US2422980A - Asbestos spinning fiber - Google Patents

Description

June 24, 1947, 1.. cl PHARO ASBESTOS SPINNING FIBER Filed Feb. 2, 1944 2 Sheets-Sheet 1 L ,e e C. Ph any,

June 24, @947. C PHARQ 2,422,930

ASBESTOS SPINNING FIBER Filed Feb. 2. 1944 2 Sheets-Sheet 2 Lpe C. Phaao",

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Patented June 24, 1947 Lee Collin Pharo, Thetford Mines, QuebetaCanada, assignor to Johnson's. Company, Thetford Mines West, Quebec, Canada Application February 2, 1944, Serial No. 520,802

INTRODUCTION This invention relates to the treatment of asbestos.

It is a principal object of the invention to provide an improved spinning fiber. It is a further object of the invention to provide an improved method of treating asbestos.

Asbestos is recovered from the rock in which it occurs in masses containing long and short fibers. In current practice, the attempt is to treat the entire mass so as to liberate all the fibers as completely as possible to form masses of liberated fibers ofv the best spinning qualities and other qualities. I There has been an impression in the trade that the longer the fibers, the better the spinning qualities and that a relatively large proportion of long fibers is necessary for adequacy in textile uses for example, yarn formation.

THE INVENTION The applicant has developed a new textile asbestos in which the staple length is'substantially uniform as compared with the asbestos textile fibers as produced today and in which this average length may be relatively short, that is, shorter than previously considered necessary for a high grade spinning fiber. A relatively large proportion of the fibers are close to the longest staple length and are substantially completely liberated and the balance of the fiber contains a proportion of relatively harsh fiber. I

Asbestos of this type is produced by first subjecting the masses of starting fiber (usually milled fiber) to a classification step in which the longest and shortest fibers are removed, then to a fiberizing step and finally to a liberation step in which a major proportion of the fibers, usually thelonger fibers, are substantially completely liberated and the balance left in the relatively harsh state.

This method and the resulting product will now be described, in certain specific embodiments, in more detail. The description will be facilitated by reference to the accompanying drawings illustrating preferred apparatus employable in the preferred method, and in which,

Figure 1 is a diagrammatic end elevation partly in section of an apparatus employed for classification of the masses of asbestos and also for subsequent partial liberation of the fibers therefrom.

Figure 2 is a diagrammatic elevation of an apparatus employable for fiberizing the asbestos.

Figure 3 is a plan view of the apparatus shown. in Figure 1, with the top housing removed.

4. Claims. (Cl. 19-,-'-65) 'Pnarsnamn Marn'on Primary treatment and classification K I The following is a preferred method of producing a fiber froma mass of standard Canadian asbestos; After primarily crushing and drying of the ore containing the asbestos, the asbestosis processed on a screen havingopen'ing's preferably of about diameter. The throughs" sepa: rated, by the screen, from the longest fibers are then run over an additional screeniat the end of whichthe fiber is removed by suction. The asbestos thus removed constitutes the mass from which is produced the special"spinning fiber according to the present invention. a

This mass is treated as follows in a specialmachine described in U. S. patent application S. N. 506,000, filed October 12, 1943, now Patent No. 2,386,715, October 9, 1945; The machine is represented diagrammatically in vertical transverse cross section in Figure 1 and in plan view with the housing removed in Figure 3. The machine includes a frame A on which is mounted a housing 10 forming an elongated horizontal passageway for the fiber and of which the bottom half is perforated to constitute ascreen. In this passage-way are operated a pair of horizontal shafts II and I2. on which are mounted beater arms l5 having special blades I6 which are inclined in such a way as to drive the material forward. The device is alsoprovided with a hopper 20 for catching fines falling through the housing I0 and a conveyor 2| for carrying. away these fines. The

shafts II and 12 are mounted-on the frame A through bracket I]. The shaft H is driven through a pulley. mounted atone end and a chain 25 affords a drive connection from a sprocket on the shaft I lto a sprocket on the shaft 12. The device is driven from a suitable source of power so as to rotate the shafts in the same direction. The blades overlap and pass each other in opposite directions as the shaftsrevolve in the same direction. The ends of the blades I6 just clear the;housing I0 so that thelatter is kept free from asbestos.

This device is operated at a relatively low speed,

preferably the equivalent of a range from between about to about 250R. P. M. in a device in which the beater arms have. a length of about 25 inches from the axes of theshafts to the tips of the blades. Thishas a combing or teasing effect which separates the longer fibers and practically holds them in suspension while'the short fibers, sand and other foreign matter fall through the perforated bottom half of the housing and are ent invention would result in such damage to the fiber that shorts would be produced as "fast as they were screened out.

