US3303009A - Mineral wool-producing system and method of producing mineral wool - Google Patents

Description

1967 G. SAGEN ETAL 3,303,009

MINERAL WOOLPRODUCING SYSTEM AND METHOD OF PRODUCING MINERAL WOOL Filed Sept. 10, 1965 \NVENTOR Kane BY w

ATTORNEY United States Patent 3,303,009 MINERAL WOOL-PRODUCING SYSTEM AND METHOD OF PRODUCING MINERAL WOOL Gunnar Sagen, Copenhagen, and Karl Ejvind Haulund Christensen, Roskilde, Denmark, assignors to 1/8 Kahler & (10., Hedehusene, Denmark, a Danish firm Filed Sept. 10, 1963, Ser. No. 307,914 6 Claims (Cl. 658) The present invention relates to a mineral wool-producing system in which a melt of mineral material, preferably a melt of slag or rock is ejected from the peripheral surface of at least one rotor constituting a part of a rotor system comprising at least two rotors of which at least one receives the melt as a liquid stream which may be poured on to the rotor in question directly from a melting furnace, for instance a cupola and of which at least one rotor exclusively receives melt that has been ejected thereto from one or more other rotors.

In its simplest form a system of this kind operates by melting a mixture of minerals such as slag and rock in a suitable furnace, for instance a cupola, pouring the melt into a drain or chute from which the melt is applied to the peripheral surface of a rotor by gravity with the linear velocity determined by inter alia the viscosity of the melt and the distance between the chute and the rotor. From the rotor receiving the melt, most of the melt received is ejected with greater velocity than that with which it was received and in such direction that it is received by the peripheral surface of another rotor, generally one with faster rotation, upon which it is distributed. From both rotors-although only sparsely from the first rotor--the melt is ejected partially in the form of fibres which are then carried away from the system of rotors by a current of gaseous medium introduced from behind the rotors and sedimented by the gaseous carrier being removed by being drawn through an advancing perforated support such as a band or wire gauze, on the surface of which the fibres are retained and form a layer of wool.

The yield and fineness of the fibres obtained from a rotor is, however, determined partially by the speed with which the rotor rotates, partially by the degree to which it has been achieved to accelerate the layer of melt present on the rotor up to the peripheral velocity of the rotor prior to its ejection thereform. If the linear velocity at which the melt is applied is too small it will mash or smear insufiiciently on the rotor surface, and the thickness of the layer thereby formed will accordingly be too great which results in that the greater part of the melt is ejected prior to having obtained the peripheral velocity of the rotor. ever, sufiiciently to obtain the peripheral velocity of the rotor before being ejected, and for this part of the melt the said velocity determines the length and thickness of the fibres.

In this simple system of two rotors, the first rotor may be considered as the melt application device for the second rotor. It is not intended that the first rotor should form fibres because the relatively small velocity of this rotor causes the fibres to be too coarse. On the other hand the functioning of the first rotor as application device is also far from ideal. In spite of the low velocity of the melt on application there is a certain adhesion of the melt to the rotor which, although it is weak, causes two inconveniences. First it causes the formation of coarse fibres, and secondly it causes the direction in which the cascade of melt delivered from this rotor is ejected is not sufiiciently distinct. On the contrary, there is a tendency against the solidified drops to be ejected with or without adherent fibres along the whole peripheral surface. In the same system the second rotor may be considered as the spinning device. However, the linear Another part of the melt adheres, howvelocity of the melt that can be obtained by using a single rotor for the application device is too small to secure a complete smearing or mashing on the peripheral surface of the second rotor. Accordingly, the melt transferred to this rotor will only partially obtain the peripheral velocity of the rotor and consequently a substantial part of the melt will be used up in forming coarse fibres or get lost in the form of greater and smaller drops leaving the rotor as a more or less indistinct cascade.

