US2870819A - Apparatus and method for forming a sheet of integrated mica - Google Patents

Description

Jan. 27, 1959 M. D. ,HEYMAN APPARATUS AND METHOD FOR FORMING A SHEET OF INTEGRATED MICA Filed Feb. 6. 1952 INVENTOR. M0555 0 HEYMAN L ATTORNEY United States Patent ()fiice 2,870,819 Patented Jan. 27, 1959 2,870,819 APPARATUS AND METHOD FOR FoRMrNd A SHEET F INTEGRATED MICA Moses D. Heyman, Woodmere, N. Y. Application February 6, 1952, Serial No. 270,242 7 Claims. (Cl. 154-2.5)

This invention relates to an apparatus and method for forming a sheet of integrated mica from thinly split flakes and deals more particularly with an apparatus embodying means for utilizing flakes that may otherwise be wasted and which render diflicult proper cleansing of the liquid medium in which the flakes are borne so that said medium may be re-circulated.

Reference is made to my pending application Ser. No. 201,020, filed December 15, 1950, issued as U. S. Patent No. 2,659,412. In the production of a continuous sheet of integrated mica according to said application, a ma- .terial proportion of the mica flakes are so extremely fine that they settle very slowly in the liquid from which they are deposited to form a sheet. Therefore, these finer flakes remain in the upper portion of said liquid. Inasmuch as the level of the liquid in the sheet forming means must 'be maintained quite constant for best results, an excess of liquid is used and an overflow is employed to maintain the level. The liquid spilling through such overflow contains, in suspension, a substantial quantity of these finer mica flakes. Another source of loss of these finer flakes is in withdrawal of liquid by vacuum in means employed to effect efficient transition of the sheet being formed from immersion in the liquid to the atmosphere thereabove. These fine flakes, which would otherwise be wasted, are, in fact, those best suited to form integrated mica because they have great cohesive force and also because they provide the integrated sheet with fine-textured and smooth surfaces.

Accordingly, it is an object of the present invention to utilize as great a proportion of such otherwise wasted flakes as can be recovered and return said flakes to the sheet-forming means for incorporation into a sheet of integrated mica.

In the interests of economy and for other reasons, it is desired to re-circulate the liquid medium employed to carry the flakes. However, the mentioned thinner flakes that accompany the liquid withdrawn from the sheetformer are in such large quantity that they quickly clog any strainer or filter provided to intercept them and also render diflicult the proper maintenance of operation of splitting, ionizing and pumping means, etc. employed in the preparation of the flakes before they are incorporated in an integrated sheet.

Another object of the invention, therefore, is to recover the otherwise wasted thinner flakes, as above mentioned, so that the relatively few flakes that cannot be recovered can be filtered out efliciently, thereby insuring substantial freedom from mica flakes of the re-circulating liquid and proper operation of the flake preparing and producing means.

A further object of the invention is to provide novel prise the interior of the sheet.

A still further object of the invention is to provide [novel and improved flake-recovering means whereby My invention also comprises novel details of construe tion and novel combinations and arrangements of parts which will more fully appear in the course of the following description, the same having basis on the apparatus shown in the accompanying drawing which is exemplary of apparatus according to the invention.

In the drawing:

Fig. 1 is a systematic view, partly in section, of apparatus according to' the present invention.

Fig. 2 is an enlarged cross-sectional view as taken on line 2--2 of Fig. 1.

Fig. 3 is a greatly enlarged fragmentary sectional view of an integrated mica sheet as produced by said apparatus.

In the drawing there is shown a chute 5 which discharges liquid-borne mica flakes and a pipe 6 which returns the liquiddischarged by said chute to the source from which the flow in said chute came. It. is understood that apparatus, immaterial to the present. invention, is inter-connected between said chute and pipeto disintegrate pieces of mica into fine flakes or splittings and to provide a flow of liquid-borne flakes to chute 5.

