DE1907543A1 - Process and device for refining metals - Google Patents

Description

1907543 Patent attorney Dipl.-Phys. Gerhard Liedl 8 Munich 22 Steinsdorfstr. 21-22 Tel. 29 84 62

B 4099

Conzinc Riotinto of Australia Limited 95 Collins Street, Melbourne, Victoria / Australia

Process and device for refining metals

The invention relates to a process for the continuous refining of Metals, in which unrefined metal and an oxygen-containing gas are placed in a refining furnace, which consists of a turbulent refining zone, into which the oxygen-containing gas is added and from which the refined metal is drawn off, and a largely turbulence-free slag separation zone consists in which the slag flows from the fresh zone and from which it is withdrawn with a low metal content, as well as an apparatus for carrying out this method.

Dr. D / K

009884/0992 copy

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a, 1 9075A3

According to the present invention, an improved continuous refining process is sought be brought into proposal, which is carried out in the melt flow. Such refining or refining of raw metals, alloys or Stone for smooth: matt) is made by treating the liquid melt with a oxygen-containing gas and, if desired, with other oxidizing agents, such as the oxide or oxides of the metal to be produced. Specifically, the Improvement to a method and equipment as set out in Australian patents 48138/64 and 3170/66. Though specially for a continuous refining of pig iron to steel is the method used also for continuous refining of other raw metals, such as B. one Tin-iron alloy ("hardening") suitable.

In the following the term "metal" is used for raw metals, alloys and stone used.

This object is achieved in that

a) the unrefined metal and the oxygen-containing gas into one roughly round fresh zone are entered, in which the slag that is in this fresh zone forms, in the same direction as the melted Metal flows,

b) the partially refined metal from this round refined zone into an elongated one second fresh zone flows, which is connected to the round fresh zone and that oxygen-containing gas is entered into this second fresh zone will,

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c) the refined metal is continuously withdrawn from this second refining zone will,

d) the slag flow in the second fresh zone mainly in the opposite direction Direction to that of the molten metal takes place and the slag flows over the round fresh zone into a slag separation zone, which with is connected to the round fresh zone,

e) an inflow of the molten metal from the round fresh zone. is largely avoided in the slag separation zone,

f) the molten metal that emerges from the slag in the slag separation zone secretes, flows back into the round fresh zone, and

g) a slag with low metal content continuously from the slag separation S ' one is sucked off.

This continuous refining of metals takes place in furnaces which are characterized by certain novel arrangements, for example in that they preferably contain an elongated, roughly rectangular and channel-like fresh zone (hereinafter always referred to as the elongated fresh zone) in which the slag becomes one is caused halfway counter to the flow direction of the metal, an approximately round fresh zone (hereinafter always referred to as the round fresh zone), in which the slag is forced to a substantially uniform flow direction with the metal, and a zone in which the slag is conditioned and settled (hereinafter always referred to as the slag separation zone), into which the slag flows from both fresh zones. These three furnace zones are essentially separate chambers; which are halfway on the same level

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GOPY

communicate with each other. The slag separation zone is preferred so connected to the round fresh zone that there is a certain distance between it and the confluence of the elongated fresh zone.

The molten, as yet unrefined metal preferably becomes tangential entered to the walls of the round fresh zone; the refined metal becomes at the end of the elongated refining zone remote from the round refining zone or withdrawn near that end.

Furnaces of T-, L- or U-shape are widely used suitably. It turned out, however, that a furnace arrangement, with the one approximately round Fresh zone and a second elongated and rectangular fresh zone, together with an elongated tail, used for slag separation has certain advantages. These advantages include an increase in the contact time between slag and metal in the round fresh zone, as this both liquid phases in this zone because of the shape of the fresh zone and because of the flow pattern of the circulation a longer distance have to.

The round fresh zone acts as a reservoir for the elongated fresh zone; small and short-term fluctuations in the composition of the raw metal or Stone are also compensated there so that a uniform melt flows into the elongated fresh zone. To make the melt long lingers enough in the round fresh zone, should the capacity of this round zone must be at least as large as that of the elongated fresh ©, vos - preferably it should even be twice as large as the latter.

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The opposing and co-flowing of the two streams of slag and its final outflow into the slag separation zone is determined on the one hand by the design of the furnace itself and on the other hand by suitable means Supports angled nozzles, the oxygen-containing gas impinge on the slag in such a way that the flows in the desired Direction to be forced. The oxygen from these nozzles also helps burn carbon monoxide or other flammable gases that come out exit the bathroom. In this way both the heat and the momentum of the oxygen are transferred to the slag.

