DE2349941A1 - METHOD AND DEVICE FOR WET FILTERING - Google Patents

Description

A 33 868

Hurskauskone Oy, '

Bavitie 3,

15860 Salpakangas

FIHELAED - ''

Method and device for fine sieving

The invention relates to a continuous process for fine sieving of solid substances finely distributed in a sludge. The invention also relates to an apparatus for carrying out this method.

Is is well known in various fields of the Process industry a method for 'wet sieving' and a corresponding one Device are very much needed, with the achievable Grain fineness "(cut size) when sieving within a Range, for example, between .100 and 500 microns, In the processing of ore pulp and mineral sludge, which by Is produced, it is also "important that the The performance of the screening device is large, for example 10 to 50 tons of dry load per hour. In addition, it is assumed that the sieve surface always remains open and that it is subject to the respective loads exerted on it.

40 98 15/0382

BAD ORIGINAL -P-

withstands loads and wear and tear. In addition, it is assumed that significant changes with regard to the coarseness and: with regard to the amount of material fed in, no significant effects on the Possess quality of fine-grained product.

The present invention is therefore based on the object of a method for fine sieving of Ifaß and a method for carrying it out Specify the device that is used and that meets the requirements in the functional area specified above.

This task is, in the case of an ancestor, the one specified at the beginning Kind according to the invention in that the sludge to be screened is driven into the shape of a sludge ring and this is one Forced rotational movement: subject to a vertical axis - such that the outer layer of the Schlanm-ring at a selected constant angular velocity with respect to a concentric cylindrical screen surface is lifted off. The sieve drum itself does not rotate here. The one at the sieving Eorn fineness achievable by means of a given sieve area can be adjusted by adjusting the angular velocity of the outer layer of the formed mud binge to another " selected constant value is adjusted.

According to a further development of the method according to the invention for fine screening of hate, this can also be carried out in the manner that the sludge to be screened in the shape of a mud ring

409815/038 2

"3 _ BAD ORiGIfJAL ^e >" ■ -

is driven and thereby subjected to a forced Botationsbewegung about a vertical axis, such that the central strip of the outer layer of the sludge Einges at a selected constant angular velocity in relation to a concentric cylindrical Siebfläche.angehoben is, this · Fra-ction passes through the sieve and forms the finely sieved product, while the top strip of this layer comes off as a fine overflow product and the bottom strip of this layer is drained down as a coarse-grained product (sand grit).

In the described Verführensweise arises that interfering effects the _f-stress and wear effects may be exerted on the Siebouerfläche on the result of the screening process of the material and ITberkorngröße infolge.you virtually completely come in omission, namely because the vertical directed screen surface does not need to carry the material to be screened.

To carry out the method according to the invention for I% β-sieving Wyrp, a device is preferably used which has the following characteristic features: The device has a stationary, open container with a cylindrical upper section and a conical lower section. A sieve drum forms part of the cylindrical upper portion of the device. Us to effect the fundamental erosion movement of the Schlanü-Binges around the vertical axis of the device,

409815/0382

BATH·

this device has a centrally and vertically arranged drive mechanism with vertically aligned brushing wings is provided, which control the rotating movement of the sludge inevitably in such a way that it is on a circular path at a selected constant angular velocity circulate in the immediate vicinity of the inside of the sieve drum, but do not touch the drum itself. Around To ensure continuous operation, the device is still equipped with the necessary means to initiate the Loaded goods as well as for collecting and discharging the fine-grained and coarse-grained products.

The mechanism of the device according to the invention can still be used to be completed by such a manner of training that at the same time it acts as an effective and well-adapted distribution device for the load. For this purpose is the Mechanism provided with a disk-shaped distributor plate or with a conical distributor element, which about the vertical axis of the device at the selected angular velocity of the mechanism rotates. The vertically aligned brushing wings are preferably on the band of the distributor device appropriate. The basic rotating movement will then correspond to the movement of that section of the mud body limited, which is held above this distributor device «The diameter of the cylindrical upper section the device and that of the sieve drum are sufficiently larger than the diameter of the distributor device so that the

409815/0382

BADORfGiNAt

the resulting slot in between sufficiently wide outflow channel for the coarse-grained material "forms, which drains downward into the conical lower portion of the device. Because this annular channel is made even further, the performance of the device or their capacity for the coarse-grained product can be increased as required. Depending on the sieving conditions the distribution device either arranged below the level of the lower belt of the sieve drum, or at the same level or but below. In order to allow the material to be screened to be mixed, the device can also be equipped with special mixing devices be equipped, which are arranged above the distribution device.

