US2646593A - Method and apparatus for fiberizing molten material - Google Patents

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July 28, 1953 R. M. DOWNEY METHOD AND APPARATUS FOR FIBERIZING MOLTEN MATERIAL 2 Sheets-Sheet 1 Filed Nov. 4, 1950 y 28, 1953 R. M. DOWNEY 2,646,593

METHOD AND APPARATUS FOR FIBERIZING MOLTEN MATERIAL Filed Nov. 4, 1950 2 Sheets-Sheet 2 wad/2Q %%M, wzwwa Z.

Patented July 28, 1953 METHOD AND APPARATUS FOR FIBER-IZING MOLTEN MATERIAL Richard M. Downey, North Judson, Ind., assignor to United' States Gypsum Company, Chicago, 111., a corporation of Illinois Application November 4, 1950, Serial No. 194,180 In Canada May 1, 1950 The presentinvention relates to an improved method and apparatus for fiberizing molten material.

The invention concerns itself primarily with an improved method for converting molten vitreous material such as slag, glass, or fusible rock, into filamentous form or fibers such as are generally known as slag wool, glass wool, or mineral wool, and the like.

The production of mineral'fibers such as slag wool, glass wool, rock wool, or mineral wool, has been the subject matter of many patents and processes, and a large variety ofv difierent kinds of apparatus has been devised to accomplish the fiiberization of such molten vitreous materials.

In the past this has almost always been done by directing a powerful blast of a gas, usually steam, either superheated or not, against a stream of molten slag orlsimilar material with the result that the stream would become disintegrated into individual droplets which, under the momentum imparted thereto by the. steam blast and due to the resistance ofieredeto their progress by the air through which they were propelled, would elongate themselves into more or less fine fibers. If this were done with insuflicient speed the fibers were rather coarse and short, and usuallycarried on their far end a small globule which almost invariably detached itself and formed what is known as shot. If the viscosity of the molten material was high enough and the speed of the gaseous distintegrating. blast great enough the fiber would befairly long and there would be. relatively little shot. disintegrate a stream of downwardly flowing slag required a very powerful ,blastof gas, and almost invariably that part of the stream which was iurthest away from the point of impingement of theblast would not be properly fiberized.

Attempts have been made to overcome thisdifficultyby subdividing molten material such as slag into as many fine streams as possible prior to havingit encounterthe disintegrating blast. This, however, almost invariably led to. a con,- siderable cooling orthe material whereby its viscositywas very greatly increased, withthe result that the fibers were thick and generally quite unusable; Another method which has found some favor is to attempt to impart to molten slag and the like sufiicient velocity by mechanical means instead of byagaseous blast, For instance, it has been proposed to hurl molten slag and similar vitreous materialwfrom the. pe riphery ofarapidly rotating disclwith aspeed However, thoroughly to 20 Claims. (Cl. 18-25) 2 l high enough to cause the desired fiiberization of the peripherally discharged droplets. V

However, this requires rather high speeds.- For example, with a disc 11 inches in diameter and with slag at the usual temperature at which it discharges from a melting cupola, it was found that it required a peripheral velocity of around 12,000 to 14,000 feet per second, which for a disc of this size meant a rate of revolution of around 4500 to 5000 revolutions per minute.

It will be readily appreciated that such speeds are accompanied by considerable danger of the explosion of the disc, and, moreover, require considerable application of power to attain the desired speed.

A further alternative has been to pour the melted slag upon a very rapidly rotating cylinder, but there the length of the contact between the molten material and the surface of the cylinder was so short that enormous speeds were necese sary to obtain fiberization.

The presentinvention solves this problem in an exemplary way by providing an apparatus and method for the production of fine silky mineral fibers from either slag, glass, meltable rock and the like, by a method which involvesboth preliminary centrifugaldistribution of the mole ten material and the propulsion of the material by means of a gaseous blast.v

It is therefore one of the objects of the present invention to provide a method and apparatus for the efficient conversion of melted slag, glass, melted rock, and the like into mineral fibers, and the collection thereof into the form of an adherent sheet or bat. 1

It is a further object of thepresent inventionto disintegrate molten vitreous material by centrifugal means into a plurality of very closely adjacent individual tangentially discharged molten streams which encounter a transverse strong gaseous fiberizing blast which changes their direction and converts them into fibers. I It is afurther object of the invention to effect. a separationbetween fibers, shot, and slugs of metal, such as iron, which latter occasionally accompanies slag, such asmay be used as the raw material for carrying out the process features of the present invention. a. x i It is also an object of the present invention to provide an apparatus, andlmeans associated therewith, for fiberizing molten material and to efiectthe above-mentioned objects. In order that the present invention may be, more thoroughly understood, reference is directed to the concurrently filedndrawings, in which; l