If molten pig iron is refined according to the above procedure with a system manufactured according to the present invention, a little of the basic flux can get into the round fresh zone near the Inlet opening for the molten pig iron are added. However, the larger proportion of the basic flux is preferably closer to that the outlet opening for the steel-containing end of the elongated refining zone is added; the slag that forms near this end is replaced by a Wall or baffle causes it to flow against the metal. This prevents the slag from flowing out with the metal.

The main purpose of the round fresh zone is to ensure uniform desilicon removal to obtain, also to initiate the removal of the carbon. Titanium and other rapidly oxidizable elements are also found in this zone removed.

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% 1307543

The greater proportion of the basic flux is preferred at the end added to the elongated fresh zone where the steel is tapped. The resulting slag is highly basic and well oxidized, so that it can possibly contains more than 25% FeO and the remainder mainly CaO. This well-oxidized slag reacts violently with the carbon-containing metal and produces considerable amounts of carbon monoxide, and thereby violent boiling of the bath. This is a favorable phenomenon for steel preparation, because with it a correct mixing of the hocüibasischen refining slag is guaranteed with the steel from which it removes sulfur and phosphorus.

If one wishes to produce steels with a low carbon content, such as distressed steel, it is advantageous to avoid, by suitable means, large amounts of slag flowing into the very low carbon area at the end of the steel very flat nozzles or by a slag nozzle. By this means, He fresh chamber is divided into three fresh zones, the circular zone, in which the slag flows rectified with the metal, that refining zone in which the slag flows in the opposite direction and a final refining zone with little or no slag flow. This third fresh zone receives the metal with a low carbon content, from which sulfur and phosphorus have already been removed by refining. No large slag formation occurs here because only the carbon that leaves the bath in the form of carbon monoxide bubbles has to be removed. Nevertheless, a thin film of slag usually forms in this third fresh zone due to the

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Reaction of iron oxide and basic flux as well as smaller ones Reactions with the refractory wall material; this film of slag helps to reduce the great heat that is emitted from the hot metal surface the ceiling of the fresh chamber is reflected.

Devices such as nozzles or slag collectors placed at shallow angles, can be installed in order to avoid the slag flow from the second fresh zone into the third fresh zone or at least to keep it as small as possible. Otherwise, in this third fresh stage, iron oxides would burn up in the slag.

Some foaming of the backward-flowing slag is beneficial, very strong foaming in one or the other fresh zone can, however, be caused by spraying or injecting (by lances or other means) suitably finely divided solids, e.g. lime, limestone or fluoride, onto the surface the optic varnish can be contained.

The accompanying drawings serve to further explain the invention. They show typical oven arrangements in which the round fresh zone - with 10, the elongated fresh zone is marked with 11 and the lacquer separation zone with 12 are,

1 shows the sectional view of a furnace according to the present invention, in which the round hairdressing zone 10 is arranged at the apex of a right angle which is formed by the elongated hairdressing zone 11 and the slag separation zone 12; 009884/0932

Fig. 2 shows the sectional view of an oven in which the elongated fresh zone 11 and the slag deposition zone 12 parallel to one another are attached so displaced that they open into this on two opposite sides of the round fresh zone 10;

Fig. 3 shows the sectional view of a U-shaped furnace in which the elongated fresh zone 11 and the slag separation zone 12 the Leg of the U and in which the round hair dryer zone 10 in this U die Form connection of the two legs;

FIG. 4 shows a cross section along line 4-4 of FIG. 2.

The corresponding reference numbers have the same in the different figures Meaning. In Fig. 1 through 3, the flow direction of the metal is shown by solid lines, the flow direction of the slag by dash-dotted lines Lines.

The furnaces shown in FIGS. 1, 2 and 3 all contain a round refining zone 10 in which the slag and the metal flow halfway in the same direction and an elongated second refining zone 11 in which the slag flows halfway in the opposite direction to the metal, as well a slag separation zone. In these figures, zones 11 and 12 are always connected to zone 10. The relative arrangement of the zones 11 and 12 to one another and to the zone are chosen essentially by way of example and do not indicate any limitations of the method according to the present invention. The respective choice of

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ORJGfWAi. INSPECTED

Furnace design is determined by the special factors of each facility determined, e.g. by the available space, the operating arrangement, Transport options and the specific fresh processes that are to be carried out with the system. For example, in Fig. 1 there are zones 11 and 12 arranged at right angles to each other. The open arrangements shown in Figs. 1 and 2 have the advantage that the various parts of the furnace are easily accessible for maintenance and repair, whereas the Fig. 3 shown furnace has a small base size, which is particularly suitable for systems with limited size.

