EP1013778A1 - Method and apparatus for producing metal from metal ores - Google Patents

Abstract

Metal production from oxidic ore, comprising tuyere injection of plastic supplied by a compressed air transport line (10) equipped with shut-off valves (24, 28, 29) for avoiding blockages and hot blast back-flow, is new. Metal production from oxidic ore comprises supplying fluidized plastic particles to tuyere injection lances (18) of a shaft furnace (1) by a transport line (10) equipped with shut-off valves (24, 28, 29), a compressed air entry connection (31) being provided in the transport line (10) or in each lance. The first shut-off valve (24) is closed when plastic blockage of the transport line or lances occurs; the second shut-off valve (28) is closed when hot air flows back through the injection lances (18); and the third shut-off valve (29) is closed when compressed air passes over and cools the injection lances. Independent claims are also included for the following: (1) a plant for carrying out the above process; and (2) a blast furnace in which the above process is carried out.

Description

The invention relates to a method and an apparatus for producing metal from metal ores, in particular pig iron from iron ore, in which the metal oxides containing ore with a carbon and / or hydrogen (and possibly their compounds) containing reducing gas brought into reaction contact is, which previously from solid carbon and / or hydrocarbonaceous Substances was obtained.

It is known that for the most part (even with iron different) Ore existing in metal oxides must be subjected to a reduction process, before the metal can be extracted. This reduction is done with the help of Carbon and possibly hydrogen - or their compounds - which are in one Reducing gas is included, which is brought to act on the metal ore.

The reduced metal ore then enters a smelting process. That for the reduction required gas is in the area of the reduction and melting process obtained by using carbonaceous substances (e.g. coke, coal, oil, natural gas) are added to the zone of the already reduced and heated metal, whereby with the addition of (air) oxygen a decomposition or conversion into carbon-containing gas takes place, which is fed to the previous reduction becomes.

In this respect, the conventional blast furnace process, in which in the blast furnace of Continuous from top to bottom - both the reduction of the metal ore and the formation of the reducing gas and the subsequent melt liquefaction of the metal takes place. In this blast furnace process, iron ore is aggregated Coke added as a carbon carrier. It is also known to better control of the blast furnace process and to save coke in the Wind power in the area of the frame of the blast furnace oil or carbon over lances with blowing, which also reduces the consumption of coke. This in addition Blown material (oil or coal dust) must be introduced very finely divided to ensure clean and sufficient gasification. Summaries on blowing coal dust into blast furnaces contain two Article in the journal "Stahl und Eisen", No. 4 of February 25, 1985, pages 211-220. The blowing in of coal dust became especially in the course of increasing Oil prices accelerated. It turned out that because of the short, available time of approx. 10 ms good results, namely a almost complete gasification of the coal dust, only with grain sizes below 0.1 mm could be achieved, even if tests were also carried out on some systems larger grain sizes were successfully carried out.

It has also been suggested instead of injecting oil and coal dust other carbonaceous waste such as dried sewage sludge or other carbon-containing waste such as garbage, waste paper, lignite, as well as waste from Wood, plastic, rubber or the like to bring (DE-A 29 35 544). As a corresponding However, experiments or results are only speculated like this Substances are to be introduced into the blast furnace. Also in DE-A 41 04 252 it is proposed to use plastic waste of this type via the wind forms to be blown into a blast furnace in fine-grained and dusty form, whereby as Example the introduction of sewage sludge (free-flowing dust) is given. Also this procedure eliminates the need for fine grain of the air to be blown Substance expressly emphasized.

Based on the known method described at the beginning, it is the goal of the invention, plastic waste, also in organically and / or inorganically contaminated Form, usable as a supplier for the components of the reducing gas do. Plastic waste is constantly accumulating in large quantities and is serious Disposal problem. It is mostly, if not exclusively, in solid form, be it as - often heavily contaminated - packaging waste as a waste or similar in the course of the production of plastic objects.

