EA037602B1 - Pneumatic method of separating mineral and technogenic raw materials according to particle shape - Google Patents

Abstract

The invention relates to the field of separating mineral and technogenic raw materials and can be used for producing mobile separating plants intended for processing and classifying raw materials according to shape in virtually any weather conditions, including at ambient air temperatures of -50 to +50°C. A pneumatic method of separating mineral and technogenic raw materials according to particle shape is claimed, comprising placing raw materials to be processed on an air-permeable surface in the form of a conveyor that passes below the base level of a separating chamber, in which a volumetric pseudo-boiling layer of particles having a specified density is formed by selecting an airflow velocity. Particles of smaller density enter into and pass through said layer without obstruction and are then transferred by a rising airflow from a vertical chamber into a gravitational settling chamber. The invention is novel in that an additional stream of air, tangentially oriented towards a wall of the separating chamber, is directed into the separating chamber and creates auxiliary eddy flows at the walls and the base of the chamber, after which particles of flat, needle-like or thread-like shape are lifted by a rising flow of air and are transferred to the gravitational settling chamber, in which one or more cross-directional eddy flows depositing the particles in the chamber are created, from which chamber said particles are then removed.

Description

The invention relates to the field of enrichment of mineral and technogenic raw materials and can be used to create mobile processing plants intended for processing and classification of raw materials in shape in almost any weather conditions, including at ambient temperatures from -50 to + 50 ° C.

Prior art

It is known that during the processing of raw materials to obtain products of the required quality, separation is carried out by physical methods according to various parameters, such as size, density, magnetic susceptibility, etc. One of these parameters is the shape of the grains. It is very often necessary to separate materials that are similar in their basic properties, but differ in shape. For example, in crushed stone used for road surfaces and construction, the content of lamellar grains or flaky grains is regulated. This is due to the fact that flat grains are less strong, and also reduce the bearing capacity of bulk materials by reducing the adhesion forces between the grains. Traditionally, a low flaky grain content is achieved through the use of multi-stage rock crushing schemes with a small reduction in product size at each stage. This solution results in a high dropout rate of the 0-5 mm class, which is a low quality product with limited use. For example, in the production of crushed stone of classes 5-10 mm and 10-20 mm, which are most in demand in road construction, a dropout of 0-5 mm is formed in an amount of 60 to 75%, Moreover, the more durable and valuable rock is used in the production of crushed stone, the greater the dropout yield. When using crushing schemes with a smaller number of stages, the screening yield is reduced to 30-35%, but the resulting crushed stone contains flat grains in large quantities and must be removed from the commercial crushed stone. It becomes clear that the further development of enrichment technologies is impossible without effective technologies that ensure separation by shape. At the same time, the technology for enrichment of raw materials in shape must meet several stringent requirements.

First, the method must be universal, easily reconstructed for processing various types of mineral raw materials (crushed stone, asbestos, mica and other mineral or man-made products).

Secondly, the processing method should provide for the ability to quickly and smoothly change technological modes depending on the properties of the processed raw materials (mass and size of particles, density and shape), which will make it possible to create mobile processing plants of a modular type using the same type of equipment, with a low level of capital costs for their delivery and installation.

Thirdly, the method of enrichment of raw materials should be highly effective, ensuring high quality of the products obtained, as well as that after its use, only those wastes remain that are not suitable for further processing or for direct use. Fourth, the raw material enrichment technology should be all-weather and year-round, so that the process does not take place seasonally with the temporary involvement of labor resources, but goes on constantly - with year-round employment of the local population. For this reason, the technological cycle for enrichment of raw materials should include an ambient temperature range of -50 to + 50 ° C and should allow equipment to be placed in the open or using light-type shelters.

There is a known method of separating lumpy material in shape (patent RU 2119393, CL. B07B 13/00, 1998), in which, due to the difference in frictional forces and dynamic characteristics of particles of flat (flaky) and cuboidal shape, separation of particles occurs by feeding the material on an inclined plane, followed by collision with a rotating cylindrical surface.

The main disadvantage of this method is the low separation efficiency and the possibility of implementing the process only on coarse material, despite the fact that in industry it is necessary to process to a greater extent just fine material. An analysis of waste products from processing natural materials with the extraction of mica using a similar technology showed that as a result, about half of the commercial mica with a particle size of 13-50 mm was lost, and the extraction of mica in smaller classes did not occur at all.

