AU778802B2

AU778802B2 - Method and device for forming mineral wool by internal centrifuging

Info

Publication number: AU778802B2
Application number: AU18697/01A
Authority: AU
Inventors: Pascal Decker; Daniel Guyot; Laurent Pierucci
Original assignee: Saint Gobain Isover SA France
Current assignee: Saint Gobain Isover SA France
Priority date: 1999-11-24
Filing date: 2000-11-22
Publication date: 2004-12-23
Anticipated expiration: 2020-11-22
Also published as: PL197681B1; TR200201376T2; RU2252199C2; AR026601A1; FR2801301B1; KR20020049012A; RU2002116704A; NO20022394L; JP4842481B2; BR0015756A; JP2003514757A; DE60003953D1; CA2392338C; HU226280B1; FR2801301A1; WO2001038245A1; NO20022394D0; BR0015756B1; CA2392338A1; PL355499A1

Description

WO 01/38245 I Wa 013824 -1-PCT/FRQ0/ 03 243 PROCESS AND APPARATUS FOR FORMING MINERAL WOOL BY INTERNAL CENTRIFUGING The invention relates to techniques for forming of internal centrifuging combined with extension or attenuation by a high-temperature gas blast. It applies especially to the industrial production of glass wool intended, for example, to form part of the composition of thermal and/or acoustic insulation products.

The fibre-forming process to which the invention relates consists in introducing a stream of molten glass into a spinner, also called a fiberizing dish, rotating at high speed and pierced around its periphery by a very large number of holes through which the glass is thrown out in the form of filaments due to the effect of the centrifugal force. These filaments are then subjected to the action of an annular hightemperature, high-velocity attenuating blast along the wall of the spinner, which blast thins down the filaments and converts them into fibres. The fibres formed are entrained by this attenuating gas blast towards a receiving device generally consisting of a gas-permeable conveyor belt.

This process has formed the subject of many improvements. Thus, the patent EP 0 189 354 B1 relates to an improved burner generating the annular attenuating blast, namely an internal combustion burner comprising an annular combustion chamber.

Patent WO 97/15532 also relates to an improvement to this burner, the improvement consisting in that the attenuating gases have a radial temperature gradient, by being hotter close to the spinner.

Patent EP 0 519 797 Bl relates to the addition of a blowing ring placed at some radial distance from the axis of the spinner greater than that of the burner generating the attenuating gases, this blowing ring emitting individual and divergent jets of gas which 2 meet below the lowest row of holes of the spinner and which have the function of generating a cold gas layer which channels the hot-attenuated fibres.

The invention relates more particularly, but without any limiting character, however, to thermal high mechanical properties, for specific applications requiring such properties. These are especially insulation products which support masonry elements and which consequently have to withstand high compressive loads, such as the elements used for the insulation of flat roofs allowing traffic. This is also the case with products which are used as exterior insulation and which must be able, in particular, to withstand tearing forces.

To achieve such performance, this type of insulation product generally has a high density, for example at least 40 kg/m and has undergone, after the fiberizing operation proper, an operation whose purpose is to ensure that the fibres inside the felt assume directions as varied as possible without appreciably modifying excessively the overall orientation of the layer of fibres coming from the centrifuging. This operation consists especially in "creping" the fibres, this being obtained by passing the layer of fibres between two series of conveyors which define its upper and lower faces, a longitudinal compressive force resulting from the layer passing from a pair of conveyors driven at a certain speed to a pair of conveyors of lower speed than the previous pair. This type of operation is described, for example, in patent EP 0 133 083.

However, it has been found that this creping operation does not always allow the expected improvement in mechanical properties to be obtained.

The object of the invention is therefore to improve the mechanical properties of thermal and/or acoustic insulation products (or at the very least to ensure that the constancy of these properties from one 3 product to another is improved), without degrading their insulation properties, by concentrating more particularly on the high-density insulation products that have undergone a creping operation.