Further refinements of the device according to the invention emerge from the subclaims.

For a more detailed explanation of the construction and the puncture method of the device for fine sieving according to the present The invention serves the following description of an exemplary embodiment, reference being made to the accompanying drawings will. In this, a vertical section through a device is shown schematically.

As can be seen from the drawing, the device for sieving as the main component a fixed, open Container 1, which has a cylindrical upper portion 2 and

4 098 1 5 / 0.3 82-

BATH

has a conical lower section 3. A cylindrical screen drum 4 comprises the middle and / or the upper region of the cylindrical upper section of the device. The most essential components of the mechanism 5 of the device are a vertically extending shaft 6 which is arranged in the central axis of the device, a disc-shaped distributor plate and a number of vertically directed brushing wings 8 which are attached to the edge of the distributor plate. The free vertical slot between the outer edges of the blades 8 and the inner surface of the drum 4 has a substantially constant width. The known means which serve to support the mechanism and to set it in rotation are not shown. As further essential components, the device has a centrally arranged ring 9 serving for loading, furthermore a channel 10 or the like which surrounds the upper section of the device and serves to sanimulate and drain the fine-grained product, one between the distributor plate 7 and the cylindrical upper one Channel 11 extending through section 2 of the container which serves to drain the coarse product from above the distributor plate 7 into the conical section 3, and finally a valve assembly 12 of any known construction through which the coarse product is drained. To keep the settled sand grit in a continuously flowing state also in the lower part of the conical section 3, wings 15 can be arranged at the end of the shaft 6. Dilution and / or washing water, which is often required for wet sieving, can be fed into the conical section 3 through a line 14

409815/03 82

_ 7 _ BAD Üp ^

be initiated. Furthermore, a number of τοη overflow channels 15 can be arranged above the upper edge of the drum 4.

The actual sieve surface is preferably attached to a sieve plate of the so-called wedge-bar type, which consists of any suitable alloy, of .G-ummi or of plastic. The drum, which is formed τοη such a plate, is arranged in such a way that the trapezoidal rods of the plate Tertikai are aligned. The outwardly widening slots between the rods Terlauf also Yertikal. The inner surface of the drum is smooth. The sieve drum can be combined from a number of identical sieve segments. The preferred ratio between the drum height and drum diameter is 1: 3 to 1:10; the drum is therefore designed to be relatively flat. Knocking or vibration mechanisms known per se can be attached to the sieve drum, or else to the sieve segments or to a suitable frame supporting the sieve device, which help to keep the sieve surface open. In such a case, the sieve device is separated from the main body of the device by a flexible connection. To enable the operation of the mechanism described regulate the device may be equipped with a sensing device, the _Ee: ^ ulierungswirkung based on the height of the sludge ring above the distributor plate. 7 The mechanism is then put into operation when the sludge height has reached a certain upper limit. , -.

409815/0382

BATH

2343941 "

Me distribution plate 7 can be formed from a single plate? -or "but also from different plates or from elements that are arranged one above the other, as can be seen from the drawing inclined, stair-like arrangement results. If desired, a free tree can be left between a pair of plates, this rauia communicating with the conical section 3 through openings in the respective plate or in the plates below be constructed "that they imitate the inlet of a centrifugal pump in order to bring about a forced sludge circulation downwards and outwards. The distributor plate or a number of plates can also be replaced by a downwardly widening S ₉ conical distributor element" A desired number of mixing devices 16 can be arranged in the space above the distributor plate 7.

