EP1301642B1 - Method and device for reducing the oxygen content of a copper melt - Google Patents

Abstract

Reducing the oxygen content of a copper melt comprises melting the copper initially in a shaft furnace, and subsequently feeding it to a treatment furnace via a transporting channel so that rinsing gas in the region of both the channel and the treatment furnace rises by flowing from the porous plugs. The rinsing gas containing 30-70% reduction gas and 70-30% inert gas flows from at least one of the plugs. The melt is electrically heated/moved in the treatment furnace. An independent claim is also included for an apparatus for reducing the oxygen content of a copper melt comprising a treatment furnace (1) having an inlet (2), a central part (12) and an outlet (3). Preferred Features: The reduction gas is provided with carbon monoxide, preferably carbon dioxide. The porous plug is made of Al2O3, SiC, SiO2 or MgO.

Description

The invention relates to a method for Reduction of the oxygen content of a Molten copper, in the lower part of the Copper melt arranged at least one purging plug is, from the at least one purge gas exits rises in the molten copper.

The invention also relates to a Device for reducing the oxygen content a molten copper, essentially as a self-contained treatment vessel or a closed treatment furnace is formed and in which the molten copper by means of electric Current tempered and / or can be mixed.

There are already many known methods, copper and its alloys with very low Contamination levels, for example less than 50 ppm, and / or with very low Oxygen levels, for example less than 5 ppm, produce. Become in technology Similar methods also for other metals (e.g. in aluminum and iron).

Entfernen von im flüssigen Metall befindlichen Reaktionsprodukten und/oder Verunreinigungen und/oder Schlacken und/ oder einzelner/mehrerer Elemente.

The objective of the different technologies according to the prior art usually includes the following:

Removal of reaction products present in the liquid metal and / or impurities and / or slags and / or individual / multiple elements.

The use is known in this context for example, of filters, the provision of residence time for weaning, treatment by with the impurities reacting additives, the Use of physical separation methods such as e.g. Rinsing, applying vacuum, etc. in one or several steps, in combination with above Technologies or in individual application of these technologies to the desired ones To achieve refining effects.

These methods have become known and have Widest application found in the treatment of Aluminum and steel and their alloys, while only partially in the copper industry to be used.

In the production of copper has been around since ancient times poles with tree trunks and with reducing ones Gases to remove the oxygen content generally applied. Also known is the Addition of reducing elements, e.g. Phosphorus and lithium or boron in the form of e.g.

Mother alloys. Likewise, filters, Slag sumps, vacuum chambers / ovens and / or Settling times used to clean the metal.

All the above procedures are for copper to reduce very high levels (e.g., larger than 200-2000 ppm) of impurities and / or Oxygen used and widely used. It is also known that deoxidizer such as. Phosphorus also as Alloy element to achieve certain Material properties are used.

For the production of very clean Küpfermaterialien is almost continuously as a base material electrolytically refined copper (cathodes) whose level of contamination by the previous refining steps (thermal and chemical) in international stock exchange registries Varieties below 100 ppm.

At the then always following another thermal processing steps by melting and casting is done through further procedural steps, partly through the technologies listed above, the impurity content and / or the Oxygen content further reduced or by the melting and casting caused or still Existing contamination levels eliminated.

For example, as discontinuous or continuous standard method of reduction the oxygen content below 5 to 15 ppm the electrical melting of copper cathodes used, the cathodes additionally at some procedures before. Increase the Melting power or removal of adherent / trapped Impurities up to 950 ° C via Gas burners are heated.

The melting takes place in a with Charcoal and / or reducing, largely hydrogen-free inert gas provided electric furnace, preferably in induction furnaces. Subsequently a transfer of the liquid copper takes place one, if necessary, electrically heated and also flooded with reduction / inert gas Gutter in a holding / buffering / settling furnace, also usually designed as an induction furnace, the again covered with charcoal and / or with Reduction / protective gas is flooded. After this Leaving this oven, the melt is over a, if necessary, also electrically heated and with Reduction / inert gas flooded gutter into one convicted electrically heated tundish, the also covered with charcoal and / or with Reduction / protective gas is flooded. From the tundish The liquid metal usually passes through the soil attached ceramic valve in the z.T. likewise with reducing / protective gas and / or for Example with carbon black covered mold in which the Metal continuously solidifies and continuous or discontinuously withdrawn.

