An Improved Ball Mill.
Year: 1896

page_text: Date of Application, 23rd Nov., 1896-Accepted, 24th Dec., 1896
COMPLETE SPECIFICATION.
An Improved Ball Mill.
1, REINHOLD STEINBACH, of 115 Schönebecker-strasse, Magdeburg-Buckau, in
the Empire of Germany, Foreman, 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 :-
Ball-mills, hitherto used in grinding or crushing harl bodies, generally comprise
ball-containing drums or cylinders the casings of which are made up of a number
of separate, perforated or slotted, grinding plates, underneath which sieves are
arranged, the size of the meshes of the sieves being determined according to the
fineness to which it is desired to reduce the material to be crushed or ground.
Now sieves or sifting fraines of this class are very liable to become obstructed or
clogged, when a high degree of fineness to be attained; the serviceableness
of the mill is thereby impaired and he difficulty of obtaining a fine product is
increased.
The present invention relates to a ball-mill consisting of a number of chambers
or compartments, wherein the material-by being continuously passed through the
mill-is reduced to any required degree of fineness, from that of coarse grit to that
of dust, without the aid of sifting frames.
The mill mainly consists of a cylindrical or conical drum, which is divided into
two or more compartments, by means of partitions arranged at right angles to its
axis. Each compartment is partly filled with balls. The first compartiment com-
municates with the second one by apertures or slots provided in the partition at
points close to the casing of the drum; while communication is established between
the second and third compartments by perforations at or near the centre of the
second partition. The said compartments thus, centrally and circumferentially, in
alternate succession, communicate with each other.
The material which has undergone a preparatory grinding process in another
mill, to reduce the particles. thereof to a suitable size, is, by means of controllable
feeding apparatus, introduced, through the centre of one of the side-walls of the
drum, into the first compartment or chamber. The said material descends between
the balls (by which it is further ground) to the casing of the revolving drum; and
thence, through the perforations provided for the purpose, passes into the next
chamber. The reduced particles behave somewhat like a fluid, and rise between
the balls of the second chamber, until they reach the same level as the layer
of material in the first chamber; and, in so doing, they are further gradually
reduced.
In
Before, however, they reach that level, they come up to the perforations in the
centre of the second partition and, through them, flow into the third chamber.
this and the following chambers (if any) the samne process is repeated. Thus the
material in travelling through the mill, from the inlet to the outlet, takes a
serpentine or winding course and, eventually, leaves the last chamber through the
outlet provided in the centre of the end, wall of the drum in the desired fine
condition.
When it is desired to vary the degree of fineness of the ground material, for
example to change from a coarser to a finer product,-instead of (as has been
necessary in the ordinary ball mills heretofore employed) changing the sifting
frames, and reducing the charge of material accordingly, all that is required in the

page_text: case of this improved mill is to reduce the rate of "feed" of the material by
properly adjusting or setting the feeding mechanism in such a manner that the
material takes more time to travel from one compartment to the next, remains
longer in contact with the grinding surfaces of the balls and is, consequently,
ground to a greater degree of fineness.
A ball mill, constructed in accordance with this invention, is shown, by way of
example, in Figures 1 and 2 of the accompanying drawings, Figure 1 being a vertical
longitudinal central section of the mill, and Figure 2 a transverse section on the
Jine v, r,, y of Figure 1.
The said mill consists of a drum a with end walls a' and divided by a partition
or two or more partitions arranged at right angles to its axis. These partitions
divide the drum into a corresponding number of compartments or chambers c the
number of which depends mainly upon the hardness of the material to be ground,
and, secondarily, upon the desired size of the "grains" or particles of the pro luct
to be obtained. Each chamber is partly filled with balls or spherical casting of
steel or other hard material. The end walls a' are provided with hollow pivots or
trunnions one of which d serves as an inlet and the other of which e serves as an
outlet. The inlet pivot or trunnion turns in an ordinary bearing f, while the outlet
pivot or trunnion rests upon rollers g. The drum receives motion through the
belt pulleys h, shaft i and pinion k, which engages with an annular rack or toothed
ring secured to the drum. The grits to be crushed are supplied by means of a
controllable feeding device of any suitable construction. In the drawings a
conveyor screw having an increasing pitch from one end to the other is shown, by
way of example, for this purpose. The outlet is fitted interbally with a cylindrical
wide-meshed sieve m the object of which is to keep the balls from dropping out of
the drum. At the inner end of this sifting cylinder is a cone n the apex of which
is turned outwards. The said cone serves to deflect the fine material which is
carried up by the end wall and sieve and which falls through the sieve into the
hollow trunnion e from the top. The partitions & have as above stated a number
of apertures or perforations p of any suitable shape, alternately at their periphery
and at or near the centre, and through these apertures the material is enabled to
pass from one chamber to the other as previously described. The size of these
apertures is such that the balls will not pass through them. By the above
described means the material is compelled to travel through the mill in the direction
indicated by the arrows in Figure 1.
When hard materials are to be dealt with, both the drumn-walls and the partitions
may be provided with exchangeable or renewable plates of correspondingly hard
material, as suggested in Figures 1 and 2.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A ball mill having its grinding or crushing chamber divided into ball-
containing compartments by partitions having apertures or passages so arranged
that the material to be ground, being admitted at one end of the mill, is compelled to
follow a serpentine course to the outlet orifice situated at the other end of the mill,
substantially as, and for the purpose, specified.
2. A ball mill constructed substantially as described with reference to the
accompanying drawings for the purposes specified.
Dated this 23rd day of November 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.