RU1794496C - Rotating probability screen - Google Patents

Abstract

Usage: for the classification of bulk materials in mining, construction. industry, in the production of mineral fertilizers. SUMMARY OF THE INVENTION: the screen comprises rod screening surfaces rotating in a horizontal plane, estrus for collecting separation products, and loading and unloading nozzles. The sieving surfaces are made in the form of disks consisting of concentrically arranged rings. Fastening the spiral wire under the rods of the peripheral rings of the screening surface is new in the screen. An additional screening surface is installed on top of the vertical shaft, made in the form of a truncated cone of radially spaced rods and equipped with a conical distribution cap. 2 ill. (L

Description

The invention relates to the construction, mining, coal industries, can be used in the manufacture of mineral fertilizers, and is intended for the classification of bulk materials at a grain size boundary of 2-15 mm.

The Ro-Pro rotational probability screen is known for separating coals with a moisture mass fraction of 8-14%. The principle of operation of the machine is based on the action of centrifugal forces on the particles of the classified material with a fusible increase in the size of the holes of the rotating screening surface.

However, in this apparatus, the screening surface is not used rationally, because a significant part of it is not working. This leads to a decrease in the productivity of the apparatus, as well as to a decrease in the efficiency of classification, since the length of the screening surface, and hence the residence time of the material on it, is not long.

The closest in technical essence is a centrifugal classifier having several layers of string rotating sifting surfaces made in the form of disks, which consist of concentrically arranged

1

ABOUT

N 4 O O

rings, while the strings of the screening surfaces are fixed on each ring with a deviation from the radial direction,

Centrifugal classifier provides an effective classification of bulk materials, including wet.

The disadvantage of this apparatus is the low productivity and low classification efficiency, due to the fact that all the source material is fed to the first Rus screening surface. The largest particles of material moving along the screening surface to its periphery make sieving through the holes of the smallest particles difficult. Therefore, the separation products are inter-clogged,

The purpose of the invention is to increase the productivity of the apparatus and the efficiency of the screening process.

This goal is achieved by the fact that in a rotational-probing screen, including a housing, a vertical shaft with rod screening surfaces fixed on it, made in the form of disks consisting of concentrically arranged rings, separation collection collecting leaks, loading device and unloading nozzles, an additional working surface is fixed on a vertical shaft, made in the form of a truncated cone formed by radially arranged rods and ending with a cone-shaped cap, and under the rods of the screening ring of the largest diameter, spiral distribution elements are additionally installed.

Thus, in a rotational probabilistic screen, by installing an additional screening surface, the initial source material can be divided into two streams and fed to different points of the main screening surface: small material to the beginning, and large material to the middle. This will reduce the residence time on the main screening surface of the largest particles. Dividing the main screening surface into a series of annular sections with a different number and spacing of the rods makes it possible to more fully use the area of the screening surface, making the apparatus more compact, more efficient. :

The fastening under the rods of the main screening surface of the helical elements allows to reduce the ingress of large flat particles of classified material into the sublattice product.

Particles of classified material move along the screening surface

from the feed point to the periphery under the action of centrifugal force, the stepped shape of the profile of the main screening surface allows the largest particles to be cleared of adhering fine particles upon impact on the rods.

The different number and pitch of the rods in different annular sections of the main screening surface allows us to take into account the difference in centrifugal forces acting on the particles of the classified material located on them. The width of the slit of the screening surface increases from the center to the periphery of the screening surface, which also avoids clogging of the material.

In FIG. 1 shows a general view of a rotational-probabilistic screen; in FIG. 2 is a plan view of the main screening surface.

The rotational-probable screen includes a loading device 1, a conical cap 2, an additional working screening surface 3,

5 mounted on the main screening surface 4, having in the central part the same cone-shaped cap 5, roller bearings 6, vertical shaft 7, bevel gears 8, gear motor 9.

0 The screen is equipped with estruses for collecting large product 10, with unloading nozzles 11 and estrus for collecting small product 12 with unloading nozzle 13.

The main screening surface

5 (Fig. 2) is divided into a number of annular sections II, III, IV, the Central section 1 is closed by a cone-shaped cap 5, The annular sections II, III, .IV are made of a set of radially spaced rods 14, under which they are fixed. spiral-shaped distribution elements 15 in the form of a wire or strip.

The roar (Fig. 1) works as follows. Source material (IM) through-.

5, the load ring 1. Is fed onto a rotating cone-shaped cap 2 and gravity is poured onto a rotating additional working surface 2. The largest particles with additional

0 the working surface 3 is poured into the middle part of the main screening surface 4, where, under the action of centrifugal force, they move to the periphery and fall into the estrus of the large product 10. The undergrowth of the 5th additional screening surface falls on the rotating cone-shaped hood 5 and moves along the entire length under the action of centrifugal force main screening surface 4. During its movement

on the main sifting surface, particles of material having a particle size sufficient to possibly pass through predetermined holes (slots) are sifted through a rotating sifting surface under the influence of gravitational force 4. Despite the fact that the gap width is different in different parts of the sifting surface, due to different peripheral velocity, the probability of passage of particles of a given size is close in value.