The molten metal to be refined becomes Tangentially entered into the furnace through an Al vine 13, the fresh material is withdrawn through the tap opening 14. However, openings other than those shown can also be used for charging the material to be freshened.

Radiate oxygen or become jets of an oxygen-containing gas blown into the slowly flowing molten metal. this happens in the fresh zones 10 and 11 by a plurality of lances, e.g., 34, 15, 16, 17 and 18. The lance 34 is preferably approximately tangential to the fresh zone 10 attached. The lances can be given a suitable inclination, so that they the co-flowing or counter-flowing slag flow in the direction of the Allow slag separation zone 12 to flow. As an alternative to the inclination of the whole lances it is sufficient to attach the end pieces of the gas-carrying holes to the

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To arrange lances at such angles that the flow of slag in the desired Direction is steered.

A little of the basic flux can be added to the round fresh zone 10 be (is the arrangement of such a supply of such materials not critical and therefore it is not shown in the figure), but the majority of these fluxes are preferred by the lance 17 or by additional In the vicinity of this nozzle ',

in
In the / Fig. The embodiments of the loading shown in 1 and 3 are heat-resistant islands 19 along the walls of the fresh zone 1! attached in suitable places (generally at a distance of susgsiliisr 2/3 to 3/4 of the total length of the elongated zone 11), it is favorable to place one or more nozzles 23, 24 in ffc in this narrowing between such islands. At an angle to arrange it, blow the oxygen-containing gas onto the surface of the liquid. that a slag flow into the final or third fresh zone 22 can be avoided. The islands 19 may be liquid cooled by metal tubes or blocks (not shown in the figures). Their shape is expediently designed with smooth surfaces 21.

The refractory islands 19 can either be used as part of the refractory lining of the furnace. They can also be made from heat-resistant materials, such as building up dolomite blocks that are lowered into the furnace or be introduced in another way through suitable openings.

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In the slag separation zone 12, a slag dam 27 (in FIG. 4 can be seen), and a slag shaft 28, which is arranged between the slag dam 27 and the outlet opening 29 for the slag. The slag dart. m 27 can be liquid cooled by metal tubes or blocks 35 will.

In the slag separation zone 12 there is less turbulence than in the other oven zones. The bottom 30 of the slag separation zone 12 (to be seen in Fig. 4) is designed with a gradient that runs continuously from the slag dam 27 down to the confluence of the zone 12 in the Fresh zone 10 of the oven extends. There the floor level is also approximately s, ui the same height as the metal surface 31 in the fresh zone 10. This means the metal that separates itself on the slag 31a in the zone 12 is caused, the round fresh zone 10 of the oven flows back along the bottom 30. A flow of metal from the fresh zones 10 and 11 into the slag separation zone 12 is prevented halfway through this.

The slag well 28 has a much greater depth and a much greater total volume than the relatively flat and sloping part of the zone 12. It thereby allows the dewing time of the slowly flowing towards the slag tapping hole 29 Grow slag effectively. This gives the slag greater opportunity for a gravitational separation of fine metal beads from the Slag. The metal slowly accumulating at the bottom of the shaft 28 can be tapped at suitable intervals (which only needs to be done rarely) and returned to the main freshening zone 10 with a pouring ladle.

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-tfc-

But it can also be pumped over the dam 27, so that it is due to the Gravitation flows back into the fresh zone 10.

The area of the slag separation 12 is also suitable for adding additives to the To give slag (possibly via the passage 33). When refining pig iron, these additives can be added to prevent the iron from separating out To improve slag (e.g. by adding ferrosilicon, calcium carbide, coal, coke or other reducing substances), or to improve the slag to make it suitable for other uses after tapping (e.g. silica, soda, etc. to convert the lacquers into glass).

A gas outlet 32 is at a suitable point in that shown in FIG Embodiment mounted above the slag shaft 28.