Tn.t-ad of seeking to modify the parameters of the usual creping process, the inventors of the present application have studied the reasons why this creping operation is not always satisfactory. They came to the conclusion that, after creping, it turns out that the fibres did not sufficiently have the isotropic orientation hoped for, this being due to the fact that, in particular, their dimensions were not necessarily the most suitable: excessively long fibres were difficult, by simple creping, to reorient as randomly as was necessary to ensure the best tear strength and compressive strength.

The invention therefore consists in modifying the fiberizing conditions in order to adjust the dimensions of the fibres so that they lend themselves better to creping, especially by making them shorter. This modification has, inter alia, relied on the way in which the fibres, having undergone the hot gas attenuation, are channelled, as described below.

Thus, the subject of the invention is firstly an apparatus for forming mineral fibres by internal 25 centrifuging, comprising: a spinner into which material to be fiberized is introduced, the spinner being rotatable about an axis

X

1 and includes a peripheral band having a plurality of holes through which material is ejected to form 30 fibres; S* a high-temperature gas attenuating means for attenuating fibres ejected from the peripheral band; a pneumatic means, for channelling/adjusting the 'i dimensions of the fibres; and a mechanical means comprising a cooled wall placed around the spinner in a location at least opposite to the peripheral band of the spinner, the cooled wall H.\ChrisL\keep\speci\18697-Ol.doc 26/10/04 3a supplementing the channelling and adjustment of the dimensions of the fibres performed by the said pneumatic means.

The subject of the invention also relates to a process for formg I mineral fibLes by internal centrifuging, combined with high-temperature gas attenuation, comprising: pouring the material to be fiberized into a spinner which rotates about an axis X 1 ejecting the material from a peripheral band of the spinner, the peripheral band having a plurality of.

holes through which the material is ejected to form fibres; attenuating the ejected fibres by a hightemperature gas blast emitted by a high-temperature gas attenuating means; and channelling/dimensionally adjusting the fibres by a pneumatic means, wherein the channelling and the dimensional adjustment of the fibres is supplemented by at least a mechanical means forming a physical barrier to the propagation of fibres radially with respect to the axis X, of the spinner.

The invention furthermore provides for the channelling/adjustment of the dimensions of the fibres, 25 adjusted by the said pneumatic means, to be supplemented by at least one other means, including a *.g H.\ChrisL\keep\speci\18697-Ol.doc 26/10/04 4 mechanical means comprising a cool wall placed around the spinner at least opposite its peripheral band.

The annular burner may, for example, be of the type described in the aforementioned patent EP 0 189 354.

The hi owi -in ri nn mr f r '=v'mr:i C, T% nf the type described in the aforementioned patent EP 0 519 797. This patent has already explained that the layer of gas at ambient temperature emitted by the blowing ring enveloping the jets of attenuating gas from the annular burner had the role of channelling the fibres and of gripping the torus formed by the fibres between the moment when they are ejected by the spinner and that when they are gathered by the receiving device located beneath the spinner.

In fact, schematically this layer of gas is not an "impermeable" pneumatic barrier in that all or some of the fibres are driven with a sufficient centrifugal force to pass through it. On the other hand, this pneumatic barrier brakes them and possibly inflects the direction of their movement, but also varies their dimensions: when the fibres strike the layer of cold gas, the resulting shock is high enough for the fibres to be possibly broken.

This is therefore one means of controlling the length of the fibres. However, it has proved to be insufficient for truly obtaining a fibre length short enough to allow creping under ideal conditions without correspondingly compromising their insulation capabilities. The additional mechanical means recommended by the invention has been shown to be highly effective in supplementing the action of the blowing ring and in increasing the options for controlling the length of the fibres. What is involved here is therefore the addition to the pneumatic barrier of the blowing ring of another barrier which this time is a mechanical barrier, based around the spinner beyond the pneumatic barrier, and which also fulfils two roles: firstly, it channels all the fibres all 5 those that have already been able to break through the first pneumatic barrier beneath the fibre-receiving device and then it allows the length of the gathered fibres to be more finely adjusted: the impact of the fibres against the physical wall allows them to be very effectively RhnrtenH in obtain opt mum creping. Apart from the easier creping, the invention also makes it possible to obtain fibres whose dimensions are less dispersed, the histogram of the sizes of which tends to be narrower. Finally, the shorter fibres also have a lesser tendency to form agglomerates of mutually bonded fibres, which bonded fibres reduce both the thermal and mechanical behaviour of the final product, most particularly its tear strength.

