AU680211B2 - Introduction of additives in powder form into a furnace - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMEPLETE SPECIFICATION STANDARD PATENT Applicant: ISOVER SAINT-GOBAIN

S.

Invention Title: INTRODUCTION OF ADDITIVES IN POWDER FORM INTO A FURNACE S S S 5 5 The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 INTRODUCTION OF ADDITIVES IN POWDER FORM INTO A FURNACE The invention relates to industrial furnaces, and in particular to cupola furnaces or blast furnaces, of which the inner atmosphere and the gas supply pipes are usually at different pressures from those of the outer environment, and into which substances in powder form are i to be introduced. j There are many industrial methods for hot processing products from raw materials which use a fuel, such as coke for example, which is mixed with the raw material. In this case the combustion gas, air and/or ii oxygen is introduced under pressure at one end of the i furnace by means of supply pipes, whereas the fumes are ii 15 discharged at the other end. It is often required to introduce into the furnace specific components used for processing the substance, either by having them conveyed by the gas introduced under pressure, or by introducing 4tlj !-m in a countercurrent into the fumes, but in all cases preventing the inner atmosphere from coming into contact with the outer atmosphere.

Thus for example, in the production of rock wool ir from raw materials based on blast furnace slag and basaltic i rock melted in a cupola furnace, it is required to 25 introduce substances in powder form such that they are added to the vitrifiable mixture.

0 These techniques for producing rock wool from substances with a high melting point are more generally known as "free centrifuging". In this case, the substance to be drawn into fibres is conducted in the m(.)ten condition to the periphery of three or four horizontal axis centrifuging wheels which are disposed adjacent one 1 II~ C 3.another, the substance being poured onto a first wheel which accelerates it, and passed on to the next wheel.

Each wheel transforms part of the molten substance into fibres, and passes the excess onto the following wheel.

The substance i the "cupola" type used ii which generally have a c3 axis, are loaded from the layers of fuel, which is to be drawn into fibres.

in the lower part of the the supply pipes through combustion gas, which is be enriched with oxygen.

combustion gives rise to drawn into fibres, which .s normally melted in furnaces of i foundries. The cupola furnaces, rlindrical shape and a vertical Stop with successive alternating generally coke, and the substance The combustion area is disposed cupola furnace, in the vicinity of which there is blown the generally .air which can optionally The heat released by the melting of the substance to be escapes through a casting hole .fl .t t

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disposed at a level slightly lower than the level of the supply pipes. Finally at the base of the cupola furnace there accumulate the residues of cast iron obtained both 20 from the nodules included in the slag, and from the reduction of iron oxides in the remainder of the load.

Although the highest density cast iron is separated naturally from the substance to be drawn into fibres in the molten condition, the casting hole must be at the highest 25 possible level, in order to prevent escape also of small quantities of cast iron, which would give rise to rapid wear of the centrifuging wheels.

These melting enclosures are very advantageous, if account is taken of the very high outputs of molten products, and the low energy cost of this melting. In an enclosure of this type, the rock is melted relatively slowly, and it must be ensured that the combustion gases and the gases produced by the combustion can circulate very easily in the melting area, and in particular that the latter can escape in the direction of the chimney. For 4 this reason the load must not be too compact, otherwise excess pressure would be created in the melting area and would lead to an increase of turbulence in the casting area. This is why the load of raw material is preferably introduced in the form of extruded, for example cylindrical blocks or briquettes.

A method of this type for preparing the briquette load is well known for example from US 2 020 403. In addition, these briquettes have the advantage of possibly being constituted from products recovered from the fume powders, unmelted products, and fibre waste which can thus be reintroduced into the cupola furnace. The technique also permits adjustment of the composition of raw materials. However, in the case of the products recovered from the fumes in particular, it is relatively complicated i to gather them together, store them after cooling, and transport them to the place of production of the briquettes. Furthermore, the production of the briquettes, which consists of agglomerating the substances in powder 20 form by means of a binder, is expensive. It would be a advantageous to be able to carry out the recycling directly on the spot, which in addition, in the case of the powders obtained from the fumes, would enable energy to be saved by avoiding the need to reheat the powders.

Similarly, in blast furnaces, the technique is i known of introducing the coke in powder form, and having it conveyed by the combustion gas.