Closest to the claimed technical solution is a method of pneumatic enrichment of mineral raw materials (see Eurasian patent No. 022959, CL. B07B 4/08, B03B 4/04, 2016), including the placement of the enriched raw materials on an air-permeable surface crossing the vertical chamber with an ascending air flow, lifting light fractions from an air-permeable surface made in the form of a conveyor, passed below the level of the lower base of the vertical chamber, in which a volume pseudo-boiling layer of particles of a given density is formed by choosing the air flow rate, into which particles of lower density enter and freely pass through it, and then the ascending air flow is transferred from the vertical chamber to the gravity settling chamber. When using this method, it is possible to separate materials not only in terms of density, but also in shape, due to the fact that grains of a flat or acicular shape have a greater value of the ratio of the force of aerodynamic resistance to the weight of the particle.

The known method allows for year-round enrichment of raw materials in the open air

- 1 037602 or with the use of light-type shelters, as well as to carry out a quick restructuring of the technological process for the processing of various types of mineral raw materials by changing the air flow rate.

The main disadvantage of the known method is its functional limitation in the separation of mineral and technogenic raw materials, which contains many flat or filamentary particles.

Firstly, this is due to the complexity of lifting from the conveyor with a vertical flow of those particles, the length, width and height of which can differ by several tens of times. Such thin flat or filamentary particles can face the vertical suction flow with their narrow edge or needle end, while their aerodynamic properties when exposed to the suction flow will be very different from the properties of particles lying flat on the conveyor.

Secondly, this is due to the fact that the deposition chamber does not allow capturing thin flat or filamentary particles due to their low velocity in the air, and, therefore, to ensure their deposition, it is necessary to disproportionately increase the dimensions of the deposition chamber.

Disclosure of invention

The basis of this invention is the task of expanding the functionality of the pneumatic method for separating particles, capable of enriching particles of various types of mineral raw materials and industrial waste, such as mica, asbestos ore, crushed stone, and household waste, differing in shape.

The specified task in the pneumatic method for separating mineral and technogenic raw materials in the form of particles, including the placement of the processed raw materials on an air-permeable surface made in the form of a conveyor, passed below the level of the lower base of the separation chamber, in which a volumetric pseudo-boiling layer of particles of a given density is formed by choosing the air flow rate, into which particles of lower density enter and freely pass through it, and then are transported by an ascending air flow from the vertical chamber to the gravitational settling chamber, solved by the fact that an additional air stream tangentially oriented to the chamber wall is directed into the separation chamber, creating auxiliary vortex flows at the walls and the lower base of the chamber, after which particles of a flat, needle-like or filamentary shape are picked up by an ascending air flow and transferred to a gravitational settling chamber, in which one or more oppositely directed vi sludge flow, settling particles in the chamber, from where they are then removed.

Due to the additional air jet tangentially oriented to the wall of the chamber, it is possible to create vortex air flows at the walls and base of the separation chamber, and thereby avoid adhesion of particles of the separated raw materials to the walls of the separation chamber with the formation of particle agglomerates, as well as to act at the base of the chamber on thin flat or threadlike particles that are directed by their narrow edge or needle end to the vertical suction flow in order to facilitate a change in their spatial position, and therefore to improve their interaction with the suction flow. In this case, one or more vortex currents are created in the gravitational settling chamber, which sharply reduce the kinetic energy of the moving particles, which leads to their rapid deposition to the bottom of the chamber.

To create controlled vortex flows near the walls of the separation chamber, capable of exerting a predetermined vortex effect on thin flat or filamentary particles, which face their narrow edge or needle end to the vertical suction flow, an additional tangentially oriented air stream is fed through a tangential nozzle, which is installed with the possibility of changing its position in the vertical plane.

Since each emitted fraction of particles has its own aerodynamic properties, the speed of an additional tangentially oriented air jet is selected experimentally.

To perform the simultaneous multistage pneumatic separation of mineral and technogenic raw materials into particles of a given shape and dimensions of a flat, needle or threadlike shape, several separation chambers are installed in series, in each of which individual parameters are selected for the selection of particles of a given shape and dimensions, while each chamber is connected to its own a gravity settling chamber.

To remove particles deposited on the walls of the gravity settling chamber, a contact method of action, for example, mechanical scrapers, or a non-contact method, for example, by exposure to an air jet, or a combination of both of these methods are used.

Thus, the claimed pneumatic method for separating mineral and technogenic raw materials by particle shape allows separating mineral raw materials into almost any number of fractions having different shapes in one cycle of movement on a conveyor, while the method separates fractions with great efficiency and productivity, which has no analogues among known methods of pneumatic separation of thin flat or filamentary particles, which means that it meets the criterion of inventive step.

- 2 037602

Brief Description of Drawings

The inventive method is illustrated by the drawings shown in FIG. 1 and 2.

