RU2805755C1 - String classifier - Google Patents

Abstract

FIELD: mining and coal industries.

SUBSTANCE: devices designed for size classification of both dry and wet materials with irrigation, can be used, for example, in the mining and coal industries. The string classifier contains a sequentially installed raw material supply unit, a string classifier module containing at least one vibrating inclined tray with string sieves, a low-ash product receiving hopper with a dosing actuator, and a high-ash product receiving hopper. In this case, the string classifier module is designed to increase the vibration amplitude of the strings at the end of the last third of the sieve compared to the first third of the sieve and to separate the sieve overflow material by ash content based on the point transfer of kinetic energy from the strings to the particle during dynamic contact of the particles with the point surface, moving inertly along string circumference.

EFFECT: improving the quality of the enriched product.

5 cl, 1 dwg

Description

TECHNICAL FIELD

The invention relates to devices designed for classification by size of both dry and wet materials with irrigation and can be used in the mining, coal industries and other sectors of the national economy. The device allows you to combine the technological tasks of classification by size and enrichment of minerals by elasticity in a string module in flow mode.

BACKGROUND OF THE ART

String rumble is known, disclosed in SU 778818 C1, publ. 11/15/1980. The screen contains loading and unloading devices, an inclined box with a comb for attaching a string screening surface, and a directional vibrator.

The disadvantage of the technical solution disclosed above is the low sifting performance due to the longitudinal direction of vibration transmission to the sieve, and the absence of circular inertial movement of the strings. The limitation of longitudinal vibrations of the sieve does not allow combining the processes of enrichment and classification.

In addition, the shock-elastic separator disclosed in RU 2609271 C1, publ. 02/01/2017, prototype. Impact-elastic separator for beneficiation of fine grades of coal using a dry method, having a frame, an unloading device for enrichment products, and bunkers for enrichment products. In this case, the separator is a double-sided two-stage roller system of rollers rotating at a certain speed, above which impact plates with gaps corresponding to the size of the coal being processed are installed across the entire width.

The disadvantage of the technical solution disclosed above is the presence of a gumized coating of the rollers, which, when the ambient temperature changes and the presence of contaminants on the coating, leads to a change in the elasticity coefficient of the coatings and the amount of rebound, which reduces the quality of separation.

In the considered shock-elastic system, different variations of the redistribution of kinetic energy are used along the contact area of one of the planes or the face of the particle along the contact area of the deck; this technical solution reduces the magnitude of the particle rebound and, accordingly, the selective capabilities of the technology.

DISCLOSURE OF INVENTION

The objective of the claimed invention is to develop a device that allows you to combine classification and enrichment technology in one module in flow mode, without loss of productivity and quality of sieving, and also to obtain enriched classified material on each module.

The technical result of the invention is to improve the quality of the enriched product.

This technical result is achieved due to the fact that the possibility of transferring concentrated kinetic energy at the point of contact with the surface of inertially moving strings around the circle with the contact point of a dynamically moving particle is realized, which increases the effective selectivity of the rebound height by 3-5 times, in contrast to the redistributed energy of the dynamic contact along the particle area and the deck plane.

The string classifier contains a sequentially installed raw material supply unit, a string classifier module containing at least one vibrating inclined tray with string sieves, a low-ash product receiving hopper with a dosing flag, a high-ash product receiving hopper, and the string classifier module is configured to increase the amplitude of vibration of the strings at the end of the last third of the sieve compared to the first third of the sieve and separating the over-sieve material by ash content based on different rebound heights.

The string classifier modules are located one above the other.

Receiving bins for low-ash product and high-ash product are equipped with walk-through scales.

A vibrating tray with string sieves is inclined at an angle of 10-30° to the horizontal.

The string classifier contains an automatic control system (ACS) designed to control the dosage of raw materials, the vibration amplitude of the string classifier module and the position of the dosing flag.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clear from the description, which is not restrictive and is given with reference to the accompanying drawings, which show:

Fig. 1 - Declared string classifier.

1 - raw material supply unit; 2 - string classifier module; 3 - unbalance shaft; 4 - receiving hopper for low-ash product; 5 - receiving hopper for high-ash product; 6 - walk-through scales for high-ash product; 7-pass scales of low-ash product; 8 - ACS; 9 - conveyor motor control unit; 10 - string module engine control unit; 11 - flag servo drive.

