shown in Fig. 1.
Fig. 7 is a side view of the same.
Figs. 8, 9, & 10 are details on an enlarged scale; and Figs. 11, 12, 13 & 14 are
details on the same scale as the other parts of the machine.
Fig. 15 represents the machine when set up for operation in connection with a
number of auxiliary devices required in carrying out the several methods herein
described and claimed.
Fig. 16 is a central vertical section on line 16-16 Fig. 15, on reduced scale.
Upon two main shafts, 1 and 2, mounted in suitable bearings and driven from
pulleys 3 and 4, or by means of other suitable connection with a motive power, are
mounted, within the pulverizing chamber 5, hubs 6 and 7, from which project arms 8
carrying beaters 9. These arms, 8, circular in cross section, are bent to the shape of
the beaters and the direction of their bent portion is determined by the inclination
desired to be given to the beaters. Preferably these arms are made in one piece with
the hub end of cast steel, but they may be set into a separately cast hub, as indicated
by the broken lines extending into the hub in Fig. 4. They are made comparatively
large near the hub, their large portion being reduced so as to form shoulders against
which the beaters bear when attached. The beaters 9 are channeled so as to receive
the arms 8 and are attached thereto by a bolt 10 and a clip 11. The beaters are
herein shown flat, for convenience, and in such form are serviceable but I prefer a
spiral or screw shaped form. This construction enables me to change the beaters
when they become worn without disturbing or replacing the hub, and likewise enables
me to replace the beaters with others of different shape if for any reason this. becomes
desirable. This construction, moreover, is cheap, strong and durable. Ribs, 12, are
formed on the beaters, one on each side of the channel, to more securely grasp the
arm; but a plain groove or channel may be used, if preferred. The casing of the
pulverizing chamber is double-cone shaped and for convenience I prefer to cast it in
five pieces, a base piece 15, provided with a bottom discharge opening 16, two end
pieces 17 and 18, and two side pieces 19 and 20. These several pieces are flanged
and ground so as to fit each other at the joints, and are bolted together as shown.
For convenience it is desirable that one of the side pieces, as 20, should be hinged at
one of its corners as shown, that it may be opened to permit access to the interior of
the pulverizing chamber. A handle 21 is provided for conveniently pulling out this
hinged side.
Two currents of air are delivered to opposite ends, respectively, of the pulverizing
chamber, pipes 22 and 23 being provided for that purpose and forming part of the
end and side pieces of the casing. These pipes project toward the same side of
the machine for convenience in attaching pipes thereto, and pass down to diagonally
opposite parts of the pulverizing chamber near its bottom. It is desirable that the
air should enter at the bottom of the chamber in order that the beaters and the
material operated upon may be between the air as it enters and the passage-way
through which it leaves the chamber, since, were the air pipes otherwise located, the
air would be too readily and quickly drawn out from the chamber. It is desirable
that they should enter at diagonally opposite parts of the chamber in order that the
beaters, which revoive in opposite directions, may receive the air as they pass down,
and, sweeping it along the bottom of the chamber, give it the most perfect rotary
motion possible.
Instead of making the chamber simply double-cone shape, as heretofore, I propose
to introduce a modification which enables me more readily to adapt the machine to
grinding with different degrees of fineness; and this modification consists in an
annular extension, 24, of the pulverizing chamber, surrounding the latter at its center,
and adapted to be put into communication with it by means of the spaces between
grate bars 25, or to be cut off from it entirely by solid segmental pieces 26.
These grate bars or segmental pieces are held in position between the edges of two

page_text: annular strips of lining, preferably of chilled metal, placed about the interior cone-
shaped surfaces of the pulverizing chamber. This lining is in part shown in Figs. 2,4
and 13, and is made, preferably in eight parts, two parts, 13-14, fitting into and
corresponding with the interior cone-shaped surface of the bottom piece of the
casting 15, four parts (two of which 27, 28 are shown) corresponding to and fitting
the interior curved surfaces of the side top pieces of casing 19 and 20, each of these
parts being provided with an upwardly extending flange 31, lying along the inner
face of one of the sides of the upwardly projecting discharge openings 32, and two
parts, 33 and 34, spanning the gap between the parts 27 and 28 and the two other
similar parts not shown, respectively, just above the annular extension 24. These
parts, 33 and 34, are attached by bolts passing through slots 29 so that they may be
pressed down with greater or less firmness upon the grate bars (or solid segments,
when the latter are in place) and may be readily removed when it is desired to replace
the grate bars by the segments or vice versa. The grate bars and segments are made
of the shape shown, so as to accurately fit the space left between the adjoining edges
of the annular strips of lining and to be held therein, and are inserted preferably
from the top, one of the readily removable pieces of lining 33 or 34 having been
taken out for that purpose. These grate bars are each provided with lugs, 35, 36
and 37, one at each end and one at the center for holding them at proper distances
from each other. The lower edges of adjustable plates 33 and 34 are beveled, as
shown in Fig. 4, so as to give them a bearing upon the bars or segments. The object
of these grate bars and of the annular extension 24 will now be explained. When it
is desired to pulverize to a considerable degree of fineness the segmental plates are
used, completely cutting off the annular extension 24 from the pulverizing chamber
proper but when it is only desired to comminute the material operated upon to a
moderate degree, the grate bars are inserted, and as fast as the material is reduced
sufficiently to pass through the openings between them, it enters the chamber 24 and
is permitted to pass out through the bottom discharge-opening 16. During the
operation of the machine for fine grinding, this opening 16 is closed, and all the
material passes up in the form of dust through the top passage-way 32. When,
however, the comminution is moderate, the air current is not depended upon to carry
off the ground product, but it drops down, as stated, by gravity, passing through the
grate bars, and out through the opening 16.
The degree of comminution effected by the machine is determined, when the grate
bars are used, by the width of the spaces between them, and a complete machine
should be provided with a number of sets of bars adapted to various degrees of com-
minution. I find it desirable to use the suction fan and the entire air passage
attachment when the machine is doing coarse work, as well as when it is doing fine
work. In the former case the increased air pressure due to the fan assists in holding
the material being operated upon up from the bottom of the pulverizing chamber and
between the beaters, where it is most rapidly attacked, and thus very materially
increases the capacity of the machine. When so used, the material should be allowed
to drop out into a closed box. The use of the air blast with the screen has the further
advantage that such fine dust as is formed is carried off to the settling chambers
instead of being mingled with the coarser product, as would otherwise be the case,
which is also a distinct advantage. It will, of course, be understood, that I do not
limit myself to the use of the machine for coarse grinding with the air blast, as useful
results, though in a minor degree, are obtainable without the air blast.