Accordingly, the invention provides that those referred to in the method of the beginning Genus for the extraction of the reducing gas supplied carbon and / or hydrocarbonaceous substances, at least partially of plastic in crushed, fluidized form as an agglomerate in the wind power in the rack of the metallurgical shaft furnace, in particular a blast furnace become. This happens via lances, which protrude into the shaft furnace and which are connected to a transport line. Via this transport line the plastic to be blown is led to the lances. In the event that reflected Expect blockages to occur or hot winds from the blast furnace into the lance and so that should strike back in the transport line, several shut-off devices proposed in the transport line so that it is not only protected is, but an immediate resumption of the overall operation of the plant and blowing in the plastics. To solve blockages in the plastic material A first and a third shut-off device are in the transport line provided to prevent the return transport of plastic or one Setback of the hot gas masses from the blast furnace into the transport line a second shut-off device is formed. Their functionality is described in the Claims, but in particular also explained in more detail in the figure description.

The invention makes use of the fact to solve blockages in the transport line take advantage that there is a pressure in the transport line which is 4 to Is 6 times the atmospheric pressure. So becomes the inside of the transport line relaxed to the outside atmosphere (approx. 1 bar) via a ventilation opening, there is a very large pressure and suction effect on the blockages that come loose and are transported out of the system from the transport line become.

This means that when the blowing system is at a standstill, the blowing lances that go into the blast furnace protrude, do not overheat, a connection for compressed air is provided, which is then always activated.

Further advantageous refinements of the invention can be found in the subclaims remove.

The invention is described below using an exemplary embodiment with reference to the accompanying drawings explained in more detail.

Figur 1

eine schematische Darstellung eines Hochofens einschließlich der entsprechenden Einrichtungen zur Zuführung von fluidisiertem Kunststoff und einschließlich der entsprechenden Einrichtungen zur Zuführung eines erhitzten Windstromes;

Figur 2

eine alternative Ausführungsform; und

Figur 3

eine Düsen-Lanzen-Anordnung zum Einblasen von fluidisiertem Kunststoff in die Windformen oder Düsen eines Hochofens;

Figur 4

eine vergrößerte Darstellung der Transportleitung für den Transport des Kunststoffs zur Lanze.

Show it:

Figure 1

a schematic representation of a blast furnace including the corresponding devices for feeding fluidized plastic and including the corresponding devices for feeding a heated wind stream;

Figure 2

an alternative embodiment; and

Figure 3

a nozzle-lance arrangement for blowing fluidized plastic into the wind molds or nozzles of a blast furnace;

Figure 4

an enlarged view of the transport line for the transport of the plastic to the lance.

FIG. 1 shows a blast furnace 1 constructed in a conventional manner, which has a plurality of nozzles or wind molds 20 distributed uniformly around the circumference in the lower frame region (see FIG. 3), which are connected via a line 5 and a ring line 2 in a wind heater 4 heated wind 3 is supplied. In addition, the wind 3 can also be enriched with oxygen 3a (O ₂ ). For the sake of clarity, only one nozzle 20 is indicated in FIG. 1.

Some or all of the nozzles 20 have one or more lances 18 over which Additional fuel can be blown in. With the previously known blast furnaces This was either coal dust or oil, which resulted in better performance of the blast furnace 1 and a saving in coke could be achieved. The usual number of nozzles 20 of the windform arrangement is e.g. 32, and each nozzle has one Diameter of e.g. 140 mm. When adding coal dust or oil usually two lances are provided, which typically have a diameter of 12 or Have 8 mm. In the present case, only one lance 18 is to be supplied in each nozzle 20 of fluidized plastic and has e.g. a diameter of 28 mm.

In the windform arrangement, either all of the lances 18 can be fluidized Plastic are loaded, or the nozzles 20 are mixed, i.e. some nozzles e.g. two oil lances on, while other nozzles 20 turn are equipped with a plastic lance 18. However, it is convenient to distribute of plastic lances 18 and oil lances evenly with each other over the Make the scope of the windform arrangement.

The processing of the plastic takes place in the present exemplary embodiment as follows:

A plastics processing plant 6 becomes a silo 7 shredded plastic in the form of an agglomerate with a high specific surface area and a grain size of 1 to 10 mm, preferably 5 mm. It has proven itself Use of plastic that forms an agglomerate with a bulk density of leads greater than 0.35. Plastic packaging cups or the like are used for these purposes. suitable, e.g. Plastic films when shredding to a lower bulk density lead so that special precautions are taken before or during blowing to be able to blow in a sufficient amount.

