AU6414600A - Device for granulating and comminuting liquid slag or foamed slag - Google Patents

Description

Device for Granulating and Comminuting Liguid Slags or Foamed Slags The invention relates to a device for granulating and 5 comminuting liquid slags or foamed slags, in which the slags are supplied with vapour and/or water, including a slag tundish and a slag outlet opening arranged in the bottom of the slag tundish. The slag tundish may be under pressure. 10 Methods in which pressurized water or vapour jets are directed against a slag jet have already been known to granulate and comminute liquid slags. In WO 95/15402, the melt was, for instance, introduced into a mixing chamber under pressure with pressurized steam or water vapour mixtures having been nozzled 15 in. Due to the rapid expansion, a pressure is built up by that method, which pressure causes the solidified particles to be ejected via a diffuser, the kinetic energy of the particles being utilizable for comminution. In the method according to SU 1 761 704 Al, a vapour jet is directed against a freely 20 flowing slag jet, whereby a defined jet speed is maintained for the vapour jet such that the quality of the granulates will be enhanced. Other methods of this type have been described, for instance, in SU 903 328 A, DE 32 40 142 Al, DE 39 19 155 Al, WO 86/5818 and DE 43 27 124 C2. 25 To granulate and comminute liquid slags, it has also been proposed to eject the same into granulating chambers by the aid of vapour or a propellant gas, further comminution being subsequently effected in jet mills using propellant gas jets. 30 Such a method is known, for instance, from WO 99/42623. Slags usually occur at temperatures of between 1400 0 C and 1600 0 C, and, due to the relatively high temperature difference between the propellant gas jet and the liquid slag, such methods entail the risk of the formation of more or less large 35 agglomerates as well as the danger of thread formation which, as a result, would increase comminution expenses and considerably reduce the cooling speed. In all those proposals, the main target has so far been as rapid a cooling of the - 2 slags as possible, which may naturally be impaired by the formation of agglomerates and threads. It has, furthermore, been suggested to eject the liquid slag 5 into a granulation chamber by the aid of combustion off-gases in order to reduce the risk of the slag outlet opening from the slag tundish to be obstructed by solidifying slag. In such methods, the slag particles injected into the granulation chamber get into a consecutively provided cooling zone at 10 substantially higher temperatures, said higher temperatures resulting in a lower slag viscosity and a reduced surface tension of the slag droplets so as to enable a finer disintegration of the slag droplets as the latter are entering the cooling zone. The fine dispersion of slag droplets brings 15 about accordingly small droplets having relatively high specific surfaces such that cooling may be achieved in small structured cooling chambers. Such configurations, however, call for the installation of burners in the region of the slag runout from the tundish, which involves high expenditures in 20 terms of construction and apparatus. In the main, the known proposals each employed a fluid under pressure to eject liquid slags from a slag tundish into a consecutively arranged granulation chamber such that, in 25 particular when using vapour as a propellant, an appropriate vapour generation means had to be arranged upstream of the injection opening to generate high-pressure vapour. The invention aims to structurally simplify a device of the 30 initially mentioned type by obviating separate, preceding vapour generators when using vapour as a propellant. To solve this object, the device according to the invention essentially consists in that the slag outlet opening is designed as an annular overflow weir and that a water and/or vapour supply 35 tube is arranged coaxially or concentrically with said annular weir, the outlet openings of which supply tube open within a slag outlet tube or in a manner projecting from the slag outlet opening. By designing the slag outlet opening as an annular overflow weir, a jacket-like liquid melt jet may be -3 immediately obtained, which flows out in the manner of a hollow melt cylinder, whereby it is most readily feasible, on account of the annular overflow weir, to adjust the wall thickness via the slag flow rate and its viscosity. Due to the 5 fact that a water and/or vapour supply tube is coaxially or concentrically arranged within this hollow melt cylinder, which supply tube preferably is connected by a spraying head whose spraying openings are arranged within the slag outlet opening, or in a manner projecting from the same, and 10 preferably are at least partially oriented radially, rapid heating of the supplied pressurized water and its respective evaporation are achieved in the region of the outlet from the tundish, while the slag temperature is lowered at the same time. Departing from usual slag temperatures of about 15001C, 15 the cooling of the molten slag to 1350 0 C is, however, uncritical, since melts within that temperature range are still highly liquid enough. Cooling from 1500OC to 1350OC allows for the simultaneous evaporation or heating (superheating) of the medium fed through the supply tube 20 arranged coaxially or concentrically with the annular weir so as to enable the directed spraying out of vapour through the spraying head arranged within or below the opening and a rapid atomization, and hence efficient comminution without difficulty. If, in such a configuration, pressurized water at, 25 for instance, 10 bars is fed at approximately 800C, it is feasible to heat this pressurized water up to 13500C, thus naturally causing evaporation. In this manner, up to 50 kg pressurized water may be readily evaporated per ton of slag melt with a vapour volume of approximately 20 to 40 m 30 vapour/ton slag resulting. The sonic speed within the water vapour at 1350C is about 960 m/s. The flow speed, as a rule, will create subcritical conditions after the respective evaporation, if pressurized water under a pressure of, for instance, 10 bars is used, so that conventional nozzles will 35 do. The droplet cooling procedure following the atomization process may subsequently be effected by radiation cooling or even by directly injecting water, hot water or wet vapour.