Jets of oxygen or an oxygen-containing gas are emitted from the lances 25 and 34 generated to burn at least a portion of the carbon monoxide present in the furnace gases in a significant percentage, the out the boiling bath rises. The lances 34 also aid circulation of the liquids in the round fresh zone 10. Furthermore, the lances 25 help the slag from the round fresh zone 10 into the slag separation zone to transport.

example

The method according to the present invention has been described in the works of Sulphide Corporation, Cockle Creek, New South Wales, for three years

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wraps; During this time, more than 25 fresh tests were carried out. A typical 6 hour experiment is described below;

Molten pig iron was placed in a furnace of that shown in FIG Type given with a filling rate of 4 to / hour. The pig iron had the following composition:

C 3.75

Si 1.15

Mn 0.8

P 0.09

S 0.06

Fe rest.

A high quality quicklime (-1/16 "particle diameter) to which finely ground fluoride was added was used as the flux. This flux was added via the lance 17 at a rate of 120 lbs of lime and 5 lbs of fluoride per ton of steel produced A vigorously foaming slag was produced in the fresh zone. This slag, with an initially almost infinite ratio of CaO to SiO «, flowed freely backwards in the direction of the round fresh zone and through it. With a final basicity ratio (CaOtSiO ₀ ) of 2.2 to 27 it turned into a graining groove

(not shown) cut off.

009884/0892 4099

During the first two operating hours, that of the oxygen was chosen so that steel with a high cooling resistance (0.9 to 1.0% C) was produced. The other elements were represented with the following percentages:

Si 0.06

Mn 0.30

P 0.008

S 0.008

Fe rest,

And there were 85% of the sulfur removed so more than 90% ueos phosphorus isasei at a lime addition, ui & as was lower at a Stshlber © with koEventionelier Speisosig. The Emm's host cell was hocJij, as only 1300 cubic fui Ssn®irsl © ff were used on di® Nettotöim © steel.

For the remaining hours of the 'Vsreiiclies the glelclie Eoii used to make a low carbon steel which had the following composition:

C 0.15

Si 0.02

Mn Q. 03

P 0.004

8 0.006

Fe rest

In this case, over 95% of the phosphorus and @ ©% of the sulfur

removed. 009884/0992

Because of the favorable influence of freshening with slag running in the opposite direction
Here the iron losses in the slag were hardly greater than 0.6% of the steel produced, in the production of steel with a high carbon content these losses were less than 0.5%. The heat generated was so great that an addition of 12 to 15% coolant in the form of cold, crushed scrap could be added. Evidence suggests that when this fresh processing is carried out on a commercial scale, the scrap consumption can be in excess of 35 ^% , and thus greater than in conventional steelmaking using oxygen.

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Claims (23)

