EP2334829B1

EP2334829B1 - Device for smoothing the surface of a sinter mixture

Info

Publication number: EP2334829B1
Application number: EP09736372.5A
Authority: EP
Inventors: Helmut Barowski
Original assignee: Outotec Oyj
Current assignee: Metso Corp
Priority date: 2008-10-09
Filing date: 2009-09-15
Publication date: 2013-11-06
Anticipated expiration: 2029-09-15
Also published as: CN102177261B; CN102177261A; EA018399B1; EP2334829A1; PL2334829T3; BRPI0920427A2; AR073734A1; WO2010040442A1; ES2442022T3; DE102008051063A1; EA201100341A1; BRPI0920427B1; ZA201101554B; DE102008051063B4; UA104727C2

Description

This invention relates to a device for smoothing the surface of a sinter mixture in a grate carriage, before the same enters an ignition furnace, by means of at least one scraper between the charging point of the sinter mixture and the ignition furnace.
During sintering in iron metallurgy, fine ores and concentrates not immediately ready for use should be agglomerated, so that they can then be supplied to the blast-furnace process. For sintering purposes, a sinter mixture is produced, which contains iron ores, aggregates and coke as fuel, and via a charging device is charged onto the grate carriages of the sintering machine circulating as an endless belt. The coke contained in the sinter mixture is ignited, and an induced-draft fan disposed below the grate carriage belt draws the burning front through the sinter mixture, so that a sinter cake completely burnt through is obtained at the dumping end of the belt. Due to the heat produced in the process, the fine ores will melt at the surface, so that their grains undergo a firm connection. Upon separation of rust layer and sinter returns, the finished sinter is supplied to the blast furnace.
When charging the sinter mixture onto the grate carriage, longitudinal and transverse grooves are formed on the surface of the sinter bed. For technical reasons, these grooves are undesirable because of their influence on the ignition behaviour in the ignition furnace and because of their influence on aeration. To remove such surface irregularities, rigidly mounted scrapers have been used so far. The same have the disadvantage that the sinter mixture is dammed up and sheared off when moving through below the same in flow direction. In this way, an undesired compaction of the surface is obtained, which impedes a good aeration.
EP 0 286 381 A2 describes an inclined screen for feeding a raw mix onto a pallet of a sintering apparatus. The sintering mix is fed from a drum feeder onto a sloping plate and adjacent bars extending longitudinally of the sloping plate. As the bars are sloped, the forward end of the pallet becomes the lower portion and the top end portion of the bars has level differences, so that the gaps between the bars are wider at the top edge side. Thus, fine particles of the raw mix falling on the bar fall through to the pallet from the basic edge side, and coarse particles of the sintering raw mix fall through to the pallet from the top edge side of the bars. Thereby, a sift feeding to form a lower coarse particle layer and an upper fine particle layer on the pallet is carried out so that a grain size in a height direction of a raw mixed layer can be optionally formed. There is no scraping effect by the bars onto the sintering mix fed to the pallet since the sintering mix layer is formed on the pallet only after the pallet has passed the tip of the bars.
Document JP 2002 121820 discloses a method to stabilize an upper layer part of a sintering bed even when it is exposed to circulating waste gas containing much moisture. For that purpose, the solid fuel blending ratio is increased in the upper layer part of the sintering bed and/or the upper layer part is compacted. Irrespective of the chosen way to adapt the upper layer part, material is fed by a drum feeder and falls to sloping chute from which it slides to the sinter bed.
Document JP 11 2011355 describes a device to top a groove and to flatten a surface of material prepared for a sintering process. This device includes a screw system of material scrapers which are rotated by revolution changer. To scrape up the material toward a groove, spiral veins are attached in opposition. US 4,648,900 relates to a method for producing a charge of high permeability and stable structure of a sintering bed. The method comprises the steps of compacting the moist material mixture, forming a coherent cake and breaking the cake into pieces of a size suitable or forming a suction-sinter charge. Therefore, each cake is moved down its respective support plate to a spiked role, which disintegrates the cake into pieces of given size. The pieces then fall onto a grate, forming either of two layers, depending on the position of the plate.
Document JP 2003 277841 discloses a method for improving the ventilation at the upper part of a sintering raw material layer. This method is based on a plurality of fine holes having a prescribed cross sectional shape and depth. The holes penetrate the upper surface of the upper layer part of the sintering raw material layer. During sintering, a raw material is formed by dispersing these fine holes. The raw material is fed by a drum feeder and falls to sloping chute and onto the sintering bed.
It is the object of the present invention to remove the undesired irregularities on the surface of the sinter mixture without the disadvantages stated for the prior art and thereby increase the product quality of the sintered material.
In accordance with the invention, this object substantially is solved by a device comprising the features of claim 1.
In this way, it is achieved that irregularities of the sinter bed surface are levelled out before entry of the grate carriage into the ignition furnace without damming up the material and without undesired compaction, so that a uniform ignition behaviour in the ignition furnace and the desired aeration are ensured. Due to the particular type of reciprocating scrapers, the overflow of material on the side walls of the grate carriage, which also occurs in the prior art, is avoided. Preferred embodiments of the invention are evident form the dependent claims. Advantageously, the scrapers can be subjected to a lateral oscillating movement in addition to the reciprocating movement. While the mere reciprocating movement provides for levelling out the waves (transverse waves) extending substantially transverse to the direction of travel of the grate carriage, the laterally oscillating movement of the scrapers removes the waves (longitudinal waves) extending substantially in longitudinal direction of the sinter bed surface.
Advantageously, a plurality of, correspondingly narrow, scrapers can be suspended in a row one beside the other above the travelling way of the grate carriage distributed across its width.
With regard to different sinter bed heights in the grate carriage, it furthermore is advantageous when the height of the scrapers above the travelling way is adjustable.
The bearing force of the scrapers substantially is determined by their own weight.
It is, however, also possible that one or more additional weights are mounted on the scrapers, in order to produce or adjust the desired bearing force.
In a particular aspect of the invention, the lateral oscillating movement of the scrapers can for instance be effected by means of a cam disk, cam shaft or crank drive and/or pneumatically or hydraulically.
The scrapers can be made of a metallic or non-metallic material and can have different shapes.
To initiate and maintain the reciprocating movement of the scrapers when the grate carriage with the sinter mixture accommodated therein moves through below the same, it is particularly advantageous when the scrapers are angled or bent at their free ends in direction of travel of the grate carriage.
Further objects, features, advantages and possible applications of the invention can be taken from the following description of embodiments and the drawing. All features described and/or illustrated per se or in any combination form the subject-matter of the invention, also independent of their inclusion in individual claims and/or their back-reference.
In the drawing:

Fig. 1: shows a schematic side view of a device of the invention for smoothing the surface of a sinter mixture in a grate carriage before the same enters an ignition furnace, and
Fig. 2: schematically shows an oblique view of such smoothing device with a grate carriage disposed below the same.

As shown in Fig. 1, the direction of travel of a grate carriage 1 from a charging point 4 for a sinter mixture to an ignition furnace 2 extends from the left to the right. Above the travelling way 5 for the grate carriage 1 one or more scrapers 3 is/are suspended in a row one beside the other across the width of the grate carriage 1 so as to reciprocate about an axis of rotation D transverse to the direction of travel of the grate carriage 1 such that they drag along the sinter bed surface when the grate carriage 1 moves through below the same, and thus remove any transverse waves present.
By means of an oscillation drive 6 indicated in Figure 2, the scrapers 3 can be subjected to a lateral oscillating movement, so as to level out longitudinal waves present in the surface of the sinter bed. The laterally oscillating movement of the scrapers 3 can be effected by cam disk, cam shaft or crank drives (not shown in detail) and/or pneumatically or hydraulically.
As can be taken from Figure 1, the scrapers 3 are slightly angled or bent at their free end 7, which comes to rest on the respective sinter bed surface, so that the reciprocating movement can easily be initiated and maintained when the grate carriage moves through below the same. The free ends can for instance also be formed like a rake, in order to increase the smoothing effect and make the same more uniform.
In adaptation to different bed heights, the scrapers 3 can be mounted at different levels individually or all together and/or be adjusted in their height above the travelling way 5.
The bearing force of the scrapers 3 substantially is determined by their own weight. It can, however, be changed by additional weights (not shown).

List of Reference Numerals:

1: grate carriage
2: ignition furnace
3: scraper
4: charging point
5: travelling way
6: oscillation drive
7: angled or bent end

D: axis of rotation

Claims

A device for smoothing the surface of a sinter mixture in a grate carriage (1), before the same enters an ignition furnace (2), by means of at least one scraper (3) between the charging point (4) of the sinter bed mixture and the ignition furnace (2), the at least one scraper (3) is suspended above the travelling way (5) of the grate carriage (1) so as to reciprocate in and against its direction of travel such that the scraper (3) drags along the sinter bed surface when the grate carriage (1) moves through below the same,
characterized in that the at least one scraper (3) can be subjected to a lateral oscillating movement.
The device according to claim 1 , characterized in that a plurality of scrapers (3) are arranged in a row one beside the other above the travelling way (5) of the grate carriage (1) distributed across its width.
The device according to any of the preceding claims, characterized In that the height of the scrapers (3) above the travelling way (5) is adjustable.
The device according to any of the preceding claims, characterized in that the bearing force of the scrapers (3) is determined by their own weight.
The device according to any of the preceding claims, characterized in that on the at least one scraper (3) one or more additional weights can be mounted.
The device according to any of the preceding claims, characterized in that the lateral oscillating movement of the at least one scraper (3) is effected by means of a cam disk, cam shaft or crank drive and/or pneumatically or hydraulically.
The device according to any of the preceding claims, characterized in that the at least one scraper (3) is made of a metallic or non-metallic material.
The device according to any of the preceding claims, characterized in that the scrapers (3) have different shapes.
The device according to any of the preceding claims, characterized in that the at least one scraper (3) is angled or bent (7) at its free end in direction of travel of the grate carriage (1).