In fact, when high-density insulation products are manufactured, the diameter of the fibres is a less crucial parameter for obtaining a good level of thermal insulation than for the lighter products: it is possible to "avail oneself" of coarser fibres for better mechanical strength. The diameter is a characteristic that can especially be controlled by the choice of operating parameters of the annular burner and by the flow rate of glass feeding the spinner.

However, the coarser the fibres the longer they are in general. It is here the invention comes into play, the mechanical wall being used, very schematically, to chop these coarse fibres in order to facilitate their creping while maintaining their mechanical properties.

However, the invention applies more generally to fibres of any dimension and any diameter.

The pneumatic barrier and the mechanical barrier work in combination, the first one making it possible to vary the velocity and direction of movement of the fibres, or indeed already to chop them, the second one stopping them from expanding radially and completing their length adjustment. Generally speaking, most of the fibres ejected from the spinner, especially at least 80 to 90% of the fibres, will strike the 6 cooled wall, the remainder having mostly been stopped by the gases from the blowing ring. Just like the pneumatic barrier, the configuration and the parameters of this wall, especially its geometry and its position relative to the spinner, to the annular burner and to t.h hi owi n rinn. ma be vried rJ fre e T A l..

is cooled so that there is no risk of the fibres which come into contact with it, and which are still relatively hot, becoming stuck thereon.

Advantageously, the outer surface of the cooled wall, facing the spinner, is mainly made of metal, especially one based on stainless steel.

Preferably, this outer surface is concentric about the axis of the spinner and made of one or more parts fastened together by mechanical linking elements.

This outer surface is preferably at least partially cylindrical or in the form of a truncated cone. (In the latter case, the cone is preferably flared in its upper part. Throughout the present text, the terms "lower" and "upper" refer, by convention, to a height projected on a vertical axis). This conicity is favourable since it allows the fibres to be pulled back down better and makes it easier for them to interact with the gases emitted by the blowing ring, as will be explained in detail below. Advantageously, the cooled wall is at least partly in the form of a truncated cone inclined at an angle c 1 with respect to the axis X 1 of the spinner, of between 0 and 300, especially strictly greater than 00, for example between 2 and 200 or between 5 and 150. (In the cases most often encountered, the axis of the spinner is vertical or close to vertical) The cooled wall may also be characterized with respect to the axis X 2 along which the jets of gas (or the layer of gas) emanating from the blowing ring are projected. Thus it may be advantageous to have an angle of inclination a 2 of the wall in the form of a truncated cone with respect to the axis X 2 which is 7 between 0 and 60 or 700, especially between 2 and 20 or 300, or between 5 and 150.

The angle a 3 that the axis X 2 makes with the vertical may be equal to 0. In this case, given the a 1 and/or (x 2 values described above, the gases from the blowing ring will converge on the cooled wall.

However, this angle a 3 may differ from 00.

Advantageously if a 3 is between +300 and -300, the situation remains as in the aforementioned case of convergence of the gases from the blowing ring onto the cooled wall. On the other hand, if a 3 has a magnitude greater than 300 (up to 900), the situation may therefore be one in which there is no longer, necessarily, convergence of the gases emanating from the blowing ring onto the cooled wall, but rather convergence of these gases on to the plane on which the peripheral band of the spinner, pierced with holes, lies.

Preferably, the height of the cooled wall measured along a vertical axis is greater than that of the peripheral band of the spinner, the distance measured vertically between the lower end of the said wall and the lowest row of holes of the spinner being at least half the height of the peripheral band, especially between half and twice the said height.