When it is desired to change the machine from a condition adapted to coarse
grinding to one adapted to fine grinding, instead of replacing the grate bars by the
segmental plates, discharge opening 16 may be merely blocked up, and the annular
extension 24 allowed to fill with dust, or more or less comminuted particles, which it
will speedily do, until the spaces between the grate bars and the sides of the annular
extension are thoroughly packed. The pulverizer will now operate for fine grinding
precisely as it would if the annular extension 24 were cut off by the segmental plates,
the only disadvantages being the retention in the machine of the material filling the
annular extension and the liability of the new material worked upon to become more

page_text: or less mixed with the old remaining in the machine, which, according to circum-
stances, may or may not be a disadvantage. Formed as an upward extension or
continuation of the top passage-way 32 is what I may term a separating chamber 38,
its top curved as shown in Fig. 6, and provided with a discharge pipe 39. This
separating chamber is made comparatively large, so that the air and pulverized
material will have an opportunity to circulate freely about in it, that the coarser
portion may fall back into the chamber, while only the finer passes out through the
discharge pipe 39. To assist this action of the separating chamber I provide a screen
er partition, 40, placed near the entrance to the discharge pipe 39, so that the material
as it passes up into the separating chamber will be forced by the configuration of the
top of the latter to pass over the screen and take a downward direction; whereupon
the coarser parts of such material will fall and return under the partition, as indicated
by the arrow, into the pulverizing chamber, while the finer portion will be drawn out
by the air current through the pipe 39. It will be noticed that the size of the top
discharge opening 32 is large, relatively to the pulverizing chamber, said discharge
opening being practically of the same length as the pulverizing chamber and nearly
two-thirds of its width. While I am unable to explain with entire certainty the
action of the machine in this particular, I find by experiment that a top discharge
opening of approximately the relative size shown gives far better results than are
obtained where it is considerably smaller.
It appears that the material in the pulverizing chamber, having attained a rapid
rotary motion, is driven past the opening when the latter is relatively small, without
entering it, while when the opening is sufficiently large it is drawn up into it and out.
I have found that good results are obtained when the upward opening is even as large
as the maximum cross section of the pulverizing chamber; but the relative size of the
opening shown is more convenient and gives equally good and perhaps somewhat
better results. The large opening, when used in connection with the separating
chamber, also permits the upward current of air, charged with the material under
treatment in a more or less pulverized condition, to circulate freely and to some extent
to return upon itself without passing over the screen, so that the coarser particles fall
back directly into the pulverizing chamber.
I suppose that there are two continuous streams of the coarser material diverging
from the center of the pulverizing and the separating chambers. curving over sidewise,
and passing down the end walls to the beaters, as indicated in Fig. 5. Indeed there is
a considerable suction-a strong current of air-down each end wall to the beaters.
These currents carry back the coarse materials to be further comminuted. This is
impossible where the separating chamber or the opening between it and the pulverizing
chamber is of relatively small dimensions. On the contrary, the coarse particles are
effectually prevented in this case from returning by the pressure in the narrow throat,
and some such device as an automatic valve arrangement is necessitated.
The material to be pulverized is introduced through a hopper 41 placed on one side
of chamber 38, its opening being near the bottom of the latter. The feed of the
material is insured and regulated by a cog roller 42 journaled in the hopper and inter-
mittently rotated by a shaft 43 journaled in the bearings 44-45 attached to the
outside of the separating chamber; the shaft 43 being connected by bevel gearing
with the shaft of the cogged feed roller and having on its other extremity a pawl and
ratchet connection with a rod 46 eccentrically pivoted at its upper end to a pulley 47
geared to any suitable source of motive power. The pawl and ratchet connection
referred to consists of a ratchet wheel 48, rigidly attached to the shaft 43, and an
arm 49 pivoted thereon and carrying a pawl 50, the other end of arm 49 being
connected with rod 46 by a pin 51, a number of holes being provided in the end of
arm 49 for this pin, whereby the amount of motion of the pawl 50 may be regulated
so as to give a more or less extensive rotary motion to the feed-roller on each recipro-
cation of the arm 49 and thus push the raw material into the pulverizing chamber
more or less rapidly. This pawl and ratchet movement is more readily adjusted and
on the whole more convenient than a gearing down connection between the source of
power and the feed-roller, though such a connection might be used. The material is

page_text: prevented from falling freely into the pulverizing chamber by a movable bottom 52,
pivoted in the hopper at 53 and provided with a counterbalance weight 54 rigidly
attached to it, the movable bottom resting against the cogs of the feed-roller or bearing
on other bearing surfaces or shoulders formed on the sides of the hopper. This
bottom is forced down by the cogs of the feed-wheel, as the latter drives on the coarse
material, sufficiently to permit a proper feed.
Features of the improved machine to which I desire to call attention are, the
absolute distance between the contiguous faces of the oppositely revolving beaters and
also that distance relative to the total length of the machine. I find that increase of
the
space between the beaters tends to increase the fineness of the resulting product.
The best average results are obtained with a space which bears the proportion of one
to three to the total length of the pulverizing chamber; and which, with machines of
ordinary size, is about 1 to twelve inches. While, however, the proportion above
indicated of one to three is that which we believe to be the best, yet if the absolute
distance of 10 to 12 inches between the beaters be preserved, the relative length of
the chamber may be varied considerably without very greatly affecting the operation
of the machine. It appears, therefore, that the absolute distance between the beaters
If
is of more importance than that distance relative to the length of the chamber.
this space is made narrower the machine will do less work. The difference is probably
due to the fact that the rapid rotation of the beaters produces a central vacuum within
and between the beaters, towards which the air and material undergoing treatment
rushes in around the beaters and through the clear space between thein. If this space
is narrow the material is prevented from free access to the central vacuum space and
the work done by the machine is below its maximum capacity; but when the space
between the sets of heaters is large enough to permit free movement of the material as
it is drawn towards the central vacuum, the maximum capacity of the machine will be
attained. This broad space also permits the formation of eddying currents, the
tendency of which is to further comminute the material.
