DE2812486A1 - METHOD AND DEVICE FOR THE PRODUCTION OF LONGITUDINAL WORKPIECES FROM PELLETIZED MATERIAL - Google Patents

Description

The possibility of making an elongated iron or steel workpiece from purified iron oxide ore For many years, powder metallurgy has attracted the attention of people who are new to it develop metallurgical processes. Most of the suggestions involve making iron powder, which is then used Ambient temperatures according to conventional powder metallurgical Method to iron or steel strip material or rod material is processed. Despite the technical success These processes make it difficult for them to compete with conventional large-scale steelmaking methods to be carried out economically.

It is an object of the invention, a method and an apparatus for producing an elongated workpiece to create in an economical way that does without the formation of iron powder.

The present invention consists firstly in a method in which pellets are made with an organic binder bound, purified iron oxide, which can be chemically partially reduced, in a reducing atmosphere are heated to form sponge pellets and the sponge pellets at hot rolling temperature in the gap between the rolls of a rolling mill introduced and become one

S09839 / 0954

elongated workpiece can be rolled.

The purified iron oxide ore is made into pellets of between "1.5 and 15 mm shaped, and those formed from them Sponge pellets, along with any required alloying materials, are fed into the rolling mill where they are hot rolled into iron or steel strip material or rod material, or material of other small cross-section will.

In contrast to pellet rolling, hot rolling iron powder has been proposed for iron. As a result of difficulties in the case of heating, tendency to caking and loading difficulties, it became largely in practice dropped.

The difference and advantage of rolling sponge pellets is twofold. First be the adhesion and loading problems largely reduced. Second - a very important consideration - the undeformed sponge pellet in the nip is extremely small Overall density. The pellets themselves are porous and there is additional porosity between the pellets. they are therefore overly compressible compared to iron powder,

809839 / 095A

and in order to get a solid strip or rod material, one works with a much greater reduction in thickness, and far lower roller pressures are used. As a result, it is possible to have a much more even distribution across the width of the rolled strip, resulting in less edge and surface cracking than when rolling iron powder.

When describing the method according to the invention, the term "steel" is often used when the material is actually free of carbon. Strictly speaking, the carbon-free product is an iron matrix, which contains a very large number of fine, non-reducible oxide inclusions. The structure is therefore completely different of wrought iron or ordinary low carbon Stole. It is actually a new material for which a short name has not yet been found. In this context, will it is often referred to as either sponge iron in the unconsolidated state or steel after solidification, albeit it is free of carbon in some cases. When the product is carburized, there are for naming the Product of course not two options.

The rolling mill must be supplied with pellets, the average size of which is sufficient to deal with the undesired

809839/095 ^

to avoid the effect of disturbance of the particle integration caused by the gas leakage will »when the rollers are operating at reasonably high speeds. It is also desirable "when rolling weak cross-sections, ensure a good flow of the pellets into the roll gap. The preferred pellet shape is therefore rounded or almost spherical, and the preferred size is within that Diameter range between 1.5 and 15 mm. Most of the successful experimental work has been with pellets in the Range carried out from 3 to 7 mm.

During the pelletizing process it is essential that to avoid contamination of the high purity iron oxides by any harmful material that would remain in the steel strip after processing. Simultaneously It turned out to be necessary to use a binder to make the green pellets to make sure that they are sufficiently hard that they require a minimum of subsequent chemical reduction processing withstand breakage. The term "green pellets" is used for the pellets not heated to a high temperature to distinguish it from the pellets that have been heated. Binders, such as bentonite, which are commonly used in industry to aid pelletization and Containing silica are excluded. When the most

S09839 / 095Ä

- ίο -

Most satisfactory binders have been organic It has been shown that substances only decompose into carbon or gaseous products when heated, which are produced from the pellets can escape and therefore do not cause any contamination of the end product. Sulfur and phosphorus containing binders must be avoided.

The process starts from purified iron oxide. This is produced in a highly economical and expedient manner by wet or dry treatment of very finely ground iron oxide ores using very strong magnetic fields, if necessary in conjunction with differential flotation, with the formation of a concentrate of high purity. Typical concentrates available on the commercial market and suitable for the process generally contain 98% or more iron in the form of oxides. A typical composition of a concentrate based on Fe ₅ O ₄ is, for example, as follows: 97.0 % Fe ₅ O ₄ , 2.4 % Fe ₃ O ₅ , 0.16% MgO, 0.18 % Al ₂ O ₅ , 0.06% SiO ₂ and 0.16% TiO ₂ . Suitable concentrates based on Fe ₅ O ₄ or Fe ₂ O ₅ can easily be obtained worldwide from many ores by standard cleaning processes.