It follows from what has been said above, that when using three or four rotors it is possible to obtain better yields of mineral wool whenthe rotors are placed relative to each other in such a way that the part of .the melt ejected in the form of a more or less distinct cascade of drops adjacent to the place, where the melt has impinged on the rotor in question, is received by a subsequent rotor. Each previous rotor may in this case be considered the application device of a subsequent rotor and functions simultaneously as a spinning device. The linear velocity with which the melt is applied is thus increasingly greater and an increasingly greater part adheres to the receiving rotor and is delivered as increasingly fine fibres. A disadvantage in systems of this kind where more than two rotors are used is that fibres ejected from parts of the peripheral surfaces adjacent to each other tend to collide and may give rise to damaging of the individual fibres and to the formation of hard felted fibre nuclei the presence of which in the wool produces a non-uniform specific Weight of the product.

There is, however, a fiberizing system of the kind in quest-ion, by which a particularly homogeneous 'wool can be obtained, although with comparatively small yieldsby using only two rotors.

In this rotor system the two rotors are placed at a smal horizontal mutual distance and driven with opposite direction of rotation. The incoming stream of melt is caused to impinge on the peripheral surface of one of the rotors at a point a little above the point, where the distance is minimum. Consequently, most of theincoming melt is repelled at increased velocity in such direction that is can be received from the other rotor. Part of the melt thus received is again repelled to the first rotor, another part adhering to rotor 2 and being ejected as mineral wool from the rest of the peripheral surface thereof. The melt thus repelled from the second rotor adheres to the first rotor and is ejected therefrom. To a certain degree repeated injections and rejections will probably occur within the interstice between the two rotors where they are closest to each other, which contributes to the gradual increase in velocity of the melt retained on the cylindric surfaces. A considerable part of the melt, however, does not succeed in having the opportunity to partake in the ejections and rejections and, consequently, does not adhere to any of the rotors. Such melt escapes in the form of a more or less compact or concentrated jet through the interstice between the rotors. This part of the melt solidifies in the air and is lost. In this tworotor-system the ejection of fine fibres is on the whole finished before the melt has passed through a whole rotation so that, consequently, collision of ejected fibres will hardly occur. Accordingly, the formation of nuclei is avoided and the homogeneity is greater than the case of systems comprising more than two rotors, whereas the yield and the rate of production is generally small.

It has been found according to the present invention that improved results both with respect to the yield of fibres, productivity and homogeneity of the fibres as a result of the formation of tight nuclei being avoided can be obtained so as to obtain wool with even distribution of the weight per volume within the fibrous product. This is achieved by a system of the kind described above in which mineral wool is produced by ejection of a melt from the peripheral surface of at least one rotor forming part of a system of at least two rotors of which at least one receives melt as an incoming stream and at least one exclusively receives melt that has been ejected from other rotors, the feature characterizing the present invention being that a slip-producing agent is applied to the first named rotor or rotors prior to the application of the melt thereon. The term, slip-producing (or slip-increasing) agent is used here and in the following to designate an agent which substantially prevents or greatly reduces the adhesion of the melt to the rotor receiving it which would occur if such agent was not present. For brevity the term slip-producing will generally be used meaning an agent producing a slip which would not be present if the agent was not applied.

By applying the slip-producing agent it is obtained that the incoming melt when reaching the first rotor is rapidly and totally rejected at increased velocity in the form of a directed cascade of drops. Thus, the melt. does notfollow the rotation of the first rotor to any substantial degree and, accordingly, this rotor will produce no wool and cannot give rise to the formation of small solidified drops, coarse fibres or fibre collisions.

As a slip agent there can be used according to the present invention a high-boiling oil, such as steam cylinder oil. This oil will partly evaporate, partly it may char producing in that case a thin layer of carbon upon the first rotor. Carbon produced .in that way acts -as slip agent itself, and furthermore by degree it burns under the influence of the heat of the melt. Consequently, it does not tend to accumulate and form scales. Any tendency in this direction can moreover be controlled by using oil having the necessary resistance against carbonization and by controlling .the amountof oil, so that all the oil has time to evaporate d-urinig a single rotation of the rotor. The circumstance that the carbonization products which may be formed act themeselves as slip-producing agents invite the use of a current of finely distributed carbon as slip-producing agent. carbon may be used in suspension in a suitable fluid, such as oil or water.