Fiberization The fiber is thehpassedithrough fiberizing rolls such as, for instance. those described in U. S. Patent No. 2,219,077, so as to .flberize .or soften the spicules. .18, represents .the frame of the machine. 3,0, .31.;32,.33,;34,. 35,l6and .13] represent respective pairs of grooved rolls, the Hills having the even numbershaving the, grooves running in the direction of the axis of they rolls and those having the odd numbers having the grooves running circumferentially. All the rolls employed are preferablyof dimensions such that the straight line distance between corrugations, that is to sambetween the apices oi adjacent rolls is about 1 inch. The function :ofthe rolls is tofiberize the spicules by flexing-them. The product resulting is 'fiberizedasbestos. The rolls. are illustrated schematicallyin Elgu-re .2.

. Liberation The material after {being fibe ized as in the previous step is then subjected to a screening operation to remove "shorts? and alsoto fluff out, i. e. liberate a proportion of the fibers, by passing through several, preferably four, stages .of the mixing and screening machine shown in Figures 1 and 3 of the drawin s. using screens with about t! diameter round holes. In a proportion of the spicules, usually the shorterones, the fibers Results of process The process results in improved masses of fiber. The result of the treatment is that the fiber is not liberated throughout the entire mass as in previous methods, but comprises fibers substantially completely liberated and bundles of fibers in the harsh state. Usually it is the longer fibers which are liberated and the shortergbundles which remain in the harsh state. Exceptionally long and exceptionally shortjfibers are-preferably removed in the processing so as to makethemass as uniform as possible. The process isregulated sothat sufficient of the harsh bundles remain in: the mass to prevent blockingthe card clothing in the subsequent textile treatment.

In the general run of Canadianchrysotile asbestos, usually the average fiber length is about but this average'is the component of fibers ranging from aboutl inchesio about 2 inches down to fibers ranging from about /3 inch to about inch. Bythe presentarnethod, theextremely long and extremely short fiber is eliminated so that the fiber lengthof the resulting.

mass is exceptionallyuniform. Thenthis uniform mass is treated in such a waythat most of'the fiber is completely liberated. i. e. opened and- 4 fiufifed while the balance is fiberized, but remains in the form of relatively harsh, fiberized but unopened bundles of adherent fibers.

Preferred products Preferably the treated mass is made up of fibers which all approximate in length. Of this mass, of the fibers are completely liberated, whilesufficient of the remainder to prevent blocking-the card clothing is in the harsh state. The amount remaining in the harsh state is usually from about 2% to about 10% of the total by weight, the applicant preferring to have between about 2% and about 4% in-the harsh state. The limitation in achieving these results is, of course, the nature of the starting asbestos as it comes from the mine'considered in conjunction with thedifilculty of handling asbestos without injury thereto. Theoretically, a mass containing assorted lengths could be treated in several stages to size all the fiber so as to approximate the optimum average length, but this would result in injury to the fibers which are. thoroughly fiberized and a'tremendous fiber loss in the treatment. An aim of the present process is to bring the uniformity of the fiber length substantially to a maximum commensurate with the potentialities of the starting fiber and commensurate with reducing injury to the fiber substantially to-a minimum. In conjunction with this attempt is the substantially complete liberation of the greater proportion of the fibers while leaving in the substantially harsh condition sufilcient harsh material to prevent blocking of the cardclothing,

More specifically, it is possible from a characteristic mass of Canadian fiber of a type which would normally be milled, by treatment according to the invention, to produce a mass of fiber having an average staple length ranging from about A inch to about inch with all the fibers in the mass being close to this average and an upper length close to inch. Actually, it is possible. by eliminating over-long and over-short fibers according to the invention, to bring the average quite close to the preferred inch. With such a mass treated according to the invention, the fibers remaining in the harsh state would represent the shortest spicules, i. e. those passing through a one-quarter inch mesh screen. It should be explainedthat these spicules contain fibers which are more than one-quarter inch in length and the only reason they pass through the screens is that they are in spicule form. When these spicules receive textile treatment on pickers or cards they are often brought up close to the average length of the fiber in the mass.

types of asbestos used for spinning. The "shorts may be returned to the circuit to produce shingle fiber and paper stock and so forth.

EXAMPLES In order that the invention may be still more clearly understood, specific examples will be notbe considerediin;a;limiting-,sense.

given. These are only illustrative'nd should."

Example 1 One hundred pounds of asbestos were passed 1g procedure through the screening.- andfiberiti asdescribed .in general above.

Onscreen analysis. it: was found that it had.

beenipossible-to keep, the minus /4 inch asbestos in the harsh state. The remainder was substantially completely-liberated;

Amass or" fiber: treated as described in theexample' was carded and spun. It was found to produce excellent: yarn. The fiber- Was substantially equaliin spinning qualities to "1'8 -cut?with the additionrof only; aboutx8%- toabout-2 cotton;

Examplesv The following example: is; taken from the; rec ords ofja largev spinner in the United States,

There was used; 200 pounds of fiber made: according; tothe invention as defined above; of; which the" averagestaple length is about 4-inch, and the longest and? exceptionally shortestfibershave been" eliminatedusothat about%, of the fibers are:under about /;=.inchiandj the remainder: over about /5, inch. About 3% of' the fiberv re+ mained in the substantially harsh state.