This described standard method is based in essential to a reducing atmosphere in the Oven and the gutters, and in particular on the large Exchange surface between metal and reduction / inert gas within the overpass in the gutters and on the long residence time inside the furnace. Within and beside this standard procedure are also known methods, some of which are the above Procedural steps without or only partially with Operate reduction / shielding gas. Also known are procedures that only last for long residence times of the liquid metal in one Induction oven under charcoal cover low Seek to achieve oxygen levels.

Furthermore, methods are known which additionally and / or to the above standard method or to its Modifications the treatment of the liquid metal by vacuum.

From DE-OS 36 40 753 it is already known, for Removing oxygen from a copper melt a mixture of a gaseous hydrocarbon and an inert gas in the molten copper blow. The blowing can be done by using a porous brick or by using a special nozzle done.

From DE-OS 20 19 538 a further process and a device for degassing and cleaning Metal melts known. In particular, the Reduction of the oxygen content of a Copper melt when using purging stones described, from which an inert gas leaks, the rises in the molten copper. The inert gas can be reducing or oxidizing gases be added.

The tempering of a copper melt during the melt transport from a shaft open is already known from JP-A-53064617 become.

Devices and methods according to the state The technology is not sufficient for that suitable, reproducible and with sufficient Production speed as well as reasonable Costs in the implementation of the method Oxygen content of the molten metal to one Less than 5 ppm.

The object of the present invention is therefore to a method of the type mentioned in the introduction indicate that in large-scale application specified oxygen content reproducible and too reasonable and lower cost compared to the State of the art as described above, achieved can be.

This object is achieved according to the subjects of claims 1 to 3. The copper first in a gas-fired Shaft furnace melted and then over a gas-fired gutter to one Treatment furnace is passed.

As shaft furnace, a device according to the DE 2 517 957 C2 can be used.

It occurs both in the area of the gutter or in the area of Treatment furnace, the purge gas by flowing out the purging stones from below through the molten copper from, wherein at least one of the purging stones the Purge gas in a composition of 30% to 70% Reduction gas and 70% to 30% inert gas flows out. The shaft furnace is designed such that continuously copper with low acidity Hydrogen and gas contents melted and attached to the Gutter is passed.

Another object of the present invention is a device of the type mentioned in the introduction such that a reduction in the Oxygen content of the copper melt in one continuous process and with appropriate Production speed to be performed can.

This object is achieved in that in the field the floor and the sides as well as in the outlet area of the treatment furnace flushing blocks are arranged so that of the rising purge gas vertical flow is formed within the molten copper, wherein In addition, the treatment oven is completely self-contained closed system with controlled conditions forms for metal and gases.

Basically, the method and the Device suitable to the full extent to be operated continuously. The casting The molten copper may vary depending on the used treatment stoves also discontinuous be performed. In particular, it is thought, the starting material initially in one inexpensive gas-fired shaft furnace melt down.

By the inventive method and the Device according to the invention, it is possible a continuous production of copper with a Oxygen content of less than 5 ppm and with to produce a density greater than 8.9. It will both the investment costs for the production the manufacturing plant as well as the operating costs in DM / t in the implementation of the procedure lowered in the prior art.

Figur 1
einen Querschnitt durch einen Behandlungsofen und

Figur 2
ein Blockschaltbild zur Veranschaulichung des Materialflusses.

In the drawings, embodiments of the invention are shown schematically. Show it:

FIG. 1
a cross section through a treatment furnace and

FIG. 2
a block diagram illustrating the flow of material.

From the schematic cross-sectional view in FIG Figure 1 can be seen that the procedural Treatment of molten copper within one Treatment furnace (1) takes place. The treatment oven (1) is with an inlet part (2) and a Spout (3) provided. The copper melt is preferably via an inlet (4) from above into the Inlet part (2) transferred. Within the Inlet part (2) becomes a level height of the melt provided such that in the vertical direction Above a filling level (5) a free space (6) between the melt and an inlet cover (7) remains. The melt is within the Inlet part (2) with a cover layer (8) provided, for example, from soot or charcoal can be trained. The inlet (4) extends in the vertical direction to the melt into it, so that the supply of the melt below the cover layer (8) takes place. In the illustrated embodiment is in Area of an inlet floor (9) one or more Einlaufspülstein / e (10) arranged, from which the Purging gas mixture for the reduction of Oxygen content of the melt rises.