The existing techniques for introducing powdered coke are divided into two main groups, one which uses an additional vector gas, and the other which uses the Venturi effect. In both groups, the problem consists of controlling the quantity of substances in powder introduced into each supply pipe. In these two types of techniques, the problems are associated with the fact that the 2) i 4 -iS gof.r 5 quantities of powder introduced are highly dependent on the flow conditions of the vector gas in the supply pipes, and, downstream of the latter, in the furnace itself.

The object of the invention is to provide a technique which enables specific quantities of substances in powder form to be introduced into a reactor in which solid substances and gases are processed, such as a furnace for processing molten substances, cast iron or vitrified substances, and in particular in the gases of furnaces such as cupola furnaces or blast furnaces.

In particular, the invention must allow this introduction to be performed at flow rates which are independent of the conditions of use of the furnace, such as the pressure of the gases at the outlet, or the pressure or velocity of the gases in the supply pipes.

Amongst the documents which propose methods for introducing powders into blast furnaces, most propose introducing the powders into the combustion gas supply pipes, for example US 5 123 632, in which coal dust is stored in silos, in order to be distributed in the supply pipes by means of a distributor which distributes the powder flow equally between the ducts which lead to each supply pipe. By means of an additional gas, the document proposes maintaining the pressure constant in each of the 25 ducts, such that the flow rate also remains constant at the aperture of each supply pipe, despite the pressure (and temperature) variations in the furnace.

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e* I Another document, US 5 070 79' Venturi system for introducing various form, mainly coal, into the combustion Sfurnace, in the supply pipe. The syste, Spressurised air circuit which narrows at introduction of the powder near the nar: ~Ii 7, proposes using a components in powder air of a cupola m comprises a nd then widens, and rowest point. S. Q I i, I r 6 US 5 070 597 also includes a pressure compensation system such that the flow rate is independent of pressure fluctuations which can exist in the cupola furnace.

Amongst the substances which it is envisaged to introduce into the furnace by the means described, are both the various original by-products and powders recovered during filtering of the cupola furnace fumes.

Thus, the known means for introducing substances in powder form into a cupola furnace or a blast furnace require additional systems which guarantee a specific flow rate. These systems are relatively complex, since they require detection of pressure variations in the supply S' pipes, such that variations of the resulting flow rates can r c be compensated. t* 15 According to the present invention there is provided a method for introducing substances into gases of k a reactor wherein a seal prevents any exchange of gas i VC. between the interior and the exterior of the reactor during too the introduction of the substances, said method comprising introducing the substances in a powdered form, forming the substances into a compact mass so that the substances form a seal preventing exchange of gas between the interior and exterior of the reactor and supplying a desired amount of powdered substance to the reactor from the compact mass. i The object of the invention is a method for introducing substances into the gases of a reactor such as a blast furnace or a cupola furnace, in which the substances are in powder form and where the substances in powder form themselves, in a compact mass, form the seal between the area to be supplied and the exterior.

Preferably, the introduction is performed in the supply Spipes of the combustion gas reactor, or in the gases M:stairi6kep/pa/retyposI4943.94 31.1.97 /i 4 o, ii II I II L I: :i :I i 6a obtained from the reactor, as they are conveyed to the outlet.

This method thus permits introduction of granulated substances in the areas where the gases are usually pressurised and/or dangerous, and where it is consequently essential to prevent any exchanges of gas between the interior and exterior of the reactor.

According to the invention, the method is applied for the introduction into the reactor of raw materials, and 10 for recycling in the reactor of endogenous or exogenous waste, if necessary after crushing or shredding, as well as .0 *0 o a *000 000* r*00 9 0* a

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N, starindkoeplpat/relypes/54943.94 31.1.97 r V# tv Ct S00 0 C4 *4*4 0 ttC *4 4 606 ::06 6 60 4044 *d S *i .4 7 for recycling in the reactor of the powders obtained from the gases produced in the reactor, and in the case of production of fibrous products, for recycling in the reactor of the grains not drawn into fibres.

When thus applied, the method according to the invention permits direct use of raw materials in powder form, or immediate, cheap recycling of the most varied substances.