The first stage in the process is to make green pellets from high purity oxide concentrate, whereby one

809839/095 4

introduces a thick slurry of water, concentrate and an organic binder into the pelletizer. Pelletizing is a standard metallurgical process «The green pellets are sieved to achieve the correct size distribution to avoid either very large or very small fractions, and then dried. Then two slightly different paths can be taken. The green pellets can either be partially reduced with reducing gases such as Hp or mixtures of Hp and CO "at high temperatures to a high degree of metallization, ie about 95 % i , without going to complete reduction. These partially reduced pellets are Alternatively, the green pellets can be fed directly into a reduction reactor, where they are completely reduced at high temperatures - as described below.

The dried green pellets and the pre-reduced pellets are hard and easy to handle. the Pre-reduced pellets can advantageously be used in place of the Ore deposits are formed. This improves the economy of the entire process and avoids the Shipment of unnecessary oxygen in the bound form of the oxide. It also allows the production of very hard,

"809839 / 095A

abrasion-resistant, pre-reduced pellets, so that the through. Losses caused by dust can be reduced. If the transport is over long distances, there is none Advantage of performing the reduction well over 95%, since Some oxidation occurs during subsequent transport and handling, and thus a subsequent chemical reduction makes necessary. In this way, the pre-reduced pellets can be transported to the geographical location in this form, where the steel products are made.

The next stage in the process is total reduction the green or pre-reduced pellets to sponge iron pellets at high temperatures by Hp or mixtures from Hp and CO. The reduction reactor can be different Shape, so also be a vertical shaft reactor. A particularly effective form is the horizontal rotary kiln.

It is essential to feed the mill with the pellets at 900 C or more. At temperatures of up to 1000 ^° C. there is only weak agglomeration of the pellets, but if the temperature is increased further, the agglomerate formation increases. The extent of agglomeration, however, is not a concern and is small compared to that which usually occurs when ground oxides are reduced at the same temperatures.

809839/09 5 4

At the discharge end of the reduction reactor, the hot, fully reduced pellets pass through a distributor and sorting device and are introduced directly into the gap of a rolling mill.

It is of course necessary to reoxidize the reduced pellets after they have left the reduction reactor to avoid. Hence one cares in the way of that; Exit; of the reduction reactor to the gap of the rolling mill for covering with neutral or reducing gas.

ν It is possible for the material to be processed to be small Add alloy additives. In certain cases and under special circumstances, the entering the reactor Pellets metal or alloy powder or carbon powder be added; in other cases, however, especially with chromium and often with manganese and carbon, it is desirable the powdery additives to the pellets after their Exit from the reduction reactor when the oxygen is in the gases and in the particles or pellets has reached a very low concentration.

Second, the invention relates to a device for producing an elongated metal workpiece, marked

"B09839 / 0954

characterized by a reactor vessel for the reception of Pellets made of purified iron oxide bound with an organic binder, with a device for heating the pellets is equipped in a reducing atmosphere to form sponge pellets, a rolling mill for hot rolling the sponge pellets into an elongated workpiece, and means providing a path for the hot Forms sponge pellets from the outlet of the reactor vessel to the nip of the mill.

The type of rolling mill that is fed with the hot sponge pellets depends on whether it is strip or bars should be generated. In the case of strip material, a rolling mill with large diameter cylindrical rollers is used required, the axes of which lie in a horizontal plane, while for rod material one arranged in the same way Rolling mill with profiled rolls of large diameter is necessary.

For easier understanding of the invention this is now described by way of example only with reference to the accompanying drawing in which

Figure 1 is a schematic side view in section of the gate direction according to the invention for the production of steel

809839 / 09S4

2812488

tape, -

Figure 2 is a plan view of another form of roller of the rolling mill,

Figure 3 is a side view of parts of the rollers shown in Figure and

FIG. 4 shows a vertical longitudinal section of a device for transferring sponge pellets reduced to about 95% into iron or steel belt.