The wall thus provides a surface large enough to confine the path of the fibres beneath the spinner, in order to better accompany and channel their paths towards the receiving member and to guarantee that all or almost all the fibres are affected by the presence of this wall, even those emanating from the lowest rows of holes of the spinner.

The simplest embodiment of this cooled wall consists in incorporating it into a mechanical device having a cavity provided with a cooling system based on the circulation of a fluid of the water type, especially a device of the water-jacket type. An annular water jacket is also used around and below the spinner.

8 Advantageously, the configuration of the pneumatic means and that of the wall are such that the jets of gas emanating from the blowing ring have an emission direction on leaving the ring which converges on the cooled wall, the convergence preferably occurring at a height below that of the middle of the peripheral band. In fact, the jets of gas may be designed so as at least partly to hug the wall. Since these jets are generally emitted vertically, the conicity of the abovementioned wall makes it possible for the jets of gas to converge gradually and constrains them to hug the wall, at least in its lower part. As mentioned above, this convergence is not systematic and certain embodiments forming part of the invention include a divergence, the jets of gas emitted by the blowing ring possibly being directed towards the wall of the spinner rather than towards the cooled wall according to the invention.

Preferably, provision is made for the upper edge of the cooled wall to be further from the axis of the spinner than are the points of emission of gas from the blowing ring. Preferably, the cooled wall may be configured so that its upper edge is beside the points of emission of the gases from the blowing ring, which points of emission are, for example, in the form of holes in an annular pipe, of nipples or of nozzles, as will be explained in detail below. The upper edge may also be moved slightly further away; advantageously, it is at a distance x, (measured radially with respect to the axis of the spinner) from the axes of projection of the gas jet (or, in other words from the centres of the holes emitting the jets of gas) of at most 40 mm, especially at most 20 mm and at least 0.5 mm.

The preferred blowing ring comprises elements generating preferably individualized and divergent jets of gas which meet below the lowest row of holes of the peripheral band. Two embodiments are preferred: a tubular ring pierced with holes, to which nipples are fixed, or a series of nozzles.

9 Advantageously, the temperature of the attenuating gases emitted at the exit of the annular burner is at most 1600 0 C, especially between 1350 and 1450C; this is a temperature which may therefore be lower than that possibly encountered in the internal centrifuaina. the temperaturp of thp Ail-t-nuatingT gases= generally being at least 1500 0 C and, rather towards 1600 0 C. "Cooler" attenuating gases, apart from the resulting energy saving, have the advantage of causing less damage to the binder which it is desired to spray onto the fibres beneath the spinner, the fibres having in fact a lower temperature at the time of spraying. It is also probable that fibres attenuated at temperatures below the usual temperatures would be mechanically more "brittle", something which would make them easier to chop into short fibres during their passage through the cold layer emitted by the blowing ring and then to impact against the mechanical wall according to the invention. This choice of attenuation temperature thus would also help, indirectly, in adjusting the dimensions of the fibres.

An optional additional means for channelling/adjusting the dimensions of the fibres is structural: it consists in adjusting the piercing of the peripheral band so that the size of the holes, arranged in concentric rows, varies from the top down over the height of the spinner in the centrifuging position, this hole size decreasing and then again increasing over the said height.

According to a preferred embodiment, the holes are distributed in groups of concentric rows with, from the top down, at least one first group of nl "high" rows of circular holes having a diameter dl, a second group of n 2 "intermediate" rows of circular holes having a diameter d 2 less than dl and finally a third group of n 3 "low" rows of circular holes having a diameter d 3 greater than the diameter d 2 where ni, n 2 n 3 1 and especially between 3 and 10. Preferably, the 10 following relationship exists between the diameters dl, d 2 and d 3 dl is close to d 3 with dl d 3 0.2 mm, especially dl d 3 0.1 mm, d 3 d 2 di d 2 a,-d is h6r 01 and especially where d 3 d 2 0.1 mm or 0.2 mm.