In an embodiment of the invention which is illustrated in the drawing which shows diagrammatically seen from the side, a system which comprises four rotors the two upper of which receive slip-producing agent (not shown) and producing no wool and the two lower of which receive no such agent and produce wool (not shown), the above described system is used. I The melt rejected from the first rotor is received'by another rotor placed close to the first one, and having the same functioning and preferably opposite direct-ion of rotation. From this second rotor it is transferredto the rotor or the rotors the function of which is to produce the wool. The second rotor receives also slip-producin-g agent either directly applied simultaneously with the cascade from the first rotor, or slipproducing agent still present cascade of melt received from the first rotor. Accordingly, it rapidly rejects the melt received at further increased velocity in the form of a directed cascade of drops. In all circumstances the amount of slip-producing agent applied must be controlled so that no slip-producing agent leaves the second rotor in active state in order to secure that fiberization can occur on the subsequent rotor or rotors.

The fiberization is hereafter carried out in known way, the ejected cascade being received by a rotor from the surface of which fibres are ejected in normal way. This rotor is capable of yielding a high and homogeneous production of fibres because the melt received has a great linear velocity and obtains by smearing a high degree of contact with the peripheral surface. In order to further increase the production capacity a fourth rotor may be placed adajacent to the third one at a small distance therefrom, in order to receive rejected drops of Such finely distributed.

melt therefrom and effect the fiberization thereof. This system of four rotors is particularly advantageous when using the present invention because the precise receipt of the melt on the third rotor makes it possible to place the point where this melt is received rather close to the fourth rotor thereby utilizing practically the whole of the peripheral surface of the third rotor for fiberization and avoiding the risk of fibre collision.

Between the set of rotors consisting of the two first rotors and the set of rotors consisting of the two latter rotors the distance may be relatively great for instance exceed 8 centimetres in each point of the peripheral surface of the rotors. The latter set of rotors is thereby caused to work in a similar way to the rotors of a tworotor-system in so far as there will be only a very slight possibility of collision between fibres ejected and between the fibres and the incoming melt or solidified drops, since in the interstice between the four rotors practically no other material occurs than the cascades of melt transferred from the first set of rotors to the second one and transfers between the two rotors of the second set. This is due to the fact that practically the whole amount of fibres produced by the third and fourth rotors is ejected before each of the rotors has made a single rotation and to the fact that the first and second rotors do .not produce fibres but only the said cascades. Both rotors of the second set furthermore function with greater effectivity being capable of forming finer fibres and less solidified drops, socalled beads, because the linear velocity with which the melt is applied to the first of these rotors is greater than in a two-rotor-system.

Thus, according to the present invention a particularly advantageous embodiment is characterized in that the melt from the second rotor is directed down against two rotors with opposite direction of rotation placed below the first and having downwardly directed motion of the peripheral surface .parts turning towards each other, so that it reaches at least one of the rotor surfaces at a point of the peripheral surface which is close to the point Where the two lower rotors are closest to each other.

The systems comprised by the invention are, however, not bound to the embodiment described above in detail, but comprise any system in which a slip-producing agent is applied to a rotor receiving the melt as an incoming fiuid'stream, and in which there is furthermore at least one rotor to which the melt rejected from the first one is transferred and .which does not receive slip-producing agent, but functions as a fiberizing rotor. Thus incoming melt in the form of a stream of fluid may be applied to more than one rotor, for instance to two rotors, both of which receive slip-producing agent and both of which being in a position to provide one or more fiberizing rotors with rejected material, or in a position to cooperate in applying melt to one or more subsequent rotors functioning mainly as fibre-forming rotors. Furthermore, there may be more than two rotors placed in cascading sequence, the melt being transferred from one of such rotors to the other at a constantly increasing velocity, one or more of which receive slip-producing agent, preferably in gradually reduced amount. Slip-producing agent may be applied as a coherent stream or, advantageously, in atomized form by means of suitable jets.