The inlet part (2) is connected to a connecting channel (11) to the central part (12) of the treatment furnace (1) coupled. The connecting channel (11) extends below the level of the melt in the Treatment furnace (1). In particular, it is thought, the connecting channel (11) directly to arrange above the inlet floor (9) and a upper limit of the connection channel (11) with a distance to the inlet bottom (9) to such locate that the inlet channel (11) in vertical direction upwards about half way Level of the melt within the Inlet part (2) is limited.

In the area of the middle part (12) is a crucible-like or tunnel-like depression (13) provided, in which the melt flows. According to the embodiment in Figure 1 is in particular thought, in the area of an input (14) of the Middle part (12) an input bottom (15) to arrange a height of about the height or a height lower level of the inlet floor (9) of the Inlet part (2) corresponds. In the area of Entrance floor (15) or above the Entrance floor (15) may be one or more Sink / e (16) are positioned.

The melt within the middle part (12) can also be provided with a cover layer (8).

Above the cover layer (8) is a gas collection room (17) arranged in the vertical direction is bounded above by a furnace lid (18). Of the Furnace lid (18) has a gas outlet (19).

In the region of a bottom (20) of the middle part (12) One or more Spülstein / e (21) is arranged. The sink (s) (21) is / are preferably placed so that of rising gas bubbles a flow of melt within the well (13) is generated such that in a middle Area the flow direction in vertical Direction facing upwards and in peripheral areas a Flow direction in the vertical direction down is realized. These flow directions are e.g. by electric fields or inductors amplified so deflected that the exchange reactions between sink and melt strengthened / lengthened. , This will ensures that in the area of the middle part (2) inflowing melt initially in the direction of the bottom (20) is passed and that thereby a sufficient contact with the from the sink (s) (21) effluent purge gas is ensured. The trained flow may possibly by a provided electric heating still supported become.

The middle part (12) is above an outflow channel (22) connected to the spout (3). Of the Outflow channel (22) has a height localization similar to the connecting channel (11). A upper height limit of the outflow channel (22) at about half the level of the melt provided within the spout (3). in the Area of a channel bottom (23) of the outflow channel (22) can have one or more sinks (24) be arranged.

In the area of a transition of the middle part (12) in the discharge channel (22) is an output bottom (25), which is about the same Height as the channel bottom (23) and the Entrance floor (15) extends. In the area of Starting floor (25) or above the Exit floor (25) can one or more Sink / e (26) to be placed.

Also within the spout (3), the Melt be provided with a cover layer (8) and above the cover layer (8) is between a Spout cover (27) and the filling level a free space (28) provided. In the area of a spout (29) is a spout opening (30) for discharging the Melt arranged.

In the highly schematic representation in FIG. 2 is illustrated that to be melted Starting material (31) first a melting furnace (32) is fed and then via a Gutter (33) in the area of the treatment furnace (1) is transported. An application of purge gas can both in the area of the gutter (33) and in the Area of the inlet part (2), the spout part (3) and the middle part (12). drawn are each supply lines (35) for the purge gas.

The melting with gas in the shaft furnace, whose Well how a heat exchanger works is essential more efficient and thus more energy efficient than that Melting by means of electricity in the induction furnaces the standard procedure.

The melted and already pre-set (inter alia, with respect to oxygen, total gas content and Impurities) liquid metal passes continuously from the stitch hole in the Gas-fired gutter (33), which in a similar way the cathode shaft furnace controlled and equipped is.

From the gas-fired and / or electrically heated and covered and / or closed channel (33) the copper enters the treatment furnace (1), the at the same time can be casting furnace.

Within the gutter length can beside the Slag sump further marshes may be arranged, the heated by inductors and those in the ground and / or rinsing stones are arranged from above that in these swamps an intimate mixture of liquid metal takes place with the purge gases. These marshes are either in direct run or via siphons connected to the channel (33).

