EP0865505B1 - Process for hot briqueting granular sponge iron - Google Patents

Description

The invention relates to a method for hot briquetting granular sponge iron, taking the granular sponge iron with Temperatures of 600 to 850 ° C for forming the hot briquettes Roller press gives up and a band structure made of sponge iron molded hot briquettes spaced from each other generated, from which you can smash the hot briquettes isolated, whereby fragments of the band structure arise.

A known method of this type is in U.S. Patent 5,082,251 described. Here one gives the ones formed with the roller press Hot briquettes directly into a rotating drum when hot. As a result, the rotary drum is subject to heavy wear exposed.

The invention has for its object the manufacture of Hot briquettes are inexpensive and require little equipment perform, in particular the wear and tear Susceptibility to interference should be kept as low as possible. According to the invention, the task at the beginning Process solved in that after smashing the Band structure the hot briquettes and at least part of the Fragments at temperatures in the range of 20 to 400 ° C and preferably cools at most 200 ° C that the cooled Briquettes and fragments passed through a rotating drum, whereby from the briquettes and fragments of fine-grained abrasion is formed, and that the abrasion from the briquettes and Separates fragments.

Grainy and especially fine-grained sponge iron is very pyrophoric, so that only under an inert gas atmosphere can be worked. A suitable protective gas is e.g. Nitrogen or carbon dioxide or a mixture of these inert gases. When the granular sponge iron is briquetted, it is no longer or hardly pyrophoric and the handling of the briquettes and their Storage are very simplified. At temperatures from 600 to 850 ° C and e.g. like the sponge iron from one Reduction system comes, it can be with the help of a Shape the roller press into hot briquettes in a known manner. Here you create a band structure made of sponge iron with molded, hot briquettes spaced apart. This The tape structure is then broken to close the hot briquettes singulate, creating fragments of the band structure. If these fragments are large enough, it is appropriate to them to be processed together with the hot briquettes.

The sponge iron suitable for the process can be in a any known iron ore reduction plant can be generated. The sponge iron usually has an Fe content of 90 to 98% by weight.

In the method according to the invention it is important that the Hot briquettes and the fragments before discharge into the Rotary drum cools. This cooling avoids the Giving up the rotary drum hot goods and turning the rotary drum to To process this hot good. It has it has been shown that when the drum is hot With temperatures above 400 ° C, wear gives up well the drum is very high and the rotary drum is frequently repaired must become. Such frequent repairs require one Have spare rotary drum ready if you have hot briquettes wants to manufacture continuously. In contrast, the procedure the invention has the advantage that the rotary drum is only cooled Feeds well, which means that the drum is less stressed and an outage due to repairs is rarely necessary becomes. At the same time it is now possible to keep the chilled goods during the time the drum was repaired in a container necessarily under protective gas and the goods to be fed to the rotating drum after the repair has been completed. In this In this case, a replacement drum is not necessary.

Figur 1

das Fließschema des Verfahrens,

Figur 2

die aus der Walzenpresse kommende Bandstruktur des Eisenschwamms in Ansicht und

Figur 3

einen Querschnitt durch den Innenraum der Drehtrommel in vergrößerter schematischer Darstellung.

Design options of the method are explained with the aid of the drawing. It shows:

Figure 1

the flow diagram of the process,

Figure 2

the band structure of the sponge iron coming from the roller press in view and

Figure 3

a cross section through the interior of the rotary drum in an enlarged schematic representation.

Hotter granular is in the storage container (1) Sponge iron with temperatures in the range of 600 to 850 ° C and usually 650 to 750 ° C. Because the sponge iron is very pyrophoric is here and also in the following Processing steps held under an inert gas atmosphere, as it is known per se and not explained in detail here is. The hot sponge iron comes e.g. from a reduction furnace or heater (6) and is introduced through line (6a). The sponge iron flows continuously from the container (1) a roller press (2) in which the sponge iron forms a Band structure (3) with molded hot briquettes is pressed. Figure 2 shows the band structure (3) and the hot briquettes (3a) in View.