1307543 claims 1. Process for the continuous refining of metals in which not refined metal and an oxygen-containing gas placed in a fresh furnace are made up of a turbulent fresh zone, into which the oxygen-containing gas is added and from which the refined metal is withdrawn, and a largely turbulence-free slag separation zone, into which the slag flows from the fresh zone, and from which it has a low metal content is deducted, characterized in that a) the unrefined metal and the oxygen-containing gas into one roughly round fresh zone can be entered, in which the slag that forms in this fresh zone, in the same direction as the molten metal flows, b) the partially refined metal from this round refined zone into an elongated one second fresh zone flows, which is connected to the round fresh zone and that oxygen-containing gas is fed into this second fresh zone, , c) the refined metal is continuously withdrawn from this second refining zone will, d) the slag flow in the second fresh zone mainly in the opposite direction Direction to that of the molten metal takes place and the slag flows over the round fresh zone into a slag separation zone, which is connected to the round fresh zone, e) an inflow of the molten metal from the round frisclizone into the Slag removal zone is avoided at all times, 4099 009 884/0992 £) the molten metal that emerges from the slag in the slag separation zone secretes, flows back into the round fresh zone, and g) a low metal content slag continuous from the slag separation zone is deducted. 2. The method according to claim 1, characterized in that the unrefreshed Metal and the oxygen-containing gas is introduced largely tangentially in the direction of flow of the molten metal into the round fresh zone. 3. The method according to claim 1 or 2, characterized in that the in opposite direction to the metal flowing slag of the second elongated fresh zone halfway tangential in the round fresh zone, namely in the direction of the molten metal in it flows. 4. The method according to claim 3, characterized in that the partially refined metal of the round refining zone flows into the elongated second refining zone at one end thereof, and that the refined metal from the second Fresh zone at the opposite end, or close to it, is withdrawn. 5. The method according to claims 1 with i, characterized in that the slag from the round fresh zone flows into the slag separation zone at one end of the same and that the iJchluiike von der Hchhuikenabfioheidun ^ iJioiUi at the ont ■ end or must in Ίϊοπϋΐη UbJjU-UM ₁ On v / lr.l, 1009 00 M H-J Λ / 09 92 -HT- - ■. ■ ■■:., 130754 3 6. The method according to any one of claims 1 to -5, characterized in that the main residence time of the molten metal Ie of the round fresh zone at least is as long as the residence time of the -freshed Metal® in the second fresh zone. : - ". 7. The method according to claim 6, characterized in that the residence time of the molten metal in the round fresh zone is at least twice as large than that of the molten metal in the second fresh zone »* 8. The method according to any one of claims 1 to 7, characterized in that the metal from the second fresh zone through a narrowing into a third fresh zone flows where the metal is further refined, raid that the refined metal. is withdrawn from this third fresh zone. 9. The method according to claim 8, characterized in that the slag ß is restricted from the second fresh zone to the third fresh zone. 10. The method according to any one of claims 1 to 9, characterized in that the slag in the slag separation zone flows into a slag basin in which a further deposition of the slag and a separation of the metal from the slag takes place, and from which the slag is withdrawn . 0 09 88 4 / 0-9 92 lh 11. Apparatus for performing the method according to claim 1, consisting from an oven with a turbulent fresh zone and a largely turbulence-free slag separation zone, into which the slag flows from the fresh zone, and in which the refined metal flows from the fresh zone and the Slag is withdrawn from the slag separation zone, whereby the molten metal is largely at the same level in both zones, characterized in that a) the oven from an oven chamber with an approximately round first fresh zone exists, as well as an elongated second fresh zone and a slag separation zone, b) the second fresh zone is connected at one of its ends to the round fresh zone is, and that a metal outlet opening at the other end of the second Zone or close to it is provided, c) that the slag separation zone at one of its ends with the round one Fresh zone is connected, at a point that is remote from the connection between the round fresh zone and the second fresh zone and that an outlet opening for the slag is provided at the opposite end of the slag separation zone or close to it, d) Facilities for introducing unrefreshed metal and oxygen containing gas are provided in the round fresh zone, as well as devices, to introduce the oxygen-reverberant gas into the second fresh zone, Ί 907543 e) Facilities are provided which remove the slag that is in the round fresh zone forms, to one of the flow direction of the metal cause a movement in the same direction, f) facilities are provided, which in the second fresh zone forming slag to a substantially molten one Cause metal to flow in the opposite direction, as well as to one Drainage through the round fresh zone into the slag separation zone, g) and devices are provided which largely prevent the metal flows from the round fresh zone into the slag separation zone. 12. The apparatus according to claim 11, characterized in that the capacity of the round fresh zone is at least as large as that of the second fresh zone is. 13. The apparatus according to claim 12, characterized in that the The capacity of the round fresh zone is at least twice as large like that of the second fresh zone. 14. Device according to one of claims 11 to 13, characterized in that there are devices through which the metal, which separates from the slag in the slag separation zone, flows back into the round fresh zone. 009884/0992 4099 15. Device according to one of claims 11 to 14, characterized in that that a lance is largely tangential to the direction of flow of the molten Metal of the round fresh zone is arranged to introduce an oxygen-containing gas into this zone. 16. Device according to one of claims 11 to 15, characterized in that the bottom of the slag separation zone at the connection this zone is roughly on the same level as the round fresh zone the molten metal lies in the round fresh zone. 17. The device according to claim 16, characterized in that the bottom of the slag separation zone upwards in the direction of the slag outlet increases. 18. Device according to one of claims 11 to 17, characterized in that that a number of lances spaced along the second Fresh zone are arranged through which oxygen-containing ^ gas into the molten material is introduced into this zone. 19. Device according to one of claims 11 to 18, characterized in that that there is a restriction in the second fresh zone, as well as devices which largely cause a slag flow through this constriction '" in the direction of the outlet for the metal '. 009884/0992 4099 20. Apparatus according to claim 17, characterized in that a Slag basin between the higher bottom end of the slag separation zone and the outlet opening for the slag is attached. 21. Device according to one of claims Π with 20, characterized in that the second fresh zone and the Schladcenabscheidungszone in "are arranged approximately at right angles to one another. 22. Device according to one of claims 11 to 20, characterized in that the second fresh zone and the slag separation zone are mounted on opposite sides of the round fresh zone and approximately parallel to one another. I _t 23. Device according to one of claims 11 to 20, characterized - shows that the second fresh zone and the slag separation zone on the same side of the round fresh zone and roughly parallel to each other are appropriate. 00 98 84/0992
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