RU2668603C1 - Vibration screen - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to loose material classification and may be used in mining, metallurgy, construction industry, etc. Vibrating screen contains a carrier box with side surface mounted on elastic supports and kinematically connected vibrating drive, and also contains a sieve. Sieve is provided with vertical longitudinally oriented perforated partitions, which together with the bottom of the sieve form sieving chutes separated from each other by gaps for express unloading into throughproduct of material sieved between the holes of perforated partitions. Perforated partitions have a wavy form in plan. Holes of perforated partitions have the same characteristic dimension as the holes in the bottoms of sieving chutes. Holes in the bottoms gaps for express unloading have a larger characteristic dimension. Bottoms of sieving chutes and the bottom of gaps form a single bottom of the sieve. Characteristic dimension of the holes in the bottoms of mentioned gaps is 1.5–3.5 times larger than the size of the holes in the bottoms of sieving chutes.EFFECT: increase in specific performance and screening efficiency.1 cl, 2 dwg, 1 tbl

Description

The invention relates to a device for the separation of bulk materials by size and can be used in the mining, metallurgical, construction industries, etc.

In vibrating screens, the separation of raw materials by a given size occurs under the influence of vibrations due to the passage of small pieces through the screening surface (with unloading into the so-called sublattice product), and by unloading pieces larger than determining the size of the holes in the screening surface to the top (overgrate product )

In the context of this application, the term “determining hole size” (characteristic size) means: for round holes, its diameter, for square holes, the side of the square, for rectangular holes, the short side of the rectangle, for regular polygons, the diameter of the inscribed circle, etc.

Designs of a vibrating screen consisting of a box (supporting structure) based on elastic elements, vibration exciters and a working screening surface are known and widely used. A sieve installed horizontally or at an angle to the horizontal, and made in the form of a plate with a hole size selected for classification, is used as a working surface [Reference ʺ Vibrations in Engineering ’ed. E.E. Lavendela. - M.: Mechanical Engineering, 1981, v. 4, p. 349-352]. Bulk material, moving along the sieve under the action of vibration to the discharge end, is sifted - particles with a particle size less than the determining size of the holes pass through a sieve. One of the representatives of ʺclassicalʺ type screens is the GIL 051 Inertial Screen [for information, see the Internet https://vibromotors.ru/files/docs/manuals/astek/11_grohot_inercionnyy_gil052.pdf]

The relatively low efficiency of separation by size on screens with flat sieves is especially often observed at high specific loads of the raw material entering the sieve, and, above all, when screening a relatively light material, for example coal. In these cases, screening is forced to take place in a thick layer of material to be separated, and it is obvious that the fine fraction of material to be passed into the lower (sublattice) product must first pass through a layer of larger particles, i.e., pass the stage of vertical vibrational segregation. This naturally reduces the speed and efficiency of the separation of the material on the screen.

This disadvantage is eliminated by using the developed screening surface of the sieve without increasing the size of the sieve in the plan. So in the patent US 5551575, publ. 09/03/1996, a screen is described with a corrugated sieve surface, including the most developed surface with rectangular corrugations, through the vertical walls of which the material is also sifted. In this case, the holes in the vertical walls and on the horizontal surfaces of the sieves are the same, and since the efficiency of sifting through straight vertical walls (along which the material slides in an even flow, heading towards the discharge end) is significantly lower than through horizontal ones, the overall screening efficiency does not increase significantly.

As a prototype adopted Vibrating screen described in patent RU 2616042, publ. 04/12/2017. The sieve of the screen also has a more developed surface than a flat sieve, since it has the form of a tray (trough) with inclined side screening surfaces. However, in contrast to US Pat. No. 5,551,575, a constructive technique is used to increase the efficiency of screening through the side screening surfaces, namely, determining the size of the holes of the side screening surfaces is less than determining the size of the holes of the bottom of the gutter. The increase in screening efficiency in the prototype is due to the physical phenomenon of a decrease in sliding friction and internal friction in a mixture of granules of bulk materials with a decrease in the content of small grains (fractions) in a polydisperse mixture when some of the fine fractions are removed into the sublattice product through vibration screening through lateral inclined surfaces of the sieve. However, as in the design described above in US Pat. No. 5,551,575, the side walls of the gutter are flat, the sifted material freely slides along them with little mixing and, accordingly, with a low probability of screening of the under-grid class through these surfaces.

The basis of the invention is the task of expanding the arsenal of means and creating a new and relatively simple construction of a vibrating screen with increased screening performance, adopted per unit area of the sieve bottom. Achievable technical result - increased screening efficiency.

The problem is solved in that the vibrating screen contains a supporting box mounted on elastic supports with a bottom and sides, and a kinematically connected vibrator, and also contains a sieve. It differs from the prototype in that the sieve is equipped with vertical longitudinally oriented perforated partitions that divide the sieve into alternating functional zones:

- sieving gutters,

- the gaps located between the sieving troughs for express unloading into the sublattice product of the material sifted between the holes of the perforated partitions.

In this case, the perforated partitions (walls of the gutters) have a wavy shape in plan, their holes have the same determining size as the holes in the bottoms of the sieving gutters, and the holes in the bottoms of the gaps for express unloading have a larger determining size.

In the context of this application, express unloading of an under-sieve product is understood to mean its unloading under the action of gravitational forces at maximum speed through openings in the bottom of the sieve in the gaps between the sieving gutters, practically without lingering in these gutters, and without forming a layer of material in them.

In a preferred embodiment, the determining size of the holes in the bottoms of said gaps is 1.5-3.5 larger than the size of the holes in the bottoms of the sieving troughs.

The maximum value of the specified interval is determined by the preservation of the strength characteristics of the sieve.

