US2621793A - Screen centrifuge for cleaning clays - Google Patents

Description

Dec. 16, 1952 K. L. GERECHT 2,621,793

SCREEN CENTRIFUGE, FOR CLEANING CLAYS Filed July 27, 1951 3 Sheets-Sheet l Dec. 16, 1952 K. GERECHT SCREEN CENTRIFUGE, FOR CLEANING CLAYS 3 SheetsSheet 2 7 Filed July 27 1951 my a J/WM/WB Mk4 Ll/OL/IG 669156197 Dec. 16, 1952 K. L. GERECHT SCREEN CENTRIFUGE, FOR CLEANING CLAYS 5 Sheets$heet 5 Filed July 27 1951 H Raw w P W m 7W W U mmzm/ Patented Dec. 16, 1952 OFFICE SCREEN CENTRIFUGE FOR CLEANING CLAYS Karl Ludwig Gerecht, Kassel, Germany Application July 27, 1951, Serial No. 238,910 In Germany December 30, 1948 12 Claims.

This invention relates to a centrifuge for cleaning the raw material for brick works and the like.

For making ordinary ceramic ware of loam, clay, or the like, such as, e. g., in brick works, it is necessary as much as possible to remove the mechanical impurities from the raw material. The disturbing admixtures are'on the one hand remnants of plants, roots etc. and, on the other hand, stony admixtures, more particularly, limestone.

The machines hitherto used'for removing such impurities are very complicated and expensive.v

Moreover, ordinarily several machines have to be arranged in series. Thus, for instance, a coarse disintegration takes place in the edge mill from which the mass comes to a finishing rolling mill for crushing all stones etc. to a size of 1 mm. diameter in maximum. Especially the finishing mill is very highly stressed, and the hard steel rollers have to be reground very often.

It is an object of the present invention to provide a machine avoiding such disintegrating processes which would involve heavy wear and tear of the disintegrating machines. 7

Another object of the invention is to free the raw material for ordinary ceramic ware from the mechanical impurities, such as, stones, roots, remnants of plants, etc. by means of centrifugal force, and to carry out this cleaning continuously.

Still another object of the invention is to free the raw material from all impurities Whose dimensions exceed a certain minimum size, e. g., 1 to 3 mms., because these impurities primarily include limestone which in the finished product may cause disturbances, e. g., scaling of parts of the product.

Still a further object of the invention is to provide a centrifugal separating apparatus which is of simple construction, easy to clean, and adapted to the rough working conditions prevailing in brick works.

With these and further objects in view, the present invention relates to a centrifugal separator in which a plurality of screening baskets are concentrically arranged around a vertical shaft, in such a way that the size of the screen openings decreases from the innermost towards the outermost basket, while the outermost screening basket is encompassed by a f stationary wall adapted to receive or collect the purified clay. The sieves may consist, for instance, of perforated plates,'the diameter of the perforations being larger in the innermost basket than in the .next larger basket, in order to retain the differtionated form. It is important that the last or outermost screening basket has openings whose diameter amounts to a few millimeters only, e. g., about 1 to 3 mms.

Preferably the screening baskets consist of grates which may be formed of wires, bars or the like, and the width of the gaps of the grates decreases from the innermost to the outermost basket.

The clay or similar material is fed, advantageously in a soaked condition, from a stage arranged above the separator, near its axis. The clay substance travels successively through the different grates by which the impurities are retained in different fractions. Preferably some of the grate baskets are conically shaped and alternately tapered in an upper and lower direction, so that the impurities separated therein are discharged, under action of the centrifugal forces, partly in a downward and partly in an upward direction.

Ahorizontaldisc may be mounted on the centrifugal shaft, below the grate baskets, for collecting and removing the coarse stones which are imparted a considerable centrifugal acceleration, so that they will freely flow out of the operating range of the centrifuge, through the clay slipping down from the stationary collecting wall.

In order that the raw material fed in the central part is immediately imparted the desired peripheral speed, it is advantageous to provide means in the inner basket for setting the mass in rotation. To this end, e. g., vanes or blades may be provided on the shaft in a substantially vertical direction. In addition to, or instead of, the vanes, horizontal baffle plates may alsobe provided. Preferably these vanes are forwardly inclined in their upper part, in the direction of rotation, e. g., they may form an angle of about with the vertical plane of the lower vane part.