We claim:

1. Mineral wool producing rotor system consisting of at least one rotor having a peripheral surface, means for supplying a stream of molten mineral melt to said peripheral surface and at least one further rotor receiving mineral melt ejected from another rotor and rotating at such velocity that it produces a fine wool, in which system at least one rotor has means for applying to its peripheral surface, prior to the application of the mineral melt, an amount of a slip-producing agent, and at least one other rotor which receives mineral melt ejected from another one as above set fort-h, and rotates at a speed at 5 which fine wool can be produced, has no slip-producing agent applied thereto.

2. Mineral wool producing rotor system according to claim 1 in which the first rotor transfers melt to another rotor placed adjacent thereto and means to supply said last-named rotor with slip-producing agent and a third rotor receives the melt from the second rotor and works without slip-producing agent.

3. Mineral wool producing rotor system according to claim 1 in which the melt transferred to a rotor Working without slip-producing agent from a rotor working with means for supplying slip-producing agent is partially transferred to a further rotor working without slip-producing agent.

'4. Method of producing mineral wool by acceleration of movement of mineral wool on revolving surfaces and transferring melt from one rotating surface to another in which the melt is first applied from a liquid stream to revolving surfaces wetted by a slip-producing agent which reduces adhesion of the melt to the surfaces and is repelled from said surfaces to rotating surfaces to which no slip-producing agent is applied and from which it is ejected in the form of fine wool.

5. The method of claim 4 in which the slip-producing agent is a car-bonization agent.

'6. The method of claim 4 in which the slip-producing agent is a high boiling oil.

References Cited by the Examiner UNITED STATES PATENTS 2,520,169 8/1950 Powell 658 FOREIGN PATENTS 149,397 2/ 1952, Australia.

DONALL H. SYLVESTER, Primary Examiner.

R. L. LINDSAY, Assistant Examiner.

Claims (2)

1. MINERAL WOOL PRODUCING ROTOR SYSTEM CONSISTING OF AT LEAST ONE ROTOR HAVING A PERIPHERAL SURFACE, MEANS FOR SUPPLYING A STREAM OF MOLTEN MINERAL MELT TO SAID PERIPHERAL SURFACE AND AT LEST ONE FURTHER ROTOR RECEIVING MINERAL MELT EJECTED FROM ANOTHER ROTOR AND ROTATING AT SUCH VELOCITY THAT IT PRODUCES A FINE WOOL, IN WHICH SYSTEM AT LEST ONE ROTOR HAS MEANS FOR APPLYING TO ITS PERIPHERAL SURFACE, PRIOR TO THE APPLICATION OF THE MINERAL MELT, AN AMOUNT OF A SLIP-PRODUCING AGENT, AND AT LEAST ONE OTHER ROTOR WHICH RECEIVES MINERAL MELT EJECTED FROM ANOTHER ONE AS ABOVE SET FORTH, AND ROTATES AT A SPEED AT WHICH FINE WOOL CAN BE PRODUCED, HS NO SLIP-PRODUCING AGENT APPLIED THERETO.

4. METHOD OF PRODUCING MINERAL WOOL BY ACCELERATION OF MOVEMENT OF MINERAL WOOL ON REVOLVING SURFACES AND TRANSFERRING MELT FROM ONE ROTATING SURFACE TO ANOTHER IN WHICH THE MELT IS FIRST APPLIED FROM A LIQUID STREAM TO REVOLVING SURFACES WETTED BY A SLIP-PRODUCING AGENT WHICH REDUCES ADHESION OF THE MELT TO THE SURFACES AND IS REPELLED FROM SAID SURFACES TO ROTATING SURFACES TO WHICH NO SLIP-PRODUCING AGENT IS APPLIED AND FROM WHICH IT IS EJECTED IN THE FORM OF FINE WOOL.

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