According to FIG. 1, a feed hopper 1 contains high-purity pre-reduced iron pellets 2 with a diameter of 3 to 7 stroke, which are introduced by a screw mechanism 3 into an inclined, refractory-lined, rotating furnace 4, which is in the hottest zone at a temperature of 950 to 1200 ⁰ O is operated in countercurrent. Preheated reducing gas with a content of about 91% Ε «and 9% CO, as it can be produced by reforming naphtha or natural gas, is introduced into the furnace at 5 and leaves it at 6 after use Exiting gas serves as fuel to preheat the fresh entering gas, and part of it passes through heat exchangers and then through

809839/095 k

a cleaning and drying device (not shown) in which water and COp are removed. The clean one dry gas is then preheated, recirculated along with fresh reducing gas, and re-enters the reactor at 5 a. The technique of reducing iron oxides using hot gases in conjunction with the necessary recycling process is well established in V fluidized bed reactors as well as in the known Midrex process and has been described many times.

In the rotary kiln 4, the high-temperature reducing gas completely turns the pellets into sponge pellets is reduced, and this process is facilitated by the constant movement of the pellets due to the rotation of the furnace. Due to the small size of the pellets, the reduction time in the reactor is short. In the example given is the time one hour, so that it results in a high throughput. A typical rotary kiln is 10 m long, one Diameter of 1 m and rotates at a speed of 2 rpm. As a result of the rotation of the furnace, the agglomerate formation remains limited to a minimum; however, some small particles or pellets can become agglomerated pellets with a diameter of more than 10 mm grow while a small amount of fine iron particles or powder is formed. The particles or pellets 7 migrate down the furnace and come up

809839/095 *

a scattering or dividing grid 8, which the pellets evenly distributed over the width of a sieve 9, i.e. in the Direction of the axes of the rollers on which they fall. Of the The purpose of the sieve is to remove oversized pellets with a diameter larger than e.g. 15 mm. These oversized pellets are formed in very small quantities; however, as far as they are formed, they are withdrawn at 10, cooled, ground and recycled.

The pellets can. While they are still hot and have a temperature of about 950 to 1200 ⁰ G, fall into the gap between the two rollers 11 and 12, which rotate in the same direction of rotation. The distance between the rollers can be varied arbitrarily; in the present case they are separated from each other by a distance of 7 mm. The rollers can have different diameters; a roller 11, however, has a higher peripheral speed than the roller 12. The higher peripheral speed of the roller 11 allows particles whose diameter is smaller than 7 mm to fall through, while larger particles or pellets are pressed against the oncoming roller 12, are exposed to compression and very high shear forces at the same time. When exposed to this combination of forces, sponge pellets will break even at high temperatures. The smaller fragments come through

- ^ λ 90903 9/0954

the rollers passed through it while the larger fragments rotated and re-enter the rollers to be broken again until all of the larger pellets are in the size are crushed to about 7 cm. It's an essential one The feature of the shear rollers is that they are operated in the manner set out. If they are in opposite directions of rotation If the circumferential speeds are the same as in a conventional rolling mill, the over grain n-sponge pellets or pellet aggregates are simply plastically deformed and condense rather than break through vision. The roller 11 rotates at such a high speed that no substantial accumulation of pellets occurs at the gap. In the example, each of the rollers 11 and 12 has a diameter of 50 cm at circumferential speeds of 200 and 200, respectively. 20 m per minute. These relatively high rotational speeds compared to the feed speed of the sponge pellets from the furnace ensure that the pellets are sufficiently separated from one another in the gap between the rollers 11 and 12 occur and that they remain discrete particles and are not compressed into a band at this point.

The hot pellets then fall at a temperature between 900 and 1150 ^° C. into the gap of a rolling mill with rollers 13 and 1 * 1-, which rotate in opposite directions of rotation. Due to the hot compression of the PelLets

η ο 9 π :.) π / η ^c i R a

becomes a hot-rolled strip 6 mm thick and 40 cm wide generated, which is wound at 15. The speed of the rollers 13 and 14- of the rolling mill is variable, so that the Can adjust the rolling mill speed to the pellet delivery at the gap. In the example is the peripheral speed of the two rollers 13 and 14 the same, but between the Limits of 40 and 10 m / min variable. The speed is always kept low enough to ensure that a durable, coherent, hot rolled ribbon is produced.

Typical operating speeds are around 15 meters each Minute with a roll gap of 6 mm. The exact operating speed is set so that a full pellet load is observed and there is an effective reduction in thickness of about 80%. It is essential that the rolls have a large diameter, since it is necessary to measure the material thickness in a large rolling pass to reduce. In the example, each of the rollers have a diameter of 90 cm and a front width of 40 cm.