It has been found that in operating the centrifuge an intensive outwardly directed air current is produced. It it preferred, to direct this air current in such a Way that air eddiesare prce vented but that the air current promotes the separating process and the slipping down of the clay from the clay collecting wall. Thiseifect is obtained by the provision of fan like vanes at the centrifugal basket, e. g., by the above mentioned use of bent-off blades in the innermost screening basket. Moreover, it is preferred to provide vanes also between the screening baskets, which vanes likewise are forwardly inclined in the direction of rotation, throughout their length,

or in the upper part, in order to produce a downwardly directed air current during the rotation of the centrifuge. Moreover, the centrifugal basket may have vanes at its outer periphery to the same end, which vanes may be forwardly inclined entirely or partly, in the direction of retation.

It has been found that in general it will be sufiicient to provide two screening baskets or grate baskets, the interior of which, for instance, has slits of a few centimeters, e. g., 3 cms., but not more than oms., while the outer basket has a slit width of a few millimeters, at least about 1 mm. and not more than about 3 to 4 ms; preferably the slit width in this case is 2.5 mms.

In order to facilitate the slipping down of the impurities retained at the screens. or. grates, the grates may have an inclined cross section, i. .e., the baskets may be conically shaped. In this case it is advantageous to construct theinner basket in such a way that it is conically tapered in an upward direction,.while the outer basket is conically tapered in a downward-direction. The coarse impurities,v e. g.,;stones,, are thus passed downwards, falling onto, a-disc;mountedon the centrifugal shaft, from whiehthey are centrifuged outwards, outside the reach of the centrifuge. The finerin purities, e. g,, sn allypai'- ticles of limestone, are retainedat-the-Outergrate basket, slipping outwards overthe upper edge,

thereof. The entire centrifuge may be encompassed by a collecting wall or a casing by-which thefractions of the impurities discharged; by ,the two baskets are collected.

The purifiedor cleaned clay slips downwards on the stationary clay collecting wall surrounding the outer screening basket, falling, into a funnel provided underneath the-centrifuge, from which funnel it may be delivered, through conveyor belts, conveyor worms, elevators or the like, to the subsequent processing plants. -It is also possible, however, to transport thepurified clay by means of wheel-barrows, conveyor wagons or the like.

.It will thus be seen that the whole cleaning ofthe .clay or loam is achieved .by means of a single machine comprising amultiple centrifuging basket, a clay-collecting wall, a funnel for delivering the clay and a casing for. collecting the impurities separated by centrifuging. .Ad-

vantageously the centrifuge is suspended like, a

pendulum and the driving motor is provideddie rectly on the upper end of the shaft of thecentrifuge on a stage from which the raw material is fed to the centrifuge continuously or discom,

tinuously.

Other and further objects, features andadvantages of the invention will be pointed out hereinafter and. appear in theappended-claims forming part of the application.

In the accompanying drawings a now preferred embodiment of the inventionis shown by wayof illustration and not byway of limitation.

Fig. lis an axial section through the separator,

Fig. 2 is a section on line II-II of Fig. 1,

Fig. 3 is an-elevation of the separator, a part of the outer wall being removed,

.Fig. 4 is a fragmentarysection, on a larger scale,

Fig. 5 isa development showing the arrangement of the vanes.

Referring now to the drawings in greater detail, in whichsimilar reference numerals denote similar parts, it will be seen that a supporting structure for the separator, comprising girders I, I, and I of steel, reinforced concrete, wood or the like bears girders 2 and 3 on which the driving motor 4 with the rotary part of the separator and the stationary casing is mounted.

The lower bearing 5 of the driving motor A is reinforced to resist the heavy loads bearing thereon. A braking device 6, adapted to be operated by a hand lever 1, permits quick braking of the centrifuge which is driven at a suitable rate of speed, e. g., of about 960 R .P. 'M.

The rotary part of the centrifuge is secured on the shaft 8 with a conical seat. The

..carrier body. 9 bears the screening means and comprises a hub 10 and an angular ring I I which parts are interconnected by six ribs 52 in such .a wayv that hollow spaces for passage of the. large- 1 11.65. are le A ring plate l3 secured on the carrier 9 bears the inner screening basket with the sieving bars M which are held in three rings l5, 5" and l'5' of section steel as shown. The inner screening-basketjs, conically tapered from bottom to top. Mounted within'this basket, on the shaft 8, are vertical vanes .16. whose upperpart it is e o f a an ang e- The outer screening basket is built up of rings with angle irons H and I1. Theangle irons serve -to,fasten the tentering frame for the wires. The upper and lower rings of the tentering frame are interconnected by. inclined-bars l8 bearing one or two rows of perforations for the reception ofsteel wires 1,9..which are drawn in under tension in. a peripheral direction, thus forming a sieve. By .wayof alternative it is also possible to use. annularslit. sieves of metal or the like. The upper ring for theangleirons H is carried by round iron bars 20. Moreover, flat iron bars 2| are arranged between the upper ring with the angle iron H. for holding the sieving frame and the. outer edge of the centrifuge-disc l3, Fig. 3, in such a manner that. said flat iron bars are directed fromone round iron support 251 to the next, forming an angle of about 45". This inclination servesto produce an air current in a downward direction,.WhQse intensity is further reinforced. by inwardlydirected plate or sheet members 22 provided on thefiat iron bars 2 8.

