Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a method for continuously
refining contaminated copper in the molten phase.
German Patent 2,061,388, discloses a process in which
the molten copper is passed, in a ~reatment area, through a plu-
rality of reaction zones in counterflow to the heating gases, and
is thus freed of impurities. As a result, the final reaction zone
(in the direction of travel of the molten metal) is supplied with
fuel and an oxygen-containing primary gas in a ratio less than
stoichiometric, its combustion, in the absence of oxygen, producing
a reducing heating gas and in the zones before the final reaction
zone, afterburning of the unburned fuel carried along with the
heating gas is effected by an additional supply of oxygen-containing
secondary gas,
Patent 2,061,388 thus provides an efficient, continuous
process for refining copper in the molten phase.
The technical and economic advantage achieved by this
method is an inducement to further improvement by providing auto-
matic control. This has been delayed by the dif~iculty of achiev-
ing accurate and at least quantitative control of the heat-
exchange in the gas-phaselmolten-metal reaction mechanism.
To make this control of the reaction mechanism possible
- it is essential to achieve and maintain controllable and repro-
ducible convection-e~change and material-exchange ratios, adapted
to the individual situation, between the reaction gas and the
molten copper/slag phase. ; '
It is therefore an aim of the invention to improve the -~
copper-refining method of Germa~ Patent 2 ,061!388 ~ from both the
qualitative and quantitative points of view, through controllable
reaction patterns.
To this end, the invention proposes that the supply of
at least the secondary gas be carried out in a manner such that
it is first brought into contact with the molten phase of the
metal bath, as a reaction yas, thus effecting a definite material
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exchange into the metal bath9 and is only then used for com-
bustion with the heating gas.
In accordance with the invention, there is provided
a method for continuously refining copper in the molten phase,
in which the molten copper i~ passed~ in a treatment area,
through a plurality of reaction zones, in counter~low to the
heating gases, and thus ~reed of impuritie~, the final reaction
zone, in the direction of flow of the molten metal, being
supplied with fuel and an oxygen-containing primary gas in less -
than stoichiometric amount, the combustion of which~ in theab~ence of oxygen, produces a reducing heating gas 9 and in the
zones before the final reaction zone9 aterburning is brought
; about of the still unburned fuel carried along with the
heating ga~ by an additional supply of an oxygen-containing
secondary ga~, in which the supply of at least the secondary
ga~ is effected in a manner such that it i~ fir~t brought
into reactive contact with the molten phase of the bath of
metal, thus effecting a definite material exchange into the
metal bath, and is only t~lereafter caused to burn ~ ~h the
heatin~ gas.
According to one particularly effective step, the
secondary gas is blown suhstantially vertically, in the form of
at least one powerful jet of ga~ channeled through an accelerat-
ing nozzlej onto the sub~tantially free surface of the bath,
thus e~fecting a definite material exch~nge from the gas to the
~aid bath, before th~ secondary ga9 is burned with the fuel-
containing heating ga~
This ~tep is hig~ly ~igni~icant in that the ~et o~
ga3 pushes a3ide the floating layer of ~la~ and is thus brou~h~
into forced contact, at a controllable flow rate~ wit~ the
metal. A3 a result, rapid and thus controllable material .
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exchange is achieved in the molten-metal convection field
produced by the said jet of gas at the stagnation point.
As a further improvement J the jet of secondary gas
may be blown with such force that the substantially torus-like
stratified flow o~ molten metal, rotating about the blow--
depression located beneath the iet, produces 9 with the ~t, a
definite convective system~ with a definite material exchange.
This arrangement produce~ optimal, deinable, and
particularly rapid reaction patterns which can be controlled
in accordance with the order of magnitude of their speciflc
energy.