The subject of the invention is also a process for forming the fibres, using especially the apparatus described above and consisting of internal centrifuging combined with high-temperature gas attenuation in which the material to be fiber [sic] is poured into the spinner which rotates about an essentially vertical axis and the peripheral band of which is pierced by a plurality of holes, from which the material is ejected and then attenuated by a high-temperature gas blast emitted by an annular burner, the fibres being channelled and dimensionally adjusted by a pneumatic device in the form of a blowing ring. The process is such that this channelling, this dimensional adjustment are supplemented by at least one other means which include a mechanical means forming a physical barrier to the propagation of the fibres radially with respect to one [sic] of the spinner: this is the cooled wall described above.

The process of the invention consists in adjusting the configuration of this mechanical means, the parameters of the attenuating gas and of the gases from the blowing ring, and optionally the piercing of the peripheral band of the spinner by [sic] the manufacture of mineral wool having a micronaire of between 3 and 8 under 5 grams. The mean diameter of the fibres forming the mineral wool is advantageously between 4 and 13 pLm.

The invention also relates to the application of the process and of the apparatus which are described above to the manufacture of thermal and/or acoustic insulation materials having a density greater than 11 kg/m3, especially from 40 to 160 kg/m 3 the mineral wool of which has especially been creped.

The invention also relates to these highdensity insulation products themselves, especially those intended for making insulation panels for a car roof. In aeneral. for a thic~ness f 50 mm, sity of 80 kg/m 3 and a binder content by mass with respect to the glass wool of approximately the following are obtained: a tear strength of approximately 20 3 kPa; a 10% compressive strength of approximately 5 kPa; a thermal conductivity of at most 38 W/m.K The invention will be described in greater detail below with the aid of the following figures: Figure i: a schematic vertical sectional view of the fiberizing plant according to the invention, Figure 2: an enlarged schematic vertical sectional view of the spinner according to a first embodiment, Figure 3: an enlarged schematic vertical sectional view of the spinner according to a second embodiment.

Figure 1 shows highly schematically a fiberizing plant suitable for implementing the invention and similar to the teaching of patent EP 0 519 797 with regard to the spinner, the annular burner and the blowing ring. This plant essentially consists of a bottomless spinner 1, the peripheral band 2 of which is pierced by a large number of holes, fixed to a hub fastened to the spindle 3 for rotating about an axis X1, mounted vertically and driven by a motor (not shown). The stream of molten glass feeds the spinner, passing via the hollow spindle 3 and flows into the solid-bottomed basket 5 provided with a cylindrical wall pierced by a small number of relatively large holes, by drilling, and for example, having a diameter of about 3 mm by means of which holes 12 the molten glass is delivered in the form of primary streams 7 directed towards the inside of the peripheral band from which it is [sic] expelled due to the effect of the centrifugal force in the form of filaments 8.

The spinner is surrounded by an annular burner 9 an by A blowing r ing The rws are distributed in three groups from the top down: the intermediate rows have a smaller hole diameter than the high and low rows by at least 0.1 or 0.2 mm.

The annular burner 9 (in accordance with the teaching of patent EP 0 189 354) generates a gas jet whose temperature at the lips of the burner is about 14500 C.

The fineness of the fibres is determined by the value of their micronaire under 5 g. The micronaire measurement, also called the "fineness index" takes into account the specific surface area by virtue of the measurement of the aerodynamic pressure drop when a given amount of fibre extracted from an unsized blanket is subjected to a given pressure of a gas, generally air or nitrogen. This measurement is commonplace in mineral fibre production units; it is standardized (DIN 53941 or ASTM D 1448) and it is performed by an apparatus called a "micronaire apparatus" The blowing ring 10 consists of a tubular ring, the holes of which are provided with nipples 11 fastened by welding, for example. By allowing prolonged guiding of the jets, the nipples lead to greater stability of the individual-jet emission conditions and consequently the operating uniformity of the ring is thereby favourably affected.

