Improvements in or in connection with Drums for Mixing and otherwise Treating Granular and like Materials and small Bodies or Articles in Bulk.
Year: 1896

page_text: Date of Application, 6th Aug., 1896-Accepted, 24th Oct., 1896
COMPLETE SPECIFICATION.
Improvements in or in connection with Drums for Mixing and
otherwise Treating Granular and like Materials and small Bodies
or Articles in Bulk.
We, HEINRIOH HIRZEL of 13 Nonnenstrasse Leipzig-Plagwitz and RUDOLF
HOFFMANN of Reichenbach near Plochingen, both in the Empire of Germany,
Manufacturer and Chemist respectively, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
This invention has for its object an arrangement of mixing and agitating devices
within a rotary drum, which drum may be used for mixing, parching, roasting,
charring, carbonising and rendering incandescent materials of equal or approximately
equal specific gravity, and also for the distillation, extraction and diffusion of substances
and the sorting or separating of bodies according to their specific gravity.
The feeding and discharging of the mixing drum takes place during the operation
whilst in the separating drum the filling and discharging or emptying necessitates the
drum being brought to a standstill.
The novelty of the mixing and also of the separating drum consists in a peculiar
arrangement of scoops or paddles on the inner casing of the same.
In the accompanying drawings, Figures 1-6 show two longitudinal sections, two
cross sections and two end views of a mixing drum with hollow axle for mixing
materials of approximately equal specific gravity. Figures 7 to 9 show a separating
drum built on the same principle as the mixing drum hereinbefore mentioned, and
which only differs from the mixing drum in that in accordance with its separating
object, it is intended for separating materials of unequal specific gravity. The
separating drum is made somewhat longer and instead of being fed through the
hollow axle the materials are fed into and discharged from the drum by means of
special openings in its casing capable of being closed by means of slides or flaps.
The mixing drum A which is made of suitable material according to the use to
which it is to be put, and which is closed at the end by two covers B, rotates with
its hollow shaft attached to the cover or end piece, in bearings, which however
are not shown in the drawing. Scoops Care arranged inside the drum so as to
lie obliquely to the drum axle in such a way that the scoops on the left hand half of
the drum have an opposite pitch to those on the right hand half of the drum. The
scoops C themselves may have an even or spiral form. The scoops do not however
form an uninterrupted continuation but consist for each circumference of two parts,
between which there remain two openings lying diametrically opposite each other,
as shown in Figures 3, 6 and 9. There are thus formed along the whole length of
the drum two diametrically opposed passages running parallel with the shaft, the
object of which passages will be immediately apparent from the following description.
The feeding of the mixing drum is effected during its rotation, by means of the
two hollow axles or trunnions, simultaneously from both ends of the drum, and
conveying worms or other suitable forwarding devices may be employed for this
object in the hollow axles. The material falling therethrough into the drum is
conveyed from both ends to the centre of the drum, accumulates there and returns
through the two longitudinal passages between the scoops, to the ends of the drum.
In the return movement of the material from the centre to the ends of the drum
in the longitudinal passages of the latter it crosses the material forwarded by the.