Provided in the space between the inner and outer screening baskets are. vertical plate members. 23, Figs 4,and 5,.whoseupper part is bent off at an angle of about 45. These plate members 23 are fastened, on a frame of steel bars formed by the horizontal bars .24, 2 5 26 and the vertical bar 21. theirupper part projecting v r the outer s r enin ba ket he nc n d plate members 23 are outwardly extended, the extensions 23, alsobeing downwardly enlarged. A reinforcing bar 28 serves to support the. enlarged pa t 2.3 of the p a membe Thespaces, between the, bars [4, are adapted in such a way that stones of a diameter of 2 ems. and more are retained by them, while the mesh width of the screen wires l9 does not exceed 1 to 2.5. mms, depending on the conditions of the raw material.

Mounted .on the shaft 43, below the grate basketaiis the collecting plate 29 with a suitable space for-discharging the stones retained by the grate l4 and falling down; onto plate 29.

The rotary centrifuge is enclosed in a stationary casing 3| bearing on the frame 2 by mean o an le r 3." and c in eta-cy in rical out r- ;i rket 3 and a losure ring 32 on which is secured a covering plate 33 provided with a circular aperture 34 for feeding I the raw clay to be treated. Secured to the sheet iron cover 3| by means of screws and spacing sleeves 36 is the clay collecting plate 3'! whose upper part 33 is inwardly contracted.

Provided in the downward extension of the clay collecting plate 31 is the clay collecting funnel 39 serving to collect the clay slipping off from the clay collecting plate 3?. Suspended on pivots 4| at the lower edge of the collecting plate 3'! are sheet metal strips 453 which in their vertical position substantially cover the space between the sheet member 3'l and the funnel 39.

The operation of the apparatus is as follows: The raw clay entered through the feed hole 34 is seized in the innermost sieving chamber by the blades or vanes l6 driven by the motor 4 through the shaft 8 and centrifuged againstthe sieve M by which the coarse stones of a size of more than 2 cms. are retained and guided downwards, under centrifugal and gravity action, until they fall onto the disc 29 by which they are centrifuged beyond the reach of the funnel 39. The clay thus preliminarily purified enters into the central sieving space where the impuri ties e. g. above 1 mm. or up to 2; 5 mms., are retained by the screen wires IE on its passage through this screen the clay is homogenized and worked through, whereby aging of the clay is superseded, more particularly, if the amount of water contained in the clay is properly adjusted. The small limestones retained by this sieve will travel upwards, where they are discharged over the upper edge of the sieve, under centrifugal action. It may be that some of them are caught in the wires; however, their quantity is so small that it is sufiicient to have this screen cleaned once a day after the working period. The clay discharged from the centrifuge is deflected by the collecting wall 31 towards the funnel 39 from which it is carried off by means of wagons, conveyer belts, or conveyer worms.

In order to prevent the clay from sticking in the narrow slits of the sieve l9 it is necessary to have additional air pressure act upon the sieve. This air pressure is produced by the vertical plates 23. Owing to the fact that the upper portion of the plates 23 is bent at an angle of the air pressure is uniformly distributed in the spaces between the plates and the air is preventing from escaping in an upward direction.

In order to permit the air current to be eniciently discharged in a downward direction and to prevent the particles of clay from sticking at the clay collecting wall 3?, blast deflector plates 2| are provided, with their extension 22 behind the screen l9, at an angle of 45.

In order to prevent the mixing of clay and separated stones in the interspace provided for centrifuging the larger stones between the clay collecting wall 31 and the funnel 39, it is necessary to produce a downward air draft also in the space between the clay collecting wall 31 and the outer casing 3|, which draft is produced by the enlarged upper portions of the plates 23. The subsequent mixing of clay and smaller stones can also be prevented by strip-shaped sheet members suspended on the outer side of the clay collecting wall in such a way that their lower ends are outwardly moved by emitted stones only and will fall back to the border of the funnel by their own gravity.

The output of the separator may be adapted to the actual working conditions. It is determined primarily by the construction of the outer grate. In a separator having a grate passage 6 area of about 0.4 m. the output is higher than that of any conventional brick press or brick moulding machine. I

While the invention has been described in detailwith respect to a now preferred example and embodiment of the invention it will be understood by those skilled in the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. A centrifugal separator for the cleaning of raw material for ordinary ceramic ware, comprising a vertical rotary shaft, two sieving baskets concentrically arranged on said shaft, the outer basket having a smaller mesh width than the inner basket which is upwardly tapered, a collecting wall for the cleaned raw material surrounding the outer basket, and a horizontal disc mounted on the shaft below said baskets, for discharging the coarse impurities.