IMPLEMENTATION OF THE INVENTION

The string classifier contains a sequentially installed raw material supply unit (1), a string classifier module (2), containing at least one vibrating inclined tray with string sieves, a low-ash product receiving hopper (4) with dosing flags, a high-ash product receiving hopper (5), wherein the module (2) of the string classifier is configured to increase the vibration amplitude of the strings at the end of the last third of the sieve compared to the first third of the sieve and to separate the over-sieve material by ash content based on different rebound heights.

Modules (2) of the string classifier are located one above the other.

The receiving hopper (4) for the low-ash product is equipped with a pass-through scale (7) for the low-ash product, and the receiving hopper (5) for the high-ash product is equipped with a pass-through scale (6) for the high-ash product.

A vibrating tray with string sieves is inclined at an angle of 10-30° to the horizontal.

The string classifier contains an automatic control system (ACS), configured to control the dosage of raw materials, the vibration amplitude of the string classifier module (2) and the position of the dosing flag.

The claimed classifier works as follows. To obtain a classified material, for example, coal of a fraction of 2.5-6 mm, coal after a crusher with a particle size of 0-6 mm is supplied in portions to the raw material supply unit (1), for example, a belt conveyor, to the string classifier module (2), containing one vibrating inclined tray with string sieves, and the distance between adjacent strings, depending on the angle of inclination of the sieve, is 2.5-6 mm. As coal and waste rock move along the vibrating tray, coal and waste rock with a particle size of less than 2.5 mm are sifted into the sub-sieve space and then, according to an individual transport scheme, are supplied to magnetic separation. Due to the reduction in the load of classified material in the final third of the sieve and the difference in mass at the beginning and end of the sieve, the amplitude of the strings at the end of the sieve increases. The released kinetic energy of dynamic vibrations and self-oscillations of the strings at the end of the sieve, upon collision with particles of coal and waste rock, depending on the elasticity characteristics and masses of the particles, the vibration energy is transferred in equal shares to particles that are not equal in density and mass at point contact of the particles and the surface of the strings, causing an unequal reaction in the particle rebound height. Due to the unequal ash content of the sifted oversieve material, which is similar in size, particles with low ash content have greater elasticity and bounce off the strings higher than particles with high ash content. Not the same elasticity of particles of the same size makes it possible to separate the classified material according to the height of the rebound trajectories, into low-ash material in the upper part of the trajectory and high-ash material (including waste rock) in the lower part of the over-sieve space, separating more than 50% of the coal material with commercial ash content into the receiving bunker (4) low-ash product. The controlled position of the separating flag allows you to regulate the flow of classified particles (due to the flight of the separating flag) into the receiving hopper (4) of the low-ash product, having values close to the parent ones, or values with acceptable commercial ash content, as well as the flow of classified particles with high ash content, which move along a lower trajectory and bounce off the separating flag, ending up in the receiving hopper (5) of the high-ash product. The claimed invention allows, in addition to classifying the material, to carry out its enrichment; the enriched material is collected in the receiving hopper (4) of the low-ash product. Upon completion of classification, the separated products in bins (4, 5) are sent, as appropriate, to further processing stages.

To classify the rock mass into several fractions, for example, 1.5-2.5 mm and 2.5-6.0 mm, two vibrating inclined trays with string sieves installed one below the other are used in the string classifier module (2). The classification process is identical to the single-tray classification process, except that the material from the first screen goes into the low-ash and high-ash product receiving bins for the 2.5-6.0 mm fraction, the material from the second screen goes into the corresponding low-ash and high-ash product bins for the fraction 1.5-2.5 mm, and sub-sieve material 0-1.5 mm is sent for magnetic separation.

Low-ash and high-ash material are supplied through the corresponding receiving bins (4, 5) to the corresponding pass-through scales (6) of the high-ash product and pass-through scales (7) of the low-ash product.

Data from walk-through scales (6, 7) make it possible to adjust the amount of rebound of particles of the classified material from the sieve, because the rebound value of low-ash and high-ash particles (with the same particle size, in particular coal), is in the range of 150-400 mm, with an average vibration frequency of the string sieve of about 25 Hz, a string cross-section of 2 mm and a tension force of each string within 10- 100 kg. The amount of string tension depends on the individual physical properties of the raw material (mass and elasticity of particles), and also affects the frequency characteristics of the sieve and the magnitude of amplitude fluctuations.

Using the automatic control system (8) and the servo drive (11), which controls the angle of inclination of the dosing flag of the receiving hopper (4) of the low-ash product, according to signals from the walk-through scales (6, 7), the mass balance of high-ash and low-ash material is controlled, supporting the task set by the operator to the balance of quality indicators of low-ash and high-ash products (the ratio of the masses of low-ash and high-ash products).

