US2386401A - Method of fiberizing asbestos - Google Patents

Description

0d. 9, 1945. W 1 JQYCf-gy JR 2,386,401

METHOD OF FIBERIZING ASBESTOS Filed Jan. 24, 1944 Patented Oct. 9, 1945 METHOD F FIBERIZING ASBESTOS William J. Joyce, Jr., Manheim, Pa., assignor to Raybestos-Manhattan, Inc., Passaic, N. J., a corporation of New Jersey Application January 24,1944, Serial No. 519,580

l0 Claims. (Cl. 191) chrysotile form being of most predominant occurrence and production, and also of,most usefulness due to its content of ilne, long fibres of high tensile strength. The value of asbestos lies primarily in the length of its fibres, the ability to card, spin and weave it, and the ability to produce therefrom various materials such as yarn, cloth, felt, tape, paper, miilboard and many 'speciilc products well known in the art. Thus,

Vwhat is commercially known as Ithe grade of the libre refers not to the source or variety but to the fibre length, No. 1 grade having a length of about one inch or more.

Heretofore asbestos has been subjected to crushing. beating or otherwise mechanically manipulated to open and separate the ilbres with the end in view of making them line and lit for carding, spinning and weaving, or good dry and wet felting. However, such mechanical processes inherently and in varying degree cause reduction in natural libre length with the resultant production of commercially excessive lines and dust.

It is therefore an object of the present invention to iiberize or open asbestos in a simple but novel and highly edective manner which is conducive to the production of a maximum amount of fibers of high grade, that is of good length substantially equal to the natural length of the fibers, by what is essentially a physical method, as distinguished from chemical or mechanical methods.

In general my method comprises the explosive fiberization of asbestos in either rock or partially crushed form by conning it in a pressure chamber or vessel or gun together with a gaseous medium, which is inert with respect to asbestos, under pressure,- and subsequently suddenly releasing the pressure whereby the asbestos is ejected and the fiber bundles subdivided along their natural lines of cleavage without tearing or changing their length substantially.

Other objects and advantages will be apparent from a consideration of the following specification and accompanying drawing which diagrammatically illustrates an arrangement of apparatus for carrying out my invention.

Referring to the drawing, the reference numeral I0 indicates a pressure chamber or gun" the smallest internal diameter of which, including that oi its inlet port II and outlet port I2, is sufilciently great to handle the introduced asbestos in its natural fiber length. The asbestos to be berized is introduced from a suitable hopper I3 through a valve Id, and is ejected through quickopening valve I5, the valve apertures being likewise of suicient dimension to permit straightthrough introduction, and particularly ejection of the asbestos in its natural fiber length without causing bending or pressure which will shorten the length of the fibres or break the material as it discharges. A

After the asbestos to be iiberized is introduced to pressure vessel III, and with valves I4 and I5 closed, gas under pressure is introduced through line I6 and valve I1. As gaseous agents I may employ air, carbon dioxide, nitrogen,v argon, ammonia. sulphur dioxide, steam and the like compressible fluids, or mixtures thereof which are inert with respect to the asbestos, under -a high superatmospheric pressure such as from aboutv 200 to about 1200 pounds per square inch; depending upon the nature of the'asbestos, its condition. that is rock form, crushed, coarse, etc., and the desired degree of fI-berization. I have found, for example, that a pressure of from about 400 to about 800 pounds per square inch is a suitable range for good berization of chrysotile asbestos in rock form to produce a finely divided fibrous mass of predominantly No. l grade libers. has reached the desired degree, valve I'l is closed and thereafter after a relatively short period of confinement, such as from about 5 to 30 seconds, valve I5 is suddenly fully opened by suitable quick acting means, land the material explosively discharged through exhaust line I 8 to cyclone separator I9 wherefrom the expanded gas is exhausted upwardly through line 2D and the fiberized asbestos downwardly through exhaust line 2 I.

For the purpose of quickly or suddenly opening valve I5, I may, as illustrated couple the valve stem 22 thereof through a gear segment and rack 23 to an air cylinder 24, the cylinder being connected through the inlet line 25 and exhaust line 26 to the quick acting air valve 2l, air under low pressure being admitted to the .valve 21 through line 28 and exhausted through line 29, the valve actuation being controlled through the hand lever 30.

As indicated, my process requires only the application under pressure of a gas inert with re- After the pressure within the vessel I0 l spect to asbestos, the term gas being understood to include a vaporous material such as steam, and the quick release of the pressure and discharge of the material. The process may be carried out with or without the presence of moisture and/or heat. In the employment of steam the vessel lll may -be suitably insulated or even heated to avoid loss of pressure or undue condensation. The presence of moisture or water resulting from the use of steam, or otherwise, causes the material to be ejected in a more or less tangled wetted mass of fibers. However, as indicated, the presence of moisture or heat, or pre-softening or heating of the asbestos, is not necessary to the successful operation of my process and I preferably operate with dry ashes# tos and a dry gas, under normal room temperature conditions, to obtain a finely iiberized product, the fibers being separated along their natural lines of cleavage and of substantially natural liber length.