- 4 Advantageously, the device according to the invention is devised such that the supply tube is designed to be coiled, and optionally as a finned tube, in the region of the annular weir, whereby the tubes with our without fins in the extreme 5 case may be wound so tightly that they will form a hollow cylinder. Such a coiled tube ensures a particularly good heat transmission and the rapid evaporation of the pressurized water supplied. In a particularly simple manner, the device may be configured such that a tubular wall including radial 10 passage openings for vapour and/or high-pressure water is arranged to follow the slag outlet opening, the clear width of said tubular walls being larger than the clear width of said slag outlet opening. Pressurized water, hot water, wet vapour or even superheated vapour may be fed externally through such 15 radial passage openings, wherein the wall of such a tube may be cooled, entering itself into effect as a radiation cooler. In this case, the configuration preferably is devised such that the tubular wall is surrounded by an evaporation chamber following the slag outlet opening and that the evaporation 20 chamber is connected with the vapour supply tube via a vapour duct with a vapour drum being interposed. The comminution performance may be further enhanced in that the radial openings provided in the tubular wall and the 25 radial spraying openings of the spraying head at least partially are arranged in radial planes differing from each other. In this manner, the hollow melt cylinder is fed with pressurized water and/or vapour alternately from inside and from outside, whereby oscillations may be induced, which 30 create additional shearing forces further intensifying disintegration. Depending on the temperature of the injected vapour, a quasi-isothermic atomization of the hollow melt cylinder may be realized in the limiting case, thus readily obtaining droplet diameters of below 50gm. Along with the 35 pressurized water and/or vapour supplied through the coaxial or concentric tube, a total of about 400 kg pressurized water, or the respective amount of vapour forming, may be supplied per ton of melt through the externally arranged walls in the consecutive cooling chamber so as to enable the temperature of -5 the emerging microgranulate-vapour mixture to drop to below 460 0 C. Glassy solidification is completed at such temperatures. 5 Advantageously, the configuration according to the invention is further developed in a manner that the coiled section, or section designed as a finned tube, of the supply tube carrying the spraying head is designed as a radiation vapour generator and that the outer diameter of the coiled section is smaller 10 than the clear width of the slag outlet opening reduced by twice the wall thickness of the jacket-like slag jet overflowing the annular weir. It is, thereby, ensured that the hollow melt cylinder does not collide with the spraying head or the wall at any point, so that its wear will be kept at a 15 minimum. In the main, the configuration advantageously is devised such that the spraying openings of the spraying head are designed for pressurized water having a pressure of between 5 and 25 bars, wherein the spraying openings of the spraying head are advantageously designed as converging 20 nozzles for a feeding pressure of approximately below 10 bars and as Laval nozzles for supercritical pressure conditions, vapour being ejected at temperatures of between 700 0 C and 1350 0 C, in particular about 8000C. With an accordingly elevated pressure, critical conditions are reached, which will 25 require Laval nozzles. Preferably, the supply of slag is effected tangentially to the annular overflow weir so as to safeguard also a high slag flow rate at a uniform thickness of the jacket of the emerging 30 hollow-cylindrical slag jet. The method according to the invention, for granulating and comminuting slags by means of the previously described device advantageously is carried out in a manner that the slag melt 35 is used as a foamed slag. In principle, compact slags may, of course, be readily comminuted and atomized as well. However, if defined granulate compositions are to be achieved, it is usually necessary to adjust the charging slag accordingly. Charging slag in the first place comprises liquid blast -6 furnace slag, wherein it is, of course, advantageous to admix liquid steel slag in order to raise the basicity. If also the A1203 content is to be raised for the desired end product, flue ashes from coal-fired power stations or even bauxite may 5 be admixed, too. In order to ensure the thorough blending of such mixed slags, air may be blown into such melts, whereby it has been surprisingly shown that such a mixed slag tends to intensive foam formation. In order to maintain the necessary temperature, also coarse-grained coal may be added to such 10 foamed slags, thus further promoting foam formation and enabling the iron oxide of the foamed slag resulting, for instance, from the addition of steel slag to be practically completely reduced to metallic iron droplets. A foamed slag overflow can be extremely finely microgranulated in a 15 particularly problem-free manner by the injection of water. Even chromium, manganese and vanadium oxides contained in the slag may be reduced at least in part, the desired slag composition being adjustable in such foamed slags in a particularly simple manner without requiring complex 20 additional means. The method according to the invention advantageously is carried out in that 30 to 150 kg water are fed through the water and/or vapour supply tube and a total of 400 to 500 kg 25 water is used per ton of slag, pressurized water having a pressure of 5 to 25 bars being preferably supplied to the spraying head. In the following, the invention will be explained in more 30 detail by way of an exemplary embodiment schematically. illustrated in the drawing. Therein, Fig. 1 illustrates a first embodiment of a slag tundish comprising the spraying head according to the invention; Fig. 2 is a sectional illustration of a modified embodiment analogous to Fig. 1; 35 Fig. 3 depicts a further configuration comprising an improved vapour circulation; Fig. 4 illustrates a modified configuration in a representation analogous to Fig. 3; Fig. 5 is a top view on the disc tundish; Fig. 6 illustrates a -7 further configuration; and Fig. 7 is a schematic partial view of a finned tube. In Fig. 1, 1 serves to denote a disc tundish whose outlet 5 opening is denoted by 2. The tundish comprises an annular weir 3 forming an overflow 4, via which the slag flows off as a hollow cylinder having a jacket 5. Concentric with the weir 3, whose axis is denoted by 6, is arranged a coiled pressurized water supply tube 7 which merges into a spraying head 9 below 10 the slag outlet 8 of the slag tundish. In a likewise concentric manner follows a tubular wall 10 including openings 11 for vapour or pressurized-water nozzles, whose mouths are oriented onto the slag jacket 5 in radial planes. In the region between the overflow 4 and the slag outlet 8, intensive 15 heating of the medium fed via the coil 7 takes place, which, in the case of pressurized water, is largely evaporated and may be ejected through the nozzles 12 of the spraying head 9. If these nozzles are oriented in a substantially radial manner, they may be arranged in radial planes different from 20 the radial planes in which the nozzles 11 are arranged such that the jacket 5 of the molten slag is excited to