RU2382684C1 - Screenless device for classification of granular materials by size - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: screenless device for classification of granular materials by size consists of conveyer rubber-cloth belt put on driving and driven drums, conveyer frames, electric drive, belt tensioning device, device for cleaning from small particles stuck to bunker belt for coarse size offloading, and grooves with holes for offloading of fine size. Conveyer belt is cramped to roll-plate chain interlocking with teeth installed on surface of driving and driven drums, it is installed using lifting device at angle of inclination to horizontal plane providing segregation of source material upon movement along inclined belt. Required amount (as per technology) of dividing metal strips, reinforced by rubber or polyurethane from charging side and of various height increasing downwards from 25 to 100 mm is mounted above belt at distance 1-2 mm along its whole length on columns. Upper strip is installed at distance equal to 1/3 of belt width from its upper edge. Lower strip is installed at distance 50 mm form lower edge of strip, other strips are installed at equal distance from each other.

EFFECT: improvement of effectiveness of classification by size, increase in efficiency and longevity of device, reduction of energy consumption.

2 dwg

Description

The invention relates to mining, processing and enrichment of minerals and can be used in the mining, coal and construction industries, as well as in agriculture for sorting fruits and root crops by size.

As a rule, before enrichment, coal or ore is subjected to preparatory technological operations (crushing, screening) to obtain the necessary machine size classes, which are subsequently enriched separately on the processing equipment specially designed for these classes. And only with this enrichment technology is the high quality of the concentrate ensured with minimal loss of useful components in the waste.

The raw ore or coal mined in mines and quarries in their environment contains a large number of large pieces with sizes of 400-800 mm. Therefore, the initial task of preparatory technological operations is the selection of the largest pieces from the total rock mass for feeding them to crushing. This technological operation is carried out on the screens of preliminary screening. Currently, enrichment plants for preliminary screening use grate fixed screens, drum and vibration screens.

In all designs of these screens, the separation of the source material by size occurs using scattering surfaces.

The main disadvantage of grate screens is the low screening efficiency (60-70%). And in the drum and vibrating screens there is a rapid wear of the expensive scattering surface, due to the abrasiveness of the material. So, the service life of the braided wire mesh does not exceed 3-4 weeks. Frequent replacement of expensive wire mesh increases the cost of coal processing. In addition, in the drum screens there is over-grinding of the material with intensive mixing. The regrinding of material in the coal industry reduces the yield of the most valuable high-grade coals and increases the cost of enrichment, since the enrichment of small classes is a more expensive process.

Vibrating screens in the process create large dynamic loads on the building structures of the factory and create a lot of noise. Noise and vibration have a negative effect on the health of the people serving these screens.

Based on the foregoing, in the enrichment of minerals there is a need to develop a meshesless device that allows you to effectively allocate the largest pieces from the rock mass without regrinding and noise and to distinguish machine classes of the necessary size.

Known in mineral processing is a concentration table with arithmetics, on which the material is separated by density on an inclined oscillating plane in a stream of water. But it is not intended for classification by material size, but is used as an apparatus for gravitational enrichment of small particles with sizes less than 3 mm. The performance of the concentration tables is very low and amounts to 10-15 t / h.

Known separator for sorting bulk material A.S. 1207518 (51), B07B 1/28, which uses several conveyor belts around the pulleys. The disadvantages of this separator are the complexity of the device and the low efficiency of screening. Therefore, he did not find application in industry.

Known vibroadhesive separator A.S. No. 1489855, (51) 4 В07B 13/00, in which the separation of material by size occurs on fixed planes in the form of a dihedral angle. But it has low productivity and screening efficiency. Therefore, also did not find application in industry. This separator can serve as a prototype of the proposed device.

The aim of the present invention is to develop a device for separating bulk materials by size without sieves, which will reduce the cost of enrichment processes, due to the absence of costs for the manufacture of sieves, their frequent replacement, lower cost of the proposed device compared to the cost of screens, reduce operating costs.