Where the machine is used for coarse grinding, I find it desirable to introduce
oblique guide surfaces 74, shown in broken lines in Fig. 1 and 5 and in full shading
lines in Fig. 4, for causing the coarser particles, as they fall back from the separating
chamber, to pass toward the center of the pulverizing chamber instead of striking
upon the beaters; since, if they are permitted to strike the beaters, they rapidly wear
them away. These inclined surfaces 74 are formed by the use of blocks illustrated in
section in Fig. 11. Where the grinding is fine, it is better to allow the descending
dust to pass into the current of air driven forward by the beaters, as above explained,
dispensing with the converging guide surfaces.
I
Besides the improvements in the construction of the pulverizer itself herein described,
I have made improvements in the method of using the machine which will now be
described. Where fresh air is continually drawn into the pulverizer and the air which
has been separated from the dust formed by it is allowed to escape freely, there will
always be more or less waste of material carried out from the machine by the escaping
air and the operation of the machine will be more or less irregular owing to varia-
tions in the supply of air to the machine. propose to continuously use practically
the same body of air with the machine, freeing it more or less perfectly from dust
after it passes out of the pulverizing chamber and then drawing it back into the pul-
verizing chamber for further use. I thus avoid all waste of the material operated
upon, and I also obtain a constant and uniform quantity of air in the machine and its
connections. After leaving the machine and passing through the discharge pipe 39,
the air enters a series of settling drums 55-56, provided preferably with partitions of
usual construction 57-58 for checking the air current, and connected by discharge
pipes 59 and 60, provided with weighted valves 75 and 76, with run-way 61. through
which the dust is forced by a serew-conveyor 62 to a discharge pipe 63, entrance to
which is controlled by a valve 64. From the further settling drum 56 the air passes
through a pipe 65 to a suction fan 66, whence it is delivered into another settling
chamber 67. provided with partitions 68 and connected at its other end by the pipe 69
with the air pipe 22-23 of the pulverizer. The top of this settling chamber. 67 is

page_text: formed of a considerable length of tolerably close canvas, stretched over a frame-work
formed of two sets of parallel strips 70 and 71 arranged alternately with respect to
each other, and some little distance apart; so that the air in the settling chamber 67
has free access to all parts of the canvass except such as are in immediate contact with
the strips. This canvas acts as an equalizing valve with respect to the air in the
system of pipes and chambers, permitting air to slowly enter when too little is in the
system and to slowly pass out when too much has been drawn in, and at the same
time arresting any dust which would otherwise pass out with the air. For further
regulating the suction of the fan 66 upon the settling chambers 55 and 56, a valve 72
is provided in pipe 65; and to regulate the suction of the beaters in the pulverizing
chamber upon the air in the settling chamber 67, a valve 73 is provided in
pipe 69.
A further advantage of the equalizing valve is that it prevents an overcharge of air
in the machine from forcing dust out through cracks or crevices in any part of the
machine into the outer air, an inconvenience which is often attendant upon the use of
reducing machines and is often highly detrimental to the health of the operators. To
enable the operation of the equalizing valve to be thoroughly understood, it may be
necessary to go somewhat more into detail in the explanation of the principle of its
operation. Let me suppose first that the pulverizer is used without the exhaust fan
and without the returning air pipe, air being simply drawn into the pulverizer
chamber through end holes in the machine formerly and allowed to escape into the outer
air after passing through the settling drums. In this case the beaters, operating as
fans to produce a strong draught, force the air in a powerful current up through the
separating chamber and giving it a tendency to escape wherever there may be an im-
perfect joint or a gap in the walls of any part of the machine. As the dust is
exceedingly fine and it is practically impossible to make a machine absolutely imper-
vious at all points to it, it is found that more or less dust is usually given off into the
room in which the machine is situated, with its attendant inconveniences and dangers.
Now if, to a machine so placed an exhaust fan is applied on the further side of the
settling chambers, the tendency of the dust to escape from the machine itself will be
reduced. as all the pulverized material will be given a greatly increased tendency to
pass up through the discharge openings and pipes and into the settling chamber; but
at the same time a greater amount of the material will be drawn through the settling
chambers, pass into the outer air, and be wasted. If, now, in order to prevent this
waste, the air pipe is extended from the exhaust fan back to the pulverizing machine
without an equalizing valve, the difficulty experienced in the first case supposed is
again felt, but in an exaggerated degree; for one of two conditions must exist; either
the entire system of air-passage-way chamber is altogether air tight and the amount
of air contained in it therefore absolutely constant, or as is much more probable, there
are a number of opportunities in various parts of the machine and connections for air
to pass in and out.
Such opportunities are, in fact, necessary, if the machine is to be
run at varying speeds or with widely different kinds of material, that the quantity of
air used may be adapted both to the speed of the machine and the character of the
material undergoing treatment. If such opportunities for the egress and ingress of
air exist, they are apt to be irregular and uncertain in their action, giving at times a
surplus and at times a deficit of air. Under both conditions the machine will operate
with less than its normal capacity and effectiveness, both as to quantity and quality of
work done; and where there is an excess of air, there will be even a greater tendency
to force the finer dust out into the air about the machine than is observed where no
exhaust fan is used. The equalizing valve, however, overcomes both these difficulties
by causing the machine to automatically regulate, in a steady and reliable manner, its
supply of air, in accordance with its varying requirements; and altogether preventing
the tendency referred to to force out the finer dust from the machine. While other
relative positions of the equalizing valve and the exhaust fan might perhaps be devised,
it is obvious that the position shown, viz. that wherein the equalizing valve stands
in the return pipe between the fan and the pulverizing chamber, has advantages in
that, first, it throws the suction of the fan to the fullest extent upon the equalizing

page_text: chamber and, second, enables the action of the equalizing valve to be felt directly at
the entrance to the pulverizing chamber where it will be most directly and immediately
effective upon and governed by the operating parts of the machine. Many other
forms of this equalizing valve might undoubtedly be readily devised; but I regard
every device which will permit a steady and gradual interchange of
pressure between
the interior connections of the apparatus and the outer air as within this invention.