oscillations schematically indicated by 13, thus causing additional shearing forces to act on the solidifying slag jet. The extremely fine, microgranulated solidified particles 14 25 may subsequently be drawn off after an additional cooling path where pressurized water may be sprayed in through nozzles 11. In the illustration according to Fig. 2, a tubular connection piece 15 of refractory material is connected to the outlet 30 opening 8 of the disc tundish 1 such that the height of the coil 7 over which fluid is fed under pressure can be appropriately increased to ensure an appropriate vapour generation and the tubular wall 10 is protected in its the upper region. The coil 7 in this case functions as a radiation 35 vapour generator, whereby the generated vapour is again ejected from the spraying head 9 through nozzles 12 and through further, downwardly directed nozzles 16. The nozzles 11 provided in the consecutive tubular portion 10 in this case may be designed as Laval nozzles as schematically indicated, - 8 in order to ensure an appropriate cooling speed and rapid granulation even under supercritical pressure conditions. In the region of the slag outlet and radiation vapour 5 generator, respectively, the slag is cooled down, for instance, from 15000C to 1350 0 C, whereupon the hot slag melt emerging at approximately 1350 0 C is cooled to about 8000C, and atomized, by the aid of pressurized water and vapour. To this end, approximately 130 kg pressurized water at 20 bars may, 10 for instance, be used per ton of slag melt. Since the enthalpy of the evaporated water in respect to the enthalpy of the water vapour in the granulation chamber causes a supersonic speed of the vapour, flashing from the vapour nozzle head in this case must be effected via Laval nozzles. 15 If pressurized water at only 5 bars at a final vapour temperature of up to 800 0 C is used to cool the slag from 13500 to 8000C, approximately 130 kg water are likewise required per ton of melt, yet no Laval nozzles need be employed. Since 20 vapour in the device according to the invention may occur both at a high temperature and at a comparatively low temperature, the high-temperature vapour circulation may advantageously be operated separately from the low-temperature vapour circulation in order to thereby achieve exergetic 25 enhancements. The temperature limit for the separate energetic exploitation of the vapour is chosen, for instance, at about 650 0 C. Fig. 3 depicts another configuration including an 30 exergetically enhanced vapour circulation, wherein the same reference numerals have been retained for identical parts. 1 again serves to denote a disc tundish, which may be under a pressure of about 5 bars and to which is connected the tubular part, which is designed as a quarter bend 17. The quarter bend 35 17 is sheathed by an evaporator coil 18 fed with pressurized water via a duct 19. In the evaporator coil, the pressurized water is conducted in counterflow to the solidifying slag jet flowing in the quarter bend 17 and is ejected into the quarter bend 17 via nozzles 11 as pressurized water in a first - 9 section, as wet vapour in a second section and as hot vapour in a third section. In this manner, a perfect counterflow heat exchanger is provided for the heat exchange between slag and water or vapour, respectively, with a heat exchange by 5 convection and radiation being effected at the same time and an effective disintegration of the slag being, moreover, achieved. The diversion of the vertical two-phase flow (microgranulates and vapour) 'into the horizontal is strongly promoted by the water and/or vapour nozzling provided in the 10 quarter bend 17. This enables the overall microgranulator to be designed with a low structural height, thus facilitating manipulation. The hot vapour is drawn off the evaporator coil via a duct 20 and subsequently is fed to the supply tube 21 for the spraying head 9. The supply tube 21 in the instant 15 configuration is not coiled, since the intensive heating of the supplied medium is no longer required. A partial amount of hot vapour may optionally be drawn off through duct 20 for further energetic utilization. In the main, an energetically particularly beneficial configuration results from the 20 circulation of vapour. From Fig. 4, a modified configuration according to Fig. 3 is apparent, in which the disc tundish 1 is made of graphite. The annular overflow weir 3 is constructed as a separate 25 structural component and may be made of a ceramic material. The choice of a material different from graphite in the instant case is of particular relevance, because graphite should not get in direct contact with water vapour at such high temperatures, since this might lead to the formation of 30 C02 and hydrogen. The graphite tundish 1 in this case may be electrically heated by a coil schematically indicated by 22, whereby the central runout tube of the tundish may be accordingly extended downwardly. Following the slag exit, an annular chamber 23 is provided, which functions as an 35 evaporation chamber. In the configuration according to Fig. 4, pressurized water is again supplied via the connection 19, whereby this final partial region, which functions as a radiation cooler, does not necessarily lead to the evaporation of the pressurized water. The pressurized water reaches a - 10 further chamber 24 provided in the region of the quarter bend and in which evaporation already occurs at least partially. Via nozzles 11, vapour or pressurized water is injected into the particle stream from this box 24 corresponding to the 5 quarter bend, whereby the respective valves may optionally be controlled and accordingly closed, as indicated by 25. After this, the vapour or the pressurized water, respectively, through duct 26 reaches the above-mentioned annular chamber 23 where rapid evaporation takes place due to the high 10 temperature difference. Again, controlled valves may be provided, whose valve closing members are indicated by 27 and through which vapour may subsequently be ejected against the outflowing liquid slag. The vapour formed in this evaporation chamber 23 then gets back into the vapour supply duct 21 15 through duct 20, as already indicated in Fig. 3. This vapour supply duct 21 may again be provided with a spraying head 9. With the appropriate dimensioning of the tube connected to the slag outlet, also the direct spraying of pressurized water or vapour without using a separate spraying head 9 is feasible. A 20 separate vapour connection is schematically indicated by 28. In the configuration according to Fig. 5, it is to be seen that the slag is introduced into the slag tundish 1 tangentially to the annular weir denoted by 3. In this manner, 25 a circulating flow is formed in the disc tundish, which ensures that a uniform wall thickness of the jacket of the outflowing slag will be safeguarded even at a high flow rate of the slag. 30 In the representation according to Fig. 6, in which the reference numerals from the preceding Figures have been largely retained, the vapour duct 21 opens already in the interior of the runout tube 2 from the slag tundish 1. In a first consecutive path, intensive cooling is effected by the 35 injection of water and/or vapour through nozzles 11, whereupon the -comminuted and already substantially solidified material reaches a fluidized bed chamber 29 arranged therebelow. In this fluidized bed chamber 29, cooling coils 30 are arranged which may also be referred to as immersed cooling surfaces.

