WO2018132023A1

WO2018132023A1 - Device for pneumatic sorting of grainy materials, and method of sorting

Info

Publication number: WO2018132023A1
Application number: PCT/PL2017/050072
Authority: WO
Inventors: Tomasz JANOSZEK; Andrzej BAJERSKI; Jacek Marian ŁĄCZNY; Sebastian IWASZENKO; Kamil STAŃCZYK; Jadwiga PROKSA; Magdalena FILIPEK-MARZEC
Original assignee: Główny Instytut Górnictwa
Priority date: 2017-01-15
Filing date: 2017-12-30
Publication date: 2018-07-19
Also published as: PL420190A1; PL234492B1

Abstract

The subject of the invention is a device for the pneumatic separation of grain materials and a separation method, especially of rock materials. It is known from the Polish patent application P.410602 there is a method and apparatus for processing coals, in particular for processing hard- enrichable coals with separation of concentrate and intermediate products suitable for use as a hard fuel. The method of processing coals is characterized by the fact that coal of the same grain-size class, larger than sieve dimension, is fed to a conveyor with a mesh band, and then, in form of monolayer, from chute from to a nozzle, where the lightest fraction of the material, with a density of 1250 - 1350 kg/m³ and ash content A_d = 8-11%, is sucked out by means of air. For this purpose, the nozzle is set to a suitable position in relation to the conveyor mesh surface; underpressure inside the nozzle is set to necessary value in range of 400-800 mm water column, where the sucked material falls out of the air stream into the jig. Additional nozzle located under the mesh band creates a negative pressure of a set value, which holds the fractions that are not meant to be sucked off.

Description

A device for the pneumatic separation of grain materials and separation method

The subject of the invention is a device for the pneumatic separation of grain materials and a separation method, especially of rock materials.

It is known from the Polish patent application P.410602 there is a method and apparatus for processing coals, in particular for processing hard- enrichable coals with separation of concentrate and intermediate products suitable for use as a hard fuel. The method of processing coals is characterized by the fact that coal of the same grain-size class, larger than sieve dimension, is fed to a conveyor with a mesh band, and then, in form of monolayer, from chute from to a nozzle, where the lightest fraction of the material, with a density of 1250 - 1350 kg/m³ and ash content Ad = 8-11%, is sucked out by means of air. For this purpose, the nozzle is set to a suitable position in relation to the conveyor mesh surface; underpressure inside the nozzle is set to necessary value in range of 400-800 mm water column, where the sucked material falls out of the air stream into the jig. Additional nozzle located under the mesh band creates a negative pressure of a set value, which holds the fractions that are not meant to be sucked off. The dry enrichment method is known from the industry using the FGX separators. Such devices consist of a perforated vibrating device, an air chamber and a drive mechanism and a mechanism allowing to set a variable table slope angle and vibration frequency. The feed material is fed to the work table inclined at various angles in both transverse and longitudinal axis. The table is introduced into vibrations using a vibrator. Under the table there are several air chambers fed by a centrifugal fan. Air turbulence passes through the holes in the table and creates a rising air movement. In this way, the material of the feed is sorted depending on the grain density.

There are known from RU2456099, RU2282503 sorting devices for grain materials, especially coal. The disadvantage of the pneumatic sorting devices known to date is the lack of the possibility of introducing the feed grains into relative movement to one another when they are sucked. This causes the grains to adhere and tend to stick together. This adversely affects the suction process due to the uneven distribution of aerodynamic potentials around the sucked grain. In addition, the present invention allows to create an air cushion under the layer of sorted material, which is not feasible using only a suction stream of air. The sorting process has been improved by introducing the seeds into a transient motion, drying the moist grains, initial grain separation due to their bulk density and shape factor.

An additional feature in relation to the known devices is running the feed stream under the suction nozzle along the arced working surface of the perforated rotary cylinder - the curvature of the stream enabling the effective and even operation of the negative pressure around the feed grain.

