UA63539C2 - Method of screening materials - Google Patents

Abstract

A method of screening materials includes supply of material into the vertical channel, in which vibro-excited grates are installed one under another in zigzag manner. The grates are located in two vertical sections, in which forced dynamic effect is achieved. The process of screening is achieved due to the joint kinetic energy of the flow of material, energy of forced oscillations of grates and energy of vibroexcitation of grates. Forced dynamic action is carried out separately in each section with different fixed vibration frequency: resonance frequency and frequency larger than resonance frequency. The invention ensures the improvement of the quality of screening of moist fine-fraction materials and output of the process of screening.

Description

The invention relates to the distribution of materials using sieves and can be used in the metallurgical, mining, and chemical industries.

A known method of sieving materials (Patent of Ukraine Me44592A, MIPK7 80781/00, 15.02.2002|), which includes cyclic feeding of the material onto the grating vibration-exciting sieving surfaces, located one below the other, vibrating movement of the material through them due to the use of the material's gravitational forces, that falls, and partial sieving of sub-grating fractions on each sieving surface.

The disadvantage of the known method is the insufficient efficiency of the process of sifting wet fine-fraction materials with the advantage of grating fractions, where the gravitational forces of the falling material do not lead to effective vibration excitation of the sieving surfaces, and the use of a high frequency of cyclic feeding of the material on the sieving surface leads to smoothing of the dynamic impacts of portions of the material against the elastic grates. In addition, with insufficient vibration excitation of the sieving surfaces, the self-cleaning of the sieves deteriorates, which leads to a deterioration of the screening quality.

The closest technical solution chosen as a prototype is the method of screening materials (Patent

of Ukraine Me49714A, MIPK7 VO781/28, 16.09.2002, in which the material is fed into a vertical channel, where vibration-excited grates are installed in a zigzag manner under one another, located on two vertical sections, on which they exert a forced dynamic influence with a frequency equal to the frequency own vibrations of grates, while the screening process is carried out due to the combined effect of the kinetic energy of the material flow, the energy of forced vibrations of grates and the energy of vibration excitations of grates.

The disadvantage of the known method is insufficient screening efficiency of wet fine-fraction materials prone to sticking, where the resonant frequency of vibration of the grates is not enough for their effective vibration excitation and cleaning from sticking. In addition, the use of only the resonant frequency of forced dynamic influence reduces the reliability of the equipment.

The invention is based on the task of creating a method of sieving materials, which would ensure an increase in the quality of sieving wet fine-fraction materials and increase the productivity of the sieving process by improving known methods.

In the proposed invention, this task is solved with the help of the method of screening materials, which includes feeding the material into a vertical channel, where vibration-excited grates are installed in a zigzag manner under each other, located on two vertical sections, where these sections are subjected to forced dynamic influence. At the same time, the screening process is carried out due to the combined effect of the kinetic energy of the material flow, the energy of the forced vibrations of the sieves and the energy of the vibration excitations of the sieves. In accordance with the invention, forced dynamic influence is carried out separately on each section with a different fixed frequency of oscillation; resonant and greater than resonant.

In addition, forced dynamic influence on sections with a higher than resonant frequency of oscillation is carried out with a frequency of oscillation equal to 1.5-2.0 of the resonant frequency of oscillations of grates. A comparison of the claimed method with the prototype shows that what is new is the implementation of a forced dynamic effect separately on each section with a different fixed frequency of oscillation: with resonance and greater than resonance.

The grating section, which oscillates with a resonant frequency, more efficiently sorts the material with the required productivity. The second section with grates, which oscillates with a higher than resonant frequency, more effectively cleans the sieving surface from sticking wet fine fraction materials. When moving the sorting material between grates, one of which oscillates with a resonant frequency, and the second grate oscillates with a frequency greater than the resonant one, a more efficient movement of the material is ensured due to the braking of individual layers of the material, which increases the quality and productivity of screening.

In Fig. the schematic diagram of the screen design, which implements the proposed method, is shown.

The screen contains a receiving hopper with a loading device 1, a vertical channel 2, which is formed by two vertical removable sections 3, each of which consists of two springs fixed at the edges in the lower part, interconnected by several inclined deflectors 5 with attached to them vibrating grates 4, which are placed one under the other, with a step in the vertical plane equal to the oscillation period of the sinusoidal curve of the vertical channel 2.

