AU731372B2 - Arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron - Google Patents

Description

Arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron The invention relates to an arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron in the form of a conveyor located in a tank.

An arrangement for cooling is disclosed in German patent specification DE 29 28 501 C2. This arrangement is comprised of a quench tank and a conveyor placed therein in inclined position for transporting connected briquettes.

In the different processes for the direct reduction of iron, solid oxidic input material is reduced to iron by means of reduction gases. The pellets or lump ores formed thereby can only be stored under special protective conditions as due to the microporosity of the products an exothermal reaction with atmospheric oxygen may occur. Therefore, a hotbriquetting plant has been connected downstream of several processes in order to compact the reduced material and, thus, to reduce the risk of reoxidation due to the surface which is reduced thereby.

00 The briquettes formed during hot briquetting have a temperature of approx. 750°C and are cooled to approx. 50°C in order to prevent self-ignition. However, the energy stored in the cooled briquettes must still suffice to dry them up.

Cooling is performed in a quench tank, i.e. a tank filled with water, in which conveyors, for example wire mesh belt conveyors are located onto which the hot briquettes drop.

The apron conveyors consist of perforated plates connected to one another, to which wheels running on rails are mounted by means of pins. The plates are connected to one another by fishplate bush links. The conveyors are driven by a conveyor chain connected :'with the wheel axles.

000**** •0o0 The fines accompanying the briquettes get onto the bottom of the tank as well as onto the rails through the holes in the plates. Combined with aggressive substances in water, with the high surface pressure acting on the supporting surfaces of the wheels at the rails and with the radial stresses occurring, primarily the wheels and pins are highly worn. As the wheels run dry in front of the point of briquette discharge, the aforementioned conditions are aggravated by the alternation of wet and dry condition.

\\melb-iles\home$suzannet\Keep\Spec574 1 SPECIdoc 2501/01 The object of the invention is to develop a cooling system to reduce the wear of the conveyor elements and thus to increase the availability of the cooling system due to the lower maintenance expenditure. The design of the plates and of the drive is to be modified so that less fines penetrate into highly stressed areas.

According to the present invention, there is provided an arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron in the form of a conveyor located in a newly revised tank, characterized in that the conveyor includes a plurality of conveying troughs and wherein: the conveying troughs are driven by means of a drive chain that connects each conveying trough to the other, and the conveying troughs are bearingly supported on a conveyor slideway by means of slide plates which support the conveyor troughs from the opposed longitudinal sides thereof and which slide upon the slideway.

A novelty of this invention is that the drive and the bearing can-be separated as the 0 conveyor troughs are supported by means of sliding plates and the drive acts directly on the conveyor trough by means of at least one chain.

As the translation elements are designed as sliding plates and slideways, the surface pressure is reduced to less than one hundredth compared to wheels running on rails. As :25 a result, the wear of the translation elements is reduced. The sliding plates cover the slideways partly from the material flow so that less fines get directly onto the slideways and wear is further reduced.

A preferred feature of the invention is that one mounting plate each is located on the two opposed longitudinal outsides of the conveyor trough, to which mounting plate one sliding plate each is fixed on its upper and lower sides. This type of mounting of the sliding plates on the conveyor trough enables the sliding plates to be easily exchanged if they are worn.

\\melb_files\home$\suzannet(eep\Speci\57403-98.1 SPECl.doc 25/01/01 Another preferred feature of the invention is that, if two sliding plates are placed on each longitudinal outside and at each conveyor trough, the upper sliding plate-seen in the direction of conveying-is thinner than the lower sliding plate. This feature takes into account that the lower sliding plate is subject to higher wear due to the loading of the conveyor trough and the direct action of fine material and the upper and lower sliding plates can thus be simultaneously exchanged, which results in increased plant availability.

Another preferred feature of the invention is that the individual conveyor trough is driven by means of at least one chain, preferably a round link chain (an anchor chain), a detachable connection being established between the conveyor trough and the chain.