In the pneumatic sorting process, based on forcing the difference of aerodynamic potentials by creating a vacuum and sucking in certain types of grains, three characteristics of grains determine whether a grain is sucked or not: grains density, shape coefficient of grains and roughness coefficient of grains.

Although the physics of the pneumatic sorting process is well-known, the process is rarely used in practice of rock materials separation. This is due to the difficulty in obtaining desirable sorting efficiency. The required sorting efficiency is difficult to obtain for small grains, grains in a wide size class range and grains with very different shapes. The efficiency of pneumatic sorting of materials such as rock materials, coal mines and other minerals or rock waste materials, is heavly dependant on the content of clay and silt fractions, which in humid conditions may cause grain to stick, thus making even distribution of aerodynamic potential around a single grain impossible. The effectiveness of the process in such cases may be improved through the use of the perforated surface at the suction point of the feed or implementation of solutions that introduce the grains into motion relative to each other, thereby preventing their sticking and adherence.

An object of the present invention is a device for the pneumatic sorting of grain materials and a sorting method, in particular rock materials such as spoil from coal mines and other minerals, rock waste materials.

The sorting method of the grain materials according to the present invention applies to the sorting of materials in grain sizes 0-200 mm, preferably 10-30 mm. It is not necessary to specify other parameters, in particular the limit values of the density of sorted materials, their shape and surface roughness coefficient, which is important from the point of view of the application of technology.

Sorted material, i.e. grain material in the grain class from 0-200 mm range, preferably 10-30 mm, is introduced by known methods into a loading tank placed above the conveyor belt equipped with a scraper levelling the layer thickness on the belt. The thickness of the feed layer on the conveyor belt is set by a scraper whose height above the mobile conveyor belt is equal to 1.5 of the maximum grain size diameter in the feed material.

By means of a conveyor ending with a chute, sorted material is fed into the suction zone consisting of a rotating cylinder, a suction nozzle placed above the rotating cylinder and a directional nozzle located inside the rotating cylinder. In the suction zone, by creating a difference in aerodynamic potential, the sorted material is sucked. The diameter of the rotating cylinder is 200-5000 mm.

By means of a rotating cylinder with a perforated working surface and installation of a directional nozzle in its interior, causing air movement in a direction perpendicular to the working surface of the rotary cylinder and directed towards the outside of the cylinder generatrix, the grains of sorted material are moved in relation to each other at the moment of sucking. The dimensions of the holes in the perforated working surface of the rotary cylinder range from 1 to 40 mm.

Overpressure under the sorted layer and the curvature of the cylindrical surface cause a breakdown of the feed layer and the introduction of grains into vibrations, i.e. their mutual displacement, as well as their drying, which limits the possibility of their sticking together. The sucked grains, caught within the airstream, are directed through the suction nozzle into the particle separator.

The feed grains are delivered in form of curved layer placed on a perforated rotating cylinder with a diameter in the range of 300-2000 mm. The perforation of working surface of the cylinder consists of holes with a diameter in the range of 1-40 mm. The separation process consists of creating a difference in aerodynamic potential: underpressure in the range of 1-30 hPa and overpressure in the range 1-10 hPa, acting on grains vertically upwards and resulting in grains being sucked.

Inside the particle separator, the sucked fraction is separated from the air stream by means of gravity, removed through a hole equipped with a rotary slide, and then poured into a sucked fraction resevoir. Air flow in the system is forced with use of a fan. The air, together with the sucked fraction, is directed through the underpressure channel to the particle separator. The unseparated particles are directed through the discharge channel together with the air to the dust collector. The smallest feed fractions are captured in the dust collector and discharged using known methods, e.g. with use of filters or mechanical/wet cleaning. From the dust collector, the filtered air is directed through the overpressure channel to the directional nozzle in the rotary cylinder.

The unsucked grains are discharged by the rotary cylinder into the non-sucked fraction reservoir.