This material was run directlyywithout cleaning, from the bag ontothe:cardin-wthe-mixtfor the high grade yarn; substantially no loss being taken inthe preparation. I

In the other test, thefiber was run alone and directly from-the bag-s asasubstitute for ahigh grade of spinning fiber-making 18jcut yarn; carding conditions were entirely, satisfactory; The :burn-out' test. was satisfactory. The fly. loss was normaL Thespinning: qualities and tensile strength were in. every respect equal to those of; the yarnmade fromthestandard mix in which Canadian crudeswere-used.

ADVANTAGES An advantageof'fiberproduced according to this invention is that it has "very high grade spinning and-:othertextile qualities- With the addition of relatively small amounts of cotton, the new fiber, according to the. invention (derivedfrom fiber which would normally beclassed as. milled fiber), can be spun equivalentlyto fiberin which up tonow crudes have necessarily been used. This unusual result, is believed to flow mainly from thefact that the fibers are as close as possible to uniform length and also to the fact,

that the shorter spicules are in harsh condition andthus prevent the fiber from blocking the card clothing.

Dsrmrrrons fiberized asbestoswhich has been subjected to beatlng or other agitation, the process sometimes referredto in this and other: arts as teasing or fiufiingvto separate the loosened. fibers, one

from theother so as to; bring them up intoa, nutty-condition,

((1) Harsh isiintended to-indicate the state offiberized.spicules orsmall bundlesof fiber in which; although the individual fibers have-been loosened from one anotherby fiberizi-ng, they have not: been liberated.

(e) Masses? is generally used to indicate asbestos in commercial quantities.

Itwill be understood that, without departing 'fromrthe. spirit of," the inventionvorlthe scope of the claims; various modifications may be. made in thespecific expedients described; The-latter areillustrative only and not offered in a restricting. sense, it being desired that only such; limitations shall be placedthereon as may be.

required: by, thestate of the prior art.

tionpare-merelyv tel-simplify reference thereto and should otherwisebedisregarded;

I claim: x

1; A- processor-treating asbestos, which cornprises the steps of; eliminating from asbestos masses the-longestnand shortest fibers whereby the averageflber' length of the masses is in therangefromabout. inch to about inch and a the greater portion of' thefibers exceeding inch, fiberizinggthe masses, liberating from about: to about; 98% of the fibersinthe masses substantially completely and; allowing the re maind'er of the masses toretain a substantially harsh condition.

, 2. Asbestos-spinning fiber in a condition. readyfor carding, characterized by high spinning qualities, the average staple length being within the range from about inch toabout "V inch, the greater portion of the fibers exceeding inch, from about 2% to'about 10% of the fiber being in the substantially harsh state and the remainder of the fiber being substantially completely liberated; said fiber being. made in accordance with the process of claim 1.

3.- A' process of treating 'asbestos, which comprisesthe steps of; screening crushed and dried asbestos ore to eliminate the 'rockand the spicules containing the longest fiber thereby to obtain the masses free from the longest fiber; subjecting said free masses to a classification step substantially equivalent to that which comprises feeding the asbestos masses into one end of a closed unobstructedsubstantially horizontal passage having a perforated area to allow the escape "of extremely short .fiber by gravitation, moving said masses through the passage by subjecting them to the action of a succession of intermeshing rotatlngcbeating armsextending throughout Q the passage and inclined with respect to the iongitudinal, axis .thereof in a direction to advance the masses continuously through the passage, passing the beating arms closely adjacent toone another while rotating them in intermeshing relation for agitation and advancing the mass thereby to cause the long fiber to be liberated and the extremely short fiber to escape by gravitation, the beating arms being moved at a slow speed efiective to maintain the long fiber in suspension andcause the undesirable short fiber to gravitate and to reduce injury to the long fiber substantially to a minimum, subjecting the masses thus obtained to afiberizing operation, and subjecting the masses to a screening step to remove shorts and to fluff out the fiber.

The sub-titles used throughout. the specifica 4. A process of treating asbestos, which comprises the steps of screening-crushed .anddried asbestos ore to eliminate the rock and the-spicules containing the longest fiber thereby to..0btain the masses free from the longest fiber; subjecting said free masses to a classification step substantially equivalent to that which comprises feeding the asbestos masses into one end of a closed unobstructed substantially horizontal passage having a perforated area to allow the escape of extremely short fiber by gravitation, moving said masses through the passage by subjecting them to the action of a succession of intermeshing rotating beating arms extending throughout the passage and inclined with respect to the longitudinal axis thereof in a direction to advance the masses continuously through the passage, passing the beating arms closely adjacent to one another while rotating them in intermeshing relation for agitating and advancing the mass thereby to cause the long fiber to be liberated and the extremely short fiber to escape by gravitation, the beating arms being moved at a slow speed equivalent to the speed at which arms about one foot long would intermesh with each REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 7 Name Date 2,219,077 'Pharo Oct. 22, 1940 2,199,137 Magnani Apr. 30, 1940 1,484,208 Davis Feb. 19, 1924 2,280,902 Ellison Apr. 28, 1942 FOREIGN PATENTS Number Country I Date Great Britain Mar. 24, 1938

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