The device sur lass sieving according to the present invention works as follows;

The material to be screened is introduced into the middle part of the device through the charging ring 9. The charging material spreads out in the form of a layer above the plate 7, always over a range of 360 degrees. The coarsest and heaviest grains settle in the bottom. Layer from ₉ above

. '_ ■' k 09815/0382

_ 9 "

BAD OFUGfNAU

wherein the particulate material forms a sludge layer _D All of the material above the distributor plate 7 is driven in a rotating movement about a vertical axis by means of the drive mechanism of the device brought about by the _s attached to the mechanism vertically directed and inevitably actuated Bestreichungsflügel 8 _p reaches the rotating movement of the mud a desired, constant angular speed at the outermost band of the mud bing _o At the same time, the acting forces ₉ cause the mud to rise up to a certain height along the vertical cylindrical wall. This outer layer of mud is at the selected constant angular velocity with respect to the non-rotating sieve surface lifted the preferred ^a ls peripheral speed designating G-eschwindigkeits range is from O ₅ 5 to 5ia / so Under these circumstances and at a low centrifugal iCraft the Hauptmas® is d he fine particles easily through the screen in the form, of a relatively thin slurry _s in the channel 10 flows _o The part of the substances read; " which does not pass through the sieve, flows through the channel 11 downwards into the conical section 3 and is from here as the heavy-grain end product, by regulating by means of the valve 12. _? discharged from the apparatus, in those cases in which the middle strip of the sludge ring screening is subjected alone, the top strip may be through the channels 15 as a fine overflow - product flow out = This fraction also includes annoying Holssplitter _B SCBC at a treatment of ore from underground pits _c

/ Π £ $ P 1 C / Λ '2- a ο

<■■: wc? υ ( QS U ύ> ο &.

~ 10 = - ■ BAD QBiGfNAL

■ - ίο - '

With regard to the actual sieving process, it is already known that by choosing the speed difference between the sieve surface and the sludge layer in such a way that a suitable value is achieved, the grain fineness that can be achieved by sieving will be significantly lower than the free sieve opening «, Usually you want to achieve a grain fineness. containing about 1/2 tone of the length is the wire-passage opening "This principle of screening is useful because it achieves by means of a relatively sieve opening wide possible is _s to achieve a substantially smaller grain fineness" In the eriinaungsgemäßen sieving process, the Additional advantage that the greater the fechwincig-Leit ρ at which the Schla-iam layer is lifted in relation to the sieve surface, the better the grain fineness that can be achieved with a given sieve surface, _etc.

Since it is essential, from the point of view of the steepness of the sieving, that all fine-grained particles have the opportunity to also go on the lower layer formed by the coarse-grained particles in the actual Sahlüein-Sing, it is advantageous to do so The layer of coarse particles moving in uniform proximity to the upper side of the VerMierplatte 7 is opened ;: mixed and washed in sufficient degrees _o This effect can now be achieved more completely because the distributor plate is designed in a step-like arrangement As shown in the drawing, a remover of small grains can furthermore be advantageous if some of the washing and / or thinning water is thrown through the open spaces between the

f η Ο- ^c > 1 P / Γι. '.' e · "

t »u fe ö I y / <j ν © ά,

BATH ORIGINAL

■ ■ ■ '' 2348941-

Plates in distributor element 7 can flow from the conical section 3 into the tree above the plate. A counter flowing Stron from your inventory of water added through the annular channel 11 passing upwards against the wall of _t due to its gravity settled material contributes to an effective legged of the coarse-grained product with _o

It has already been pointed out that the coarse-grained. The material does not stress the vertical screen surface. Furthermore, it should be noted that in the present method the wear of the screen surface due to coarse grains is largely eliminated the device can be changed at selected time intervals in order to compensate for the wear on the corners of the bars of the screen. Since the wear is most strongly directed against the inner ^ lower band _? It is also useful that the drum can be turned over as a unit from top to bottom _Q

Essential regulations within a given device are directed towards the regulation of the inlet quantity, on the regulation of the sand outflow quantity ₉ on the regulation of the botation speed of the drive mechanism, on the regulation of the washing and dilution water and finally on the regulation of the operation of the knocking and / or vibration mechanism "A number of water jets or nozzles ^ which are directed against the sieve drum • from the outside inwards ^ can also be used to help keep the sieve open", 4098 15/0382

- 12 BAO.