According to the invention, and as is shown more clearly in Figure 2, there is an annular device 12 comprising a stainless steel outer wall 13 facing the spinner 2 and in the form of an upwardly flared truncated cone. This wall makes an angle a, of about to 120 with respect to the vertical. In the nonlimiting particular case shown in Figure 2, the vertical axis is coincident with the axis of rotation 13

X

1 of the spinner and with the axis of emission X 2 of the jets of gas emanating from the blowing ring The upper edge 14 of the wall 13 is beside the wall of the nipples 11 of the blowing ring. Its lower edge is at a significantly lower height than that of the lnwe~t row of holes of the s-inrer This wall 13 therefore belongs to a device of approximately annular shape placed opposite the spinner, which is of the "water jacket" type; it is provided in its cavity with a water-circulation cooling system in order to ensure that the wall with which the fibres come into contact remains at a temperature low enough for them not to remain stuck to the wall, but to "rebound" and possibly be broken under the impact.

In operation, the fibres in the course of being formed for the most part break through the layer of cold gas emitted by the blowing ring 10 and strike the wall 13 so as to be taken back down, in a convergent direction towards the receiving device (not shown) Also not shown, since it is conventional, is the binder-spraying ring below the spinner. The mineral wool gathered in the form of a layer is then conventionally heat-treated, especially to crosslink the binder, and then undergoes a creping operation according the teaching of patent EP 0 133 083.

The fibres obtained have a micronaire of approximately 7 under 5 grams.

Their thermal and mechanical performance at kg/m 3 was mentioned above.

Moreover, it has been found that the mechanical properties of this type of heavy insulation product was as good, or indeed better, when, for the same spinner, the output of 22 tons/day is increased to 35 tons/day.

This is quite remarkable insofar as the opposite tendency is generally observed, namely a progressive deterioration in the mechanical properties when the production output increases in the case of so-called lightweight or low-density products (that is to say a density of less than 40 kg/m 3 This is a surprising 14 and advantageous consequence of the invention, which may perhaps be explained by the fact that the higher the output of glass ejected from the spinner, the more substantial/violent the impact of the fibres on the cold wall and the arpeat-r the size reducti on of the Figure 3 repeats the structural elements already described in Figure 2. In this embodiment, the jets of gas emanating from the blowing ring 10 are emitted along an axis X 2 which makes an angle a 3 of approximately 600 with the vertical. These jets are directed towards the peripheral band 2 of the spinner and not towards the cooled wall 13.

The two embodiments shown in Figures 2 and 3 do not limit the invention many other configurations are possible. Thus, the element 12 and the ring 10 with its nipples 11 may be configured so that the approximately horizontal surface of the upper part of the element 12 lies at a higher level with respect to the vertical than the end of the nipples 11 (either by modifying the geometry of the nipples, for example by inclining them, or by modifying the geometry of the upper region of the element 12, especially that of its edge 14): thus, the 25 element 12 is "raised" with respect to the nipples 11. It is also possible to take the opposite approach, by slightly "lowering" the element 12 with respect to the said nipples 11, the sole constraint being, however, to prevent the fibres from being able to pass above the 30 cooled wall 13.

S"Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described.

It is understood that the invention includes all such variations and modifications which fall within the spirit and scope.

H,\ChriL\keep\speci\18697-01.doc 26/10/04 15 It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these docmments forms part of the common general knowledge in the art, in Australia or in any other country.

In the following claims and the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

S 0 H,\ChriaL\keep\speci\18697-01.doc 26/10/04

Claims

1. Apparatus for forming mineral fibres by internal centrifuging, comprising: spinner into which material to be fib .urized is introduced, the spinner being rotatable about an axis X 1 and includes a peripheral band having a plurality of holes through which material is ejected to form fibres; a high-temperature gas attenuating means for attenuating fibres ejected from the peripheral band; a pneumatic means, for channelling/adjusting the dimensions of the fibres; and a mechanical means comprising a cooled wall placed around the spinner in a location at least opposite to the peripheral band of the spinner, the cooled wall supplementing the channelling and adjustment of the dimensions of the fibres performed by the said pneumatic means.

2. Apparatus according to claim 1, in which the axis X 1 the spinner rotates about is a vertical axis.

3. Apparatus according to any one of the preceding claims, in which the high-temperature gas attenuating means is in the form of an annular burner.