The settling chamber to which it is applied is not an essential part of the apparatus ;
but has value both for the reason that it affords a convenient point of application for
the equalizing valve and that it recovers a considerable amount of fine dust from the
current of air which is passed through the fan, which it would otherwise be necessary
to return to the pulverizing chamber.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.

page_text: Improvements relating to the Pulverization
or Reduction of
Mineral or other Substances and to Apparatus therefor.
I, HENRY HARRIS LAKE of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex 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 the pulverization or reduction of minerals and other
substances and to apparatus therefor.
The said invention consists partly in an improved method of using air in such
pulverization.
Hitherto in pulverizing by means of air it has been usual to force fresh air into the
machine and to free the air which is drawn from the machine from the particles of
dust which it carries by means of settling chambers subsequently permitting this air
to pass off. A certain amount of material is wasted in this way, being carried off by
the escaping air, and this system is subject to further disadvantages which will
hereinafter be explained at length. The improved method contemplates the continuous
and repeated use of the same body of air so that all waste of material, as well as the
other disadvantages above referred to, are thus obviated.
The invention further partly consists in certain features and details of construction
of the machine and its attachments hereinafter fully described.
In the drawings annexed forming a part of this specification.
Figure 1 is a side elevation of our improved pulverizer, a part of the top being
represented as broken off, and shown on the left hand of the main part of the
figure.
Figure 2 is a plan view, partly in section, through line 2, 2 Figure 1.
Figure 3 is an end view of the pulverizer as it appears when viewed from the
position indicated by arrow 3, Figure 1.
Figure 4 is a vertical cross section of the machine.
Figure is a vertical longitudinal section of the machine.
Figure 6 represents the separating chamber as it appears when seen from the side
opposite to that shown in Figure 1.
Figure 7 is a side view of the same.
Figures 8, 9 and 10 are details on an enlarged scale; and Figures 11, 12, 13
and 14 are details on the same scale as the other parts of the machine.
Figure 15 represents the machine when set up for operation in connection with a
number of auxiliary devices required in carrying out the several methods herein
described and claimed.
Figure 16 is a central vertical section on line 16, 16 Figure 15, on reduced scale.
This machine is an improvement upon Letters Patent of the United States
Nos. 293,786 and 293,787, dated February 19, 1884, and is constructed as follows:
upon two main shafts, 1 and 2, mounted in suitable bearings and driven from pulleys
3 and 4, or by means of other suitable connection with a motive power, are mounted,

page_text: within the pulverizing chamber 5, hubs 6 and 7, from which project arms S carrying
beaters 9. These arms 8, circular in cross section, are bent to the shape of the
beaters and the direction of their bent portion is determined by the inclination desired
to be given to the beaters. Preferably these arms are made in one piece with the
hub and of cast steel, but they may be set into a separately cast hub, as indicated by
the broken lines extending into the hub in Figure 4. They are made comparatively
large near the hub, their large portion being reduced so as to form shoulders against
which the beaters bear when attached. The beaters 9 are channelled so as to receive
the arms 8 and are attached thereto by a bolt 10 and a clip 11. The beaters are
herein shown flat, for connveience, and in such form are serviceable but we prefer the
spiral or screw-shaped form shown in our previous patents. This construction enables
us to change the beaters when they become worn without disturbing or replacing the
hnb, and likewise enables us to replace the beaters with others of different shape if
for any reason this becomes desirable. This construction, moreover, is cheap, strong
and durable. Ribs, 12 are formed on the beaters, one on each side of the channel, to
more securely grasp the arm; but a plain groove or channel may be used, if preferred.
The casing of the pulverizing chamber is double-cone shaped and for convenience we
prefer to cast it in five pieces, a base piece 15, provided with a bottom discharge
opening 16, two end pieces 17 and 18, and two side pieces 19 and 20. These several
pieces are flanged and ground so as to fit each other at the joints, and are bolted
together as shown. For convenience it is desirable that one of the side pieces, as 20,
should be hinged at one of its corners as shown, that it may be opened to permit
access to the interior of the pulverizing chamber. A handle 21 is provided for con-
veniently pulling out this binged side. Two currents of air are delivered to opposite
ends respectively, of the pulverizing chamber, pipes 22 and 23 being provided for
that purpose and forming part of the end and side pieces of the casing. These pipes
project toward the same side of the machine for convenience in attaching pipes
thereto, and pass down to diagonally opposite parts of the pulverizing chamber near
its bottom. It is desirable that the air should enter at the bottom of the chamber in
order that the beaters and the material operated upon may be between the air as it
enters and the passage-way through which it leaves the chamber, since, were the air
pipes otherwise located, the air would be too readily and quickly drawn out from the
chamber. It is desirable that they should enter at diagonally opposite parts of the chamber
in order that the beaters, which revolve in opposite directions, may receive the air as
they pass down, and sweeping it along the bottom of the chamber, give it the most
perfect rotary motion possible. Instead of making the chamber simply double-cone
shaped, as heretofore, we propose to introduce a modification which enables us more
readily to adapt the machine to grinding with different degrees of fineness; and this
modification consists in an annular extension 24, of the pulverizing chamber,
surrounding the latter at its centre, and adapted to be put into communication with
it by means of the spaces between grate bars 25, or to be cut off from it entirely by
solid segmental pieces 26. These grate bars or segmental pieces are held in position
between the edges of two annular strips of lining, preferably of chilled metal, placed
about the interior cone-shaped surfaces of the pulverizing chamber. This lining is in
part shown in Figures 2, 4 and 13, and is made, preferably in eight parts, two parts
13, 14, fitting into and corresponding with the interior cone-shaped surface of the
bottom piece of the casting 15, four parts (two of which 27, 28 are shown) corres-
ponding to and fitting the interior curved surfaces of the side top pieces of casing 19
and 20, each of these paris being provided with an upwardly extending flange 31,
lying along the inner face of one of the sides of the upwardly projecting discharge
openings 32 and two parts 33 and 34, spanning the gap between the parts 27 and 28
and the two other similar parts not shown, respectively, just above the annular exten-
sion 24. These parts 33 and 34, are attached by bolts passing through slots 29 so that
they may be pressed down with greater or less firmness upon the grate bars (or solid
segments, when the latter are in place) and may be readily removed when it is desired
to replace the grate bars by the segments or vice versa. The grate bars and segments
are made of the shape shown, so as to accurately fit the space left between the

page_text: adjoining edges of the annular strips of lining and to be held therein, and are inserted
preferably from the top, one of the readily removable pieces of lining 33 or 34 having
been taken out for that purpose. These grate bars are each provided with lugs 35, 36
and 37 one at each end and one at the centre for holding them at proper distances
from each other. The lower edges of adjustable plates 33 and 34 are bevelled, as
shown in Figure 4, so as to give them a bearing upon the bars or segments. The
object of these grate bars and of the annular extension 24 will now be explained.