The present apparatus comprises, generally, sheetforming means 7, means 8 conducting liquid from said means 7, means 9 to recover mica flakes in the liquid flowing in means 8 and returning the same to the sheetforming means, a settling tank 10 receiving the discharge of liquid from means 9, means 11 interposed between tank 10 and pipe 6 to strain or filter the liquid from tank 10, and means 12 to periodically flush or cleanse the filter means 11. I

The sheet-forming means 7 comprises, generally, a tank 13 that is preferably provided with an upwardly sloping bottom 14, a relatively narrow transverse static head settling chamber 15 disposed intermediate the ends of tank 13 and defined between transverse walls 16, the

tank being divided by chamber 15 into a deeper chamber 17 and a shallower chamber 18, and conveyor means 19 moving through the tank, substantially parallel to the sloping bottom thereof, and receptive of mica. flakes settling downward in chambers 15, 17 and 18. The conveyor means moves in the direction of arrow20 and said means comprises a support belt or chain 21 preferably formed of articulated links or otherwise formed to be non-stretchable, and a relatively thin woven nylon web 22 for which belt 21 serves as a support. The conveyor means 19 thus provided moves through the tank 13 in an upwardly sloping direction with web 22 uppermost. Suitable pulleys 23 may be provided to guide conveyor means 19 as desired.

It will be realized that, as conveyor means 19 moves along the inside of tank 13, mica flakes in the flow discharging from chute 5 into static head chamber 15 will settle onto Web 22 and, that such of the flakes that do not settle on the web in said chamber pass with the liquid into chambers 17 and 18, and that the flakes in the latter chambers also settle onto the web. It will be seen, however, that the relatively finer flakes in chamber 17 settle on the web first to form a layer 24 of such finer flakes; that as the web passes'beneath chamber 15, the relatively thicker and heavier flakes therein are deposited on layer 24 to form the coarser layer 25; and that as the web moves through chamber 18, the finer flakes in the latter chamber settle on layer 25 to form the fine layer 26. Fig. 3 shows the product resulting from such successive deposit of flakes.

Means 8 comprises an overflow trough 27 positioned in tank 13 to maintain a constant level of liquid in said tank, saidtrough discharging, under pressure of a suction pump 28, into a pipe 29. It will be evident that such liquid contains mica flakes that are too fine to settle rapidly and, therefore, are drawn off with the surface liquid from tank '13. Means 8 also includes vacuum means 30 disposed below web 22 where the same moves out of the liquid in tank 13 and provided to preventwashby a suction pump 31 and is 'efiectivethrough.tlie'inter sticesof the woven web to firmly hold the deposited flakes on the web as thelat terbreaks through thesur face-of the liquid. Since m anss'o isfpartly imm'er sed in said liquid, pump 31 draws liquid andiflakes suspended therein out of the ta'nkthrou'gh a-pipe 32 which joins pipe 29 to form a pipe 33 that terminates in a perforatedheader34. It will be clear that the flow from the peiforations 35. of said header comprises liquid and Tflakes' an duthat said flakes, being removed with the. topliquid, are the finer and slower settling flakes.

The flakes deposited on web 22 become an integrated sheet and said sheet is removed from the web in amanner and by means not pertinent to thepresent invention. In any case, the web returns to the deeper part of tank 13 to again receive deposits of mica flakes as above set forth.

The mica flake-recovering means 9 comprises, generally, a woven belt or web 36 similar to web 22 and disposed toreceive the discharge of header 34, a set of concavely' formed rollers 37 supporting an upwardly sloping run 38 of web 36- so as to impart a trough-like transverse sectional form to said web run, a tank 39 to receive the flow of liquid passing throughthe interstices of web 36, and a set of pulleys'40 over which said web is trained so that the same has a substantially vertical run 41 terrninatir g above chamber 17.

