Improved Means of Mixing Molten Metal in Furnaces or Converters.
Year: 1890

page_text: Date of Application, 16th Jan., 1890
Complete Specification Left, 15th Nov., 1890-Accepted.. 16th Feb.. 1891
PROVISIONAL SPECIFICATION.
Improved Means of Mixing Molten Metal in Furnaces or Converters.
I, REINHARD MANNESMANN of Landore, R.S.O., South Wales, Engineer, do
hereby declare the nature of this invention to be as follows:-
Mechanical agitators have been employed for mixing molten metal in furnaces,
but these give way under the high temperature to which they are subjected
particularly in steel melting furnaces where mixing the fluid metal is often
necessary. My invention relates to means of mixing the molten metal in a furnace
or converter without the use of mechanical agitators. For this purpose when my
invention is applied to a furnace, I form outside the furnace a well communicating
freely by a channel with the lowest part of the furnace bed, and over this well
fix an air vessel lined with refractory material, this vessel being closed at the top
and open at the bottom to the well. I connect the top of this vessel with an air
pump or displacer, and by alternately rarefying and compressing the air I cause the
fluid metal to ascend and descend in the air vessel and thus to flow to and fro in the
furnace bed. There may be several such wells and air vessels communicating with
various parts of the furnace bed, with their channels directed at various angles so
as to ensure more thorough mixture of the fluid metal. Instead of connecting the
air vessels directly to a pump or displacer, they may communicate with reservoirs
of rarefied or compressed air or with both, with suitable cocks or valves for
alternating the pressure. I apply a similar air vessel at the side of a converter
communicating through a cock or valve with the air supply for the blast of the
converter.
..
In some furnace operations where the action of air on the metal is objectionable,
the alternating pressure of a suitable gas may be employed instead of that of air.
Dated this 16th day of January 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Means of Mixing Molten Metal in Furnaces or Converters.
I, REINHARD MANNESMANN, of Landore, R.S.O., South Wales, 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:-
Mechanical mixing devices have often been tried for mixing molten metals in
furnaces, but they have on the one hand imperfect action, and on the other hand
they do not last long under the high heat to which they are subject, in particular
when dealing with steel melting furnaces in which a mixing of the liquid metal is
often required.
The present invention relates to means for effecting the mixing of molten metal
in furnaces, converters, or casting ladles without the use of mechanical stirring
devices. For this purpose in the case of a furnace, a channel freely communicating
with the lowest point of the furnace bed is led to the outside and is there made to
communicate at the top or side with an air tight chamber lined with refractory
material and can be connected at top with an air compressing or rarifying
apparatus, while from the furnace bed a tube lined with refractory material extends
into the channel.
If now the upper part of the air vessel be made to communicate with an air pump
or displacer, the air in the vessel can be compressed and rarified.

page_text: At each rarification the atmospheric pressure forces a portion of the liquid steel
out of the furnace into the air vessel, while on increasing the pressure in the latter
the liquid metal will be driven back out of the same again.
In the above operation rarefaction alone may be employed in which case the
bottom level of the air vessel must at times be above the level of the metal in the
furnace, the flowing back of the metal into the furnace being effected by its own
gravity.
When using air pressure, the bed of the air vessel can be placed any distance
lower than the level of the metal in the furnace.
The metal then flows by siphon action of itself into this lower space when the
air pressure in the vessel is taken off.
Instead of varying the level of liquid metal in the chamber or vessel by the
action of air, it can be varied by causing the entire chamber or vessel to be raised
or lowered, or by causing a displacer of refractory material to be alternately raised
and lowered in the metal within the chamber, whereby the level of the metal will
be made to rise and fall, and thus the backward and forward flow of the metal to
and from the furnace be effected.
In this case the chamber or vessel need not be hermetically closed, and the
displacer might also be contained within the furnace so as to dip into the metal on
the hearth.
Several such air chambers or chambers or recesses with displacers can be made
to communicate with different parts of the furnace; the channels leading to the
same can be placed at varying angles to each other or to the furnace bed in order
to effect a better mixing of the metal.