- 11 These cooling surfaces or cooling coils are fed with pressurized water via a connection 31, wherein the pressurized water emerging from the cooling coils may be fed to the nozzles 11 through duct 32. From the fluidized bed chamber 29, 5 the material may be conveyed into a consecutively arranged screening means or sieve 34 via a duct 33, fine material being discharged via a sluice 35. The gaseous phase, which contains vapour to a large extent, is fed to -a condenser through duct 36. 10 In the vapour recycling system already apparent from Figs. 3 and 4 and comprising duct 20, a vapour drum 37 may be installed, which may simultaneously be used as a distributor for the vapour required in the process. To this end, vapour 15 may, for instance, be fed into the fluidized bed chamber 29 through duct 38 to maintain a fluidized bed, export vapour may be drawn off through a duct 39, and optionally required additional vapour may be introduced through a duct 40. 20 Fig. 7 finally schematically illustrates a wall section of a finned tube used instead of the coiled configuration of the supply tube 21. The windings, which correspond to the coils, in this case are formed by helically extending tubes 41 welded together by webs to form an altogether coherent wall having a 25 substantially cylindrical shape, through which water or vapour may flow in a helical manner. When using foamed slag, which is preferred, various slag qualities may be mixed together. This is readily feasible in the context of the production of a foamed slag, as will be described below. Blast furnace slag, 30 steel slag and flue ashes having the following compositions were mixed together.