FIG. 1 then shows an injection vessel 8 into which the plastic agglomerate is introduced via a coarse-grain sieve 14 and fluidized by blowing in a fluidizing gas by means of a blower 11 via lines 12 and 13. In the case of an injection vessel of, for example, 3 m ³ volume, approximately 2 to 25 m ³ fluidizing gas / h are required. The fluidized plastic is then metered in a separate metering device 9, for example a mechanical screw metering device or a cellular wheel metering device, and is fed uniformly to the corresponding lances 18 of the windform arrangement via a line 10. The plastic particles are conveyed here by entrained-current flow, ie with a high gas content, for example at a ratio of 5 to 30 kg of plastic per 1 kg of fluidizing gas. Compressed air is used as the fluidizing gas in the present example, since there is no risk of explosion due to the size of the plastic particles of 1 to 10 mm.

The injection quantity of the plastic can be varied over a wide range (e.g. 30-150 kg plastic / t RE). It was also found that with the same good gasification, a 1.5 times higher amount of plastic compared to oil can be blown in. If the amount of plastic injected is more than 70 kg / t RE, O ₂ is expediently added to the wind stream for good gasification, as already mentioned above. The wind should then be enriched with 0.05 to 0.1% O ₂ , preferably 0.08% O _2, for each kg plastic / t RE above the value of 70 kg / t RE. For good gasification, the mixed wind temperature from the blast heater 4 is above 1100 ° C. The blowing pressure at the lances 18 is expediently 0.5 × 10 ⁵ to 1.5 × 10 ⁵ Pa above the pressure in the blast furnace 1.

Since plastic at higher temperatures - in contrast to coal dust or oil - melts, there is a risk of the plastic caking before it escapes from the blowing lance 18 by heat reflection from the nozzle. For this Basically, the flow velocity of the gas with the floating Plastic particles are sufficient in comparison to the tube cross section of the lance 18 be high in order to melt or melt and thus bake the plastic to avoid in the lance 18 by heat reflection. A suitable relationship the flow velocity to the lance cross section is in the range of 20,000 up to 40,000 1 / sec x m, preferably at 25,000 1 / sec x m. Is this value too low, if there is a risk of caking, if the value is too high, this occurs excessive wear in the lances 18. In addition, for all transport lines, especially in the connection area 18a of the lances 18, discontinuities and constrictions in the flow and radii of less than 1 m in the event of curvatures.

In the arrangement according to FIG. 1, the metering is carried out by a separate metering device 9. Another solution is shown in FIG. 2 and can consist in perform fluidization and dosing in one go. This is in the bottom In the area of the injection vessel, a ball valve 19 is provided as a metering device. The Fine adjustment is made via the pressure setting and the amount of fluidizing gas. However, this solution requires precise and rapid control of the compressed air supply on the upper line 13 of the injection vessel 8 depending on the fluctuating Internal pressure of the blast furnace 1. For this purpose it is in a suitable place In the blast furnace 1, a pressure sensor is provided, which is connected via a control loop 17 Valve in line 13 quickly readjusted to an exact dosage come.

The fluidization and metering of the plastic particles can also be done by means of a pressure-tight rotary valve. In this case, the injection vessel 8 omitted.

Figure 4 shows an enlarged view of the as l. designated section in figure 1 and 2 of line 10, via which the plastics to be blown into blast furnace 1, in particular plastic waste in agglomerated form, transported to the lance 18 become. This transport line 10 is connected to the fittings in Injection tower (these include, for example, the metering device 9, but also e.g. the connection for the compressed air or the supply for purge air / nitrogen) formed by a piece of hose 21. This is followed by a shut-off block 22 of the transport line 10 and to the shut-off block in the direction of the blowing lance 18 in turn connects to an essential lance fitting part 23 including the blowing lance 18.

