FR2646169A1 - Device for pelletising and/or granulating molten inorganic materials - Google Patents

Abstract

The device is of the type which comprises a casting channel 2 for the molten material, equipped with an overflow edge 4 having internal cooling 5, the stream 1 of material overflowing onto one or more feed tables consisting of one or more slabs 6, 7 of steel or of a metal alloy cooled by tangential injections of water 8, 9. Suitably arranged water sprinkling nozzles 10, 11, 12 ensure cooling the material which, after being cast onto the one or more feed tables, is fed out into the atmosphere by means of the drum 13, whose vanes 14 are in the shape of a spoon or chistera (basket-like scoop). Application to the production of granulated or pelletised slag on steelwork sites.

Description

 The present invention relates to the field of processing and packaging of molten mineral matter, in particular slag, metallurgical slag and other silicate materials with a view to obtaining cooled and expanded aggregates and / or pellets for various uses. It relates more particularly to improvements made to pelletizing installations and devices for obtaining dry materials having good homogeneity from a particle size point of view.

In the field of metallurgical slag treatment and in particular blast furnace slag, the pelletizing technique makes it possible to obtain expanded particles.
by subjecting the molten material to a mechanical dispersion obtained by means of a rotating drum, the blades of which fragment the vein of expanded molten material partially cooled by means of water jets and project the particles formed into the atmosphere where continues cooling. After falling on a sloping receiving area to evacuate unvaporized water, the pelletized material is taken up using mobile machinery and sent to the classification facility.

 Several improvements have already been made to this technique, including: the use of devices to regulate the flow of molten material (French patent N "76.28855 dated 24/09/76); the tank combination provided with a cooled overflow rim and a table, also cooled, bringing the molten material to the rotary drum ensuring its shredding (French patent no. 77.26551 of 2/9/1977); adapting the number and arrangement of the blades on the drum to obtain granules of variable dimensions (French patent no. 80.08 368 of 15.1.1980); the use of a sealed drum fitted with blades with a special profile of " chistera "and of a system for receiving expanded particles constituted by det series of vibrating tables (French patent N" 83.04354 of 17.3.83).

 According to the general method described in the aforementioned patents and used to ensure the cooling and the expansion of the particles of slag or equivalent materials, installations or devices are implemented comprising the combination of the following successive elements; a slag for casting molten slag, provided with an internally cooled overflow rim; one or more feed tables, arranged in inclined plan and internally cooled, constituted by hollow elements with water circulation pipes and also sprinkled by external water spraying; under these tables, a sealed rotary drum, internally cooled and preferably provided with special blades in the form of spoons; the solid particles of expanded and vitrified slag, projected into the atmosphere, then accumulating on an inclined or pit storage area, while the non-vaporized water flows towards the bottom point of the pit and is evacuated by known means such as pumping or the like.

 Such a process, in which relatively small quantities of water are used (of the order of approximately 1 m 3 per tonne of slag), makes it possible to obtain granulated slags or balls of excellent characteristics and usable for numerous applications. such as: raw material for construction compositions (cements, concretes, glasses, ceramics, tiles, bricks), for incorporation into binders in road constructions, as metal stripping materials; as additives to fertilizers and soil improvers ,. as light fill, etc.

 However, the use, as feed tables of the molten material at its outlet from the overflow rim, of hollow steel elements in the form of longitudinal boxes provided with internal cooling pipes, entails a certain number of drawbacks. Such devices, which are relatively expensive, are fragile to repeated thermal shock and have a fairly short lifespan which generally corresponds to the casting of approximately 10,000 tonnes of slag.

 It has now been surprisingly found that this type of hollow element could advantageously be replaced by a slab of steel or metal alloy and in particular slabs which may have surface defects and which frequently constitute waste during Laminating for the manufacture of tales. Contrary to the lessons and the practice known until now, according to which it was thought that only a water box with strong internal cooling, considering the big thermal shocks supported, could contain as feeding table, it has been found that a slab with simple external cooling allows, without harmful wear and / or deterioration, the treatment of masses of slag or other mineral matter in fusion much larger.

 In practice, one or more slabs of approximately 10 to 25 cm thick, of width 1 to 1.5 m and whose lengths are preferably limited to a maximum of approximately 2 m are used in the device according to the invention. alleviate the phenomena of premature deformation or erosion.

 Very schematic representations of the processing of molten slag for the production of pelletized slag in a steelworks are shown on the appended plate of drawings.

 The slag flow 1 here comes from a flow regulation device constituted by a channel 2 whose bottom 3 allows the settling and the evacuation of the liquid iron entrained with the slag and which is provided with a weir rim 4 in refractory material functioning as an overflow threshold dividing the liquid slag into a blade of determined length. This rim 4 is internally cooled by water circulation piping 5 from a water box such as, for example, that described in French patent No. 77.26651.

 According to the improvement of the invention, a slab 6 (for example made of steel) - FIG. 1 - or slab gods 6 and 7 FIG. 2 - is installed, as an inclined feed table, very close to the overflow rim, tangential spraying of cooling water via nozzles 8 and 9. Other water spraying ramps 10, 11, 12 are arranged above the slab (s) to cool the slag to a temperature of about 1200 to 12500C before its dispersion and ejection into the atmosphere by the drum 13. The latter is advantageously designed with blades 14 in the form of a shistera as described in the French patent No. 83.04354 cited above.

 The solid particles of expanded and vitrified slag then accumulate on an inclined storage tank or pit (not shown) in the form of a heap without the need, as in the previously known technique of moistening the bottom of the pit .

 The slags or granules of slag, obtained according to the invention, have good expansion and a low density and are suitable for all applications such as those described above.

 In addition, he found that it was possible to vary the particle size of the pellets obtained, depending on the type of application envisaged, by judiciously modifying the speed of the drum.

 For example, during the manufacture of expanded particles intended for the preparation of binders where it is desirable to have a large majority of particles of diameter 0 to 4 mm and few particles of diameter greater than 10 mm, a speed of adoption is adopted. rotation of approximately 300 revolutions / minute for the drum. On the other hand, if it is particles of slag expanded for the manufacture of light embankments (for example with a view to reducing the sections of retaining walls), a speed of rotation of the order of 230 revolutions / minute will be chosen. so as to obtain at least 30% of particles with a diameter greater than 10 mm.

Claims (4)

- CLAIMS  1. Device for treating molten mineral materials, such as slag and metallurgical slag, for the recovery of expanded particles and / or granulated or pelletized products, of the type comprising: an overflow rim (4) with internal cooling (5) installed at the end of the channel (2) for casting the molten material; at least one inclined feed table arranged under said rim and watered by series of water jets (8,9,10,11,12); a sealed rotary drum (13) cooled by internal circulation of water and provided with blades (14) in the form of a spoon or "chistera", this drum projecting into the atmosphere the particles of cooled molten material, which are recovered in the form expanded pellets or pellets on a sloping receiving area or pit; CHARACTERIZED in that the feed table consists of a slab (6) of steel or metal alloy.  2. Device according to claim 1, characterized in that two successive slabs (6,7) are used, offset in height each of which is cooled by tangential spraying of water outside  3. Device according to any one of claims 1 or 2, characterized in that the pit for receiving the expanded pellets is not itself humidified.  4. method of implementing the device according to any one of claims 1 to, characterized in that the rotation speed of the drum is varied according to the range of particle size desired for the expanded pellets for application given.