In the example, the roller speed was in the area of 15 m per minute. Fine adjustments the speed ensured that a pellet height above the center line of the rollers of not less than 15 cm

809 83 9/0 9B U

was adhered to. With a roll gap setting of 6 mm, this resulted in an approximately 85% reduction in the thickness of the pellet mass when passing through, the reels. Under these circumstances provided that the pellet charge was always completely full, it was necessary to maintain a constant one The height of the pellets is not critical.

In general it can be said that the maximum thickness of the tape that can be produced is the greater, the larger the roller diameter is. If tape material that is much thinner than 6 mm, using rollers with 90 cm diameter is required, it is advisable to use two

to attach adjustable plates just above the roll gap, the planes of which are parallel to the axes of the rolls. The plates act as funnels for the pellets when they fall into the roll gap.

The rollers are equipped with side plates to prevent pellets from emerging laterally from the roller gap. This ensures that a full load of pellets is maintained.

The sizes, speeds and temperatures given above are only examples and are intended to do so Do not limit procedures in any way. The shear roller device

809839/0954

Tüng is not essential to the process, but valuable because the material to be treated is sponge material. This condenses through compression at high temperatures and becomes ductile j however, it has not been ascertained that it breaks when subjected to high shear forces at high temperatures. In this relationship behave Sponge pellets other than perfectly dense iron pellets or particles that have been found to be at high Temperature under combined pressure and shear ductile remain and be plastically deformed. Sponge pellets also differ in behavior from particles of iron oxide or other brittle oxides that are produced by simple pressing between the counter-rotating rolls of a conventional rolling mill break.

In the example, the oxidation of the reduced sponge iron pellets after leaving the rotary kiln is prevented by maintaining a weak flow of reducing gas which is introduced at the openings 17 and 18 into a water-cooled housing 19 which is pressed against the rollers 11 and 12 and the rollers 13 and 14 are sealed. The additional reducing gas then enters the main reduction reactor. To avoid reoxidation, an inert gas such as nitrogen can also be used, but in this case the flow must be weak.

809839 / 095A

to avoid inadmissible dilution of the reducing gases in the Avoid reduction reactor.

The rollers 11 and 12 have scratches 20 and 21 that prevent the accumulation of iron particles on the seals against the housing.

If rods or bars are desired, will profiled instead of the flat rollers shown at 11 and 12 Rollers used; otherwise the facility is the same.

In Figure 2 is the gap between the two rollers 22 and 23 shown in plan view. Each roller is adjusted so that the roller tips 24-, which may be slightly rounded, almost touch or actually touch one another are. The hot pellets 25 are made in the same way as in the case of cylindrical rolls, fed to the roll gap. By the side plates 26 in Figures 2 and 3, the side surfaces of the rollers are tight, the pellets are prevented from escaping to the side. Fill the pellets the roll gap up to a level 27 which is at or above the level at which the pellet compaction by the rolls begins. The roller diameter must be large enough for the Pellet height up to this level, so that a reduction

809839 / 09.54

tion of the thickness on the line of the roll centers of about 80% or more is achieved. Thickness reductions of less than 75% are likely to leave the rolled bar 28 greater porosity while reducing thickness of much more than 85% is generally unnecessary. "

In the example, the profiled rollers rotate at a peripheral speed of about 22 m per minute. The rotation of the rollers, which have a diameter of 150 cm and are 16 cm wide causes compaction the pellet mass 29 beginning at a height of about 20 cm above the connecting line of the center points and their separation into four square bars 28 with one side of 2 cm through the tips of the profiled rollers 22 and 23 (Figure 2). There is a degree of transverse flow the compacted pellet mass in the body of the rods, often with a very thin press burr connecting them emerge from the profile rollers. However, this can break easily and allows multiple rods to be made from a single batch of pellets. For bar rolling Other rolling shapes can also be used from pellets; however, the form described has proven to be special proven expedient. Usually it proves necessary to make the rollers thinner at the outermost edge, like this

809839/0954

that no pellets are rolled between the flat roll parts with their roll gap that is too small. It is also advisable to a narrow, flat piece, as shown in Figure 2, to be provided on the roll edges so that the furthest the bars on the outside are fully loaded.