The invention also proposes a device for implementing the method, comprising a pipe which conveys the substances to be introduced in powder form, which form a plug therein, of which the thickness is such that the substances prevent passage of the gases. Alternatively, the pipe which conveys the substances in powder form opens into an area of the reactor through which the gases pass before being discharged, and in this case, the pipe opens into an area through which the burnt gases being discharged from the cupola furnace or blast furnace pass, before passing through a filtering device in order to reach the 20 fume outlet, the filtering device preferably consisting of the raw materials themselves through which the exhaust gases must pass through before being discharged, or the pipe which conveys the substances in powder form opens into a reactor gas supply c(uct, and in particular into the air or oxygen supply pipes of a cupola furnace or blast furnace.

The pipe which conveys the substances in powder form, and which constitutes the basis of the device according to the invention, is advantageously either an Archimedean screw, or a standing pipe filled with powdered substances up to a minimum level, and of which the base is obtured. Alternatively, the base of the pipe is obtured by if a shutter valve which is controlled so as to maintain the thickness of the plug of substances in powder form greater i( i .4 jj i Sr i i l 1: x -IYL- Y~ i mn 8 than a minimum value, or the lower part is elbowed, and a vibrator in the lower part of the pipe maintains a specific level therein.

It can be seen that the devices provided for implementing the method according to the invention are very simple and cheap.

The techniques according to the invention enable the flow rate of introduction of substances in powder form into the gases to be controlled, either, in the case of introduction of raw material components or exogenous waste, at a rate which is selected in accordance with the production parameters, or, in the case of immediate recycling of endogenous waste, with full, instantaneous reintroduction of the waste produced. However, the rate of introduction is always independent of the pressure conditions inside the reactor. I The following description and Figures will enable the operation of the invention to be understood.

In the Figures, Figure 1 shows a cupola furnace with particles added to the fumes; Figure 2 shows an Archimedean screw introduction device; Figure 3 shows a device for reintroducing powders recovered from the fumes, into the combustion gas supply :2 25 pipes; and pi|e. \Figures 4 and 5 are devices which use a standing pipe.

In the production of rock wool using the technique of a cupola furnace and ".free centrifuging", the raw materials are introduced substantially in the form of blocks, which can be natural in the case of fragmented basaltic rocks, or which are obtained from previous AlI L -Y W 2 t_ 9 processing such as coke or slag, which are by-products of the production of cast iron, or in the form of briquettes constituted especially for reintroduction of the waste and adjustment of the composition. For various reasons, it is advantageous to introduce certain components of the composition directly in powder form. These are firstly substances produced on the spot such as those not drawn into fibres, i.e. grains of substance ejected from the centrifuges which could not be formed into fibres, or in particular solid residues which are ejected from the cupola furnace and carried in the fumes. These last substances are composite powder and coke mixtures. The product can thus be assimilated directly, since its composition differs only slightly from that of the substances loaded into the furnace. In addition, its temperature is high, and its immediate reintroduction saves the heat which would be required in order to reheat it. It is also required to introduce raw materials in powder form, for the purpose of adjusting accurately the composition of the substance being 20 processed in the cupola furnace. Introduction of waste of external origin, reduced to powder .form is also advantageous.

Figure 1 shows the upper part of a cupola furnace in which vitreous substance is being processed in order to 25 allow rock wool to be produced by centrifuging.

51 is the body of the actual cupola furnace with too. its double wall in which the cooling water 52 circulates.

This cupola furnace has been modified in order to introduce o the device according to the invention. Normally, the parts 30 marked 53 and 54 do not exist, and the hopper 55 and the duct 56 which discharges the fumes to the cyclone dust catcher and to the chimney not shown, are both disposed lower, i.e. the hopper 55 on the upper aperture of the cupola furnace at 57, and the duct 56 on the wall 58, at the same level as the duct 54 which emerges from the device 0

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10 63. The parts which are added to the conventional cupola furnace are the pipe 53 which is filled with raw materials 59, and thr device 54 for supplying substances in powder form. This modification of the cupola furnace has permitted creation of a buffer area 60 through which the fumes pass before being discharged between the outer pipe 53 and the inner pipe 61 which constitutes an extension of the hopper 55. In normal operation the pressure in the buffer area is low, i.e. approximately 1000 Pa.