At the same time, the concave surfaces of the grates 4 of each section C are directed toward the axis of the vertical channel and are offset relative to each other in the horizontal plane by an amount equal to half the oscillation period of the indicated sinusoidal curve. Sections C in their middle part are connected to sources of forced oscillations 9.

Regulation of the size of the passage section of the channel is carried out by changing the angle of inclination of each section Z relative to their vertical position by changing the length of the stabilizers 8.

Deflectors 5 are made in the form of cantilever fixed vibration-exciting inclined rectangular sheets, to which vibration-excited grates 4 are attached.

The screen also contains channels for moving sub-grating fractions 6, nozzles for the output of distributed fractions 7.

The method is carried out as follows.

The material to be sorted is fed into the receiving hopper with the loading device 1, where it moves under the influence of its own weight along the vertical channel 2, which is formed by two vertical removable sections C, each of which consists of two springs fixed at the edges in the lower part , interconnected by several inclined deflectors 5 with vibration-excited grilles 4 attached to them. Forced vibration sources 9 transmit a forced dynamic influence separately to each section with a different fixed frequency of oscillation: resonant and higher than resonant

As a result of the dynamic effect of vibrating grates on the flow of material moving along the vertical channel 2, particles of material that are smaller in size than the gaps of the sieving surface pass through the sieving surface of the grates 4 and, under the action of their own weight, move along the exit surfaces of the deflectors 5 to the channels for moving the under-grate fractions 6, and further to the nozzles for the exit of distributed fractions 7. Particles of material that are larger in size than the gaps of the sieving surface, as well as particles of the fine fraction that did not have time to be removed on the first sieving surface, enter the next ones, where the described sieving process is repeated. The number of sieves with 4 screening surfaces depends on the desired screening quality and its initial fractional composition. Large particles of material, passing under the influence of their own weight through the vertical channel 2 of the screen, interact with all the surfaces of the sieves 4 and go to the nozzles for the output of the distributed fractions 7.

The section that oscillates at the resonant frequency has the largest amplitude of oscillations. This contributes to intensive mixing of different fractions of the material, thanks to which high sorting productivity is achieved.

A section that oscillates at a frequency greater than the resonant one has a smaller amplitude, but a higher frequency of oscillations. This frequency contributes to more intense mixing of small material fractions and their better contact with the grate surface, which ensures better sorting.

Oscillation of the sections with a high frequency and/or amplitude contributes to a better cleaning of the grate surfaces, especially when sorting wet fine fraction materials, which also increases the quality of sorting.

It has been experimentally established that the best indicators of sorting quality and productivity are observed if more than the resonant frequency of oscillations is specified, 1.5-2.0 times higher than the resonant frequency. At a frequency lower than 1.5 times the resonance improvement of the sorting quality was not noticed. A frequency greater than 2.0 times the resonant frequency leads to a strong increase in energy consumption without a significant improvement in sorting quality.

The application of the proposed method for sieving materials allows for effective sorting into fractions of wet fine-fraction materials with a content of pre-grated fractions greater than 90905, at the same time, the sieving productivity increases by 3 times and the probability of cluttering the sieving surfaces with small fractions decreases. The method for sieving materials can be obtained by modernizing the sieving machines available at enterprises of the metallurgical, mining, and chemical industries. 1 8 " ; I Ei is is and

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Claims (2)

1. The method of sieving materials, in which the material is fed into a vertical channel, in which vibrating grates are installed in a zigzag manner under one another, located on two vertical sections, where these sections are subjected to a forced dynamic influence, while the sieving process is carried out due to the combined influence of kinetic the energy of the material flow, the energy of forced vibrations of grates and the energy of vibration excitations of grates, which differs in that the forced dynamic effect is exerted separately on each section with a different fixed frequency of oscillations: resonant and higher than resonant. 2. The method according to claim 1, which is distinguished by the fact that the forced dynamic influence on the sections with a vibration frequency higher than the resonance frequency is carried out with a vibration frequency equal to 1.5-2.0 of the resonance frequency of the grates.