4. Apparatus according to any one of the preceding 25 claims, in which the pneumatic means for channelling/ adjusting the dimensions of the fibres is in the form of a blowing ring.

5. Apparatus according to any one of the preceding to*% claims, in which the surface of the cooled wall facing the 30 spinner substantially comprises metal.

6. Apparatus according to claim 5, in which the surface of the cooled wall facing the spinner substantially comprises stainless steel.

7. Apparatus according to any one of the preceding claims, in which the cooled wall is concentric about the axis of the spinner and has an outer surface which faces Hi\ChriL\keep\speci\18697-Ol.doc 26/10/04 17 the spinner and is at least partially cylindrical or in the form of a truncated cone.

8. Apparatus according to claim 7, in which the cooled wall has a flared upper part. in which the cooled wall is at least partly in the form of a truncated cone inclined at an angle with respect to the axis X, of the spinner, of between 0 and 300 Apparatus according to claim 9, in which the angle a, with respect to the axis X 1 of the spinner is strictly positive and between 2 and 200.

11. Apparatus according to one of the preceding claims, in which the cooled wall is at least partly in the form of a truncated cone inclined at an angle a 2 2 with respect to the projection axis X 2 of the jets of gas emanating from the blowing ring of between 0 and 60, or 700

12. Apparatus according to claim 11, in which angle a 2 is equal to 0 or between 2 and 200, or 300.

13. Apparatus according to claim 11, in which angle a 2 is between 5 and 150.

14. Apparatus according to one of the preceding claims, in which the projection axis X 2 of the jets of gas emanating from the blowing ring makes an angle a 3 with the vertical which is 0 or differs from 0 by 300 or greater. 25 15. Apparatus according to one of the preceding claims, in which the height of the cooled wall, measured along a vertical axis, is greater than that of the peripheral band of the spinner, the distance measured vertically between the lower end of the said wall and the lowest row of holes 30 of the spinner being equal to at least half the height of the peripheral band.

16. Apparatus according to claim 15, in which the distance measured vertically between the lower end of the S-said wall and the lowest row of holes of the spinner being between half and twice the said height.

17. Apparatus according to one of the preceding claims, in which the cooled wall forms part of a mechanical device H.\ChrieL\keep\speci\18697-O.doc 26/10/04 18 having a cavity provided with a cooling system based on a circulation of fluid.

18. Apparatus according to claim 17, in which the cooling system based on a circulation of fluid is a device C; nf t11sm ri~LP +m

19. Apparatus according to one of the preceding claims, in which the configuration of the pneumatic means with respect to that of the cooled wall is such that the jets of gas emanating from the blowing ring have a direction of emission which converges on the cooled wall. Apparatus according to one of the preceding claims, in which the blowing ring comprises elements for generating individual divergent jets of gas which meet below the lowest row of holes of the peripheral band, the said ring especially consisting of a tubular ring pierced with holes to which nipples are fixed or of a series of nozzles.

21. Apparatus according to one of the preceding claims, in which the temperature of the attenuating gas emitted at the exit of the annular burner is at most 1600 0 C.

22. Apparatus according to claim 21, in which the temperature of the attenuating gas emitted at the exit of the annular burner is between 1350 and 1450 0 C.

23. Apparatus according to one of the preceding claims, in which an additional means is provided for channelling/adjusting the dimensions of the fibres, which structural means consists in making the size of the holes of the peripheral band vary, from the top down in the S: centrifuging position, by decreasing and then by 30 increasing over the height of the peripheral band.

24. Apparatus according to claim 23, in which the holes of the peripheral band are distributed in three, high, intermediate and low groups of rows having diameters dl, d 2 and d 3 which satisfy the following relationships: O dl d 3 0.2 mm, O d 3 d 2 di d 2 d 3 d 2 between 0.1 and 0.5 mm, H.\ChrisL\keep\epeci\18697-O1.doc 26/10/04 19 Apparatus according to claim 22, in which: di d 3 0.1 mm and/or, d 3 d 2 greater than 0.1 or 0.2 mm.