The above inductors can Be channel inductors as well as crucible inductors. The groove (33) can be fixed or movable be arranged, depending on the use of one or several treatment / pouring furnaces.

The transfer with gas heating is like that Melting much more efficient and therefore more energy efficient than transferring to the Fully electrically heated gutters (33) of the Standard procedure.

The treatment furnace (1) is preferably an in a closed, fireproof walled vessel. This can be arranged stationary or movable be, continue only one or more times be present, depending on the casting technology and / or Power rating.

That in the treatment furnace (1) coming Pre-treated liquid copper is removed from the gutter (33) e.g. over a floor drain under bath or in the shallow inflow in the with reducing agents, e.g. Charcoal covered and with lids against the Atmosphere sealed inlet area (2) of the Treatment furnace initiated.

The bottom (9) and / or the sides and / or the Cover (7) of the inlet part (2) are with rinsing nozzles equipped so that an intimate mixture of the incoming copper is ensured with purge gas. The inlet part (2) can also - depending on its capacity - with inductors as in the Be provided channel (33).

The thus treated liquid copper passes from the inlet part (2) directly or via a siphon to the central part (12) of the treatment furnace (1). This part of the oven is also against the Atmosphere sealed with a lid (18) and the metal strip therein is with reducing agents, e.g. Russ, covered. The bottom (20) and / or the sides and / or the Input and output areas of the middle part (12) are equipped with rinsing nozzles so that an intimate Mixing the incoming copper with the Purge gas is guaranteed.

In addition, the bottom (20) with one or multiple inductor (s) and / or one provided electromagnetic stirrer, so that the Melt is additionally moved and thereby a intimate mixing with the purge gases, with the e.g. continuous operation incoming and outgoing Copper takes place as well as with the charcoal cover and, if necessary, the melt in the Treatment furnace (1) on the required Held casting temperature or brought to this becomes.

From the central part (12) the melt passes directly or via a siphon to Ausgußteil (3), which also with reducing agents, e.g. With Charcoal, covered and with lids (27) against the Atmosphere is sealed.

Depending on the construction, in the spout part (3) also rinsing stones and inductors similar to installed at the pouring part (2). The melt then passes under the bathroom via a ceramic valve and a ceramic tube incl. nozzle under bath in the mold / molds.

Depending on the casting process, the mold can also directly be flanged to the spout (3) under the bathroom, so that then the above-mentioned ceramic valve eliminated. Is the mold flanged over bath, so can e.g. between spout (3) and mold one appropriate mechanical or electromagnetic Pump installed in closed version be, or in self-contained mold by known method, the melt through the solidified strand pulled into the mold.

The non flanged mold and in the upper part the mold liquid metal is e.g. by Inert gas and / or soot and / or soot - Charcoal mixtures covered against the atmosphere.

Flanged as not flanged molds are also at their metal outlet end against the atmosphere covered with inert gas. The metal is now frozen, but still hot.

The in the gutter (33), in the treatment furnace (1) and the protective gas used in the mold is in essentially from inert gas such as e.g. Argon, Nitrogen and from CO / CO2 - mixtures, where Mixing ratios of inert gas from 100% to 70% each by injection site and by CO / CO2 from o% to 30% each after injection in the application after the described method as for the Purpose of the invention proved effective to have.

Generally, it is expedient to look at the total gas volume Reduction gas and inert gas in the area of Flushing a portion of the reducing gas in Range from 40% to 60%. typically, the proportion of the reducing gas is about 50%. Provide all the above shares volume shares.

The proportion of the reducing gas in the Furnace atmosphere should be in the range of 10% to 40% lie. Typically, the proportion is about 20%. The proportion of oxidizing gas constituents in the Furnace atmosphere is about 0% to 10%. Typically, there is a 5% share.

The purgatives, their inner training and theirs Arrangement in the refractory lining or in the lids and thus with their overlying Bath height or their Einblastiefe and their local Distribution and number in the channel (33) and in the channel Treatment furnace (1) depends on the respective existing or auszulegenden parameters.