According to the invention, it is into this space that the substances in powder form are introduced. The device according to the invention must: Sallow the powders or granules to be introduced in controlled quantities; prevent them from being drawn along with the S fumes; Sprevent the fumes from being discharged through the intake aperture 62 for the powders or granules.

The first and third functions are fulfilled by the device 63 upstream of the duct 54, and the second is fulfilled by a filter which traps the particles 64 which have just been introduced, and enables them to reach the raw materials 59. A filter of this type is necessary, since without it, the particles 64 would be drawn directly i S. 25 to the fume outlet (and would be mostly recovered in the cyclone dust catcher disposed between the gas outlet and 0. the chimney).

In the Figure, the filter consists of the assembly of raw materials 59 consisting of blocks or briquettes, and which are disposed between the base 65 of the buffer area 60, and the gas outlet 66, between the two pipes 53 and 61. This dist nce is sufficiently long and encumbered fof the particles 64 to be stopped, provided that they are not too fini, such that they then begin to i i descend with the remainder of the composition. very fine particles such as the powders collected in the fumes by means of the cyclone dust catcher downstream of the outlet duct 56 would be liable to follow once more and in the same direction, the path they had already followed between the blocks. The experimental conditions permit determination of the lower limit of the size of particles to be introduced at this Level.

The device 63 accox~ding to the invention comprises a pipe where the substances in powder form themselves, in a compact mass, form the seal between the area to be supplied and the exterior.

Figure 2 shows an 'embodiment of a device of this type including an Archimedean screw.

which comprises a straight part 30 and an elbow 31. in the tt axis of the straight part there is a worm 34 which is rotated by a variable speed gear, not shown. A lateral hopper 32 disposed upstream of the upper part of the pipe 30 enables the screw to be supplied with substances 33 which are entrained by the screw 34 towards the-'left of the Figure. The inclination of the pipe 30 to the horizontal is not at,) rmining factor. The function of the movin~g ***~screw 34 is to create a "plug" 35 of substances, which fills the pipe 30 completely over a length (the "thickness" .of the plug) of for example 20 cm. This length may vary according to the nature and consistency of the substances to be introduced. The requirement is that it must be sufficient for the "plug" 35 to form the seal between the part downstream where there is a pressure of for example 100q pascals, and upstream which is generally at atmoaplieric pressure. The thickness of the plug 35 will thus Pe greater for example if shredded rock wool waste is to bsintroduced, than if powdered raw materials are S_ I 12 involved.

The worm device operates very flexibly. In fact it is sufficient for the length available between the end 36 of the screw 34 and the elbow 31 of the pipe to be greater than or equal to the thickness of the "plug" necessary in order to prevent the gases downstream from returning upstream, and the system then operates irrespective of the velocities of introduction of the substances into the hopper 32 and/or rotation of the worm.

The device as shown in Figures 1 and 2 are used in ord'r to recycle waste produced during the manufacture of rock wool, for example by means of the "free i centrifuging" technique described above.

According to this technique, not all of the 15 molten vitreous substance produced by the cupola furnace is k transformed into fibres. A significant part is in the form i 44.. of substances not d-wn into fibres ("slugs"), i.e. solid particles which, unlike the fibres which are entrained laterally by a jet of air, drop below the machine, carrying some fibres with them. Habitually, this waste is agglomerated into briquettes and is then reintroduced into the cupola furnace with the new raw materials. i The tec',inique according to the invention enables this waste to bf reintroduced in practice in the same place 25 as the briquettes, without needing to transform them, or even store them. In test, it was possible to obtain s( o 'proportions by weight of approximately 10% of recycled slugs relative to the total raw materials, by using only a single device.

The invention permits not only introduction of substances in powder form into an area such as the buffer area 60 in Figure 1, where the pressures are low, but also 1 1.3 into areas where the pressure is high, such as the combustion gas supply pipes, where it can reach 7 or 8000 pascals or even more.

Figure 3 shows a conventional embodiment of a cupola furnace 1 with its double walls 2 cooled by water circulation, its loading aperture 3 at the usual level, two of its air supply pipes 4, 5 loaded with oxygen, its fume extractor 6 leading to the cyclone dust catcher 7 which extracts the powders which tli an fall into the funnel 8, whereas the fumes are conveyed towards the chimney by Lie duct 9. in order to enable the powders to be extracted, the outlet of the funnel 8 is provided with a shutter valve not shown. in this same Figure, 40 is 4. hopper intended to contain the powdered raw materials to be introduced into the cupola furnace in order to adjust the composition.