Driving by means of chains has the advantage that guidance of the conveyor troughs is ensured by prestressing the chain. The detachable connection between the conveyor trough and the chains facilitates plant maintenance.

The invention is further preferably characterized in that the individual conveyor trough is driven by means of at least one chain, preferably a round link chain, which is provided with linking elements for detachably connecting fishplates located on the bottom side of each conveyor trough. The fishplate arrangement on the bottom side of the conveyor trough has the advantage that the latter protects the chains engaging there from the direct action of sponge iron briquettes or fine material. Moreover, the use of round link i chains is advantageous as these are self-cleaning.

The preferred feature of one side stop being placed on both sides of the conveyor troughs serves for emergency guidance of the conveyor troughs in case of a sideward motion resulting from loading the conveyor trough, on the one hand, and for protecting the tank, on the other hand, because the side stop prevents the conveyor trough from damaging the tank wall.

Another preferred feature of the invention is that the conveyor troughs are made of "brace plates", which reduces the probability of deformation of the conveyor troughs by impact on the side stops.

\\melb-filos\home$\suzannet\eeppSpec7403.98. 1 SPECI doc 25101101 An essential feature of the preferred embodiment of the invention whereby a side stop is provided is that the horizontal distance between the upper sliding plate and the side stop is not greater than half the average diameter of the sponge iron briquettes. This is to prevent the sponge iron briquettes from dropping between the sliding plate and side stop, from getting jammed there and locking the conveyor troughs, or from causing increased wear.

The last preferred feature of the invention is that a spraying device is placed in the area of the slideways that is located above water level, which ensures uniform sliding conditions for the sliding plates and rinses deposits of fine material from the slideways into the tank.

The invention is to be explained by an embodiment. The enclosed Figs. 1 to 3 display:a schematic representation of this embodiment.

Fig. 1 shows a vertical section through the tank in which the conveyor of the preferred embodiment of the invention is located.

Fig. 2 shows a detail of the conveyor according to Fig. 1.

Fig. 3 shows a section through A-A in Fig. 2.

Vol Fig. 1 shows conveyor 1 located in tank 2 filled with water, arranged together with drag conveyor 3, which is not described in detail here. Hot sponge iron is charged onto conveyor 1 in the area of the left wheel of conveyor 1 where the latter is located below "i water level, conveyed further to the right according to the arrow while being cooled in water and discharged at the right end of tank 2. Drag conveyor 3 only serves to discharge the fine material settled on the bottom of tank 2.

a Fig. 2 shows the left part of conveyor 1 according to Fig. 1 with the wheel about which i the conveyor troughs 4 are brought to the upright orientation. The individual plates of conveyor 1 are designed as conveyor troughs 4. The conveyor troughs 4 are preferably made of folded steel plate, in particular of so-called brace plates, which are resistant to radial stresses. The moving direction of the conveyor troughs is marked by the arrow.

Conveyor troughs 4 are fixed to chains 9 by which driving is performed. Furthermore, rolled section beams 8 are shown on which slideways 7 are mounted.

\\melbbfileshome$\suzannetj(ep\Spec57403g8 1 SPECIdoc 25/01/01 Fig. 3 shows a section through A-A in Fig. 2. Conveyor trough 4 shown on the top (in an upright orientation) moves in conveying direction, and lower conveyor trough 4 in opposite direction (in an upside-down orientation). The side walls of conveyor troughs 4 are higher than the front and rear walls. On the two opposed longitudinal outsides of conveyor troughs 4 forming the two outsides of conveyor 1 two sliding plates 5, 6 each made of wear steel are mounted. The two sliding plates 5, 6 of one side are arranged one above the other so that lower sliding plates 5 are in operation while conveyor trough 4 is moving in conveying direction and sliding plates 6, which are located on top in conveying direction, are in operation while conveyor trough 4 is moving in the Opposite direction. Sliding plates 5, 6 are fixed one to the upper and one to the lower surface mounting plate 10 which is permanently connected to conveyor trough 4.

