RU2403990C1 - Device for classification of under-sieve material (sand) of screen aspiration system - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to grading of solid polydisperse to boundary grain size and can be used in mining and other industries. Proposed device comprises box with loading chute, sieve and under-sieve space, vibrator, frame and collector. Rectangular box is furnished with clamps, while under-sieve space is formed by taper-shape hopper accommodating two lines of dissectors attached to the hopper lateral walls and made from angle-pieces. Aforesaid horizontal collector is furnished with outlet underwater inclined pipes of pneumatic line and slit exhausts that represent horizontal pipes with slit-like holes arranged at 45 to the axis and above the first line of dissectors. Second line of dissectors is arranged along the axis of slit exhausts and between them. Hopper sidewall incorporates inspection glass. Each inlet inclined pipe of the hopper pneumatic line is furnished with disk gates. To create "boiling bed", air is forced from below the hopper by adjusted disk gate arranged on pneumatic line at the hopper bottom. ^ EFFECT: higher efficiency. ^ 4 cl, 8 dwg

Description

The invention relates to technologies and devices for separating solid polydisperse materials according to the boundary particle size in air and can be used in mining, chemical, metallurgical and other industries, as well as in the production of building materials.

Known sorting devices - screens for sieving metallurgical and other bulk materials on the canvas of a given size. The disadvantages of these devices are the difficulty of separating small pieces, clogging of holes with materials, intensive wear of canvases and holes. These shortcomings are eliminated in pneumatic classifiers. Equipment for the processing of bulk materials: Textbook, a series of Mining Engineering - 2005 (7).

A common drawback of these pneumatic classifiers is the need for increased speeds for removal from the material stream and pneumatic transportation of individual small fractions.

The most widely used method of screening on vibrating screens. Depending on the type of pathogen, they are divided into gyration, inertia, self-balance and resonance. Vibro Techcenter - CT, article “The use of multi-frequency screens in building materials enterprises”. The Internet.

The disadvantages of the method of screening on vibrating screens are the complexity of repair and maintenance, significant weight, the complexity of the design of the used screens. Working elements of vibrating screens are sieves. The disadvantages of metal sieves (wire mesh) include a short service life, significant replacement costs. Perforated solid sieves, as well as rubber reinforced and rubber continuous sieves are of high cost, require the installation of a special sowing pad, have low productivity, and the complexity of repair. A common disadvantage is the inability to clean the sieves when clogging and sticking the cells, which leads to a decrease in productivity and screening quality.

A known screen, including a bed, supports, on which cylindrical grates are pivotally mounted. One of the supports is installed in the bed with the possibility of reciprocating movement, and the hinges in the grid-irons are installed with the possibility of axial movement. Khrustalev M.I. Best practices for sand enrichment. Analytical review. - M .: Building materials industry, 1990, p.19-20.

A disadvantage of the known device is the possibility of jamming particles of material, the sizes of which correspond to the width of the gap between adjacent grates, which leads to a decrease in duty cycle, lowering the efficiency and productivity of screening.

A known method of separating material by size, implemented on a roll sieve (RU 2028836 C1, 07.24.1991, B07B 1/16, B07B 1/12). A known method of screening is to feed the source material into an inclined sieve with rolls longitudinally arranged along the course of mixing the material, on which the size of the starting material is classified and then the fractionated material is unloaded into bunkers located under the roll sieve. Roller sieves are a block of inclined rollers of variable cross section, decreasing from top to bottom. The roller working bodies are informed of the rotational movement with the same angular velocity so that each subsequent roller rotates in the opposite direction compared to the previous roller.

The disadvantage of this method is the low productivity, due to the fact that to prevent jamming of material particles between adjacent rollers rotating towards each other from the side of the working surface, their slotted holes are blocked, which reduces the duty cycle of the roll sieve and, accordingly, reduces cost. The opposite of the direction of rotation in the working area causes partial removal of grains from the slotted holes, which also leads to a decrease in productivity.

The disadvantage of existing classifiers with rotating additional mechanical devices is, in addition, structural complexity.

Partially, these disadvantages are eliminated in the known device - the classifier of lump materials (RU 2110028, 28.0S.1996, F27B 21/02, V07V 4/00), containing a boot chute above the boot window in the classifier housing and an aspiration window with an aspiration outlet installed in the side wall, as well as blow nozzles and an air distribution grill. When air is blown through the grate, the material loaded onto it is separated by the height of the layer into small and large fractions, the first of which move at an angle on the air cushion, and the second are mixed in the opposite direction by the grate. By additional blowing air from the side of the blasting nozzles through the falling (loaded) layer of material, partial blowing, dust and fines are achieved before they reach the grate, which facilitates the process of separation of small and large fractions on it in the short-term residence of the material in the loading zone.