The greater the difference between the peripheral velocity of the screening surface at a given point and the tangential component of the particle velocity, the less is the probability of screening, with other basic conditions.

The particle size of the material sifted through a rotating surface depends on the relative speed of the particles and rods V, the width of the gap between the rods I, the diameter of the rods DC and can be determined from the formula:

i v (d-Dc)

(1)

where do is the fineness of a piece of material falling into the sublattice product, m

As can be seen from formula (1), when the number of revolutions of the screening surface n changes, the separation boundary do also changes, which is an undoubted advantage of the apparatus.

The under-sieve product (M) is discharged continuously through the nozzle 13, and the under-sieve product (K) is also discharged continuously from the apparatus through the nozzles 11.

The minimum required number of revolutions of the screening surface, ensuring the movement of the material along it, does not depend on the mass of particles, but depends only on the point of material supply to the screening surface g and the friction coefficient of the material on the rods kT:

. 30 V kn g, - / n --jf- - -. rpm

(twenty

A higher rotational speed of the screening surface gives a smaller separation boundary and vice versa.

The screening process is carried out at a constant rotational speed of the screening surface and on it the material can be precisely divided into two classes of fineness.

The need to install additional elements on the screen in order to increase productivity and

its effectiveness arises only with an increase in the scale of the apparatus.

Dividing the screening surface into a number of annular sections with different number and pitch of rods allows, increasing their diameter, to increase the rigidity of the design of the screening surface, reduce the gap between the rods, and therefore the number of revolutions 0 of the screening surface, increase the working area of the screening surface , therefore, the performance of the apparatus and the efficiency of screening. ,

The diameter of the screening surface 5 of the screen tested by the authors was 0.8 m, the diameter of the rods was 4 mm. the minimum distance between the rods is 1 mm; the maximum is 15 mm. their angle of inclination to the horizontal is 4 °. The diameter of the base 0 of the cone-shaped hood is 0.3 m. The installation of an additional screening surface on a screen of such compact dimensions is inappropriate, according to the authors, because the length of the screening surface 5 is only 0.25 m.

The results of the separation of crushed sylvinite ore BKRU-2 at Uralkali are presented in Table. 1, 2, 3.

As the data in table. 1, 2, 3 0, the presence of spiral-shaped distribution elements under the screening surface makes it possible to reduce the mass fraction of particles larger than the boundary grain in the sublattice product and increase the classification efficiency.

The pilot industrial screen developed by the authors has the following technical characteristics:

Productivity 250 t / h 0 Separation limit 3-6 mm Classification efficiency not less than 75% Area of the main screening surface 3.5 m2 5 Diameter of rods, for the main screening surface 8 mm For an additional working surface 14 mm 0 Diameter 1 of the central

section 0.6 mm Diameter II of the annular section 1.1 m Number of rods 216 pcs. 5 distance between the rods;

mln 0.7 mm max 8 mm Diameter III of the annular section 1.6 mm number of rods

279 pcs

Distance between rods

mln 4.3 mm max 10 mm

The diameter of the IV annular section 2.2 mm The number of rods 345pcs. The distance between the rods:

mln 6.5 mm max 12 mm

Screen height 2.5 m Screen diameter 2.6 m The angle of inclination of the rods to the horizontal of the main screening

45 ° 8 kW

Zt

0

5

surface 4 °

additional screening surface

Electric motor power

Screen weight with drive

no more

The developed screen will find application in the classification of potash ores.

A comparison of the developed screen with the Ro-Pro screen (1) speaks in favor of the first, because with a smaller diameter of screening the surface (2.2 m and 2.4 m, respectively), it provides 50 t / h greater productivity.

Claims (1)

The claims A rotational-probability screen including a housing, a vertical shaft with rod working screening surfaces fixed to it in the form of disks consisting of concentrically arranged screening rings, estrus for collecting separation products, a loading device and discharge pipes, which distinguish that, in order to increase The results of the separation of crushed sylvinite ore on a rotational-probability screen without spiral-shaped distribution elements under a screening surface, rpm performance and efficiency of the screening process, it is equipped with an additional working surface made in the form of a truncated cone mounted on a vertical shaft, formed by radially spaced rods, with a cone-shaped cap fixed to it, and spiral distributing elements are additionally installed under the rods of the largest screening ring . Table 1 The results of the separation of crushed sylvinite ore on a rotational-probable screen with spiral-shaped distribution elements under a screening surface, rpm (new technical solution) Technological indicators of the screening process table 2 Table 3 Editor A. Behr FIG 2 Compiled by O. Chernyh Tehred M. Morgenthal Corrector N. Milyukova