Figure 1 is a diagrammatic representation of the fiberizing apparatus shown in conjunction with a suitable collection and bat-forming device with which it i associated, the device being shown in vertical elevation and partly in vertical section;

Fig. 2 is a vertical cross section through the apparatus shown in Fig. 1 taken along the line 2--2 thereof;

Fig. 3 is a side view, partly in vertical section, of the more essential parts of the apparatus as shown in Fig. 1, but on a considerably larger scale;

Fig. 4 is a cross section along the line 4 4 of Fig. 3; and

Fig. 5 is a similar cross section, facing in the opposite direction, and taken along the line 5-5 of Fig. 3.

The apparatus consists of a mineral wool col lecting chamber ID, the bottom of which is closed by means of a conveyor H which operates, for example, over the pulleys l2 and l3, and upon which there gradually accumulates a more or less coherent mat of mineral wool fibers M. A suit able sealing and confining roller serves to prevent the escape of the mineral wool fibers from the chamber ill and also slightly to compress the mat l4 and to give it its desired. dimensions. The that thus produced. is further conveyed on a second conveyor it to point of use, with which the present invention is not particularly concerned.

The blow chamber ID has an inlet or throat I? defined by baffles 6| in front of which there is located the main fiber producing instrumentality 1 8, in the form of a hollow rimmed rotor.- There are also provided outwardly flaring walls l9 and baflies 20, which serve primarily for the protection of the operators, but which are readily removable for inspection and repair of the fiberizing apparatus l8.

Referring now particularly'to Figs. 3 through 5, it will be seen that there is provided a rotor i8 which may conveniently take the form of a 1101-- low cylinder having an internal wall or surface 2|, which may be parallel with the axis of rotation or may be inclined thereto so as to diverge outward-1y. This rotor I8 is keyed or otherwise secured to a horizontally disposed shaft 22.

Suitable bearings 24 and 25 serve to support the shaft, there also being provided a pulley 25, keyed to the shaft, over which runs a suitable driving means, such for example as the belt 21.

A suitable conducting chute 28 serves to direct a relatively thin stream 29 015 molten glass,- slag or the like to a point so located that the stream 29 will be directed to the inner surface ll of the rotor t8 without touching the shaft 22, the rotor being rapidly rotated at about 760 to 1500" revolutions per: minute, 1

As: a result of the dropping of the stream 29' ct molten slag on to the surface 21, there will be immediately built up annulus 3'0 of molten slag. This annulus gradually works its way over the edge 3i of the rotor 18, to be discharged from the periphery thereof under the centrifugal force as an annular mass of small closely adjacent streams 32 of melted slag.

Due to the rapid rotation of the rotor i3 and or course of the annulus 3'0 which partakes of this motion, the visual appearance of this massof material is that of an armul'ar relatively ring or aura Photographs taker-l at a speed of 7 m; of a second have proven that this is an illusion due to persistence of vision, the actual fact being that there are formed hundreds of small individual streams 32 of molten slag which are projected along straight lines which are tangents of the periphery of the rotor.

It will be self-evident from consideration of the physics involved that each particle of the melted slag, as it leaves the circular edge 3| of the rotor l8, will tend to travel in a straight line tangent to the circle that defines the said circular edge 3!. The pictures have proven this. The appearance is roughly diagrammatically illustrated in Fig. 5, each little stream (there are actually over 700 in a disc 1 foot in diameter) being collectively designated by the reference numetal 32. This is the condition with the stream shut off.

It has been definitely ascertained, so far as the discharge of the molten material from the edge 3| of the rotor [8 is concerned, that the speed is insufficient to fiberize the slag. What appears to happen is that the slag is thus subdivided into an extremely large number of individual little streams 32 which are in an ideal condition to have imparted to them the necessary momentum to convert them into fibers. For the purpose of doing this there is provided a blasting ring or nozzle 33 through which a suitable gas, for example steam, may be passed from the supply line 34. This is arranged concentric with the rotor and has a slightly larger radius than the iatter.

The steam issues from a number of individual small openings 33a which can best be seen in Fig.- 4 in which, however, only a much smaller number than those actually used is shown.

The steam, which passes out of the annular nozzle 33 under a force of from '70 to pounds per square inch,- strikes the small streams 32 of the thus subdivided slag at a point about 1 to 1 inches from the edge 3t of the rotor l8, and at a point about from A; of an inch to 1 from the outlet of the openings 33a.