Instead of connecting the chamber or vessel directly with a pump or displacer it
may be made to communicate with a reservoir of compressed air and one of rarified
air, which are provided with suitable slides or valves, for alternating the pressure
in the vessel.
In a similar manner to that described above in connection with open hearth
furnaces, a mixing of the metal can also be effected in a casting ladle, or in a
Bessemer or Thomas converter.
When applied to a converter the chamber is applied to the side thereof in such
manner that as soon as the converter is turned down the entrance aperture to the
mixing chamber is covered by the steel and this then flows by gravity into the
chamber.
If now by a slide or valve the air pressure be admitted into the top of the chamber,
it forces the metal back into the converter; if the air pressure be now cut off and
the chamber be made to communicate with the atmosphere, a portion of the metal
will flow back into the chamber, and so on, thereby effecting the desired mixing.
Or the chamber may be supplied alternately with air pressure and with rarified air.
In cases where the action of air upon the liquid metal has to be avoided, any
other suitable gas can be used, as above, in place of air. The chamber can also be
made to turn or to travel, so that it can receive metal from one part of the furnace and
discharge the same into another part. It can also be made to take the liquid metal
from one furnace and, after closing the connection by suitable valves, it can be
made to discharge the same into another furnace or other receptacle.
In order that the said invention may be readily understood I will proceed to more
particularly describe, by way of example, various arrangements of apparatus for
carrying the same into effect, for which purpose I will refer to the accompanying
drawings.
Fig. 1 shews a vertical section of a smelting furnace A, which is connected by a
passage a with a chamber k so that the molten metal can pass from A into the said
chamber. The latter is closed air and gas tight, and communicates by a pipe r with
an air pump or vessel containing air under pressure or vacuum.
If the pressure in vessel k be reduced, the atmospheric pressure in the furnace A
will force a portion of the molten metal through passage a into the chamberk, in
which consequently the level of the metal rises. If now the chamber k is again

page_text: subject to atmospheric pressure, the metal will fall again and it will consequently
pass back into the furnace A. In the same way, by introducing compressed gas or
air into the chamber k, the level of the metal can be depressed, and then by allowing
the pressure to escape into the atmosphere, the level can be allowed to rise again,
thereby causing the molten metal to flow from A to k and back again as before, or,
to obtain a still greater flow, the air or gas may first be put under compression in k,
and then be exhausted below atmospheric pressure. By the repetition of such
variations of pressure, waves or undulations may be produced in the bath of metal
in the furnace A.
In order to increase the effect of these undulatory movements, several passages a
and chambers & can be provided, and the passages a may be made to enter the
furnace more or less tangentially or at an acute angle to the walls or bottom of the
bath, so that by the backward and forward flow of the metal there are also produced
eddying or rotary motions in the bath which assist in producing an intimate mixture
of the metals.
The rarefaction of the air in the chamber k is of particular advantage in those
cases where gases are contained in the bath which it is desired to remove. In
consequence of the said rarefaction these gases expand and escape by degrees, this
being facilitated by the eddying motions produced.
This process may therefore be employed not only for mixing metals but also, at
the same time, for freeing the same from gases.
If the undulatory motions are produced by periodical rarefaction in k, the bottom
of the latter may be arranged at a higher level than that of A, while if pressure be
employed, the bottom of k may be placed lower than that of A.
The particular form of the channel a is immaterial so long as its ends are con-
nected respectively to A and to k at a sufficiently low level.
Similar undulating motions of the bath of metal can also be produced by a
displacer such as V shown at Fig. 2, which displacer is alternately immersed into
and withdrawn from the metal in k.
On immersing the displacer into the metal in k, a portion thereof is forced back
into the furnace, while on withdrawing it, the metal flows back into k; the latter
can in this case be open at top.