The invention is illustrated by the drawing of figure 1, where in dimetry is a diagram of the proposed device. The device is a short but wide belt conveyor installed in space with an inclination to the horizontal plane in the transverse direction. The tilt angle for each material is selected experimentally and is 30-60 °. Over the conveyor belt at a distance of 1-2 mm from its surface, metal strips are installed in the longitudinal direction, i.e. in the direction of the tape. In order to reduce the friction of the tape on the metal, the loading sides of the separation strips are reinforced with rubber or polyurethane.

The estimated width of the conveyor is 3100-3200 mm, the length of the conveyor 4500 mm.

The main detail of the proposed device is a multilayer rubber-fabric tape 1. Over the outer surface of the tape mounted metal strips 2 on the racks 3. Several strips can be installed. It depends on the enrichment technology adopted. In this case, the device has three bands. As metal strips, standard angular profiles are installed with the upper shelf perpendicular to the horizontal plane. The distance of the corner profiles to the surface of the tape is 1-2 mm. Metal strips have different heights, increasing from top to bottom: the height of the upper strip is 25 mm, the height of the second strip from above 63 mm, the height of the lower strip is 100 mm. The upper strip is installed at a distance equal to 1/3 of the width of the tape from its upper edge, the second strip is installed at a distance equal to 1/3 of the width of the tape from the upper strip, and the lower strip is installed at a distance of 50 mm from the lower edge of the tape. In order to avoid deflection of the tape during its movement, a steel sheet is mounted under it along the entire length and width (it is not shown in the drawing).

The conveyor belt 1 is worn on the drive 4 and driven 5 drums. The drive and driven drums on their surfaces have teeth 6 on which the roller-plate chain is mounted 7. The chain 7 is connected to the edges of the belt 1 using special brackets 8. The drums are mounted on a common frame 9. The frame changes the tilt angle using a movable lifting device mounted under frame. The belt is tensioned by the tensioner 16.

The proposed device operates as follows. Pre-conveyor using a lifting device is installed with an inclination in the transverse direction to the horizontal plane, for example, at an angle of 45 °. When you turn on the drive of the conveyor 10, the tape 1 will begin to move in the direction of the longitudinal axis of the conveyor at a speed of 0.8-1.5 m / s.

The direction of movement of the tape in the drawing is shown by an arrow. The source material (ore or coal) with a particle size of 0-800 mm is loaded directly onto the tape at its upper right corner, in the immediate vicinity of the driven drum. Large pieces of the source material, having a sufficient initial speed obtained when loading the material on the tape, rush down under the action of gravitational forces, overcoming the height of all longitudinal metal strips in its path. The presence of the angle of the tape 1 provides large pieces of movement with acceleration. Therefore, they do not meet in their way a lot of friction resistance against small pieces of material and are shipped to the hopper 11 on the basis of segregation.

Small particles of the starting material, when hit on the inclined plane of the tape, sharply reduce their initial speed, due to the large forces of friction against adjacent small particles and the surface of the tape. Therefore, they, having a low speed, cannot overcome the height of the longitudinal metal strips and are delayed by them, accumulating on the tape between the strips. It was experimentally established that the smallest particles with sizes of 0-13 mm are retained by the upper strip with a height of 25 mm due to the fact that they have the lowest speed. The retained particles in the upper strip are transported by the belt 1 to the discharge chute 12 and discharged from it through the opening 13, which is present in the bottom of the chute. Larger particles with sizes of 13-25 mm during their movement experience significantly lower resistance, therefore they have a significantly higher speed of movement, as a result of which they overcome the height of the upper strip, but are delayed by the second strip, which has a height of 63 mm. These particles are also transported by tape 1 to the discharge chute 12, but are unloaded from it through the opening 14. Particles with sizes 25-75 mm are held up by a lower strip that is 100 mm high and are discharged from the chute 12 through the opening 15. And the largest particles with dimensions +75 mm overcome the lower strip and are shipped to the hopper 11, designed for pieces of material larger than 75 mm. Figure 2 presents a diagram of the separation of material by size, which shows the mechanism of distribution of material by size using dividing strips in the form of angular profiles. The source material containing small and large pieces freely falls from a certain height onto an inclined conveyor belt 1, above which the separation strips 2 are installed. Large pieces, having gained a great speed, overcome the height of the separation strips and are unloaded from the lower edge of the belt. Small particles are retained by separation strips and transported by tape to the discharge chute.