By intercepting the outwardly traveling streams 32 with the annular steam blast, these streams are diverted into a new path, forming horizontal-1y impelled potential fiber-forming particles 35,

which, by reason of the high velocity imparted thereto, soon become attenuated into individuat fibers 36 that fail down in the blow chamber HI, and collect in the form of the already mentioned. mat l4.

The product produced by the apparatus and method of the present invention shows a signiricantly higher fiber content than is exhibited by the product of prior art processes. Mineral wooi has been made which contains as high as 70 fiber by weight, and, any event, the apparatus and method are consistently capable of producing wool containing at least 50% of fiber by weight. The economic advantages accruing to fiber yields of this order compared to the 30% yield of the prior art will immediately be apparent.

An additional advantage inherent in the pres-- ent invention is the possibility presented of e'f footing a partial separation or shot and user av the time the fiber is formed. material whose kinetic energy is sumcienuv high to allow it to penetrate the force vector of the steam blast continues in a direction of travel only slightly altered from its original path, whereby a divergence is effectedbetween the paths of shot and the path taken by the fiber. Thus a separation may be efiected. One method of sepa-ration is illustrated in Fig. 1-, where baiile 61 is erected at the entrance to a conventional collecting chameber; The ballie (H is scarrangeu as to form an opening I! into the collecting chamber.

The fiber 36 passes through opening I! into the col- :lecting chamber while shot or bead 41 are thrown against baflie 6|, and thus do not find their way into the fibrous product. The bead 41 may be .remelted if desired. The arrangement of open ing I! and baflle 6| also serves to separate iron which frequently is formed in small amounts by reduction in the melting of slag, rock, etc. This separation is also highly desirable, as iron and its oxides tend to cause dis-coloration of mineral wool products. Iron particles 50 being so removed from the product are shown in Fig. 1.

For suitable permanence of equipment it is desirable to use heat resistant materials, as molten slag ordinarily flows from the cupola at a temperature of 27003000 F. Stainless steel is quite desirable as a material of construction, but it is also possible to cool the shaft and rotor with a liquid or gaseous coolant. Water is-quite suitable.

Steam pressures and steam volumes required are generally in line with conventional practice in these respects. Steam pressures required are on the order of 60-100 pounds per square inch, and the weight of steam should be at least slightly in excess of the weight of slag.

One of the outstanding advantages of the present apparatus and method lies in the production of the vertically disposed annulus of molten maa terial which serves as a more or less constant source of supply for the tangentially peripherally discharged streamlets 32. If a disc were used instead, the rate of production would be immensely slower as only a very thin stream of slag can be discharged onto a disc, while the present comprising a hollow cylindrical slag-distributor open at one end and closed atthe other and rapidly rotatable about a horizontal axis, means for delivering molten material to the interior surface of said distributor from its open end, and means for directing an annular blast of a gas coaxially with said axis and in a direction from the open toward the closed end of said distributor against molten material discharged from the edge of said distributor under the centrifugal force developed by its rotation.

I 2.. Apparatus for fiberizing molten material comprising a hollow cylindrical rotor open at one end and closed at the other, means for rotating said rotor on a horizontal axis, means for delivering molten material to the internal wall of said rotor from its open end, and means for directing an annular blast of gas in a direction from the open toward the closed endof said rotor against molten material peripherally discharged from the edge of said rotor under the centrifugal force developed by its rotation.

3. Method of making vitreous fibers which comprises melting a vitreous material, forming a relatively thin stream thereof into a rapidly rotating substantially vertically disposed annulus from which latter outwardly moving groups of thin streams of said material extend in a vertical plane, and forcing against the sides of said streams a horizontally moving annular blast of a rapidly moving gas with force sufiicient to change the direction of movement of said streams and propelling the same with suificient momentum to draw them into filaments prior to their solidification.

4. Method of making slag wool which comprises forming molten slag into thin streams of molten slag moving outwardly in a substantially vertical plane and attenuating said streams into fibers by directing a substantially annular horizontally moving blast of a rapidly moving gas against the sides of said streams of molten slag.

5. Method of converting molten mineral material into fibers which comprises discharging a stream of such molten material upon a, rapidly rotating annular surface rotating about a hori zontal axis to eventuate a confined rotating annulus of said molten material rotating about a substantially horizontal axis, moving continuously the edge of said annulus to the end of its confining surface to discharge therefrom centrifugally into an outwardly moving plurality of finely divided streams, and blasting said streams into mineral wool by a blast of gas intercepting the path of travel of said streams to provide a horizontally moving mass of mineral wool.