26. Process for forming mineral fibres by internal centrifuqing, combined A ith high-t mperature attenuation, comprising: pouring the material to be fiberized into a spinner which rotates about an axis X 1 ejecting the material from a peripheral band of the spinner, the peripheral band having a plurality of holes through which the material is ejected to form fibres; attenuating the ejected fibres by a high-temperature gas blast emitted by a high-temperature gas attenuating means; and channelling/dimensionally adjusting the fibres by a pneumatic means, wherein the channelling and the dimensional adjustment of the fibres is supplemented by at least a mechanical means forming a physical barrier to the propagation of fibres radially with respect to the axis X 1 of the spinner.

27. Process according to claim 26, in which the axis X 1 the spinner rotates about is a vertical axis.

28. Process according to claim 26 or 27, in which the pneumatic means is in the form of a blowing ring. 25 29. Process according to claim 26, 27 or 28 in which the high-temperature gas attenuating means in the form of an annular burner

30. Process according to any one of claims 26 to 29, in which the physical barrier is a mechanical element 30 providing a wall placed around the spinner opposite the peripheral band.

31. A process according to claim 30, in which the wall is cooled and mainly made of metal, at least on the surface.

32. Process according to any one of claims 26 to 31, in which the said wall is at least partially cylindrical or in the form of a truncated cone. H.\ChriaL\keep\speci\18697-01.doc 26/10/04 20

33. Process according to claim 32, in which the wall has a flared upper-part.

34. Process according to one of claims 26 to 33, in which the blow ring emits jets of gas which converge on the wall and/or at least partly hug it. Process according to one of claims 26 to 34, in which the blow ring emits jets of gas which are individualised, divergent and meet after the lowest row of holes of the spinner.

36. Process according to one of claims 26 to 35, in which gases emitted by the blowing ring converge on the peripheral band of the spinner.

37. Process according to one of claims 26 to 36, in which the attenuating gases are emitted at the exit of the annular burner at a temperature of at most 1600 0 C.

38. Process according to claim 37, in which the attenuating gases are emitted at the exit of the annular burner at a temperature between 1350 and 1450 0 C.

39. Process according to one of claims 26 to 38, in which most of the fibres ejected from the spinner strike the wall.

40. Application of the apparatus according to one of claims 1 to 25 or of the process according to one of claims 26 to 39 to the manufacture of mineral wood of 25 micronaire of between 3 and 8, under 5 grams.

41. Application of the apparatus according to one of claims 1 to 25 or of the process according to one of claims 26 to 39 to the manufacture of thermal and/or acoustic insulation material having a density greater than 40 kg/m 3

42. Application according to claim 41, in which the acoustic insulation material is the crepe type.

43. Thermal or acoustic insulation products having a density of at least 40 kg/m 3 which are obtained from mineral wool obtained with the apparatus according to one of claims 1 to 25 or according to the process in accordance with one of claims 26 to 39 and then creped. H.\ChrisL\keep\speci\18697-O .doc 26/10/04 21

44. Thermal or acoustic insulation products having a density between 40 and 160 kg/m 3 obtained from mineral wood obtained with the apparatus according to one of claims 1 to 25 or according to the process of claims 26 to 39 and then creped. Thermal or acoustic insulation products according to claims 43 or 44, having a tear strength of approximately 20 kPa and a comprehensive strength of approximately 60 kPa for a thickness of approximately mm, a binder content of approximately 6% and a density of kg/m 3

46. Apparatus for forming mineral fibres by internal centrifuging substantially as herein described with reference to the accompanying drawings.

47. Process for forming mineral fibres by internal centrifuging, combined with high-temperature gas attenuation substantially as herein described with reference to the accompanying drawings.

48. Thermal or acoustic insulation products formed using the apparatus or process substantially as herein described with reference to the accompanying drawings. Dated this 26th day of October 2004 SAINT-GOBAIN ISOVER 25 By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia go o H,\ChriaL\keep\8peci\18697-01.doc 26110104