When it is desired to pulverize to a considerable degree of fineness the segmental
plates are used, completely cutting off the annular extension 24 from the pulverizing
chamber proper; but when it is only desired to comminute the material operated
upon to a moderate degree, the grate bars are inserted, and as fast as the material is
reduced sufficiently to pass through the openings between them, it enters the chamber
24 and is permitted to pass out through the bottom discharge-opening 16. During
the operation of the machine for fine grinding, this opening 16 is closed, and all
the material passes up in the form of dust through the top passage-way 32. When,
however, the comminution is moderate, the air current is not depended upon to
carry off the ground product, but it drops down, as stated, by gravity passing through
the grate bars, and out through the opening 16. The degree of comminution effected
by the machine is determined, when the grate bars are used, by the width of the
spaces between them, and a complete machine should be provided with a number of
sets of bars adapted to various degrees of comminution. We find it desirable to use
the suction fan and the entire air passage attachment when the machine is doing coarse
work, as well as when it is doing fine work. In the former. case the increased air
pressure due to the fan assists in holding the material being operated upon up from
the bottom of the pulverizing chamber and between the beaters, where it is most
rapidly attacked, and thus very materially increases the capacity of the machine.
When so used, the material should be allowed to drop out into a closed box. The use
of the air blast with the screen has the further advantage that such fine dust as is
formed is carried off to the settling chambers instead of being mingled with the
coarser product, as would otherwise be the case, which is also a distinct advantage.
It will of course, be understood, that we do not limit ourselves to the use of the
machine for coarse grinding with the air blast, as useful results, though in a minor
degree, are obtainable without the air blast. When it is desired to change the machine
from a condition adapted to coarse grinding, to one adapted to fine grinding, instead
of replacing the grate bars by the segmental plates, discharge opening 16 may be
merely blocked up, and the annular extension 24 allowed to fill with dust, or more or
less comminuted particles, which it will speedily do, until the spaces between the
grate bars and the sides of the annular extension are thoroughly packed. The
pulverizer will now operate for fine grinding precisely as it would if the annular
extension 24 were cut off by the segmental plates, the only disadvantages being the
retention in the machine of the material filling the annular extension and the liability
of the new material worked upon to become more or less mixed with the old remain-
ing in the machine, which, according to circumstances, may or may not be a dis-
advantage. Formed as an upward extension or continuation of the top passage-way 32
is what I may term a separating chamber 38, its top curved as shown in Figure 7, and
provided with a discharge pipe 39. This separating chamber is made comparatively
large, so that the air and pulverized material will have an opportunity to circulate
freely about in it, that the coarser portion may fall back into the chamber, while only
the finer passes out through the discharge pipe 39. To assist this action of the
separating chamber I provide a screen or partition 40, placed near the entrance to the
discharge pipe 39, so that the material as it passes up into the separating chamber
will be forced by the configuration of the top of the latter to pass over the screen and
take a downward direction: Whereupon the coarser parts of such material will fall
and return under the partition, as indicated by the arrow, into the pulverizing
chamber, while the finer portion will be drawn out by the air current through the
pipe 39. It will be noticed that the size of the top discharge opening 32 is very much
larger, relatively to the pulverizing chamber, than that shown in our former patents,

page_text: said discharge opening in this machine being practically of the same length as the
pulverizing chamber and nearly two-thirds of its width. While we are unable to
explain with entire certainty the action of the machine in this particular, we find by
experiment that a top discharge opening of approximately the relative size shown
gives far better resuhs than are obtained where it is considerably smaller. It appears
that the material in the pulverizing chamber; having attained a rapid rotary motion,
is driven past the opening when the latter is relatively small, without entering it,
We have
while when the opening is sufficiently large it is drawn up into it and out.
found that good results are obtained when the upward opening is even as large as the
maximum cross section of the pulverizing chamber but the relative size of the
opening shown is more convenient and gives equally good and perhaps somewhat
better results. The large opening, when used in connection with the separating
chamber, also permits the upward current of air. charged with the material under
treatment in a more or less pulverized condition, to circulate freely and to some extent
to return upon itself without passing over the screen, so that the coarser particles full
back directly into the pulverizing chamber. We suppose that there are two continuous
streams of the coarser material diverging from the centre of the pulverizing and the
separating chambers, curving over siddewise, and passing down the end walls to the
beaters, as indicated in Figure 5. Indeed there is a considerable suction, a strong
current of air, down each end wall to the beaters. These currents carry back the
coarse materials to be further comminuted. This is impossible where the separating
chamber or the opening between it and the pulverizing chamber is of relatively small
dimensions. On the contrary, the coarse particles are effectually prevented in this
case from returning by the pressure in the narrow throat, and some such device as
the automatic valve arrangement of our former patents is necessitated, which, however,
is not satisfactory in operation. The material to be pulverized is introduced through
a hopper 41 placed on one side of chamber 38, its opening being near the bottom of
the latter. The feed of the material is insured and regulated by a cog roller 42
journalled in the hopper and intermittently rotated by a shaft 43 journaled in the
bearings 44 and 45 attached to the outside of the sepating chamber, the shaft 43
being connected by bevel gearing with the shaft of the cogged feed roller and having
on its other extremity a pawl and ratchet connection with a rod 46 eccentrically
pivotted at its upper end to a pulley 47 geared to any suitable source of motive power.