6. Apparatus for the production of mineral wool fibers which comprises a hollow cylindrical rotor open at one end and closed at the other and mounted for rotation about a horizontal axis, means for rotating said rotor, means for delivering a stream of molten mineral-wool-forming material onto the interior cylindrical surface of sad' rotor from the open end thereof, and an annular gas-blowing nozzlepositioned to discharge a gaseous stream inthe form of an annular blast concentric with the axis of rotationv of said rotor against materialtangentially thrown off the end periphery of said rotor, said blast being directed from the open toward the closed 7 end i of said rotor.

} 7. Method for the production of mineral wool fibers which comprises forming molten mineralwool-forming material into an annulus whirling in a vertical plane abouta horizontal axis, peripherally tangentially discharging from said annulus a large number of individual fine streams of said inolten material, and abruptly changing the direction of travel of said streams by applying transversely thereto a strong blast of a car? rier gas, whereby to convert said streams into mineral wool fibers moving in a generally horizontal direction. v 8. Apparatus for fiberizing molten material which comprises a distributor bowl rapidly rotatable about a substantially horizontal axis, means for delivering molten material onto the interior side wall of said bowl from a source located beyond the open end of said bowl, and means for directing an annular blast of a gas in a direction from the open toward the closed end of said bowl coaxially with said axis against molten material discharged from the edge of, said distributor bowl under the centrifugal force developed by its rotation.

9. Apparatus-for making mineral wool and the like which comprises the combination of a collecting chamber having a receiving openingin a vertical wall thereof and a mineral fiber producing means positioned in front of and spaced from said opening, said means comprising a sooroe of molten miiiial iiiool remiss iiiatiial,

a rotor mounted for rotation about a horizontal axis aligned with substantially the center or said opening, said rotor lieifig iii the form of oyIindrial bowl having its closed one toward said orinin'g, means for condiiotin'g a stream oi said iiioltii material onto the interior Wall of said Bowlfrom a loeiis oiitsid and beyond the ooen end of said bowl, whereby said stream as the resuit or the rotation or said oowi will form an aniiiilos ormoiten material rotating about a substafi-tialli horizontal axis and from the or'ipnery of which streams or i'nltii material will be tangentially oisonarg'eo; and an afiiiiiliii gasblov'vifig' nozzle of a diameter greater than that of said bowl positioned so as to direct antiwar 'iiiOV'e' them ooaxiaiiy with the aiis' of rotation or in the term 61 tan entially outwardly tIQL-Vlifig molten-streams or mate ial, and an annular mowing nozzle or a diameter greater than that or said bowl positioned a short distance beyond the ooen end or said bowl and having its discharge openin directed toward said bowl so as to blow ooaxiany was said shaft upon the said streams to change their diitioi'i and transform them iiito fibers and dairy the latter to a locus beyond the olosed end or said bowl.

11. A device for convertin molten material into fi-berscomprising a shaft mounted for roration of a horizontal axis, a spmmog bowl losated on one end of said shaft one havin its open end directed toward the other end of said shaft, means for conducting molten material from apoint to one side of said shaft and from a source beyond the o en end of said onto the inside wail thereof, means for otating said shaft, and an annular blowing nozzle having a larger diani= eter than that'- of said bowl surrounding said 12. Apparatus for making mineral wool which oomprises a horizontal rotatable shaft, 9,- eeri trifugal distributor mounted at one end thereof and being in the form of a oylindrioai oil}? open at o'iie end with its sides extending ioaokwardly toward the other end of said shaft; a trough for molten material alongside or said shaft and extending into said cup so as to direct astream of moiten material by gravitation onto the ilifil Wall ofsaidcup, and anaririii-l'ar' blowing oozz'ie oi a diameter greater than that of said outi sin rooridmg said shaft and having its eas -discharge opening oireoted toward the open end of said cap so as to inter-dept streams of materials tan gentially discharged from the rim of saido'iip and to blow them in a direction parallel with said shaft and beyond the closed end of said cup toward a point of collection.

13. Apparatus for making mineral woo: which oomprises a ooil'eotior'i chamber having a receiv ingtoideriirigand a mineral Woo! fiber-producing groans iiositio'ned in rroot oi saio'ooniiigg said fiber-producing means ciiijifising a jyli'lidiial rotor having an open one one a oioseo end; the latter racing toward said reoeiviog' opening,

for rotatin said rotor means ror gr vitatioiiany" orooiiine molten material onto one iii sioe won or Said rotor from the open iid thereof, and an annular blowing nozzle bositioried in from of the open end of said rotor having its discharge orifioes direoteo toward said it'ieiii mg oiiomng.