Conveyor troughs 4 are moved by means of sliding plates 5, 6 on wear-resistant slideways 7 which are mounted on rolled section beams 8. Slideways 7 serve as a sliding basis for sliding plates 5, 6 and, together with rolled section beams 8, absorb the longitudinal forces and radial stresses resulting from belt movement.

Conveyor troughs 4 are driven through chains 9 provided with linking elements such as socket tappets. On the bottom side of each trough conveyor 4 fishplates 12 are arranged in a way that the projecting part of the linking element (the "pushers") of chain 9 engage with the latter. The socket tappets are secured with clamping sleeves. The connection between chain 9 and conveyor trough 4 is detachable. The tensile forces are transmitted to conveyor troughs 4 through chains 9, conveyor troughs 4 not being connected to one another. Conveyor troughs 4 thus do not have to absorb any tensile forces of the chains.

S:o- The prestress of chain 9 supports guidance of conveyor troughs 4.

o* o Chains 9 are preferably designed as round link chains. They are guided between slideways 8 beneath conveyor troughs 4 and largely protected by the latter from being contaminated.

Side stop 11 is placed on both sides of conveyor troughs 4. Due to the sponge iron load, conveyor troughs 4 may receive a short-time pulse which is largely directed sidewards, which is caught by the side stop so that the wall of tank 2 is also protected.

\\melb fileshome$\suzannet eep\SpeciA57403-98.1 SPECl.doc 25/01101 6 For those parts of slideways 7 which are located above water level, a spraying device is provided to ensure that slideways 7 have the same sliding conditions at all points.

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Claims (11)

1. Arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron in the form of a conveyor located in a newly revised tank, characterized in that the conveyor includes a plurality of conveying troughs and wherein: the conveying troughs are driven by means of a drive chain that connects each conveying trough to the other, and the conveying troughs are bearingly supported on a conveyor slideway by means of slide plates which support the conveyor troughs from the opposed longitudinal sides thereof and which slide upon the slideway.

2. Arrangement according to claim 1, wherein the sliding plate dimensions are such that they at least partly shield the slideways from coming into contact with sponge iron fines.

3. Arrangement according to claim 1, characterized in that mounting plates are located one on each opposed longitudinal side of each conveyor trough, to whose 20 upper and lower sides one sliding plate each is mounted.

4. Arrangement according to claim 3, characterized in that, when the conveyor trough is in the upright orientation and is moving in the conveying direction, tle upper sliding plate is thinner than the lower sliding plate.

Arrangement as claimed in any of claims 1 to 3, characterized in that the individual conveyor troughs are driven by means of at least one chain, and that a detachable connection is provided between the conveyor trough and the chain.

6. Arrangement as claimed in claim 5 wherein the chain is a round link chain.

7. Arrangement as claimed in any of claim 5 or claim 6, characterized in that the conveyor troughs include fishplates located on the bottom side thereof, and the \\melbfileskome$\suzannet Xeo\Specl 74 8. SPECldoc 25/01/01 8 conveyor troughs are detachably connected to the drive chain via linking elements which link the fishplates to the chain.

8. Arrangement as claimed in any of claims 1 to 6, characterized in that the conveyor troughs are made of brace plates.

9. Arrangement as claimed in any of claims 1 to 8, characterized in that side stops are located one to each side of each conveyor trough.

10. Arrangement as claimed in any of claims 1 to 9, characterized in that the horizontal distance between the upper sliding plate and the side stop is not greater than half the average diameter of the sponge iron briquettes.

11. Arrangement as claimed in any of claims 1 to 10, characterized in that a spraying device is located in the area of the slideways that is located above water level. S12. Arrangement substantially as herein described with reference to the accompanying drawings. 20 13. Conveyor substantially as herein described with reference to the accompanying drawings. A* **o*o \mef ilesvhom'.suzannet\Xeep\Spesi\57403-98 1 SPECIdoc 25/01/01