page_text: scoops from, the ends, to the centre of the drum, and a thorough admixture of the
substances to be mixed takes place..
The drum must not be made too full in. order, to ensure a proper circulation as
otherwise the material will take its return course from the centre over the enclosing
scoops until it reaches the drum ends and then is again forwarded to the centre.
No such thorough admixture of the materials would then take place and more
particularly the roasting would not be so even as when less material is charged in at
one time.
As is evident from the foregoing the materials which are to be mixed, roasted or
otherwise treated describe in the drum a circular course from the ends of the drum to
the centre and back again to the ends. In this circular course the material is
uncommonly well and evenly mixed and roasted by crossing the material conveyed to
the centre and back again to the ends of the drum. Such a capability of delivery is
attained by the drum as has not even been approximately attained by the apparatuses
hitherto employed.
The mixing drum has also the advantage that, as the larger part of the substances
to be mixed is contained in the centre of the drum whilst only a little material is at
the ends, it is impossible for the material to escape through the hollow trunnions of
the drum.
The heating may be effected, according to the object, which. it is desired to attain,
either, by. means: of steam or direct or indirect: furnacing, preferably by. firing.from the
.centre. In the use of this drum for extraction or diffusion, the hollow. axles or
trunnions serve for, supplying and carrying off the liquids and vapours or steam.
For discharging the mixing-drum, openings o are provided in the ends or covers B
of the drum, which openings are capable of being closed by means of doors. or
slides D. After these have been opened a reversed direction of rotation is imparted
to the drum, so that the scoops forward the material from the centre. to the
ends of the drum where it escapes. automatically through the openings. o to the
outside.
If the drum is intended to be employed for separating substances of different
specific gravity, (such a separating drum heing shown for instance as A¹ in
Figures. 7 and 9 of the drawing for three different degrees of separation) it is
made somewhat longer. As, when separating materials which are to be separated
in the drum according, to. their gravity such separated material must also be
removed from the drum separately, a number of flaps, or slides FF¹ F² etcetera
are arranged on the drum casing in such a way, that one flap stands at the centre
and the others lie at equal distances apart away from the centre so that always
two openings, for instance. F F and F. F, lying symmetrically to the central
opening, discharge material of approximately equal weight when the drum is opened.
The loading of the.drum A may take place as in the case of the drum A by
means of hollow, axles or trunnions. or by means of openings in the drum wall.
The discharging is always.effected through the latter.
.The separating drum A' differs from the mixing drum not only by its greater
length but also by, there being a greater space hetween the scoops which are nearest to
the..centre, so that a larger part of the material inserted may accumulate in the
centre. It is also advisable to make the distance between the next adjacent-scoops
somewhat larger, as shown for instance in Figure 7. As the heavier particles are
not so easily raised by the scoops they remain in the central larger space I of
the drum. The. lighter particles.accumulate. in the two adjacent compartments. II
at the right and left of the centre and the lightest in the chambers III. farther
from, the centre. By suitably arranging a number of openings, capable of being
closed by flaps.or valves F F F in the drum casing under the chambers I; II, III;
the materials may be separated according to gravity into various kinds and discharged
into,receptacles placed under these openings.
According to the length of the drum-A 3, 5, 7.or more openings may be arranged,
so that the material may. be separated or sorted into 2, 3, 4 or more constituents of
different gravity.

page_text: For ordinary separating, the trunnions 6' may be made solid. In separating in com-
bination with rinsing or washing or injection of air, hollow trunnions must be used
in order to allow of the washing or rinsing material or the air being injected and
withdrawn.
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 :-
1. A mixing drum of suitable sectional form for mixing materials of more or
less equivalent specific gravity, also for distilling, roasting, heating, carbonising,
extracting, diffusing or the like, characterised by scoops being mounted inside the
drum casing obliquely to the drum axis, in such a way that one half the scoops
starting from one end of the drum are pitched in an opposite direction to the other
half of the scoops, so that with a suitable direction of rotation of the drum the material,
passing into it through two hollow trunnions on the end covers, is forwarded by
the scoops to the centre of the drum and from there passes again to the ends of
the drum through longitudinal passages between the diametrically arranged scoops,
that is to say that the material describes a double circular course, and thus a
thorough mixing and equal warming or heating of the material and a great
delivering capacity of the drum
of the drum is obtained, assisted by the diametrically
arranged scoops being pitched differently to one another; the automatic discharging
of the drum being effected by a reversed rotation of the drum and the opening of end
slides or doors substantially as described.
2. A modification of the herein described drum to enable the same to be also
used for separating materials of different specific gravity, which consists in making
the drum somewhat longer and also increasing the size of the middle compartment (I)
between the scoops, and if desired the next adjacent compartments (II) also, so
that after a certain duration of rotation in a circular course the heavier particles of
the materials settle in the central part (I) of the drum, whilst the next lighter
accumulate in the next compartments (II), and the lightest in the end chambers (III)
of the drum and so forth, and the suitably sorted material is discharged into receptacles
placed beneath through openings in the casing of the drum, such openings being closed
during the rotation of the drum by flaps or slides, substantially as described.
Dated this 5th day of August 1896.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.