These may for example be sand, dolomite etc. At the outlet the hopper, a measuring valve 41 controlled by the mechanism 42 enables the f low rate of the additives to bek adjusted as required.

When they are discharged from the cyclone dust catcher 7, the hot powders (temperature higher than 150 0

C),

as well as the powdered raw materials at the outlet of the hopper 40, are taken over by a conveyor 13 which conveys *them towards a measuring device 10 according to the invention. The function of the latter is to introduce the substances into the duct 11 of the .supply pipe 5 at the rate at which they arrive. The introduction takes place **.*through the blast box 12. The duct in question passes through the cupola furnace and provi des the supply pipes with oxygenated hot air (at about 500 0

C).

Figure 4 shows a measuring device in detail. in the Figure, the cupola furnace 1 is shown with its water jacket 2 and the supply pipe 5 with its end cooled 13.

Unlike in Figure 3 the supply pipe shown here comprises an 14 oxygen lance 44 which is supplied by the duct 45. The latter is aligned with the supply pipe. The base of the cupola furnace comprises a ramming mass, of which the upper limit 14 can be seen. At the base of the cupola furnace, fluid cast iron 15 is covered by the fluid vitreous mass 16 in which there is also solid coke 17.

The blast box 12 is used to supply the supply pipes, in which the air is at pressure of 8000 Pa. In the duct 11 of the pipe, the speed of the air is 70 m/s.

the device 10 has two parts, an upper part 20 consisting of a pipe with a diameter of for example 150 mm, and a lower part which is a vertical straight pipe 18. 70 mm in diameter. This pipe 18 is attached in a sealed manner transversely to the upper part of the blast box 12, just opposite the; aperture of the supply duct 11 of the supply pipe 5. The part 19 of the duct 11 which is opposite the I pipe 18 is widened to a diameter of 128 mm. The two coaxial apertures of the pipes 18 and 19 are in the same I plane.

The upper part 20 of the device 10 has a vertical straight upper part 21 and a likewise vertical lower part i 22 which is displaced laterally. Between the two, an Sshaped area is provided. Finally, in the upper part, a widened mouthpiece 23 ensures ease of filling by the conveyor 13. The pipe 20 is made of a material which is highly resistant to temperature and abrasion by the powders obtained from the fumes, and for example is made of steel.

It is attached at the upper part by a collar, and is provided in its lower part with a vibrator 25. It is connected to the smaller diameter pipe 18 by means of a resilient sleeve 28 made of a suitable material such as asbestos, or a silicone coated fabric.

The operating principle of the device 10 is as follows: whereas the pipe 20 is separated from the blast

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1 box 12, for example by means of a valve not shown disposed on the pipe 18, the pipe 20 is filled quickly with powder taken for example from the outlet of the funnel 8 of the cyclone dust catcher 7. It then takes the form of a slope 26 which stops the powder from descending. When the powder reaches a level 27 determined in advance, the filling is stopped. The system is started up and can then operate: the valve on the pipe 18 is open, the powder is conveyed to 23 by the conveyor 13, and the vibrator is put into operation as often as is necessary for the pipe to be emptied from the base, and for the level 27 to be maintained identical. For the purpose of automatic operation, a level detector 28 has been positioned in the same place. This is for example a temperature probe which detects the presence of the hot powder inside the pipe. As soon as the powder is no longer at the level of the detector 28, the vibrator 25 stops, and since the powder is being supplied permanently, the level rises once more 0 immediately, and the vibrator starts to operate once more 20 as soon as the fixed level has been reached. J In general, whether the object is only to i reintroduce integrally and continually a type of waste produced by the unit itself, or whether the aim is to add specific quantities of raw materials in powder form, 25 persons skilled in the art will determine simply by means ij of test the parameter values to be selected for: 0 the diameter of the pipe the gradient of the intermediate area where the slope 26 is formed; and the height of the powder column (between 26 and 27) necessary to compensate for excess pressure in the blast box.