In order to better demonstrate the distinguishing features of the invention, as examples, not having any restrictive character, the preferred embodiment is described below with reference to the vibration screen shown in the drawings: FIG. 1 is a general view of a vibrating screen (schematically), FIG. 2 - sieve design (fragment).

The vibrating screen contains a carrier box 1 with sides mounted on elastic supports 2, and a vibration drive 3 kinematically connected to the box 3. The screen 4 is equipped with vertical longitudinally oriented partitions 5, which have a wavy shape in plan. The partitions 5 divide the sieve into sieving troughs 6, separated from each other by gaps 7 for express discharge into the sublattice product of the material sifted between the holes of the perforated partitions.

The sifting grooves 6 (with the exception of the grooves adjacent to the sides of the screen) have a constant cross-sectional length, that is, the waves of the partitions have a "constant amplitude" and "in-phase".

The height of the partitions is guaranteed to exceed the height of the bulk layer.

The bottom of the grooves 6 and the bottom of the gaps 7 form a single bottom of the sieve 4 and can lie in the same plane. The holes in the perforated partitions have the same determining size as the holes in the bottom of the sieving grooves 6, and the holes in the bottom of the gaps 7 are significantly larger. The shape of these holes does not matter. Their purpose is to provide the fastest possible removal of material falling into the gaps 7, sifted through holes in the partitions 5.

A power distributor may be provided in the loading zone to ensure uniform feeding of the material layer. At the same time, the design of the screen excludes the possibility of the screened material getting into the gaps 7 in the loading zone (for example, special screens, or plates, buried gaps from above, etc.). Under the carrier box, a collecting box for the under-mesh product (not shown) can be installed.

During the operation of the vibrating screen, the bulk material to be screened is fed into the loading part of the screen. Depending on the properties of the material (coarseness of fractions, humidity, bulk density, etc.), the layer thickness can reach 0.9 of the height of the partitions 5. Under the action of vibration created by the vibrodrive 3, the material moves along the sieving grooves 6, a small class passes through the holes the bottom of the grooves 6 is discharged into a collecting box for the undergrate product, and a large fraction of bulk material passes through the grooves 6 and unloaded through its open end. At the same time, the small class is also sifted through the holes in the partitions 5 and, falling into the gaps 7, wakes up through the holes in the bottoms of the gaps with maximum speed, practically not lingering in the gaps. The wavy (zigzag) shape of the partitions, and, accordingly, of the gutters, contributes to the mixing of the material, since they impart a transverse component to the speed of movement of the material, which increases the likelihood of contact of the fine fraction with the holes in the partitions. The movement of the sifted material along the curved surface of the partitions contributes to the appearance of centrifugal accelerations, which press the material against the walls, and improves the passage of the fine fraction through the holes in the walls. Thus, there is an additional possibility of efficient removal of material sifted through vertical partitions into the grating that enters the gaps, from which it is unloaded (without delay) unloaded.

Below is an example of implementation and a table confirming the achievement of the declared result. The tests were subjected to a vibrating inclined screen with a circular trajectory of the box. The area of the mirror box in the horizontal projection (projection on a horizontal plane) is 0.5 m ² . The tests were carried out on a screen using a sieve of the design described above with vertical longitudinally oriented perforated partitions wavy in plan. To confirm the claimed result, comparative tests of the same screen were performed, but with a sieve, the design of which is described in the prototype. The determining size (diameter) of the holes of the screening surfaces is 0.315 mm; 1.25 mm; 3.0 mm The starting material for testing was screenings for the production of crushed granite with a grain size of 0-5 mm.

The classification of the source material on modified and perforated sieves was carried out in the range of the following parameters of the screen:

- oscillation frequency: 13, 25-24 Hz (795-1200 count / min);

- amplitude of oscillations: 1.2-2.0 mm;

- angle of inclination of the sieve: 10-14 °.

A sample of material with a natural moisture content of 4% with a constant output feed rate in the range of 2-12 t / hm ² , which was ensured by the use of an adjustable vibration feeder, was fed to the screen.

Screening efficiency by size classes was calculated by the generally accepted method [see Vaysberg L.A., Kartavy A.N., Korovnikov A.N. Screening surfaces of screens. - St. Petersburg, ed. VSEGEI, 2005, pp. 22-24.]

The highest values of specific productivity calculated per unit area of the bottom of the sieve and the efficiency of the classification process are shown in the Table.

The table shows that the screening efficiency when dividing by size 0.315-3.0 mm, with the screen parameters specified in the Table, an average of 1.8% higher than in the prototype. Specific productivity compared with the prototype is on average higher by 26%.

Similar values were obtained for other frequencies.

Thus, the total area of the sifting surfaces increases due to the use of the partitions described above, dividing the sieve into functional zones, with the same sieve bottom area (in the same dimensions), and due to the phenomena described above, an additional possibility of intensive removal of the sifted through the sieve product through vertical partitions of the material. This leads to an increase in specific productivity and screening efficiency.

Claims (2)

1. A vibrating screen comprising a carrier box with sides mounted on elastic supports and a kinematically connected vibratory drive, and also contains a screen, characterized in that the screen is provided with vertical longitudinally oriented perforated partitions, which together with the bottom of the screen form screening channels separated from each other each other with clearances for express unloading into the sublattice product of the material sifted between the holes of the perforated partitions, while the perforated partitions have a wavy shape in plan um, their holes have the same determining size as the holes in the bottoms of the sieving troughs, and the holes in the bottoms of the gaps for express unloading have a larger determining size, the bottoms of the sieving troughs and the bottom of the gaps form a single sieve bottom. 2. The vibrating screen according to claim 1, characterized in that the determining size of the holes in the bottoms of the said gaps is 1.5-3.5 times larger than the size of the holes in the bottoms of the sieving troughs.

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