Claims (22)

1. Process for reducing the oxygen content of a copper melt in which at least one sink is disposed in a lower region of the copper melt in the vertical direction, from which sink at least one flushing gas escapes and rises in the copper melt, wherein the copper is first melted in a blast furnace and is then conveyed via a conveyor trough to a treatment furnace, characterized in that, both in the region of the conveyor trough and in the region of the treatment furnace, the flushing gas rises in the copper melt as a result of discharging from the sinks and in that the flushing gas discharges from at least one of the sinks in a composition comprising 30% to 70% reducing gas and 70% to 30% inert gas and in that the melt in the treatment furnace is electrically heated and impelled vertically.
2. Process according to Claim 1, characterized in that the flushing gas is used in a composition comprising 40% to 60% reducing gas and 60% to 40% inert gas.
3. Process according to Claim 1 or 2, characterized in that the flushing gas is used in a composition comprising about 50% reducing gas and about 50% inert gas.
4. Process according to any one of Claims 1 to 3, characterized in that the copper melt in the treatment furnace (1) is heated and stirred by an induction heating system.
5. Process according to any one of Claims 1 to 4, characterized in that the copper melt is inductively heated and stirred in the region of a trough (33) between the melting furnace and the treatment furnace (1).
6. Process according to any one of Claims 1 to 5, characterized in that the melt in the treatment furnace (1') and/or the trough (33) is covered by a top layer (8) that contains carbon.
7. Process according to any one of Claims 1 to 6, characterized in that the reducing gas is provided with a proportion of carbon monoxide.
8. Process according to any one of Claims 1 to 7, characterized in that the reducing gas is provided with a proportion of carbon dioxide.
9. Process according to any one of Claims 1 to 7, characterized in that a material containing proportions of Al₂O₃, SiC, SiO₂ and MgO is used for the sinks.
10. Process according to any one of Claims 1 to 7, characterized in that a porous material is used as sinks.
11. Process according to any one of Claims 1 to 7, characterized in that a flow inside the copper melt is generated in the vertical direction inside a central section (12) of the treatment furnace (1).
12. Process according to any one of Claims 1 to 7, characterized in that the flow in the copper melt is in places oriented upwards in the vertical direction and is in places oriented downwards in the vertical direction.
13. Device for reducing the oxygen content of a copper melt, which device essentially comprises a treatment furnace (1) and also a conveyor trough for the copper melt, wherein the treatment furnace (1) comprises an inlet (2), a central section (12) and also a drain (3), and in which device at least one inductor is used to heat the copper melt, and also in which device at least one sink (21) is disposed in the region of a bottom (20) of the central section (12) and the central section (12) has a cross-sectional design that is such that a vertical flow is formed by the rising flushing gas inside the copper melt, characterized in that a linking channel (11) is disposed below a melt level between the central section (12) and the inlet section (2) and in that the inductor is disposed as induction heater for heating and stirring the copper melt in such a way that a flow direction, generated by the inductor, of the melt is oriented upwards in the vertical direction in a central region of the central section (12) and is oriented downwards in the vertical direction in peripheral regions.
14. Device according to Claim 13, characterized in that at least one sink (16) is disposed in the region of a crossover of the central section (12) to the inlet section (2).
15. Device according to Claim 13 or 14, characterized in that at least one output sink (26) is disposed in the region of a crossover of the central section (12) to the drain section (3).
16. Device according to any one of Claims 13 to 15, characterized in that a discharge channel (2) is disposed below the melt level between the central section (12) and the discharge section (3).
17. Device according to any one of Claims 13 to 16, characterized in that a gas collection chamber (17) is disposed above the melt in the central section (12).
18. Device according to any one of Claims 13 to 17, characterized in that a free space (6) is disposed above the melt in the inlet section (2).
19. Device according to any one of Claims 13 to 18, characterized in that a free space (28) is disposed above the melt level in the drain section (3).
20. Device according to any one of Claims 13 to 19, characterized in that at least one outlet sink (24) is disposed in the region of the discharge channel (22) between the central section (12) and the drain section (3).
21. Device according to any one of Claims 13 to 20, characterized in that the treatment furnace (1) is provided with at least one magnetic stirrer.
22. Device according to any one of Claims 13 to 21, characterized in that at least one sink is disposed in the region of a sidewall of the treatment furnace (1).

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