The disadvantage of this device is, in particular, the insufficient efficiency of blowing with the help of blowing nozzles of dust and small fractions from the loaded (falling) layer of material due to insufficiently high rates of air blowing in the layer, which is due to the distribution of the falling material in a relatively large (free) volume in classifier camera. Partially, these shortcomings are eliminated in the closest in technical essence to the claimed device for classifying screen material (sand) of a screen suction system for a screen with a screen for vibrating a sieve for sieving sands developed by Stroytekhnika, St. Petersburg, where the particle flow rate in the screen space regulate by changing the bore in the pneumatic piping vibrating screen by turning the disk damper. Creating a vacuum in the screen promotes a more intensive penetration of particles through a sieve, thereby reducing clogging of the nets with a sticky layer of material or irregular particles. Particles of the boundary size, which are in dynamic equilibrium in the supply space, depending on the change in the air flow regime, fall into the large or small class. With a sufficiently large difference in the speeds of the particles, separation occurs: particles of a higher density settle down, and particles of a lower density are carried away by the air stream into the inlet openings of the inclined pipes of the pneumatic pipelines.

The disadvantage of this screen is the uneven screening of the material (sand and dust) to create a layer of suspended particles, as well as the uneven absorption of dust and sand throughout the volume of the hopper, in addition, in the feed volume of the screen, only large fractions of sand are separated from dust.

The most effective separation of finely dispersed materials due to the optimization of the aerodynamic regime is incorporated in the screening device (SU 1651996 A1, 05/30/1991, 4 pp.), Which is accepted as a prototype.

The disadvantage of this device is the imperfection of the control circuits of the air passage channel and the material to be separated, in particular, the lack of the possibility of independent adjustment of the position of the corners with fixed S-shaped elements, which limits the range of regulation of the operating parameters, makes it difficult to set up the installation. The basis of the present invention is the task of improving the device for classifying screen material (sand) in a screen suction system, in which a second level of dividers located between slotted suction units is additionally installed, which makes it possible to create a uniform scattering of a layer of suspended sand and dust particles. The regulated air is supplied from below the hopper by opening and closing the disk shutter, which allows the formation of a “fluidized bed” and the classification of various fractions of high uniformity of sand of different classes.

The problem is solved by the fact that in the screening hopper, slotted suction tubes are installed underneath the existing dividers, consisting of horizontal pipes and connecting sections of the inclined pipes of the pneumatic pipeline exiting the horizontally located collector connecting the inlets to the hopper. In horizontal pipes, slotted openings are milled at an angle of 45 °, allowing evenly capture and carry particles of smaller size sand and dust. An installed sight glass on the wall of the hopper allows you to visually control the creation of a "fluidized bed" by opening or closing the disk damper located below the hopper in the supply air pipe, and the disk shutters installed on each inclined pipe of the pneumatic pipe of the hopper make it possible to control the speed of the rarefied stream, which makes it possible to vary the size of the shared particles. With the same vacuum created in the prototype and the proposed device, the suction efficiency in the device is higher due to the possibility of controlling the rates of intake air on each inclined pipe of the pneumatic pipeline of the hopper.

Thus, the distinctive features of the proposed device are necessary and sufficient to solve the technical problem - improving the quality of classification of the feed material (sand) of the screen aspiration system.

Figure 1 shows a screen with a vibro-impact screen, side view with inclined pipes of the pneumatic pipe 9.

Figure 2 is the same, top view.

Figure 3 shows the entry of the inclined pipes of the pneumatic pipe 9 into the hopper 5.

The screen contains a rectangular box 1 with a clamp 2, a vibrator 3, a frame 4, a hopper 5, a collector 6. In the top view, there is a grill 7 with installed dividers 8.

An example of the proposed device is schematically presented in figure 4, 5, 6, 7, 8.

Figure 4 (conventionally the upper part of the screen is not shown) shows a hopper 5 with the completion of a device for classifying feed material (sand), where 8 are existing dividers, 9 are inclined pneumatic pipes with installed butterfly valves, 10 are slotted suction pumps, 11 are viewing glass, 12 - newly installed dividers.

5 is a side view with newly installed dividers 12.

6 is a side view, showing the installation of slotted suction 10, where 9 inclined pipes of the pneumatic pipeline with installed disk valves.

7 is a view B, shows slotted suction.

Fig - view BB, shows the location of the slotted holes in the slotted suction 10.

The operation of the device for classifying screen material (sand) of a screen suction system.

The device operates as follows.