I claim as my invention:

l. The method of fiberizing unflberized or partially iiberized crystalline masses of asbestos to produce asbestos fibers of a desired substantially uniform fineness and without substantial change in the original natural length of the fibers, which comprises: confining the asbestos aggregates in a closed zone together with a gaseous medium chemically inert with respect to asbestos under a superatmospheric pressure sufof the desired substantially uniform fineness, and recovering the resulting iiberized asbestos.

4. The method of fiberizing unberized cr partially fiberized crystalline masses of asbestos to produce asbestos fibers of a desired substantially uniform fiberization and Without substantial change in the original natural length of the fibers, which comprises: confining the asbestos aggregates in a closed zone together with a gaseous medium chemically inert with respect to asbestos under a'superatmospheric pressure sufficient to eiect flberization but insufficient to cause detrimental reduction in fiber length, releasing the pressure suddenly to expel the asbestos from' the closed zone into a zone of lower pressure to subdivide said aggregates into fibers of the desired substantially uniform fineness, and

recovering the resulting iiberized asbestos.

2. The method of flberizing uniiberized or partially flberized crystalline masses of asbestos to produce asbestos fibers'of a desired substantially uniform flneness and without substantial change in the original natural length of the fibers, which comprises: confining the asbestos aggregates at substantially normal temperature in a closed zone together with a gaseous medium chemically inert with respect to asbestos under a superatmospheric pressure suilicient to effect berization but insufficient to cause detrimental reduction in fiber length, releasing the pressure suddenly to expel the asbestos from the closed zone into a zone of lower pressure to subdivide said aggregates into fibers of the desired substantially uniform fineness, and recovering the resulting flberized. asbestos.

' 3. The method of fiberizing unfiberized or partially flberized crystalline masses of asbestosy to produce asbestos fibers of a desired substantially uniform fineness and without substantial change in the original natural lengthv of the fibers, which comprises: confining the asbestos aggregates in a closed zone together with a substantially dry gaseous vmedium chemically vinert with respect to asbestos under a superatmospheric pressure sumcient to effect fiberization but lnsuiiicient to cause detrimental reduction in liber length, releasing the pressure suddenly to expel the asbestos from the closed zone into a zone of lower pressure to subdivide said aggregates into bers about 30 seconds.

iicient to effect fiberlzation but insufficient to cause detrimental reduction in fiber length, releasing the pressure suddenly to expel the asbestos from the closed zone into a zone of lower pressure to subdivide said aggregates into bers of the desired fineness and of substantially uniform fiberization, and recovering the resultingr iiberized asbestos.

5. The method of iiberizing uniiberized or partially flberized crystalline masses of asbestos to produce asbestos fibers of a desired substantially uniform fineness and without substantial change in the original natural length of the fibers, which comprises: confining the asbestos aggregates at substantially normal temperature in a closed zone together with a substantially dry gaseous medium chemically inert with respect to asbestos under a superatrnospheric pressure sufficient to effect fiberization but insufficient to cause detrimental reduction in ber length, releasing the pressure suddenly to expel the asbestos from the closed zone into a zone of lower pressure to subdivide said aggregates into fibers of the desired substantially uniform neness, and recovering the resulting fiberized asbestos.

6. The method of fiberizing unberized or parl tially iiberized crystalline masses of asbestos to produce asbestos fibers of a desired substantially uniform flneness and without substantial change in the original natural length of the fibers, which comprises: confining the asbestos aggregates in a closed zone together with a gaseous medium chemically inert with respect to asbestos under a superatmospheric pressure sufiicient to effect fiberization but insuilicient to cause detrimental reduction in fiber length, releasing the pressure suddenly to expel the asbestos from the closed zone into a zone of lower pressure through an opening having a minimum dimension at least equal to the maximum natural fiber length of the asbestos being fberized and to subdivide said aggregates into fibers of the desired substantially uniform fineness, and recovering the resulting fiberized asbestos.

7. The method claimed in claim 1 wherein the pressure ranges from about 200 to about 1200 pounds per square inch.

8. The method claimed in claim 1 wherein the pressure ranges from about 400 to about 800 pounds per square inch.

9. The method claimed in claim 1 wherein the gaseous medium comprises essentially compressed air. l

l0. The methodclaimed in claim 1 wherein the asbestos aggregatesA are confined in the closed zone for a time ranging between about5 `and WILLIAM J. JOYCE, JR.

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