The pawl and ratchet connection referred to consists of a ratchet wheel 48, rigidly
attached to the shaft 43, and an arm 49 pivotted thereon and carrying a pawl 50, the
other end of arm 49 being connected with rod 46 by a pin 51, a number of holes
being provided in the end of arm 49 for this pin, whereby the amount of motion of
the pawl 50 may be regulated so as to give a more or less extensive rotary motion to
the feed roller on each reciprocation of the arm 49 and thus push the raw material
into the pulverizing chamber more or less rapidly. This pawl and ratchet inovement
is more readily adjusted and on the whole more convenient than a gearing down con-
nection between the source of power and the feed-roller, though such a connection
might be used. The material is prevented from falling freely into the pulverizing
chamber by a movable bottom 52, pivotted in the hopper at 53 and provided with a
counter-balance weight 54 rigidly attached to it, the movable bottom resting against the
cogs of the feed-roller or bearing on other bearing surfaces or shoulders formed on
the sides of the hopper. This bottom is forced down by the cogs of the feed-wheel,
as the latter drives on the coarse material, sufficiently to permit a proper feed.
Features of our improved machine to which we desire to call attention are, the
absolute distance between the contiguous faces of the oppositely revolving beaters and
also that distance relative to the total length of the machine. We find that increase
of the space between the beaters tends to increase the fineness of the resulting
product. The best average results are obtained with a space which bears the propor-
tion of one to three to the total length of the pulverizing chamber; and which, with
machines of ordinary size, is about 10 to 12 inches. While, however, the proportion
above indicated of one to three is that which we believe to be the best, yet if the
absolute distance of 10 to 12 inches between the beaters be preserved, the relative

page_text: length of the chamber may be varied considerably without very greatly affecting the
operation of the machine. It appears therefore, that the absolute distance between
the beaters is of more importance than that distance relative to the length of the
chamber. If this space is made narrower the machine will do less work. The
difference is probably due to the fact that the rapid rotation of the beaters produces a
central vacuum within and between the beaters, towards which the air and material
undergoing treatment rushes in around the beaters and through the clear space
between them. If this space is narrow the material is prevented from free access to
the central vacuum space and the work done by the machine is below its maximum
capacity; but when the space between the sets of beaters is large enough to permit
free movement of the material as it is drawn towards the central vacuum, the
maximum capacity of the machine will be attained. This broad space also permits
the formation of eddying currents, the tendency of which is to further comminute the
material.
Where the machine is used for coarse grinding, we find it desirable to introduce
oblique guide surfaces 74, shown in broken lines in Figures 1 and 5 and in full
shading lines in Figure 4, for causing the coarser particles, as they fall back from
the separating chamber, to pass toward the centre of the pulverizing chamber instead
of striking upon the beaters; since, if they are permitted to strike the beaters, they
rapidly wear them away. These inclined surfaces 74 are formed by the use of blocks
illustrated in section in Figure 11. Where the grinding is fine, it is better to allow
the descending dust to pass into the current of air driven forward by the beaters, as
above explained, dispensing with the converging guide surfaces.
Besides the improvements in the construction of the pulverizer itself herein
described, we have made improvements in the method of using the machine which
will now be described. Where fresh air is continually drawn into the pulverizer
and the air which has been separated from the dust formed by it, is allowed to
escape freely, there will always be more or less waste of material carried out from
the machine by the escaping air; and the operation of the machine will be more or
less irregular owing to variations in the supply of air to the machine.
We propose
to continuously use practically the same body of air with the machine, freeing it more
or less perfectly from dust after it passes out of the pulverizing chamber and th n
drawing it back into the pulverizing chamber for further use. We thus avoid all
waste of the material operated upon, and we also obtain a constant and uniform
quantity of air in the machine and its connections. After leaving the machine and
passing through the discharge pipe 39, the air enters a series of settling drums 55, 56,
provided preferably with partitions of usual construction 57, 58 for checking the air
current, and connected by discharge pipes 59 and 60, provided with weighted valves
75 and 76, with runway 61, through which the dust is forced by a screw-conveyor 62
to a discharge pipe 63, entrance to which is controlled by a valve 64. From the
further settling drum 56 the air passes through a pipe 65 to a suction fan 66, whence
it is delivered into another settling chamber 67, provided with partitions 68 and
connected at its other end by the pipe 69 with the air pipe 22, 23 of the pulverizer.
The sides of the top part of this settling chamber 67 is formed of tolerably close
canvass, stretched over a frame-work formed of two sets of parallel strips 70 and 71
arranged alternately with respect to each other, and some little distance apart; so that
the air in the settling chamber 67 has free access to all parts of the canvass except
those which are in immediate contact with the strips. This canvass acts as an
equalizing valve with respect to the air in the system of pipes and chambers,
permitting air to slowly enter from the outside when too little is in the system and to
slowly pass out from the inside when too much has been drawn in, and at the same
time arresting any dust which would otherwise pass out with the air. For further
regulating the suction of the fan 66 upon the settling chambers 55 and 56, a valve 72
is provided in pipe 65; and to regulate the suction of the beaters in the pulverizing
chamber upon the air in the settling chamber 67, a valve 73 is provided in pipe 69.
A further advantage of the equalizing valve is that it prevents an overcharge of air
in the machine from forcing dust out through cracks or crevices in any part of the

page_text: machine into the outer air, an inconvenience which is often attendant upon the use of
To
reducing machines and is often highly detrimental to the health of the operators.