Web run 38 is disposed at an upward slope so as to drain back into tank 37 therebeneath, the web being driven by means 4 2 at a desired speed to allow such drainback without spillage over the end of said tank. As seen in Fig}, theconcavity of the web run,-as fo rmediby rollers 37, prevents side spillage. of "liquid which, therefore, must drain-through the web and, in theprocess, deposit rnica-flakes 43 on said web. According to the direction of arrow 44, flakes 43 are carried by web run 41 toward chamber 17. These flakes are Washedfrorn the web into chamber 17 by a nozzle 45 which receives its flushing liquid from'the' discharge of -a pump 46 having an inlet'47 that draws water or liquid from tank 13. Such flakes that may cling to web 36 beyond the place impinged by the-flushing-li'quid, may be dislodged or scraped off as by a doctorblade 47a to fall into chamber 17 In the above manner, flakes removed from tank '13, in any of the Ways above described, are returned to said tank, and-more'particularly, chamber 17, to providea large proportion o-fthe -flakes that form-sheet layer 24. In practice, some'94% of 'theflakes discharged. from chute become embodied in the integrated sheet formed by-the present apparatus. The-remaining 4% are so extremely small and fine-as to passthroughthe interstices of web 36'into tank 39.

Settling tank 10,'by means- 0f a pipe 48,'receives the flow from tank 39. By'mea'ns'of batfle's or other known means within tank 10, much of the fine flakes suspended in the liquid are settled out andgfromtime to time, these 'flakes areemptiedinto' a drain byopening normally-closedvalve 49. The :upper portion of the liquid 'in tank is drawnoff through a pipe 50 to the filter means '11 by means-of a suction pump '51'connected in said pipe.

Filtermans 11 comprises a filter orstrain'er'SZ that receives liquid flow from pipe 50, filters'out'any residual 'fine' flakes from said flow, and discharges the resultant flake-free liquid into pipe 6. Between pump 5l and the inlet to filter 52, pipe 50 is providedwith a check'valve the filter is provided with anoi'inally operi valve f55 and a similar, but normally-closed valve .56, is provided 'at "It will be clear that the flow intoth filter normally 'r'ea'ch'es pipe 6 only by passing through filter unit 57 that intercepts the relatively small amount of flakes that remain in the flow. Since much of the 4% of waste flakes has been settled out in tank 10, filter 52 is able to function for a relatively long period before accumulations of flakes on filter unit 57 clog the same and impairs its liquidpassing efficiency.

The filter flushing means 12, however, is operated before a clogged condition ofuthe .filteroccursto insure continuous flow of liquid in pipe 6 as supplied from tank13. As" shown, means 12 .comprises air cylinders 58 and 59 for operating the respective valves and 56, an air line 60, controlled as by 'a solenoid-operated valve 61, to provide compressed air for operating said air cylinders, a pipe 62 from a source of compressed air, and avfilter63 to cleanse said. air of. contained. oilondirt. ,Line is connected tolfilter outlet 54. and a check valve 64 is provided to check flowbackinto line 60. In practice, valve 61 iscontrolled bya suitable timing device 65 which periodically opens said valve to:adrnit. compressed air to air cylinders 58. and 59. I

Under control of timing device f65,v compressed :air actuates cylinder 58 to close.normallyfopen-valve.55.and cylinder 59 to. open normally-closed valve 56. Therefore, as said compressed air flows past check valve 64, the samereverse.flushes filterunit 57 and the accumulation of flakes on the surface of said unitis blown out of the .filter through open .valve 56. .Three tolfive seconds ofsuch reverse. flush. is ordinarilyvsufli'cient. to clear .unit 57 vof flakes. Since timing device 65 provides an automatic and periodic flushing operation, the flow to pipe 6 is maintained and .the liquid flo-wingsin said, pipe is substantially clear of. all'flakes and quite suitable for re-circulation and re-use.