The grains located at suction zone, i.e. under the suction nozzle and over the outlet of the directional nozzle, are subjected to the forces generated by the difference in aerodynamic potentials. As a result of existing underpressure P₂ and overpressure Pi, the separated grains are lifted and then collected in subsequent stage of the process. The pressure values inside both separator and directional nozzle are important for the process according to the present method. Optimal operating pressure is determined in an empirical way for each feed material individually, by gradually increasing the pressure in the separator chamber and/or increasing the overpressure Pi and collecting separated fractions - the results need to be obtained for at least 3 different settings of these values. Optimal values of underpressure P₂ and overpressure ? i are determined on the basis of the obtained values of sorting efficiency and quality of products.

The movement speed of the feed grains at the suction location, i.e. the space between the suction nozzle and surface of the perforated rotating cylinder, is regulated by the speed of the conveyor belt and rotational speed of the cylinder in such a way that the linear velocity of the feed layer at the suction location is in range of 0.1-5 m/s.

Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

Fig. 1 is a demonstration of the present invention - a separation method

Fig. 2 is a side view of the present invention - a device The object of the present invention is a device for pneumatic sorting of grain materials, in particular rock materials, comprised of a loading tank constituting a retention tank for feed material, with a volume accordant to the planned capacity of the device. The loading tank is mounted on a steel support structure, which also supports a conveyor belt equipped with a motor. The feed material - a mixture of grains subjected to classification - is gravitationally moved onto the conveyor belt from the loading tank. The conveyor is equipped with a scraper mounted to the supporting structure above it, that distribute the feed as a uniform layer over the entire width of the conveyor belt. The feed is fed onto perforated surface of a rotating cylinder. The rotary cylinder has a supporting structure and its own drive, i.e. it is an independent element in relation to the conveyor and the directional nozzle, and is not connected to them. The cylinder is positioned under the chute so that the feed material moves directly onto the cylinder surface. The chute is fixed on a conveyor.

The directional nozzle is located inside the rotating cylinder, but is not connected to it permanently. The outlet of the directional nozzle is directed perpendicularly to the surface of the cylindrical rotary cylinder, i.e. the movement of air flowing out of this nozzle is directed upwards, towards the perforated working surface of the rotary cylinder. The suction nozzle is placed above the rotating cylinder. The suction nozzle is connected permanently to the particle separator by means of an underpressure channel, preferably made of steel. The width of the suction nozzle is selected in accordance to the width of the working surface of the rotary cylinder, in range of 0.8-1.2 of this width. The fraction of material sucked into the suction nozzle, as a result of creating a negative pressure at the outlet of the suction nozzle, is transported to the particle separator through an underpressure channel, in which the sucked grains are separated from the air stream due to inertial forces and speed reduction. The sucked fraction is transported into the sucked material reservoir through a separator outlet equipped with a rotary feeder at the bottom of the particle separator. The separator has its own support structure in the form of a steel frame that allows the positioning of the separator relatively to the rotating cylinder. The separator is connected to a fan by an outflow channel. The fan forces the air flow in the pneumatic system of the device. The channel in equipped with a dust collector that removes fine grains from the air stream. The cleaned air is discharged to the directional nozzle through an overpressure channel comprised of steel or plastic ducts.

The dust collector cleans the air stream of grains that have not been separated in the particle separator. The fan is an independent structure connected to the suction nozzle system, particle separator, dust collector and directional nozzle by means of an underpressure channel and an overpressure channel, in the form of steel or plastic ducts, preferably ventilation pipe. The grains that have not been sucked into the suction nozzle are transferred by the rotary cylinder to the non-sucked fraction reservoir, which is located next to the rotating cylinder.

According to the present invention, it is possible to regulate the following work parameters of the device: the linear speed of the belt conveyor by means of the control system controlling the rotational speed of the drive motor, rotational speed a rotating cylinder through the engine speed control system of the cylinder drive, the position of the suction nozzle above the working surface of the rotary cylinder, the air flow rate by adjusting the fan speed and/or by set of valves regulating the suction force inside the underpressure channel, the air flow rate inside the overpressure nozzle by adjusting on the valves placed in the overpressure channel.