enable the operation of the equalizing valve to be thoroughly understood. it may be
necessary to go some what more into detail in the explanation of the principle of its
operation. Let us suppose first that the pulverizer is used without the exhaust fan
and without the returning air pipe, air being simply drawn into the pulverizer chamber
through the end holes provided in the machine formerly patented to us and allowed
to escape into the outer air after passing through the settling drums. In this case
the beaters, operating as fans to produce a strong draught, force the air in a powerful
current up, through the separating chamber and giving it a tendency to escape
wherever there may be an imperfect joint or a gap in the walls of any part of the
machine. As the dust is exceedingly fine and it is practically impossible to make a
machine absolutely impervious at all points to it, it is found that more or less dust is
usually given off into the room in which the machine is situated, with its attendant
inconveniences and dangers. Now if, to a machine so placed an exhaust fan is applied
on the further side of the settling chambers, the tendency of the dust to escape from
the machine itself will be reduced, as all the pulverized material will be given a
greatly increased tendency to pass up through the discharge openings and pipes and
into the settling chamber; but at the same time a greater amount of material will he
drawn through the settling chambers, pass into the outer air, and be wasted. If, now,
in order to prevent this waste, the air pipe is extended from the exhaust fan back to
the pulverizing machine without an equalizing valve, the difficulty experienced in the
first case supposed is again felt, but in an exaggerated degree; for one or two
conditions must exist; either the entire system of air-passage-way-chamber is
altogether air tight and the amount of air contained in it therefore absolutely
constant, or as is much more probable, there are a number of opportunities in various
parts of the machine and connections for air to pass in and out. Such opportunities
are, in fact, necessary, if the machine is to be run at varying speeds or with widely
different kinds of material, that the quantity of air used may be adapted both to the
speed of the machine and the character of the material undergoing treatment.
such opportunities for the egress and ingress of air exist, they are apt to be irregular
and uncertain in their action, giving at times a surplus and at times a deficit of air.
Under both conditions the machine will operate with less than its normal capacity and
effectiveness, both as to quantity and quality of work done; and where there is an
excess of air, there will be even a greater tendency to force the finer dust out into the
air about the machine than is observed where no exhaust fan is used. The equalizing
valve, however, overcome both these difficulties by causing the machine to auto-
matically regulate, in a steady and reliable manner, its supply of air, in accordance
with its varying requirements; and altogether preventing the tendency referred to,
to force out the finer dust from the machine. While other relative positions of the
equalizing valve and the exhaust fan might perhaps be devised, it is obvious that
the position shown, viz.:-that wherein the equalizing valve stands in the return pipe
between the fan and the pulverizing chamber, has advantages in that, first, it throws
the suction of the fan to the fullest extent upon the pulverizing chamber; and, second,
enables the action of the equalizing valve to be felt directly at the entrance to the
pulverizing chamber where it will be most directly and immediately effective upon
and governed by the operating parts of the machine. Many other forms of this
equalizing valve might undoubtedly be readily devised; but we regard every device
which will permit a steady and gradual interchange of pressure between the interior
connections of the apparatus and the outer air as within our invention. The settling
chamber to which it is applied is not an essential part of our apparatus, but as value
both for the reason that it affords a convenient point of application for the equalizing
chamber that it recovers a considerable amount of fine dust from the current of air
which is passed through the fan which it would otherwise be necessary to return to
the pulverizing chamber.
Lf
We wish it understood that we claim each of the several improvements herein
described independently of and without reference to the others, and that we

page_text: contemplate using these several features without as well as in connection with each other.
Thus we claim the increased distance between the beaters without reference to the
shape or size of the upward discharge opening of the pulverizing chamber, or the
shape or size of the separating chamber, so, too we claim the increased relative length
given to the upward discharge opening independently of any change in the relative
location of the beaters or the size of the separating chamber, and, likewise, we
contemplate the use of the several novel features of the separating chamber separately
and apart from all the other features described; so, too, while the closed returning
air passage is a great addition to the machine, it is not absolutely essential to its
operativeness, and the improvements herein described in the reducing machine itself
may doubtless be made serviceable without either an exhaust fan or the equalizing valve.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is :-
First The method of reducing mineral and other substances which consists in
pulverizing them hetween beaters, causing the pulverized material to be carried off in
an air current, expanding or arresting said current so as to permit said material to
drop out of it more or less perfectly, and returning the same air to the pulverizing
machine to act as a vehicle for other material, substantially as set forth.
Second The method of securing a highly pulverized product from ore or other
substance, which consists in breaking up and reducing such substance in the presence
of an air current, conducting such current, laden with the finely pulverized material,
to settling chambers and causing its deposit, and returning the same air to the initial
point to serve again as a vehicle for finely pulverized material, substantially as set forth.
Third In a reducing machine, a circular chamber tapering in diameter from its
centre towards its two ends, in combination with two shafts, a set of beaters mounted
on each shaft, one of said shafts being set in each end of said chamber and the two
sets of beaters having between their inner revolving edges a clear space of a width
equal approximately to one third the length of the chamber, substantially as, and for
the purpose, set forth.
Fourth In a reducing machine the combination of a circular chamber, having a
greater diameter at its centre than at its ends, two shafts, one set in each end of said
chamber, and two sets of heaters, one set attached to each of said shafts and following
in their revolutions the interior curved surface of the chamber, the said chamber
baving an upward discharge opening of approximately equal length with the chamber
itself, substantially as, and for the purpose, set forth.
Fifth In a reducing machine the combination of a circular chamber, two sets of
beaters placed one in each end of said chamber, and means for causing said beaters to
revolve, the said beaters having between their inner revolving edges a clear space of
a width equal approximately to one third the length of the chamber, and the said
chamber being provided with an upward discharge opening substantially equal in
length to the length of the chamber, substantially as, and for the purpose, set forth.
Sixth In a reducing machine the combination of a circular chamber having a
greater diameter at its centre than at its ends, two sets of beaters, one placed in each
end of said chamber, and means for causing said beaters to revolve, said two sets of
beaters having between their inner revolving faces a clear space of from eight to
twelve inches, substantially as, and for the purpose, set forth.
Seventh-In a reducing machine the combination of a circular elongated
pulverizing chamber, two sets of beaters one placed in each end, said beaters having
à clear space between their revolving faces, means for causing said beaters to revolve,
said chamber having an upward discharge opening approximately equal in length to
the chamber itself, and a separate chamber forming an upward continuation of said
discharge opening, substantially as, and for the purpose, set forth.
Eighth In a reducing machine the combination of a circular elongated chamber,
beaters placed therein, means for causing said beaters to revolve, said chamber being
provided with an upward discharge opening, a separating chamber, a discharge pipe

page_text: therefrom and a partial screen or partition located in said separating chamber between
the said upward opening from the chamber containing the beaters and the entrance to
the said discharge pipe, substantially as, and for the purpose set forth.