It has been seen that in the case of powders recovered from the fumes of a rock wool production cupola furnace, which have a particle size smaller than 1 mm, the 16 diameter 150 mm was suitable for the pipe 20, the gradient of the intermediate area of the pipe 20 where the vibrator is disposed is 450, and the difference in level between the slope 26 and the upper level is 1.10 m. The vibrator is of the eccentric type, and its frequency of vibration is 7500 per minute.

I The above-described parameters permit problemfree introduction into a single supply pipe of all the powders recovered from the cupola furnace fumes by the cyclone dust catcher, i.e. quantities which can be more than 100 kg per hour. The above-described system, which does not comprise any moving mechanical component in the powder, is particularly suitable for the introduction of abrasive substances in powder form into the cupola furnace.

Figure 5 shows a variant embodiment of the device 10 in Figure 3, also with a standing pipe. The substantial S difference from the vibrator system is that the pipe is t straight and is provided with a valve in its lower part.

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In the Figure, 12 is the blast box and 11 is the I duct which leads to the supply pipe.

The pipe 70 is thus standing, for example in a t o. vertical position. Its lower part ends in a valve 71; tests have been carried out with a shutter valve. The valve is opened just sufficiently to allow the required flow of substances in powder form to pass through. The latter are stored at 72, to a height sufficient to prevent the pressurised gases in the blast box from flowing back towards the exterior. The level of the substances in powder form 72 which must remain stable in accordance with the parameters, i.e. nature of the powder, flow rate to be provided and pressure of the gases, is maintained by means of two level detectors 73 and 74 which can be thermal, such as that 28 in Figure 4, or mechanical with sensors or even 1 1' 17 optical.

The choice between the first device, in Figure 2, and the two others (in Figures 4 and 5) depends on the nature of the substance to be introduced. Abrasive powders, such as the povwders recovered from the fumes obtained from a rock wool production cupola furnace, are for example incompatible with a worm, since the level of wear is too high, but on the other hand the "passive" system in Figure 5 is highly suitable for powders of this type.

Similarly, light, separated substances which for example comprise substantial amounts of fibre waste, are unsuitable for the standing pipes in Figures 4 and since, in order to form the seal, in particular relative to S 15 the blast boxes, heights of substance which are too great i ateS, in the pipes are required.

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t The above-described two techniques constitute two c examples of embodiment of the principle of the invention, according to which it is the substance to be introduced into the supply pipes which itself constitutes the plug i between the downstream part with a higher pressure, and the upstream part at atmospheric pressure, or between the Sexternal atmosphere and the interior where there are toxic gases. It will be appreciated that other devices not described here enable the same function to be fulfilled, and these are also covered by ta present document. The form of the substances to be introduced is imortant, i.e..

powders are obviously suitable but also so are grains, provided that they are not too large, or that they can be compressed, as is the case of nodules obtained by shredding fibrous mats.

The above-described invention is characterised by its great simplicity, or even primitiveness: very simple,

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separated components to be introduced far more simply than 1 according to the prior art, directly into the fumes or into the combustion gas supply pipes of cupola furnaces or blast furnaces.

In the case of reintroduction of waste such as "slugs" or of powders obtained from the fumes, the advantage of the invention is still more significant, since firstly the costly production of briquettes is no longer required, and in the case of powders obtained from the fumes, the reintroduction takes place before cooling (saving of reheating energy).

Additionally, the invention provides a simple S 15 means of reintroducing into the cupola furnace of a rock wool production unit, exogenous waste such as fibrous 4 insulation products (glass wool or -rock wool) obtained from industries which produce thermally insulated devices, and o c which are obliged by environmental protection regulations to retrieve used devices and to recycle the constituents thereof.

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Claims (19)

1. A method for introducing substances into gases of a reactor wherein a seal prevents any exchange of gas between the interior and the exterior of the reactor during the introduction of the substances, said method comprising introducing the substances in a powdered form, forming the substances into a compact mass so that the substances form a seal preventing eichanzge of gas between the interior and exterior of the reactor and supplying a desired amount of powdered substance to the reactor from the compact mass.

2. A method according to claim 1, in which the introduction of the substances takes place in gas reactor ae supply pipes.

3. A method according to claim 1, in which the introduction of the substances takes place in the gases i tet obtained from the reactor as the gases are conveyed to the outlet of the reactor. A method according to any preceding claim, in which the reactor is a blast furnace or a cupola furnace.