With converters, the chamber k can be advantageously directly connected to the
converter body and be made to communicate with the blast pipe in such manner
that the pressure in the chamber can be continuously varied by alternately opening
or closing a cock valve or slide in such communication. The connecting channel is
so arranged that as soon as the converter is turned down the metal flows of itself
from the same through the channel into the chamber. On opening the said cock
valve or slide, the air pressure forces the metal back into the converter again, and
upon then closing the cock &c. and connecting the chamber with the atmosphere a
portion of the metal will flow back into the chamber and so on. The same effect
can of course be produced by rarefaction, as also by alternately tilting the converter
so that the metal will flow from it into the chamber, and then tilting it back again.
In many cases it is of advantage to make the chamber k separate and moveable.
Fig. 3 shews such a construction of the chamber mounted rotatable on a wheeled
framing g and provided with a siphon-like tubular spout a lined with refractory
material, and so arranged that by suitably tilting the chamber upon its trunnions by
means of handles h, the spout can be introduced into the casting ladle A' so as to
dip into the charge of metal in it.
On then producing a partial vacuum in k through the suction pipe r, a portion
of the charge will be made to flow through a into k, and on increasing the pressure
therein the metal will be made to flow back again. The same effect will be pro-
duced by alternately raising and lowering k relatively to A', when once k has been
charged, the metal being made to flow into k on lowering it, and back again on
raising it.
A similar arrangement, more particularly applicable for steel furnaces, is shewn
in vertical section, elevation and sectional plan respectively at Figs. 4, 5 and 6.

page_text: In this case the tubular spout a communicates with laterally at the bottom in a
tangential direction so as to produce an eddying or rotary motion of the metal on
entering k. The chamber is in this case mounted on an axis turning in
bearings below its bottom, which bearings can be shifted on the wheeled
framing by means of a screw spindle a.
I
By means of this spindle x in combination with an adjustable strut y, any required
position for carrying out the operation can be imparted to the chamber k, and for
introducing the spout a into and removing it from the receptacle A² communicating
with the bed of the furnace. The air pipe r is rotatably connected to the top
of the chamber by a stuffing box, and is connected by a pipe to a rotatable pipe
mounted in bearings on the frame g. The pipe 2 is connected by a three-way cock s
to the pipes d and for compressed and rarefied air.
The latter are connected by articulated or flexible pipes with fixed conduits so
that the movement of the wheeled frame with the chamber k is not impeded. At q
is provided a sight hole closed by tale.
With such a moveable chamber not only can the above described undulating
motion of the metal bath be produced, but a still more effectual mixing of the metal
can be produced by withdrawing metal by means of the chamber k from one part
of the furnace bath, and then introducing such withdrawn portion at another
portion of the bath; or the metal withdrawn from one furnace can be intro-
duced into the bath of another furnace, such as, for example, for producing steel in
different furnaces or converters, one of which is subject to basic and the other to
acid treatment.
As the chamber k has a determined capacity, the withdrawal of metal in this
manner can readily be so regulated, that perfectly definite quantities of liquid
metal can be conveyed from one furnace to another. This is easily so arranged
that the withdrawal is automatically interrupted as soon as definite quantities by
weight have been received into the chamber. It will also be evident that the
vessel k may itself be used as casting ladle.
It will be advantageous to heat the before described apparatus before using them;
neutral gases will have to be used instead of air in all cases where the latter may
have a detrimental action on the metal.
Although I have spoken more particularly of steel in the foregoing, it will be
evident that the invention is equally applicable to other molten metals.
☐ 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. The method of mixing molten metals by alternately withdrawing and feeding
back a portion of the charge of a furnace, casting ladle or converter into and
from air tight chambers or vessels lined with refractory material, substantially as
described.
2. The method of mixing metals by varying the level of a secondary metal bath
communicating with the furnace, ladle or converter, by raising the same by mechanical
means, or by the immersion of displacers, substantially as described.
3. The method of effecting a fluctuating mixing motion in open hearth furnaces
by the varying immersions of displacers in a part of the metal bath, substantially as
described.
Dated this 15th day of November 1800.
ABEL & IMRAY,
Agents for the Applicant.