The shut-off block 22 comprises a shut-off valve as the first shut-off device 24, which is closed to remove blockages (will be executed later). About that In addition, a vent line goes from the transport line 10 in the shut-off block (opening) 25, which has a shut-off valve 26.

The area of the transport line 10 adjoins the shut-off block, which hereinafter also referred to as the armature part 23 of the lance. Within this Fitting part 23 is a piece of hose 27, which is the transport line 10 of the shut-off block with a heat shut-off valve 28 as a second shut-off device connects. This second shut-off device is followed by a third shut-off device 29 for shutting off the lance 18. Behind the third Shut-off device (seen from the shut-off block) is a mouthpiece 30, via which by means of a connecting piece 31 compressed air in the lance 18 and so that it can be blown into the blast furnace 1.

The operation of the above arrangement is as follows: if from any For this reason, no plastic or other reducing agent in the blast furnace is blown in, the shut-off device (29) is closed and the connection 31 opened and then compressed air is in the standstill of the blowing system in the Blown lance. This compressed air is blown in either manually or also automatically whenever the plastic transport to the lance is interrupted is. The introduction of this compressed air prevents the Blow-in lance heats up undesirably and thus prevents heat damage. The connection 31 for entering compressed air into the lance is always opened when the plastic supply to the lance is closed by the third shut-off device is. The connector 31 itself consists essentially of a valve, which is connected to a compressed air reservoir.

In order to keep up with pressure fluctuations in the Blow mold a backflow of hot mold gas from the blow mold (blast furnace) To prevent the lance and the blowing system behind it is as Check valve designed heat shut-off valve as a second shut-off device educated. This heat shut-off valve can be a simple flap which allows material / air transport to the lance (i.e. then opens), in the opposite However, the direction automatically closes due to the mass / gas backflow.

The plastic agglomerates to be blown into the blast furnace 1 tend to be dependent on their grain shape and size, but also on their specific composition to block the line 10, which - as described above - prevents should be. If such a blockage occurs, one must rapid blockage can be provided. This is the shut-off block trained, in which in the case of a tamper after closing the shut-off valves (first and / or third shut-off device) a vent valve or the vent valve 26 is opened. This ventilation takes place above the outside atmosphere, which has the consequence that between the transport line 10 in the affected part A pressure drop of almost 4 to 6 bar can be recorded via the ventilation line 25 is, while the total pressure drop across the line from the blow fittings to the blowing lance is only about 0.5 to 0.8 bar. Through the blatant Air pressure drop will put considerable pressure on the clogging plastic mass exercised, resulting in the sudden emptying of blockages in the transport line leads, so that this in turn after blocking the valve 26 for the Blowing the agglomerated plastics is available.

Claims (16)