The present invention is presented in the attached figures.

Example 1. Sorting of the feed material consisting of a mixture of coal and gangue grains in size of 10-30 mm resulted in separation into two factions: coal and gangue material.

At pressure values P^= 0.1 hPa and ?2⁼^_'^ ^usm§ ^a rotating cylinder with a diameter of 800 mm, sorting efficiency of 90% was achieved. The obtained sucked material, collected in the separator, contained 21% of mineral fraction. The process was carried out as follows:

Material with grain size of 10-30 mm was introduced into the loading tank (1) placed above the belt (12) of the conveyor (2) equipped with a scraper (11) leveling the thickness of the layer on the belt (12). The height of the scraper above the movable belt (12) of the conveyor (2) was set to 1.5 of maximum grain diameter in the enriched grain material, i.e. 45 mm.

By means of the conveyor (2) ending with the chute (13), the sorted material was fed into the suction zone consisting of a rotary cylinder (3), a suction nozzle (5) located above the rotary cylinder (3) and a directional nozzle (4) placed inside the rotary cylinder (3). In the suction zone, by creating a difference in aerodynamic potentials, part of the feed material was sucked. The diameter of the rotary cylinder (3) used was 800 mm.

By means of a rotating cylinder (3) with a perforated working surface and installation of the directional nozzle (4) in its interior, that causes air movement in a direction perpendicular to the working surface of the rotary cylinder (3) and towards the outside of its generatrix, the grains of the material were introduced into relative movement with each other. The size of the holes in the perforated working surface of the rotating cylinder was 5 mm.

Overpressure generated under the layer of sorted material and the curvature of the cylindrical surface caused the breakdown of the feed layer, thus introducing grains into vibrations, i.e. their mutual displacement, as well as their drying which limited the possibility of particles sticking together. The sucked grains caught up in the air stream were transported through the suction nozzle (5) directly into the particle separator (6), air flowing via underpressure channel (15).

The sorted grains were subjected to simultaneous effects of the following actions: curving the feed material layer on the rotating cylinder (3) with the perforated work surface (19) and 800 mm diameter; forcing a difference in aerodynamic potential, causing suction of the grains, of approximately 8,1 hPa pressure value; forcing a difference in aerodynamic potential (overpressure), acting on the seeds vertically upwards, of approximately 0,1 hPa.

In the separator (6), the sucked fraction Fi was separated from the air stream by gravity and removed through the separator outlet (16) equipped with a rotary feeder (17), and stored in sucked fraction reservoir (9). The air flow was forced by use of the fan (7). The air, together with the sucked fraction Fi, was transported from the suction nozzle (5) to the particle separator (6) through the underpressure channel (15). The particles that remained within the airstream were transported together with the air through the outflow channel (18) into the dust collector (8). The finest feed grains were captured by the dust collector (8) and removed from the installation (filter cleaning). From the dust collector (8), the filtered air was guided via the overpressure channel (19) to the directional nozzle (4) inside the rotation cylinder (3).

The non-sucked fraction F₂, i.e. the grains not sucked by the suction nozzle (5), slid off the rotary cylinder (3) into the non-sucked fraction reservoir (10).

The feed material that remained in the suction zone, i.e. space under the suction nozzle (5) and above the outlet of the directional nozzle (4), was subjected to forces generated by the difference in aerodynamic potentials. As a result of the underpressure P₂ and overpressure Pi acting upon the feed grains, the separated particles were lifted, and then collected at a later stage of the process.

The movement speed of the feed grains is regulated by the speed of the conveyor belt (2) and rotational speed of the cylinder (3) in such a way that the linear velocity of the feed layer at the suction zone was 3 m/s.