- 12 Component Blast Steel slag Flue ashes furnace slag (%) (%) (%) Si02 37 13 48 A1203 13 6 39 FeO - 26 4 CaO 32 42 2 MgO 10 4 S 1.5 - 0.1 K20 2 0.5 3 Na20 0.5 0.1 0.5 TiO2 1 1 0.5 Cr203 - 0-1 Fe,met - 6 Total 97 98.7 97.1 C/S 0.865 3.231 0.0417 The following parameters were chosen as the target composition of the slags forming: 5 C/S basicity = 1 - 1.5 A1203 content = 6 - 16 % FeO content < 2 % TiO2 content < 2 % 10 MgO content < 15 % glass content > 95 % These parameters guarantee a high-quality synthetic blast furnace slag in terms of cement technology, while simultaneously obtaining Blaine numbers of above 4500 due to 15 the comminution achieved by the spraying of foamed slag. In order to obtain the initially mentioned parameters and to adjust a C/S basicity of 1.5, the steel slag portion (x) to be added is calculated as follows: - 13 x (C/S) . SiO 2 (HOS) - CaO(HOS) CaO(SS) - (C/S) . SiO 2 (SS) 5 hence follows X - 1.5 . 37 - 32 = 1.044 42 - 1.5 . 13 10 Thus, 1 part of blast furnace slag was supplemented with 1 part of steel slag in order to attain a C/S target basicity of about 1.5. The respective mixed slag appeared as follows: Mixed Slag Component Portion (%) reduced (%) SiO2 25.6 30.6 A1203 9.7 11.6 FeO 13.3 CaO 37.8 45.24 MgO 7.2 8.6 S 0.7 0.8 K20 1.2 1.3 Na20 0.3 0.3 TiO2 1 1.2 Cr203 0.05 0.03 Fe,met 3 _ Summe 99.85 99.67 C/S 1.48 1.48 15 By the reduction of the foamed slag, 138 kg pig iron were obtained per ton of mixed slag. 20 This mixed slag per se already constitutes a valuable cement technological component. In order to raise its early strength, - 14 the A1203 content of the final slag was increased from 11.6 to 16%. To this end, the flue ash described was used. The necessary 5 addition of flue ash is again very easy to obtain from chemical balance considerations: y (flue ash) = Al2Q3 (mixed slacg) - Z (Al 2