It is often necessary to produce steel with a low carbon content in order to maintain the mechanical properties to improve. Without the addition of some carbon or the use of a carburizing atmosphere described above in the reduction furnace, the sponge pellets emerging from it and consequently the steel strip or Steel bar product will be substantially carbon free. The carbon content can be increased in two ways. First, a small amount of finely divided carbon can be added to the hot pellets. Second - and this is more effective - maintaining a carburizing atmosphere at the exit end of the reduction furnace ensures that the carbon content increases. The technology the control of the carbon content of steels by changing the composition of the reducing gases known. A high proportion of CO or the presence of residual hydrocarbons ensures that the carbon content increases. In bar rolling, increasing the carbon content is reasonably important because

B09839 / 0954

often better mechanical properties are required than they can be achieved with a carbon-free product »

Attempts have been made with horizontal or slightly inclined rotary kilns. It was found that die.slow rotation of the with the special high purity organic Bound pellets fed tube held the pellets in a continuous rolling motion and thereby any caking was avoided. High speeds of rotation were due to centrifugal effects and danger abrasion and breakage of the pellets is not beneficial. The slow rotation speeds in the area from 6 rpm to 0.5 rpm. depending on whether the tube furnace is small or was large, proved to promote the rolling effect of the pellets and prevent the on or off: caking without significant degradation of the pellets than very effective. They also made it possible to convey the pellets along the inclined rotary tube from the upper to the lower part and finally to pour them into the nip. It has also been found that these horizontal tubes can be driven satisfactorily when they are up to halfway of the entire pipe volume or even more are filled with pellets. Even if they are half filled with pellets, become all pellets temporarily adhering to the metal pipe

809 83 9/0 9 5A

-2 B-

detached in the subsequent rotation. Any liability was therefore only temporary. Another observation was that due to the rolling effect produced in the pellets, the pellet density increased somewhat. The pellets were also smoother and more rounded. This was advantageous in terms of the subsequent loading and compaction by hot rolling.

When performing the method described above, it was found to be advantageous to use a rotating part
Use rotary tube made of heat-resistant metal. A suitable construction material was a high temperature resistant Ni-Cr alloy. The good thermal conductivity
and the high temperature resistance of this material made it possible that such a tube could be heated from the outside electrically or by gas or oil burners. This arrangement made it possible to conveniently heat the pellet charge by external means rather than internally by the hot gases used for reduction, as described in the embodiment of FIG.

Under the conditions described, the lack of caking was generally so pronounced that there was no need to use additional means of breaking any agglomerates that would otherwise have formed.

809839/0954

Figure 4 shows a vertical longitudinal section of another device zur.Umsetzung von approximately to 95 ^ reduced Sponge pellets into iron or steel strip.

The sponge pellets containing not more than 5 % iron oxide are fed by a screw conveyor 41 from a container or hopper 42 into an inclined pipe 43 of large diameter made of a heat-resistant Ni-Cr alloy. The pipe is 8 m long and has an inner diameter of 0.8 m. The pipe is surrounded by a gas-fired furnace body 44 which is equipped with gas burners 45. The burners 45 are arranged so that they fire tangentially and does not impinge the flame "directly to the pipe 43. The pipe is heated by the burner to a temperature of ⁰ C to 1100 IO5O.

The exhaust gases exit through the fire channel 46 and are used to preheat the incoming reducing gases (Hp / CO) to a temperature of 800 to 900 ^° C., which are blown in at 47 and sucked off through the vent 48. The inclined tube 43 is rotated slowly (2 rpm) so that the charge 49 in the tube gradually makes its way to the discharge at the lower end. At each end of the rotary tube, flanges 50 are attached, which are mounted on freely rotating grooved RoI-

809839/0954

len 51 rest, two of which at each end with their axes are arranged parallel to the rotary tube axis, but not in the vertical plane passing through the rotary tube axis. The pipe is driven via a chain wheel 52, the drive not being shown.

Which consists of pre-reduced pellets batch is heated during its passage through the tube to a! Temperature between 1000 and I050 ⁰ C and completely reduced sponge pellets reduced quickly, a vibrating grid 53 are supplied to the isolated below the pellet outlet from the tube and within a , fixed trigger housing 54- made of egg-Cr is attached. The grate is intended to separate oversized pellets, which are drawn off at 55, cooled, broken and returned to the inlet bunker 42. The pellets fall through the vibrating screen 53 into a feed chute 56 equipped with side plates, which is arranged in the gap between the large rollers 57 . The rollers 57 roll the pellets into a belt 58 which is rolled up at 59. An additional amount of Hg / CO is introduced into the fixed trigger housing 54- at 60. The excess Hp / CO flames away at the gap of the feed chute, so that oxidation of the fully reduced pellets is prevented as they pass through the roll gap.