Since the ~reaction between the molten copper and th~
reaction gase~ takes place mainly in the viclnity o~ the
d~pression produced in the bath by the pxessu~ of the jet,
and 5ince the area of this depres~ic)n lS measurable, and
therefore adjustable and definable, it becomes possi~le to
control the material exchange ratio~3 quantitatively~
This~possibility of programmed control of the copper-
refining process constitutes an additional advantage o~ the
invention over exlsting proces~es~ It is also desirable to
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prevent the bath from "splashing", to eliminate any disturbing
influences, for example, unduly vigorous agitation of the bath
of metal. Any such splashing would, on the one hand, upse-t the
reaction equilibrium and thus the control conditions and, on the
other hand, would produce at least local over-oxidizing and the
formation of cuprous oxide. Both are undesirable.
Still another aspect of the invention is to adjust the
force of the jet and the distance between the mouth of the nozzle
and the surface of the bath in accordance with the type of
reaction gases used to reduce splashing.
Further details, characteristics and advantages of the
invention may be gathered from the following description of the
preferred furnace installation illustrated in the drawing for the
continuous refining of impure copper. In the drawing: ~ -
FIGURE 1 is a cross-section through a refining furnace
for the execution of the method according to
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the invention,
FIGURE 2 is a perspective view of the mouth of a lance
nozzle, with the jet of gas emerging from it
onto the surface of a bath of molten copper.
Figure 1 shows a rectangular smelting furnace 1,
divided by partitions-2,3,4, into three trough-like reaction
zones 5,6,7. The partition 2 contains a passage 9 through which
the molten copper flows. Shown in reaction zone 6 is the surface
10 of the bath, thereunder the bath 11 of molten copper, with a
layer 12 of slag on top. A tapping opening 13 in the wall of the
furnace is used to remove slag 12 from the oxidizing refining-
reaction zone 6. The impure molten copper is charged into the
furnace 1 at 14, and leaves the said furnace, after purification,
at 15. A weir 8 located at the outlet end of reaction zone 6
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serves to hold back the slag.
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The molten copper by-passes the weir 8 by flowing
through a passage 16 located below the surface 10 of the bath.
A closable aperture 17, in the wall of reaction zone 5, is used
for inspection and also to add solids, e.g. copper concentrate
and/or fuel. Exhaust gases leave the furnace 1 through the stack
19.
The furnace is heated by a burner 36 arranged in an
end-wall 18 at the outlet end.
When the unit is in operation, molten crude copper is
introduced into the furnace 1 at 14, and/or copper concentrate and
fuel at 17. The charge is heated in the zone 5 to a treatment
temperature appropriate for the subsequent refining. In zone 6,
an oxygen-containing reaction gas is blown through a lance 20, in
the form of a powerful, focused jet 21, onto the surface 10 of
the bath ll of molten copper. A throttle valve 22, located in
head 23 of the lance 20, is used to control the force of the
blast and thus the jet energy. The blow depression 24 may be
seen in surface 10 of bath 11. This depression 24 is of concave
dish-like form.
The pressure of the deflected jet 21 of gas pushes
aside the layer of slag 12 floating on the molten copper 11.
~This phenomenon shown in Figure 2, on an enlarged ~ -
scale, is as observed in tests. Also shown is the mouth 25 of
the lance nozzle 20, from which a jet 21 of gas emerges and
impinges with considerable force upon the layer of slag floating
on the molten copper. The pressure of the gas jet, in the
deflection area 26, forces back the layer of slag 12, and an "eye"
28 is formed on the free surface of the molten copper. This
produces a dished depression 24, shown by the dotted line A - B,
in the bath 11. At 29, the deflected ~as flows back lnto the
surrounding area.
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As a result of this contact with the jet and the drag
produced by it, and of the lift at the edge of depression 24 in
the surface of the metal, considerable turbulence is produced in
the bath, in the form of ~circular flow zone indicated by the
flow-direction vectors 27.
Finally, Figure 1 also shows another nozzle-lance 30
in the reaction area 7, used for blowing reaction gas onto the
molten copper bath~ The head 31 of the lance has two connections
32,33. The connection 32 supplies a carrier gas and the other
connection 33 is used for fuel, e.g. diesel oil, natural gas,
propane, coal dust, or the like. Throttle valves 34 and 35 are -
used to adjust the pressure and thus the energy and flow density
of the gas jet.
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