5. Application of the method according to any one of claims 1 to 4, to the introduction of raw materials into the reactor.

6. Application of the method according to any one of claims 1 to 4, to recycling in the reactor of endogenous or exogenous waste, if necessary after crushing or shredding. i

7. Application according to claim 6 of the method j according to claim 2, to recycling in the reactor of SL powders collected from the gases obtained from the reactor. i

8. Application according to claim 6, to the i production of fibrous products in which the grains which are not drawn into fibres are recycled in the reactor.

9. A device for introducing substances in powder form Sinto gases of a reactor, comprising a pipe for conveying the substances to be introduced in powder form from outside the reactor to inside the reactor, said pipe comprising a zone wherein said substances form a compact mass so as to seal the pipe in use, the thickness of the compact mass being such that the seal formed from the compact mass of j tt t substances prevents exchange of gas between the exterior and interior of the reactor, and wherein powder from the 4.CC seal formed by the compact mass is supplied to the reactor. A device according to claim 9, in which the pipe for conveying the substances in powder form opens into an area of the reactor through which the gases pass before the Co, gases are discharged from the reactor. St o I. A device according to claim 10, in which the pipe for conveying the substances in powder form opens into an area through which burnt gases obtained from the reactor pass, before the gases pas through a filtering device in 25 order to reach the fume outlet.

12. A device according to claim 11, in which the filtering device consists of the raw materials themselves through which the burnt gases must pass before being discharged from the reactor.

13. A device according to any one of claims 9 to 12, I li in which the reactor is a blast furnace or a cupola 0> .1 S"o ae r icare rmteratr ce U yif" I c-

14. A device according to claim 12 or 13, in which e A device according to claim 14, in which the reactor gas supply duct is the air or oxygen supply pipes of a cupola furnace or a blast furnace.

16. A device according to any one of claims 9 to further comprising a supply of substances in powder form o which supplies an Archimedean screw. I- C 1 C 17. A device according to any one of claims 9 to further comprising a standing pipe filled with substances Ico in powder form up to a minimum level, and of which the base 0 co is obtured. e 0 n

18. A device according to claim 17, in which the base of the pipe is obtured by a shutter valve which is COSo controlled such as to maintain the thickness of the stopper of substances in powder form greater than a minimum value. EtC©

19. A device according to claim 17, further comprising a standing pipe which contains the substances in rrr powder form, the lower part of the pipe being elbowed, and a vibrator in the lower part of the pipe operated by a level controlling system.

20. Application of the device according to any one of claims 9 to 19, to the introduction of grains not drawn into fibres, during production of mineral fibres in a cupola furnace.

21. ApplicatJbon of the device according to any one of claims 17 to 19, to the introduction into a cupola furnace H:\Sue\Keep\54943.94.claims.doc (2I Lh 7 A 22 or a blast furnace of the powders obtained from the fumes.

22. A method substantially as hereinbefore described with reference to any one of the accompanying drawings.

23. An application of a method substantially as hereinbefore described with reference to any one of the accompanying drawings.

24. A device substantially as hereinbefore described with reference to any one of the accompanying drawings. 9 t Vc t 0 C CECC 4 "Co r t z a Ot bDC C 0C tpC C C 0 o Co C C~o CC C 15 Dated: 14 April 1997 ISOVER SAINT-GOBAIN By Its Patent Attorneys GRIFFITH HACK ellows Institute of Patent Attorneys of Australia rl i i i ii i: i i i i i I/ ere cCC cCC C C *s C H:\sue\Keep\54943.94 .claai.doc u~ jL r4 l 1 ABSTRACT A method is proposed for introducing substances in powder form into a cupola furnace or a blast furnace. The substances are introduced into the fumes or into the combustion gas supply pipes. The granules themselves form the seal between the pressurised area and the exterior. One variant does not have any moving parts in contact with the granules, and another uses an Archimedean screw. 0 The method is suitable in particular for reintroducing into the supply pipes the powders received in the fumes, and for introducing substances in powder form into the fumes. Fig. 2 *r S 55 t5 5555 St So Sir S*9 S 555, *c 5 5*e S. 5* 8 *884 Il-L- -Pi_ 1