While. I. have describedivhatflwnow. regardas. the. preferred form of my invention, 'realizingfthat the. same may be varied.without'departingfromthe spiritandscop'e of my invention, I desire to reserveto myself suchmodifications thereof that may fall within .the scope "of the appended claims. 7

Having thus describedmy invention, what I claim and desire to obtain by Letters Patent, is:

.1. Apparatus for forminga continuoussheet of,inte

grated mica comprising a tank...provided with. a static head settling chamber intermediateits ends to provide said tank with settling. chambers. one on each .side of .the static head chamber, said chambers. being connected at their bottoms, a web moving. throughthe bottomsof said three chambers and receptive of mica flakes settling-downwardly in said chambers, aninlet foraflowrofliquidborne micaflakes to sa-idstatic head chamberganoutlet for excess liquid insaiditank and.in.the uppeipportionso'f the tankto maintain. a constant level of..liquid inv the tank, means to elevate the. liquid passing. throughsaid. outlet, and a liquid-passing conveyor receptive ofsaidlelevated outlet liquid to intercept mica flakes suspended'lin said outlet liquid to collect said flakes and p'as's the outlet liquid therethrough, said conveyor having a portiondi'sposed to convey the flakes collectedthereon backto one of said side chambers.

' 2. Apparatus for forming a "continuous"sheet 'of'integrated mica'acco'rdingtoclaim 1; and means to remove said collected flakes from the mentioned portion of the .conveyor'and disposed to direct saidflakes into 'said side chamber.

- 3.-'Apparatuscfor forming a continuous.*sheetfofintegrated mica according to claim 1: andmeans to .:remove said collected flakes from the -mentioned i portionrofthe conveyor and disposed to direct =said flakes intosaidrsid'e chamber, said flake-removing means 1 comprising a nozzle to spray liquid from the tank against.the-conveyor-to wash the flakes therefrom.

. '4." In. integrated. --mica. .shee t-formii gtmeansp. act/fink,

partitions dividing said tank into three settling chambers connected at their bottoms, one of said chambers being intermediate the other two and receptive, from the top, of a flow of liquid-borne mica flakes, a web moving along the bottoms of said chambers and receptive of flakes settling downwardly in the liquid in said chamber, an overflow for the top of the liquid in said chambers, means to elevate said overflow liquid above the tank, and means to separate mica flakes from said overflow liquid and return said separated flakes to one of said other two chambers.

5. In integrated mica sheet-forming means having an overflow of liquid, means to receive said overflow liquid and intercept mica flakes suspended therein, said means comprising a liquid-passing conveyor web disposed to have a substantially horizontal run thereof in the path of said overflow liquid to pass said liquid and collect the mica flakes in said liquid and to have a substantially vertical run thereof directed toward the sheet-forming means, and means to remove the flakes from said latter run and return the same to the sheet-forming means.

6. A method for forming an integrated sheet of mica flakes on a continuously moving surface that consists in directing a continuous flow of liquid-borne flakes above and onto said surface and to immerse the same so that the flakes settle downwardly onto said continuously moving surface, maintaining the level of the liquid above said surface substantially constant by drawing ofi the liquid from the top together with flakes in suspension at said top while the incoming flow continues, separating the flakes from the liquid thus drawn off to collect the flakes, and then returning said collected flakes to the liquid above the moving surface forward of the mentioned flow so that said latter flakes settle downwardly onto said moving surface to cover the same before the flakes from the flow reach said surface.

7. A method according to claim 6: the steps of conveying the collected flakes toward the liquid above the moving surface, and utilizing said liquid to wash said collected flakes thereinto.

References Cited in the file of this patent UNITED STATES PATENTS 898,212 Gaara et al. Sept. 8, 1908 1,500,208 Shaw July 8, 1924 1,599,376 Smith Sept. 7, 1926 1,672,249 Ellis June 5, 1928 1,754,370 Raynes Apr. 15, 1930 1,807,206 Frederick May 26, 1931 1,913,877 Frederick June 13, 1933 1,950,089 Morse Mar. 6, 1934 2,077,720 Seigle et al. Apr. 20, 1937 2,488,700 Bidwell Nov. 22, 1949 2,549,880 Bardet Apr. 24, 1951 2,614,055 DeScnarclens Oct. 14, 1952 2,624,079 Duvall Jan. 6, 1953 FOREIGN PATENTS 44,376 Switzerland May 9, 1908

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