Q

3

)

Z (Al 2 03) - A1 2 0 3 (flue ash) 10 Hence follows: y (flue ash) = 11.6 - 16 = 0.1913 16 - 39 15 1 part of mixed slag was blended with 0.1913 parts of flue ash. The respective slag had the following analysis: TSH - Slag Component Portion (%) Sio2 33.92 A1203 16.25 CaO 38.9 MgO 7.33 S 0.68 K20 1.59 Na20 0.2 TiO2 1 Cr203 0.03 Total 99.9 C/S 1.15 20 This foamed slag mixture was granulated to d < 50gm and exhibited early strength values at least equivalent to OPC cements.

- 15 The addition of solids such as quick lime, flue ashes, coal, etc. into the slag is extremely simple because of the large density difference. 5 The slagging reactions proceed very rapidly within the foamed slag, and so does the metal oxide reduction, thus enabling the method to be operated continuously. The oxidant air may be enriched with oxygen to lower the specific gas load. 10 Bottom tuyeres may be obviated. The afterburning reaction (CO + 1/2 02 -> C02) likewise occurs within the foamed slag at high heat transmission rates (> 70%), only slight metal reslagging being observed. The metal sump (metal bath) may be continuously drawn off, for instance, via a siphon. 15 On account of the high A1203 content of the slag and the relatively low C/S basicity, a highly aluminous material (bricks, FF masses) was preferably used as a refractory material. 20 In the main, a low refractory consumption results from the foamed slag, since foamed slag insulates well. The energy input may also be effected via electrodes, similar to foamed slag operations in electric steelmaking plants. Yet, it is 25 preferred to realize the energy input by means of afterburning.

Claims (15)

1. A device for granulating and comminuting liquid slags or foamed slags, in which the slags are supplied with vapour 5 and/or water, including a slag tundish (1) and a slag outlet opening (2) arranged in the bottom of the slag tundish, characterized in that the slag outlet opening (2) is designed as an annular overflow weir (3) and that a water and/or vapour supply tube (7) is arranged coaxially or concentrically with 10 said annular weir (3), the outlet openings (12) of which supply tube open within a slag outlet tube or in a manner projecting from said slag outlet opening (2).

2. A device according to claim 1, characterized in that the 15 water and/or vapour supply tube (7) is connected to a spraying head (9) whose spraying openings (12) are arranged within the slag outlet opening (2), or in a manner projecting from the slag outlet opening (2), and are at least partially oriented radially. 20

3. A device according to claim 1 or 2, characterized in that the supply tube (7) is designed to be coiled in the region of the annular weir (3). 25

4. A device according to claim 1, 2 or 3, characterized in that a tubular wall (10) including radial passage openings (11) for vapour and/or high-pressure water is arranged to follow the slag outlet opening (2), the clear width of said tubular wall being larger than the clear width of said slag 30 outlet opening (2).

5. A device according to any one of claims 1 to 4, characterized in that the radial openings (11) provided in the tubular wall (10) and the radial spraying openings (12) of the 35 spraying head (9) at least partially are arranged in radial planes differing from each other.

6. A device according to any one of claims 1 to 5, characterized in that the coiled section of the supply tube - 17 (7) carrying the spraying head (9) is designed as a radiation vapour generator and that the outer diameter of the coiled section is smaller than the clear width of the slag outlet opening (2) reduced by twice the wall thickness of the jacket 5 like slag jet (5) overflowing over the annular weir (3).

7. A device according to any one of claims 1 to 6, characterized in that the spraying openings (12) of the spraying head (9) are designed for pressurized water under a 10 pressure of between 5 and 25 bars.

8. A device according to any one of claims 1 to 7, characterized in that the spraying openings (12) of the spraying head (9) are designed as converging nozzles for a 15 feeding pressure of approximately below 10 bars and as Laval nozzles for supercritical pressure conditions, and for vapour having a temperature of between 700oC and 1350oC, in particular about 8000C. 20

9. A device according to any one of claims 1 to 8, characterized in that the slag supply is connected to the slag tundish (1) tangentially to the annular overflow weir (3).

10. A device according to claim 4, characterized in that the 25 tubular wall (10) is surrounded by an evaporation chamber (23) following the slag outlet opening (2) and that the evaporation chamber (23) is connected with the vapour supply tube (7) via a vapour duct (20) with a vapour drum (37) being interposed. 30

11. A device according to any one of claims 1 to 10, characterized in that a fluidized bed chamber (29) including immersed cooling surfaces or cooling coils (30) is arranged below the slag outlet (2). 35

12. A device according to any one of claims 2 to 11, characterized in that the coiled region of the water or vapour supply tube (7) is designed as a finned tube. - 18

13. A method for granulating and comminuting slags using a device according to any one of claims 1 to 12, characterized in that the slag melt is used as a foamed slag. 5

14. A method according to claim 13, characterized in that 30 to 150 kg water are fed through the water and/or vapour supply tube and a total of 400 to 500 kg water is used per ton of slag. 10

15. A method according to claim 13 or 14, characterized in that pressurized water having a pressure of 5 to 25 bars is supplied to the spraying head.