2. A centrifugal separator for purifying the raw material for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer basket having smaller sieving openings than the inner basket, a stationary collecting wall for the purified raw material encompassing the outer basket, and substantially vertically arranged vanes within the inner basket. 7

3. A centrifugal separator for purifying the raw material for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer basket having smaller sieving openings than the inner basket, a stationary collecting wall for the purified raw material encompassing the outer basket, and substantially vertically arranged vanes within the inner basket, the upper part of said vanes being forwardly inclined in the direction of rotation.

4. A centrifugal separator for purifying the raw material for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer basket having smaller sieving openings than the inner basket, a stationary collecting wall for the purified raw material encompassing the outer basket, and vanes substantially vertically arranged between the two baskets.

5. A centrifugal separator for purifying the raw material for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer basket having smaller sieving openings than the inner basket, a stationary collecting wall for the purified raw material encompassing the outer basket, and vanes substantially vertically arranged between the two baskets and projecting over the outer basket in an upward and outward direction.

6. A centrifugal separator for purifying the raw material for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer basket having smaller sieving openings than the inner basket, a stationary collecting wall for the purified raw material encompassing the outer basket, and vanes substantially vertically arranged between the two baskets and projecting over the outer basket in an upward and outward direction, the upper part of said vanes being forwardlyinclin'ed in the direction of rotation.

'7. A centrifugal separator for purifying the raw materi'al'for ordinary ceramic products, comprising a vertical rotary shaft, two sieving baskets concentrically mounted on said shaft, the outer" basket. having smaller sieving openings than the inner: basket, a stationary collecting wall for the purified raw material encompassing theouter basket, and vanes substantially vertically arranged between the two baskets and projecting over the outer basket in an upward and outward direction, each vane being stilfenedlin at least one of the horizontal and vertical directions.

' 8. In a centrifugal separator for purifying the raw'material for ordinary ceramic products, "a vertical rotary shaft, two sieving baskets, concentrically mounted on, for rotation with, said shaft, a collecting wall for the purified raw material surrounding the outer basket, a disk rigidly connected to the shaft-and carrying the basketsjthe upper rim of the outer basket being supported on said disk thus forming a supporting structuretogether therewith, and vanes forwardly inclined in the direction of rotation, within this supporting structure.

' 9. In a, centrifugal separator for purifying the raw-'materialfor ordinary ceramic products, a

vertical rotaryshaft, two sieving baskets, concentrically mounted onjfor rotation with, said shaft, a collecting wall for the purified raw material surroundingthe outer-basket, a disk rigidly connected to the shaft and carrying the baskets, the'upper-rim of the outer-basket being supported on said disk thus forming-a supporting structure together therewith, and vanes forwardly inclined in the direction of rotation, within this supporting structure, said vanes extending inwardly up to the outer basket.

10. A centrifugal separator for the cleaning of raw material for ordinary ceramic ware, comprising a vertical rotary shaft, two sieving baskets concentrically'arranged'on said shaft, the outer basket having a smaller mesh width than the inner basket, a collectin wall for the cleaned raw material surroundingthe outer basket, a -stat10n ary discharge funnel arranged below the sieving baskets, said funnel having an upper diameter approximately equalizing that of the collecting wall, and plates pivotally suspended from the lower edge of the collecting wall and substantially covering the vertical interspace between the collecting wall and the discharge funnel.

11. A centrifugal separator for the cleaning of raw material'for ordinary ceramic ware,'com'pris ing a vertical rotary shaft, two sieving baskets concentrically arranged on said shaft, the outer basket having a smaller'mesh width than the inner basket, a'collecting wall for the cleaned raw material surroundingthe outer basket, a stationary discharge funnel arranged below the sieving baskets, said funnel having an upper edge with a diameter approximately equalling that of the collecting wall, the upper edge of said funnel being 'spaced'from the lower edge of said wall to form an opening, and plate means'secured to said shaft for the discharge of coarse impurities from said separator through said opening.

12. A centrifugal separator as in claim 11, further comprising said inner basket having a downward outwardly taperim wall, and said outer basket having an upwardly outwardly tapering wall. 7

KARL, LUDJVI'G GEREC' T.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 351,613 AlidBl'SOIi Oct. 26, 1886 942,599 Williamson M Jan. 29,1907

1,839,941 Zelezniak Jan. 5, 1932

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