Thus, the proposed device, having three metal strips, allows you to divide the source material without sieves into four classes: 0-13 mm, 13-25 mm, 25-75 mm and +75 mm.

Depending on the adopted technological scheme of enrichment of the separating metal strips may be more than three or vice versa less than three. And if you want to divide the source material into only two classes of fineness, then just one strip of the appropriate height, which is determined experimentally, is enough to set above the tape.

The size control of machine classes is carried out by three parameters: the angle of the tape, the height of the metal strips and the height of the load of the source material on the inclined tape.

The greater the angle of inclination of the tape and the loading height of the source material on the tape, the greater will be the speed of movement of the particles to be separated and, therefore, the finer the material that overcomes the height of the separation strips. The smaller the height of the dividing strips and the smaller the angle of inclination of the tape, the more small source material will be retained in the interband spaces, and the sizes of large particles will be largest, but its output will be minimal and vice versa.

Naturally, the initial load with its weight will shift the tape in the direction of inclination, i.e. way down. To prevent this, the belt is fastened with brackets with a roller-chain chain, and the conveyor drums have teeth on their surface that engage with the chain and prevent the belt from moving down. In addition, the presence of teeth and a chain will ensure reliable adhesion of the tape to the drums, which completely eliminates slipping of the tape under heavy load.

To clean the tape from adhering particles, cleaning scrapers are provided for in the discharge.

The proposed device, providing the separation of the material without sieves into the required number of particle size classes, has a number of advantages compared to screens:

1. High productivity (with a belt speed of 1 m / s and a bulk density of the material of 1.4 t / m ³ , the estimated capacity is 1000-1200 t / h).

2. Durability (standard multilayer tape lasts 3-4 years, the wear of the tape in the proposed device will be small, since large pieces fall on a layer of small material held up by metal strips).

3. Quiet operation.

4. Low power consumption (the rated power of the drive motor with a capacity of 1000 t / h is 7.5 kW).

5. High screening efficiency.

The presence of the indicated advantages of the proposed device will fully ensure the preliminary screening operation at ore and coal processing plants, as well as the final screening operation when dividing anthracite concentrates into grades, will reduce the cost of preparatory technological operations, and, consequently, the entire beneficiation process.

Literature

1. Avdokhin V.M. The basics of mineral processing. Volume 1. Ed. Moscow State University, 2006.

2. Shanourin V.E. Enrichment of placers. M .: Nedra, 1970.

3. Andreev S.E., Perov V.A., Zverevich V.V. Crushing, grinding and screening of minerals. M .: Nedra, 1980.

Claims (1)

An insensitive device for separating bulk materials by size, consisting of a conveyor rubber-fabric belt worn on the drive and driven drums, a conveyor frame, an electric drive, a belt tensioner, a cleaning device from small particles adhering to the hopper belt for shipping a large class, and the gutter with openings for shipment of small classes, characterized in that the conveyor belt is stapled with brackets with a roller chain, which engages with teeth mounted on the surface of the drive and driven drum c, and installed using a lifting device at an angle of inclination to a horizontal plane, which ensures segregation of the source material when moving along an inclined belt, and above the belt at a distance of 1-2 mm along its entire length, the required number (according to the technology) of dividing metal strips is mounted on racks reinforced from the loading side with rubber or polyurethane, having different heights increasing from top to bottom from 25 to 100 mm, while the upper strip is installed at a distance equal to 1/3 of the width of the tape from the top e edge, lower band is set at 50 mm from the lower edge of the tape, the remaining bands are set at equal distance from each other.

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