Ninth In a reducing machine the combination of a pulverizing chamber, a
separating chamber connected therewith having a curved top, a discharge pipe lealing
from a point below the top of the separating chamber, and a screen or partition
placed in front of the entrance to the discharge pipe, said curved top of the separating
chamber being so shaped as to deflect the material arising into the same towards the
entrance to the discharge pipe and over the top of the screen or partition, and a space
being left, beneath the said screen or partition for coarser particles to drop back into
the pulverizing chamber substantially as set forth.
Tenth-In a reducing machine the combination of a circular chamber having a
larger diameter at its centre than at its ends, two sets of beaters arranged one in each
end of said chamber, and means for causing said beaters to revolve, said circular
chamber having an upward discharge opening of approximately the length of the
chamber itself and of a width approximately equal to two thirds of its largest
diameter, substantially as, and for the purpose, set forth.
Eleventh In a reducing machine the combination of a circular chamber, sets of
beaters placed in said chamber, and means for causing said beaters to revolve, said
chamber being provided with a central circumferential annular extension and grate bars
adapted to form a grating between said pulverizing chamber and said annular extension,
whereby the material being pulverised may be sifted, substantially as set forth.
Twelfth In a reducing machine the combination of a pulverizing chamber, a
second chamber provided with an outlet and a grating separating the two chambers,
substantially as, and for the purpose, set forth.
Thirteenth-In a reducing machine the combination of a circular chamber having
larger diameter at its centre than at its ends, two sets of beaters placed one in
each end of said circular chamber, their inner edges having a clear space between
them, said circular chamber having central circumferential annular extension approxi-
mately equal in width to the clear space between the beaters, and a set of grate bars
adapted to form a grating between the said separating chamber and the said annular
extension, substantially as, and for the purpose, set forth.
Fourteenth In a reducing machine the combination of a circular chamber having
a larger diameter at its centre than at its ends, and provided with an upward discharge
opening, two sets of oppositely revolving beaters, one set placed in each end of said
chamber, means for causing said beaters to revolve and two air pipes leading into
said circular chamber at its base, one at each end thereof and on opposite sides, with
respect to each other, substantially as, and for the purpose, set forth.
Fifteenth In a reducing machine the combination of a circular elongated
pulverizing chamber, two sets of beaters placed, one in each end of said chamber,
means for causing said beaters to revolve, and two air pipes approaching the chamber
from the same side and entering the chainber one at each end with a downward turn
and on opposite sides of the longitudinal axis thereof, substantially as, and for the
purpose set forth.
Sixteenth In a reducing machine the combination of the hub 6, the round arm S
fixed thereto and the chanelled beaters 9 adapted to fit upon said arm, substantially
as, and for the purpose, set forth.
Seventeenth-The combination of the round and shouldered arm 8 with the channelled
beater 9 detachably fixed thereon, substantially as, and for the purpose, set forth.
Eighteenth In a reducing machine the combination of a circular elongated
chamber having a larger diameter at its centre than at its ends, two sets of beaters
one placed in each end, means for causing said beaters to revolve, said circular chamber
being provided with an upward discharge opening substantially equal in length to the
chamber itself, and deflecting guide blocks adapted to be attached one to each end wall
of the said upward discharge opening, substantially as, and for the purpose, set forth.
Nineteenth-In a reducing machine the combination of an elongated circular
chamber 5 provided with central annular circumferential chamber 24, grate bars 25

page_text: or substitutes therefor and adjustable lining plates 33 and 34, substantially as, and
for the purpose, set forth.
Twentieth-In a reducing machine a circular pulverizing chamber of greater
diameter at its centre than at its ends, said chamber being cast in five pieces to wit,
a bottom piece, two top side pieces and two end pieces, said several pieces being each
shaped substantially as shown and described and provided with flanges and ground joints
at their connecting edges, whereby they may be securely and firmly bolted together,
substantially as, and for the purpose, set forth.
Twenty first In a reducing machine the combination of a circular elongated
chamber, two sets of beaters one set placed in each end of said chamber, means for
causing said beaters to revolve, said chamber being provided with an upward discharge
opening, an upward extension or separating chamber connecting with said discharge
opening, and a hopper communicating with said separating chamber and emptying
directly into said discharge opening, substantially as, and for the purpose, set forth.
Twenty second-The combination with a reducing machine of one or more settling
drums, a pipe connecting the reducing machine with said settling drums, a settling
chamber, a pipe connecting the aforesaid drums with the settling chamber, an exhaust
fan, and a pipe connecting the said settling chamber with the reducing machine,
substantially as set forth.
Twenty third The combination with a reducing machine of a closed air passage
way extending out from and returning to said reducing machine and provided with
means for permitting the slow passage of air to and from said passage way and the
reducing machine, substantially as, and for the purpose, set forth.
Twenty fourth-The combination of a reducing machine, a closed air passage way
passing therefrom and returning to the reducing machine, said passage way being
formed in part of a settling chamber enclosed on one of its sides by cloth or other
porous material through which air may slowly pass, substantially as, and for the
purpose, set forth.
Twenty fifth-The combination of an ore reducing machine, a closed air passage
way extending from and returning to said reducing machine, said passage way being
formed in part of a settling chamber 67, one side of which is made up of strips 70, 71
placed in two rows some distance from each other and supporting a strip of canvas
or other porous material, substantially as, and for the purpose set forth.
Twenty sixth-The combination with a reducing machine of a closed air passage
way extending out from and returning to said reducing machine and having therein
settling chambers and an exhaust fan, substantially as, and for the purpose, set forth.
Twenty seventh The combination with a reducing machine in which the rotating
faces of the beaters have between them a large clear space, of an exit pipe for carrying
off the material operated upon, settling chambers, and an exhaust fan for increasing
the pressure in the reducing machine and its connections, substantially as set forth.
Twenty eighth-The combination of a reducing machine, an exit pipe for the
material operated upon, settling chambers, a pipe leading therefrom, an exhaust fan
in said pipe, another settling chamber provided with an equalizing valve, and a pipe
connecting said last settling chamber with the reducing machine, substantially as, and
for the purpose set forth.
Twenty ninth-The combination of a reducing machine, a discharge pipe for the
material operated upon, settling chambers, a pipe leading therefrom, an exhaust fan
in said pipe, another settling chamber and a pipe connecting said last settling chamber
with the reducing machine substantially as, and for the purpose, set forth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.