Process for the production of metal from metal ores, in particular pig iron from iron ore, in which the ore containing metal oxides is brought into reaction contact with a reducing gas containing carbon and / or hydrogen (and possibly their compounds), which previously consists of solid carbon and / or hydrocarbonaceous substances
characterized in that plastic is blown into the wind stream in the frame of a metallurgical shaft furnace, in particular a blast furnace (1) in comminuted, fluidized form as an agglomerate, that the plastic is injected into the air stream via lances (18) which are arranged in air nozzles of a blast furnace is blown in and that the plastic is conveyed via a transport line (10) to the lances (18), that the plastic transport line (10) has a first shut-off device (24), a second shut-off device (28) and a third shut-off device (29) is provided and that furthermore, means (31) for coupling compressed air are formed in the transport line or in the lance, so that the first shut-off device (24) is closed when there are blockages in the plastic in the transport line (10) or the lance (18) are that the second shut-off device (28) is closed when hot air into the transport line (10 ) and / or lance (18) penetrates against the usual transport direction (R _T ) and that the third shut-off device (29) is closed when compressed air is applied via the blowing lance (18) to cool it. Method according to claim 1,
characterized in that a vent outlet (26) is provided in the transport line (10) between the first and second shut-off device and, if the transport line becomes blocked with plastic, the first shut-off device (24) blocks the further transport of plastic and a vent opening (26) in the line (10) is opened so that clogged plastic particles can be removed from the transport line (10). The method of claim 1 or 2,
characterized in that the second shut-off device (28) is a heat shut-off valve with the function of a check valve, which allows the transport of plastic in the prescribed direction in the transport line, but closes when plastic particles or gas are moved against the prescribed transport direction. Method according to one of the preceding claims,
characterized in that the third shut-off device (29) is activated when no plastic is blown in and that compressed air is then blown in at the same time for cooling the lance (18). Method according to one of the preceding claims,
characterized in that the plastic to be blown is discharged from a plastic reservoir via a lock into the transport line. Method according to one of the preceding claims,
characterized in that the pressure drop across the transport line to the blast furnace is about 0.3 to 1 bar and that the pressure difference between the inside of the transport line and the outside atmosphere is about 4 to 6 bar. Method according to one of the preceding claims,
characterized in that the plastic has the shape of an agglomerate with a high specific surface area with a particle size of about 3 to 25 mm and a bulk density of greater than 0.25. Method according to one of the preceding claims,
characterized in that the injection pressure in the lances is 0.5 x 10 ⁵ to 1.5 x 10 ⁵ Pa above the pressure in the blast furnace. Method according to one of the preceding claims,
characterized in that the plastic particles are fluidized and metered in succession in separate devices before being introduced into the transport line. Method according to one of the preceding claims,
characterized in that the plastic particles are fluidized and metered in a combined fluidization and metering device, the injection pressure being continuously adjusted as a function of the oven pressure via a fast control loop (17). A method according to claim 10,
characterized in that a pressure-tight rotary valve is used as the combined fluidizing and metering device. Device for carrying out the method according to one of the preceding Claims consisting of a lance (18), by means of the plastic in crushed, fluidized form as an agglomerate in the wind stream in the frame of a metallurgical shaft furnace, in particular a blast furnace (1), can be blown in, that the lance (18) via a transport line (10) with plastic or other reducing agent is supplied and that in the transport line (10) first shut-off device (24), a second shut-off device (28) and a third Shut-off device (29) is provided that a connection (31) for introduction of air in the transport line (10) and / or lance (18) is provided that the first shut-off device (24) if the transport line (10) becomes blocked with plastic is activated that the second shut-off device (28) is activated when Plastic material or gas transported against the intended transport direction and that the third shut-off device (29) is activated if no Plastic is blown in and then a gas for cooling the lances (19) is blown in through the connection (31). Device according to claim 12,
characterized in that a ventilation outlet (26) is provided in the transport line (10) between the first and second shut-off device and if the transport line is blocked with plastic, the first shut-off device (24) blocks the further transport of plastic and the ventilation opening (26) is opened, so that clogged plastic particles can be removed from the transport line (10). Device according to claim 12 or 13,
characterized in that the second shut-off device (28) is a heat shut-off valve with the function of a check valve which permits the transport of plastic in the prescribed direction (R _T ) in the transport line (10), but closes when plastic or gas opposes the provided transport direction is moved. Device according to claim 12, 13 or 14,
characterized in that the third shut-off device (29) is activated when no plastic is blown in and that compressed air is then blown in to cool the lance. Blast furnace for the production of metal from metal ores, in particular from Pig iron from iron ore, in which the ore containing metal oxide with a carbon and / or containing hydrogen (and, if appropriate, their compound) Reduction gas is brought into reduction contact, which previously consists of solid Carbon and / or hydrocarbonaceous substances was obtained with a device for blowing plastic in comminuted, fluidized form as an agglomerate in the wind stream in the frame of the blast furnace, the plastic via lances (18), which are arranged in air nozzles of the blast furnace, into the air flow is blown in and that the plastic via a transport line (10) the lances (18) is conveyed that the plastic transport line (10) is a first Shut-off device (24), a second shut-off device (28) and a third Shut-off device (29) is provided and that furthermore in the transport line (10) or means (31) for coupling compressed air are formed in the lance (18), that the first shut-off device (24) closes when the plastic is blocked in the transport line (10) or the lance (18) that the second shut-off device (28) closes when hot air / plastic is blown through the blowing lance penetrates in the transport line against the usual transport direction and that the third shut-off device (29) closes when compressed air via the blowing lance for cooling this is abandoned.

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