The method for fine wet sieving according to the present Invention and the device used for its implementation are suitable for the treatment of all such materials, which can be subjected to wet sieving. When treating mineral products, grain fineness can easily be achieved within the range between 100 and 500 microns. Of course, sieving processes are also included finer or coarser grain sizes than those specified above are possible.

The scope of the present invention can be indicated by the following demonstrating preliminary experiment:

It became Zyklon-Gries, which came from an industrial, closed Μείΐ cycle has been obtained in a wet sieving test facility treated as essentially described above. The sieve drum used had one Inside diameter of 75 cm, an effective height of 10.2 cm and a total area of 0.24 m used for screening. The width of the sieve slot in the drum was 500 microns. In a typical test the following results have been obtained:

Infeed rate 13.2 t / h (drying hourly bins) Fine-grained product 10.6 t / h (dry hourly bins)

Specific sieving capacity 44.2 t / mh fine-grained product Fine-grained product 95 ° continuously 255 micron sieving Slope of sieving at 255 micron 36.7 ° Slope of sieving at 74 micron 95.0 fo.

4 09815/0382

1 ⁷ I ι _ •

For purposes of comparison, it can be stated that "with the specified grain fineness the corresponding specific wet sieving" performance in t / mh of a conventional sieve drum, * the.
a slightly inclined axis rotates, is in the order of magnitude of 1 ^c p of the value that has been found in the present experiment.

- patent claims -

409815/0382

Claims (8)

A 33 368 claims 1. Method of fine sieving of hate fine in a sludge distributed solid substances, characterized in that the sludge to be screened is driven into the shape of a sludge ring and is thereby subjected to a forced rotational movement about a vertical axis, such that the outer Layer of the mud ring at a selected constant ¥ inke! Speed in relation to a concentric cylindrical Sieve surface is lifted off. 2. The method according to claim 1, characterized in that the mud to be sieved into the shape of a mud ring driven and here a forced rotational movement by one vertical axis is subjected in such a way that.3 the middle Strip the outer layer of the mud bing on one selected constant angular velocity is lifted off in relation to a concentric cylindrical sieve, xfobei this fraction passes through the sieve and the finely screened product forms, while the topmost strip of this layer comes off as a fine overflow product and the lower stripes of this layer downwards as a coarse-grained one 409815/0382 - 2 BATH ORIGINAL Product is drained. 3. The method according to any one of claims 1 or 2, characterized in that that the grain fineness achievable by sieving (cut size) is adjustable in that the angle is visible. speed of the rotating sludge layer to another constant Value is adjusted. 4. Apparatus for performing the method according to one of the of claims 1 to 5, characterized by the following Components: a) a stationary container (1) with a cylindrical upper section (2) and a conical lower gate (3), b) a cylindrical sieve device (4) which is arranged in the cylindrical upper gate of the container (1), c) one arranged coaxially with the vertical axis of the device Drive mechanism (5) j of the vertically aligned Brushing Wings (8) are seen in immediate trouble on the inside of the cylindrical sieve device (4) are arranged, and d) means (9) for introducing the load as well as Means (10 or 12) for collecting and discharging the fine-grained or the coarse-grained fractions. 409815/0382 · \ - ■ BAD ORiOiIMAL - 3 - 5. Apparatus according to claim 4, characterized in that the vertical stroking wings (8) on the band one disk-shaped or conically shaped distributor device . tung (T) are appropriate. 6. Apparatus according to claim 4 or 5 »characterized in that overflow channels (15) are provided which are arranged above the upper band of the cylindrical screen device (4). 7. Device according to one of claims 4 to 6, characterized in that that means are provided for changing the direction of rotation of the drive mechanism (5). 8. The device & ö ch any one of claims 4 to 7, characterized daö, a sludge amount determining device ISSI provided by means of which attached to the screening device (4) Ätfclopf or vibration MechaniBmen _t are adjustable. ; ■■■■ ', 409815/038 2.