Monitoring and management of the processes of supply, classification and enrichment, calculated in the ACS (8), due to the ACS module receiving data on volt-ampere characteristics from the drive motors of the feed unit (1) for supplying raw materials, the drive motor of the shaft with unbalances (3) and data on mass balances low-ash and high-ash products from walk-through scales (6, 7).

The ACS controls the dosage of raw material supply of the raw material supply unit (1) to the classification module by controlling the ACS through the conveyor motor control unit (9) based on current-voltage characteristics, thereby the raw material from the conveyor is dosed to the initial section of the sieve, this allows you to organize controlled uneven loading of raw materials according to mass balance at the beginning and end of the sieve. A controlled, uneven loading of raw materials onto the sieve is necessary to stabilize the amplitude-frequency characteristics of the strings at the end of the sieve and control the engines of the sieve and conveyor, according to the reverse volt-ampere characteristics of the engines transmitted to the automated control system.

Further, as the raw material passes through the sieve, the level of raw material decreases due to sifting of small particles. In the last third of the sieve, the process of sifting small particles is completed, the amplitude of the strings increases due to a decrease in the load of raw materials. The vibrating strings of the last third of the sieve, due to the kinetic redundancy of dynamic vibrations and self-oscillations, colliding with particles of coal and waste rock, depending on the elasticity characteristics and masses of the particles, transfer approximately the same kinetic energy to particles that are not equal in density and mass.

The mass balance at the beginning and end of the sieve - critically influencing the amplitude of the particle rebound height, is also maintained by monitoring the unbalances of the string module by current sensors in the motor circuit of the drive shaft (3), controlling the engine speed through the string module engine control unit, which allows adjustment amplitude of vibrations of a vibrating tray with string sieves.

Monitoring the dynamics of current oscillations in the motor circuit of the drive shaft (3) of the unbalances of the string module together with the feed-through scales, allows you to adjust the amplitude-frequency characteristics of the string sieve using feedback from the feed-through scales (6, 7) to support the quality indicators specified by the operator through the automatic control system (8). low-ash and high-ash material. ACS-controlled (8) control of the frequency and, accordingly, amplitude characteristics of the sieve within 1500 rpm ±20% according to the volt-ampere characteristics of the feed conveyor drive motors, the string module unbalance drive motor, the position of the dosing flag that regulates the flow balances, the data of the feed-through scales, is necessary to stabilize the quality of sieving products specified by the operator, in case of abnormal imbalance of the mass of raw materials at the beginning and end of the sieve.

Archiving data in the ACS of the volt-ampere characteristics of the drive motors - the feed conveyor, the drive motor of the string module unbalances, the data of the pass-through scales, the position of the dosing flag, supporting the operator's instructions, the balances of the flows of low-ash and high-ash products and the results of analytical studies in the laboratory of low-ash and high-ash products, allow create analytical products in the form of algorithms to obtain, from specific raw materials, high-quality commercial products with pre-predicted parameters of the volt-ampere characteristics of engines, inclination angles of the dosing flag and mass balances of commercial products.

As experiments have shown, the claimed invention made it possible to combine the processes of classification and enrichment in the flow mode of classes 0-13 mm and ensure an increase in the quality of the enriched product (low-ash), namely, to obtain more than 50% of the low-ash commercial product from the initial mass at the classification stage.

The invention has been described above with reference to a specific embodiment thereof. Other embodiments of the invention may be obvious to those skilled in the art but do not change its essence as disclosed in the present description. Accordingly, the invention should be considered limited in scope only by the following claims.

Claims (5)

1. A string classifier containing a sequentially installed raw material supply unit, a string classifier module containing at least one vibrating inclined tray with string sieves, a low-ash product receiving hopper with a dosing flag, a high-ash product receiving hopper, and the string classifier module is designed to be increased the vibration amplitude of the strings at the end of the last third of the sieve compared to the first third of the sieve and the separation of the over-sieve material by ash content based on the point transfer of kinetic energy from the strings to the particle during dynamic contact of particles with a point surface, inertially moving along the circumference of the strings. 2. String classifier according to claim 1, characterized in that the vibrating trays are located one above the other. 3. String classifier according to claim 1, characterized in that the receiving bins for the low-ash product and the high-ash product are equipped with walk-through scales. 4. String classifier according to claim 1, characterized in that the vibrating tray with string sieves is inclined at an angle of 10-30° to the horizontal. 5. The string classifier according to claim 1, characterized in that it contains an automatic control system configured to control the dosage of raw materials, the vibration amplitude of the string classifier module and the position of the dosing flag.