Improvements in Mills for Crushing, Pulverizing, Grinding, or Reducing Materials.
Year: 1893

page_text: Date of Application, 6th Sept., 1893
Complete Specification Left, 19th May, 1894---Accepted, 1st Sept., 1894
PROVISIONAL SPECIFICATION.
Improvements in Mills for Crushing, Pulverizing, Grinding, or
Reducing Materials.
I, CHARLES ROBERT WESTERN, of Broadway Chambers, Westminster, in the
County of London, Engineer, do hereby declare the nature of this invention to be
as follows:-
:―
My invention relates to that description of mills for crushing pulverizing grinding
or reducing materials in which a revolving cylindrical or other shaped drum, the
periphery of which is formed of curved perforated plates, contains a number of
hard balls or lumps which, in revolving in contact with the material to be operated
upon, pulverize or grind the same so that the particles having a certain degree of
fineness pass through the perforations of the plates on to external sieve surfaces of
greater fineness, the particles that do not pass through these sieves being conducted
back into the drum again through suitable openings or channels.
My present invention has mainly for its object to provide a more convenient and
effective screening surface for the crushed material to pass through than is afforded
by the said perforated plates forming the periphery of the drum, as heretofore
constructed.
For this purpose instead of using perforated plates, I construct the periphery of
the drum of strong bars of a rectangular cross section, arranged side by side with
small intervening spaces and placed in a transverse direction parallel or nearly so
to the axis of the drum.
These bars may be arranged so as to form either a cylindrical or polygonal
surface, or they may be made to form a stepped surface either by arranging them
in a series of circular arcs placed excentrically to the centre of the drum, or
otherwise. By employing such bars in place of perforated plates I am firstly
enabled to provide a much more extended screening surface than is possible with
the latter thus enabling the crushed particles to pass off more rapidly; secondly
I am enabled to make the interstices between the bars considerably smaller than
it is possible to make the perforations in strong plates, so that the subsequent
operation of screening the inaterial passing through the drum to the required
degree of fineness is considerably reduced, and thirdly, the bars can be readily
separately removed and replaced when defective, whereas with the plates an entire
plate has to be removed, if one part thereof is defective. The ends of the bars are
secured against the side cheeks of the drum iu any convenient manner, such as by
fitting them in a groove formed between a central disc and outer segmental plates.
The drum is by preference provided, outside the said bars, with a single
cylindrical screening surface, and the particles that do not pass through such
surface are led back into the drum by one or more channels communicating at the
outer end with side openings in the space between the bars and the outer screening
surface this being made slightly conical so as to lead the particles towards the side
holes.
The drum is carried by a hollow shaft one end of which is open and communicates
with a hopper containing the material to be crushed, so that the latter enters the
shaft and passes into the drum through lateral openings in the shaft.
The inner ends of the before mentioned channels may also conveniently
communicate with lateral openings in the shaft so as to lead the material retained
by the outer sieve back into the shaft, from which it passes into the drum again.
Dated this 6th day of Santonihar 1802
ABEL & IMRAY,
Agents for the Applicant.