14. Method of making iiiiiiral woora-hd the like wnioh oomprises gravitationau'y flowing a stream of molten mineral material onto the intenor side walls or" a hollow cyiiodriooi oistrilom tor having one o en eiid and rotating on a horizontal axis to evefitiiate a comma rotating arrnulus of said molten materiai rotating on a non;- zontal axis and from the periphery of which streams of said iiiaterial are tangeritiahy discharged from the rim of the said open end, and horizontally blasting said streams into doors by a gaseo s blast originating from an anoola'r nor- 21o positioned beyond the said open ended o' iiirdrioal distributor. 4

15. The method. or separ ting'siugs and beads from newly formed minera1 woo1 comprising reducin suitabie mineral wool forming materials to a liquid omit, depositing said roit onto the inside su face of a oup=snapeo rotor rotatable ab ut a horizontal axis, rotating said r tor at sufficient speed to forth an annulus or liquid men; on the inside surface of said rotor, allowing said spinning iiielt to esoaoe at the rim of said rotor in the form or streams, intercepting said streams with a gaseous fiiiid projected with sufiicieot velocity to attenuate roost of said streams into fibers, leaving some of the melt in the form or outwardl traveling slugs and oeaos, ooiw'eyin said fibers by means of the residual velocity or said gaseous fiiiid to an openin of restric'zte'd size in a fiber ooneotio chamber, and screening the unfiberized slugs and beads from entry into said' collecting chamber.

is. in the method of claim the sreo of mm oartmgceritrifog i force to me firelt as it ieavs the rim of said rotor, fiherizing a major portion of said centrifugally energized melt by means of a blast of gaseous fluid of desired velooity interoepting said melt, qonveying the thus fiberi'z 'cl melt in the form of fibers to a restriotea opening in a collecting chamber, and screening the em fib'erized iiielt from entry into said colieoting chamber.

171 The method of removing sings, iron and tinfibeiiz'ed ,pe iiets of melt used in producing mineral wool fiber comprising the steps or merit: i'og' suitable; raw materials, placing Said melt on the inside surface of a bowl rapidly rotating a horizontal axis, forming an annulus of melt within said bowl, allowing the said annulus to slough off along tire-rimr said bowl in the forgo of streaiyrrs oonsisting' or molten material said material being ener ized oentfifiigally before partition from said annulus, interceptin the tons energized streai'r'is with a transverse cor: rent of gas'to fibe'rize' the majority of said streams, conveying the resoiting fibers to a restricted opening in a correctin chamber, and separately catch: ing th finfibrized p-eiiets and slugs.

18. Method of centrifugal separation of newly formed mineral wooi fibersfi-oai sides and beads associated therewith in the proces or roriooig said liters wiiioii oorrijoriss so ols ina molten minerai wooi formiog'material to the interior Wail surface of a cup-shaped rotor rotatable about a horizontal axis, rotating said rotor at a speed sufiicient to eventuate a confined annulus of said material therein, permitting said material to discharge from the rim of said rotor, intercepting said discharged material with a transverse annular gaseous blast, conveying the thus formed fibers into a collecting chamber through a constricted opening therein, permitting the slugs and beads, the portion of said material which is not converted into fibers by said blast, to continue their outward travel resulting from the impetus of the centrifugal energy imparted thereto, and collecting said slugs and beads separately from said fibers.

19. Method of fiberizing molten material comprising flowing molten fiberizable material into a hollow rotary distributor having one open and one closed end, rotating said distributor about a horizontal axis to effect tangential discharge of streams of said molten material from the rim of said open end and directing an annular blast of a gas substantially coaxially with the axis of rotation of said distributor from a position in front of said open end and blowing toward said closed end thereof to fiberize said streams.

20. Method of fiberizing molten material which comprises rotating about a horizontal axis a hollow distributor open at one end and closed at the other, delivering molten material onto the internal walls of said distributor from its open end, the rotation of said distributor efiecting the tangential discharge of numerous fine streams of said molten material under the centrifugal force imparted thereto by the rotation of said distributor, and blowing a strong annular blast of gas against said streams in a direction from the open toward the closed end of said distributor.

RICHARD M. DO-WNEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,601,897 Wiley et al. Oct. 5, 1926 2,318,244 McClure May 4, 1943 2,328,714 Drill et al Sept. '1, 1943 2,497,369 Peyches Feb. 14, 1950

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