809839/0954

The rollers are driven by a variable speed motor, the speed of which is adjusted will that an ample pellet load in the nip is present without the pellets being able to accumulate excessively in the loading chute. This is an essential one Process control feature, as there is insufficient pellet accumulation at the base of the feed chute the rolling mill is not fully loaded and the result is an inadequate, porous and non-permanent strip. An excessive accumulation of pellets in the loading chute leads to caking, which in turn leads to an underneath Prevent broken, steady feed to the rollers. In this connection, the vibration of the loading chute can bring an improvement.

809839/0954

Blank page

Claims (20)

; Qoädüni S-admal 2812488 PATENTANWALT - ----- - - - 5202 Hennef 1 Bröl, Hauptstrasse 46 Telephone 0 22 42/54 78 r Davy-Loewy Limited Sheffield, England Method and device for the production of elongated workpieces from pelletized material Patent claims 1. A method for producing an elongated workpiece from pellet material, characterized in that one Pellets made from purified iron oxide bound with an organic binder, which is partially chemically reduced can be in a reducing atmosphere with formation of sponge pellets and introduces the sponge pellets into the roll gap of a rolling mill at hot rolling temperature and rolled into an elongated workpiece. 2. The method according to claim 1, characterized in that the iron oxide pellets have a size in the range of 1 to 10 mm. 3. The method according to claim 1 _S, characterized in that the iron oxide pellets now have a size in the range from 1.5 to 15 '. ν / 809839/0954 4-. Method according to one of Claims 1 to 3, characterized in that the iron oxide pellets are of one size in the 3 to 7 brain range. 5 · The method according to one of claims 1 to 4, characterized in that the purified iron oxide is not
contains less than 98% by weight iron and iron oxides. 6. The method according to any one of claims 1 to 5 »thereby characterized in that the pellets in a reducing Atmosphere from a mixture of H ~ and CO heated " 7. Process according to one of Claims 1 to 6, characterized in that the iron oxide pellets are heated ^{to a temperature between 950 and 1200 ° C. in the reducing atmosphere.} 8. The method according to any one of claims 1 to 7 »characterized in that one rolls the sponge pellets at a temperature of 900-1150 ⁰ C. 9. The method according to any one of claims 1 to 8, characterized characterized in that the sponge pellets are rolled in a non-oxidizing atmosphere. »09839 / 09.54 10. The method according to any one of claims 1 to 9> characterized in that the hot sponge pellets are before a finely divided alloy material is added to the rolling. 11. The method according to any one of claims 1 to 5 »characterized in that the sponge pellets before Exposing rollers to a carburizing atmosphere. 12. The method according to any one of claims 1 to 11, characterized in that the sponge pellets into one Belt rolls. ■ 13 · Device for producing an elongated metal workpiece, characterized by a reactor vessel (4- ^ 4-3) for the inclusion of an organic binder bound pellets (7) made of purified iron oxide with a device for heating pellets in a reducing atmosphere with the formation of sponge pellets, a rolling mill (13 * 14- »57) for rolling the hot sponge pellets to an elongated workpiece and means (19 ί 54-) for forming a path for the hot sponge pellets of the exit of the reactor vessel to the roll gap of the rolling mill. 14. The device according to claim 13, characterized in that that the reactor vessel (4-) internally through the hot 809839/0954 incoming reducing gas is heatable. 15. Apparatus according to claim 13 or 14, characterized characterized in that the reactor vessel (4; 43) is a refractory lined rotatable furnace. 16. Device according to one of claims 13 to 15, characterized in that the reactor vessel (43) by external heating devices (45) can be heated. 17. Device according to one of claims 13 to 16, characterized in that the said forming the path Device (19; 54) is a housing which at one end to the reactor vessel (4; 43) and at the other end to the Rolling mill (13j 14j 57) is connected and means for the Introduction of a non-oxidizing atmosphere (17,18; 60) having. 18. Device according to one of claims 13 to 17, characterized in that a device on the way (9,11,12; 53) is arranged to prevent the entry of large grain pellets prevented in the roll gap of the rolling mill (13,14; 57). 19. The device according to claim 18, characterized in that that the facility is kept at a distance from two 8Q9839 / 09SÄ ten rollers (11,12), between which the pellets pass through, and means for rotating the rollers in the same direction of rotation at different speeds of rotation. 20. Elongated workpiece made by the method of any one of claims 1 to 12. 80983 9/0 95