page_text: CUMT LETE SPECIFICATION.
Improvements in Mills for Crushing, Pulverizing, Grinding, or
Reducing Materials.
I, CHARLES ROBERT WESTERN, of Broadway Chambers, Westminster in the
County of London, 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 :—
My invention relates to that description of mills for crushing, pulverizing,
grinding or reducing materials in which a revolving cylindrical or other shaped
drum, the periphery of which is formed of perforated plates, contains a number of
hard balls or lumps which, in revolving in contact with the material to be operated
upon, pulverize or grind the same so that the particles having a certain degree of
fineness pass through the perforations of the plates on to external sieve surfaces of
greater fineness, the particles that do not pass through these sieves being conducted
back into the drum again through suitable openings or channels.
My present invention has mainly for its object to provide a more convenient and
effective screening surface for the crushed material to pass through than is afforded
by the said perforated plates forming the periphery of the drum, as heretofore
constructed.
For this purpose, instead of using perforated plates, I construct the periphery
of the drum of strong bars of rectangular or tapered cross section, arranged side
by side with small intervening spaces and placed in a transverse direction parallel
or by preference at an inclination to the axis of the drum.
These bars may be arranged so as to form either a cylindrical or polygonal
surface, or they may be made to form a stepped surface either by arranging them
in a series of circular arcs placed excentrically to the centre of the drum, or
otherwise.
By employing such bars in place of perforated plates I am firstly enabled to
provide a much more extended screening surface than is possible with the latter
thus enabling the crushed particles to pass off more rapidly; secondly I am
enabled to make the interstices between the bars considerably smaller than it is
possible to make the perforations in strong plates, so that the subsequent operation
of screening the material passing through the drum to the required degree of
fineness is considerably reduced, and thirdly, the bars can be readily separately
removed and replaced when defective, whereas with the plates an entire plate has
to be removed, if one part thereof is defective. The ends of the bars are secured
against the side cheeks of the drum in any convenient manner, such as by fitting
them in a groove formed between a central disc and outer segmental plates.
The drum is by preference provided, outside the said bars, with a single cylin-
drical screening surface, and the particles that do not pass through such surface
are led back into the drum by one or more channels communicating at the outer
end with side openings in the space between the bars and the outer screening
surface, this being made slightly conical so as to lead the particles towards the
side holes. The drum is carried by a hollow shaft one end of which is open and
communicates with a hopper containing the material to be crushed, so that the
latter enters the shaft and passes into the drum through lateral openings in the
shaft.
The inner ends of the before mentioned channels may also conveniently
communicate with lateral openings in the shaft so as to lead the material retained
by the outer sieve back into the shaft, from which it passes into the drum again.
Fig. 1 of the accompanying drawing shews a longitudinal section and Fig. 2 a
transverse section of a ball mill constructed according to my above described
invention

page_text: Fig. 3 is an enlarged part cross section of the drum, shewing the form of the
bars employed.
The drum is composed of two side cheeks A A between which is the screening
surface B built up of bars of a tapering section as shewn at Fig. 3, and so arranged
as to leave narrow interstices between their inner edges; these bars are by
preference secured in an inclined position relatively to the axis of the drum, or in
other words, the drum formed by them constitutes an oblique polygonal surface
arranged excentrically to the axis, so that in revolving, the part of surface
situated at the bottom will alternately incline in opposite directions, causing the
crushing balls C to shift alternately from the one side of the drum to the other.
The axis D of the drum is tubular, and communicates at one end with a hopper E
through which the material to be crushed is introduced, and which has openings D'
at the middle for the entrance of material into the drum. For insuring a regular
feed of the materials to these openings, I prefer to form right and left handed
screw threads on the inner surface of the axis as shewn. Surrounding the screening
surface B is a cylindrical fine screen F on to which the materials passing through B
fall and through which the finely crushed particles pass into into the shoot of the
casing G. The screen F is made slightly conical so that the coarser materials
retained by it are caused to pass to the right hand side of the drum, in the side
cheek A of which are formed openings through which the material passes into a
circular trough H fixed to the side of the drum and from which a radial spout I
conveys the material back into the hollow axis D, which is provided with an
opening communicating with this spout and which delivers the said material back
into the drum.
The bars constituting the screening surface B may be conveniently secured in
position by forming the central portion of the cheeks A of excentric discs A'
having a polygonal periphery for the inner edges of the bars to rest upon, and
then securing the bars in that position by external segmental plates K bearing
against the outer edges of the bars and fixed to the annular part of the side
cheeks A.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In ball mills of the kind herein referred to, constructing the circular or
polygonal crushing and screening surface of separate bars having small interstices
between them arranged and operating substantially as herein described.
2. Arranging the screening bars referred to in the preceding claim so as to form
an oblique screening surface relatively to the axis and secured in position
substantially as described.
3. In ball mills of the kind herein referred to constructing the axis of the
drum tubular with lateral openings within the drum, so as to serve as the channel
for the introduction of the material to be crushed substantially as described.
4. The construction of ball mills combined and arranged as herein described
with reference to the accompanying drawing.
Dated this 19th day of May 1894.
ABEL & IMRAY,
Agents for the Applicant.