The belt structure (3) runs downwards over a stationary one Striking face (4) and is doing with a rotating Break the hammer roller (5). The roller (5) has impact cams (5a) which, when the roller rotates on the belt structure (3) especially in the areas between the briquettes (3a) have a crushing effect. This way, hot briquettes and Fragments of various grain sizes from the face (4) down on a sieve (7) to separate fine grain. This Fine grain, whose maximum grain size is 2 to 6 mm, is in withdrawn from the line (8) and reused. To this end you can first of all the fine grain of the line (8) by a Conduct cooler (22) which e.g. than water-cooled Screw conveyor is designed. With temperatures of the fine grain then preferably reaches at most 200 ° C. pneumatic conveying section (21) which is filled with inert gas from the Line (23) is fed and the fine grain up to Reduction furnace or heater (6) transported. Alternatively, you can the fine grain of the line (8) uncooled on the dashed indicated transport route (24) directly into the container (17) to be led back. a container, not shown Shielding gas supplied. The hot briquettes fall through the channel (9) and rough fragments first in a cooler (10), where a Cooling to temperatures in the range of 50 to 400 ° C and usually at most 200 ° C. The one in Figure 1 only schematically illustrated cooler (10) can e.g. as a water bath or be designed as a water injection cooler, also comes cooling with cold gas in question.

Chilled briquettes and fragments leave the cooler (10) through the channel (11) and become a rotary drum (12) given up. The inside of the drum (12) Axial parallel driving ribs (12a), like that in Figure 3 is shown schematically. When turning the drum (12) around its longitudinal axis moves the goods inside you intensely, whereby also fall stress arises, whereby corners and edges the body is rounded and fine-grained abrasion occurs. This rounding down reduces the risk that the later Transport forms fine-grained sieve that behaves pyrophorically. Around the briquettes in the rotary drum intensive fall loads it may be advisable to suspend the diameter of the drum larger than their length. In a manner not shown can also use the rotary drum (12) for cooling the to be treated Be good, e.g. through a cooling water jacket.

The material moving in the drum (12) falls through the channel (14) with temperatures of 20 to 150 ° C and usually at most 100 ° C in a screening device (15). Here are first through a coarse sieve (15a) briquettes are sieved, which one in the line (16) subtracts. Fragments and abrasion fall on the second sieve (15b), whereby the relatively coarse fragments with a Granulation of e.g. cut off at least 3 to 6 mm in the line (17) subtracts. Fine grain is discharged in line (18) and usually together with the fine grain of the line (8) in the Reduction furnace or heater (6) returned. The briquettes and the fragments of lines (16) and (17) are entered into Interim storage, not shown, now a storage is no longer required under inert gas.

An intermediate container (20) or storage is indicated in FIG. 1, which one cooled goods from the cooler (10) in the direction of Dashed line (19) feeds when the rotary drum (12) Decommissioned for a certain period of time must become. When the drum (12) is ready for use again, the goods from the container (20) or warehouse to Subsequent treatment of the drum (12) abandoned. As before mentioned, all apparatus, containers and lines in which Fine grain is present to be kept under protective gas.

example

It is assumed that granular sponge iron is present in the container (1) at a temperature of 720 ° C and is treated in a system corresponding to the drawing, but without the parts (21), (22) and (24). The data are partially calculated. 67 t of sponge iron flow into the roller press (2) from the container (1) per hour. Further information on the amounts and temperatures of the sponge iron can be found in the table below. Reference number 8th 9 11 16 17th 18th Amount / t / h 1.7 65.3 65.1 62.1 1.3 1.7 Temperature (° C) 680 680 120 90 90 90

In the cooler (10) the product is placed in a water bath, whereby adhering fine dust is removed with the cooling water. The Rotary drum (12) is rinsed with water on the outer jacket chilled. The sieve (15a) separates briquettes of at least 12 mm Diameter from and the fragments of the line (17) are in Range from 4 to 12 mm. The sieve (7) has openings of 4 mm Diameter.

Claims (4)

1. A method for the hot-briquetting of granular sponge iron, wherein the granular sponge iron is charged at temperatures from 600 to 850°C into a roller press to form the hot briquette and a strip structure of sponge iron with formed, spaced-apart hot briquettes is produced from which the hot briquettes are separated by smashing, with fragments of the strip structure being produced, wherein the hot briquettes and at least part of the fragments being cooled to temperatures in the range from 20 to 400°C, the cooled briquettes and fragments are passed through a rotary drum, with fine-grained fines being formed from the briquettes and the fragments, and the fines being separated from the briquettes and fragments.
2. A method according to Claim 1, characterised in that the briquettes, the fragments and the fines are cooled in the rotary drum.
3. A method according to Claim 1 or 2, characterised in that the briquettes, the fragments and the fines are withdrawn from the rotary drum at temperatures of 20 to 150°C.
4. A method according to one of Claims 1 to 3, characterised in that once the strip structure has been smashed the fine-grained fraction having an upper grain size limit of 2 to 6 mm is separated off from the fragments.

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