The device for pneumatic separation of grain materials comprised of a loading tank (1) constitued a retention tank for feed material, with a volume accordant to the planned capacity of the device. The loading tank (1) was mounted on a steel support structure, which also supported a conveyor belt (12) equipped with a motor. The feed material - a mixture of grains subjected to classification - was gravitationally moved onto the conveyor belt (12) from the loading tank. The conveyor (2) was equipped with a scraper mounted to the supporting structure above it, that distributed the feed as a uniform layer over the entire width of the conveyor belt (12). The feed was fed onto perforated surface of the rotating cylinder (3). The rotary cylinder (3) had a supporting structure and its own drive, i.e. it was an independent element in relation to the conveyor (2) and the directional nozzle (4), and was not connected to them. The cylinder (3) was positioned under the chute (13) so that the feed material moved directly onto the cylinder surface (20). The chute (13) was fixed on a conveyor (2).

The directional nozzle (4), located inside the rotating cylinder, was not connected to it permanently. The outlet of the directional nozzle (4) was directed perpendicularly to the surface of the cylindrical rotary cylinder, i.e. the movement of air flowing out of this nozzle was directed upwards, towards the perforated working surface (20) of the rotary cylinder (3). The suction nozzle (5) was placed above the rotating cylinder (3). The suction nozzle (5) was connected permanently to the particle separator (6) by means of the underpressure channel (15). The width of the suction nozzle was selected in accordance to the width of the working surface (20) of the rotary cylinder (3) and was equal to 0.5 m. The fraction ¥i was sucked into the suction nozzle, as a result of creating a negative pressure at the outlet of the suction nozzle, and was transported to the separator (6) through the underpressure channel (15), in which the sucked grains were separated from the air stream due to inertial forces and speed reduction. The sucked fraction ¥\ was transported into the sucked material reservoir (9) through the separator outlet (16) equipped with the rotary feeder (17) at the bottom of the particle separator (6). The separator (6) had its own support structure in the form of a steel frame, that allowed the positioning of the separator relatively to the rotating cylinder (3). The separator (6) was connected to the fan (7) by the outflow channel (18). The fan (7) forced the air flow in the pneumatic system of the device. The channel was equipped with a dust collector (8) that removed the fine grains from the air stream. The cleaned air was discharged to the directional nozzle (4) through the plastic overpressure channel (19).

The dust collector (8) cleaned the air stream of grains that had not been separated in the particle separator (6). The fan (7) was an independent structure, connected to the suction nozzle (5), particle separator (6), dust collector (8) and directional nozzle (4) by means of the underpressure channel (15) and the overpressure channel (19), in the form of plastic ventilation pipes. The non-sucked fraction F2, i.e. the grains that had not been sucked into the suction nozzle (5), were transferred by the rotary cylinder (3) to the non- sucked fraction reservoir (10), which was located next to the rotating cylinder (3).

Examlple 2. In Example 2, differently than in Example 1, the inlet and outlet ducts were made of steel instead of plastic. Separation of the feed material, consisting of coal waste mixture with a grain size of 30-63 mm, resulted in a division into two fractions: sandstone and loam.

At the pressure value P^O.2 hPa and P₂=12 hPa and rotating cylinder (3) with a diameter of 800 mm, the sorting efficiency, determined as recovered amount of the sandstone fraction, was approximately 45%.

Description of the Drawings:

1. Loading tank

2. Conveyor belt

3. Perforated rotating cylinder

4. Directional nozzle

5. Suction nozzle

6. Separator

7. Suction fan

8. Dust collector

9. Sucked fraction reservoir

10. Non-sucked fraction reservoir

11. Scraper

12. Belt

13. Chute

14. Perforation

15. Underpressure channel

16. Separator outlet

17. Rotary feeder

18. Outflow channel

19. Overpressure channel

20. Work surface

Fl - sucked fraction

F2 - non-sucked fraction

Claims

Patent claims

1. A method of sorting of grain materials with grain diameter sizes in range of 0.1-200 mm, preferably 10-30 mm, where sorted material is introduced by known methods into a loading tank (1) located above the conveyor belt (2) equipped with a scraper (11) and ending with chute (13), characterized in that sorted material is fed on a rotating perforated cylinder (3) having a directional nozzle (4) inside said rotating cylinder (3), and then sorted into a non-sucked fraction F2 and sucked fraction Fl, where the sucked fraction Fl, created by generating a difference in aerodynamic potential, is sucked by means of a fan (7) through the suction nozzle (5) inside the underpressure channel (15) to the particle separator (6), from where it is transported into a sucked fraction reservoir (9) through the separator outlet (16) equipped with a rotary feeder (17), while the air stream, together with the remaining non-separated material, is transported by the discharge channel (18) to the dust collector (8) from which the purified air flows through an overpressure channel (19) to said directional nozzle (4) that causes air movement in a direction perpendicular to the working surface of said rotary cylinder (3) and directed towards the outside of the cylinder generatrix, while the non-sucked fraction F2, i.e. grains that were not sucked through the suction nozzle (5), is discharged by said rotary cylinder (3) to the non-sucked fraction reservoir (10).

2. The method as claimed in claim 1 characterized in that said rotary cylinder (3) has perforations (14), preferably in the shape of holes with a diameter of 1-40 mm, and its diameter is preferably 300-2000 mm.

3. The method as claimed in claim 1 or 2 characterized in that the grain material is subjected to simultaneous effects of the following actions: curving the feed material layer on said rotating cylinder (3) with the perforated working surface (20); forcing a difference in aerodynamic potential, causing suction of the grains, in the range of 1-70 hPa; forcing a difference in aerodynamic potential (overpressure), acting on the seeds vertically upwards, in the range 1-20 hPa.

4. The method as claimed in anyone of the preceding claims characterized in that the movement speed of the feed grains is regulated by the speed of said conveyor belt (2) and rotational speed of said cylinder (3) preferably in such a way that the linear velocity of the feed layer at the suction zone is between 0.1-5 m/s.

5. The method as claimed in anyone of the preceding claims characterized in that the thickness of the feed layer on the belt (12) of said conveyor (2) is set by said scraper (11) located above the moving belt (12) of the conveyor, and is preferably equal to 1.5 of the maximum grain size diameter in the feed material.

6. A device for pneumatic sorting of grain materials, in particular rock materials, consisting of a loading tank (1), a motor, a conveyor (2) with a sliding belt (12) equipped with a scraper (11), and a chute (13), characterized in that it has a rotating cylinder (3) preferably perforated (14), arranged detachably under said chute (13), a separate and detachably connected directional nozzle (4), a suction nozzle (5), located above said rotary cylinder (3), connected permanently to the particle separator (6) by means of an underpressure channel (15), said particle separator (6) connected to a fan (7) and dust collector (8) by means of an outflow channel (18), said dust collector (8) connected to said directional nozzle (4) by an overpressure channel (19).

7. The device as claimed in claim 6 characterized in that the outlet of said directional nozzle (4) is directed perpendicularly to the surface of said cylindrical rotary cylinder (3).

8. The device as claimed in claim 6 or 7 characterized in that said underpressure channel (15), outflow channel (18) and overpressure channel (19) are comprised of steel or plastic ducts, preferably ventilation pipe.

9. The device as claimed in claims from 6 to 8 characterized in that the width of said suction nozzle (4) is selected in accordance to the width of the working surface (20) of said rotary cylinder (3), in range of 0.8-1.2 of this width.

10. The device as claimed in claims from 6 to 9 characterized in that said rotary cylinder (3) has perforations (14), preferably in the shape of holes with a diameter of 1-40 mm, and its diameter is preferably 300-2000 mm.

11. The device as claimed in claims from 6 to 10 characterized in that it comprises of two reservoirs- said sucked fraction reservoir (9), located under said separator outlet (16), and said non-sucked fraction reservoir (10), located detachably next to said rotary cylinder (3).