When pouring through estrus, the feed material enters the top of the screen and, under the influence of gravity, falls on it. Due to the vibration of the sieve, the particles of the material upon impact on the surface of the sieve receive translational motion. With relative motion along the sieve of the material, large particles have a higher speed and, accordingly, a larger trajectory of movement, smaller particles have a lower speed and a trajectory of movement along the sieve. Therefore, smaller particles, occupying a larger area, are more likely to penetrate through the holes in the screen. During the movement, the material is mixed due to the friction of the particles against each other, and the particles of the material are exfoliated from metal oxides. The created vacuum in the feed space of the hopper facilitates more intensive penetration of particles through the sieves, thereby reducing clogging of the nets with sticky material or irregularly shaped particles. The classification of filling sand is as follows.

Particles of sand entering the feed part of the cavity of the hopper 5 begin to settle on the dividers 8, 12, made of corners and mounted on the side walls of the hopper 5. The dividers 8, 12 are located on two levels. Under the first level of the dividers 8, slotted suction nozzles 10 are installed, connecting the inputs of the external inclined pipes of the pneumatic conduit 9. The second level of the dividers 12 is installed along the axis of the tubular slotted suction nozzles 10 and is located between them.

Particles of sand and dust, falling under the weight of their own weight, hit the side surfaces of the first level dividers, bouncing, fall on the side surfaces of the second level of the dividers and, bouncing off, create a cloud of dust and sand particles where they meet with an upward flow of air coming from the bottom of the hopper . The force of gravity pulls them down, and the particles begin to accelerate, but at the same time a force of air resistance arises, which is directed upwards. At first, the force of attraction is greater than the force of resistance, and the particles move with acceleration, but as its speed grows, the force of air resistance also increases. After some time, the force of attraction will be completely balanced by the force of resistance. After this, the particles will neither accelerate nor decelerate and begin to move at a constant speed, at which large particles cannot be carried up and hang at a certain height, forming a "fluidized bed", and small particles are carried upward and sucked up by slit suction. Since the air coming from the bottom of the hopper increases due to rarefaction, the upward flow of air increases, thereby raising the formation of a "fluidized bed" to a certain height. In the process of “boiling”, large grains are intensively mixed in a horizontal plane throughout the hopper, trying to evenly distribute and fill the entire free space of the formation of the “fluidized bed”, and since the speed of the upward flow is equal to the speed of the maximum particle size of the specified fraction, the layer of these particles begins to grow and increase in thickness, and its permeability to the air flow decreases, and there is the possibility of settling of small particles on the surface of the layer. At the same time, the air pressure under the layer increases and, as a result, the balance between the mass of the layer and the air pressure underneath is violated, it begins to swell and then a pulse breakthrough of the layer by air flow occurs with a simultaneous decrease in the velocity of the upward flow. This oscillatory movement of the air flow velocity violates the parity of the soaring of particles in the "fluidized bed", and they settle equally accelerated.

During the violation of the speed regime of the upward air flow in the hopper, the deposition rate of large particles contained in the layer manages to exceed the speed of the upward air flow restored to a predetermined value, and they settle in the hopper. Smaller particles, which during precipitation fall into the ascending air stream restored to a predetermined value, do not have time to develop their deposition rate greater than the upward flow velocity and are carried out through tubular slotted suction pumps.

The advantage of the proposed device is to facilitate the separation of the material into small and large fractions in the aspiration system. With the use of two levels of dividers, the scattering of sand and dust particles is improved, and by regulating the speed of the rarefied stream, it becomes possible to vary the size of the particles to be separated. The supply of regulated air from the bottom of the hopper allows the formation of a "fluidized bed" and the classification of various fractions of high uniformity of sand of different classes. It also creates the possibility of visual control of the "fluidized bed" through the sight glass. Used slotted suction in the hopper allows you to evenly capture and carry out particles of fine sand and dust.

The proposed device for classifying screen material (sand) of a screen suction system is industrially applicable and is used on the drying and enrichment line of sand at JSC Zolotoy Ostrov.

Claims (4)

1. A device for classifying filler material - sand of a screen suction system, comprising a box with a loading chute, a sieve and a screen space, a vibrator, a frame and a collector, characterized in that the box is rectangular with clamps, and the screen space is formed by a conical shaped hopper with fixed inside it on the side walls with two levels of dividers made of corners, the collector is made horizontally arranged and provided with underwater inclined pipes of the pneumatic pipe coming out of it and with Slotted suction pipes connecting the entrances to the hopper in the form of horizontal pipes with slotted holes made at an angle of 45 ° relative to the axis and located under the first level of the dividers, while the second level of the dividers is installed along the axis of the slotted suction and is located between them. 2. The device according to claim 1, characterized in that a sight glass is installed on the side wall of the hopper. 3. The device according to claim 1, characterized in that on each inlet inclined pipe of the pneumatic pipe of the hopper installed disk shutters. 4. The device according to claim 1, characterized in that for the formation of a "fluidized bed" from the bottom of the hopper, air is supplied by an adjustable disk damper mounted on a pneumatic pipe in the lower part of the hopper.

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