FIG. 1 shows a diagram of an installation for implementing the proposed method for separating mineral and technogenic raw materials in the form of particles, where 1 is an air-permeable conveyor with particles of enriched mineral raw materials 2; 3 - separation chamber with a lower base 4, a tangential nozzle 5, forcing the air flow 6, and a mechanism for turning the direction of the jet 7; the upper part of the separation chamber 3 is connected by an air duct 8 with a gravitational settling chamber 9, the lower base of which 10 is equipped with a rotary sluice flap 11 for periodically pouring out the fraction of raw material 12 selected in the form of particles; the deposition chamber 9 is connected through the air duct 13 to the exhaust fan 14; 15 - tangential air duct, creating a flow of air 16, opposite to the flow of air 17 with particles of raw materials, entering the chamber 9; 18 - air flow without raw materials, aspirated from chamber 9.

FIG. 2 shows a drawing of the separation chamber 3 in perspective and shows the vortex flows inside the chamber: 19 - wall vortex flow, 20 - axial vortex flow.

Best Mode for Carrying Out the Invention

The implementation of the proposed method will be considered on the installation shown in Fig. 1. In FIG. 2 shows a diagram of vortex flows inside the chamber 3. Particles of the separated raw material 2 are uniformly placed on the surface of the air-permeable conveyor 1 and move towards the separation chamber 3. Once under the base of the chamber 4, the raw material 2 enters the zone of a volumetric pseudo-boiling layer of particles of a given density, formed as a result the impact of the ascending gas flow created by the fan 14 through the air ducts 8 and 13. The separation of particles in shape occurs due to the difference in mass and aerodynamic resistance of particles of different shapes. Particles close in one linear size, but differing in one or two linear sizes, have different mass and aerodynamic resistance. For example, plane particles have a mass several times, and sometimes several tens of times less than particles of a conventionally cuboid or spherical shape, while the aerodynamic drag of plane particles is significantly higher than the resistance of spherical particles. The difference in properties leads to the fact that the speed of hovering of particles of various shapes is significantly different. The same is true when comparing needle or filamentous particles with flat or spherical or cuboidal ones. Once in the zone of the pseudo-boiling bed, the particles begin to circulate in it, and those of them that have a soaring rate less than the flow rate in the separation chamber 3 are removed with a stream 17 through the air duct 8 into the settling chamber 9. Particles with a higher soaring speed return to the conveyor 2 and are removed from zone 4 of the separation chamber 3. Simultaneously with this process, an air flow 6 enters the chamber 3 through the tangential nozzle 5. As a result of the action of the wall vortex flow 19 (see Fig. 2), it is possible to avoid adhesion of particles of the separated raw material 2 to the walls of the separation chambers 3 with the formation of agglomerates of particles, as well as create vortex flows at the walls and the lower base of the separation chamber 4, and thereby act on thin flat or threadlike particles that face their narrow edge or needle-like end to the vertical suction flow and cannot, due to poor aerodynamic properties can only be sucked up by vertical flow 20. Particles under the air The flow 19 turns, their aerodynamic properties are improved and they are captured by the flow 20. Further, the captured particles with the flow 17 enter the gravitational settling chamber 9, the lower base of which 10 is equipped with a rotary sluice valve 11 for periodically pouring out the fraction of raw material 12 selected in the shape of particles. the operation of the gravity chamber in the settling mode, the rotary airlock 11 is closed. At the same time, towards the air flow 17, the air flow 16 enters, the speed of the particles drops sharply, their aerodynamic properties deteriorate and, under the action of gravitational forces, they sink to the bottom of the deposition chamber 9.

Technical applicability

The specific implementation of the proposed method will be considered on the examples of the enrichment of various mineral raw materials.

Example 1.

Consider the separation of phlogopite ore. The pneumatic enrichment process was carried out on a pilot plant shown in FIG. 1. Before the start of processing, the ore is preliminarily crushed to a size of 0-16 mm and fed to a belt conveyor 1 with a cloth made of a mesh with a mesh of 1 mm, a width of 600 mm and moving at a speed of 0.5-1.5 m / s, over which one after another the other has two cylindrical chambers 3 with conical bases 4 equal to the width of the conveyor - 600 mm. The cylindrical part of the chamber has a diameter of 1200 mm and a height of 2000 mm. Each of the chambers is connected to its own gravity settling chamber 9 in the form of an inverted truncated cone with a diameter of the upper base of 2400 mm, the lower base of 900 mm and a height of 3200 mm. The deposition chamber 9 has a design that provides the formation of two oppositely directed vortices 15 and 17, while the vortex 15 is introduced into the chamber 9 tangentially to its wall clockwise, and the vortex 17 is also tangential, but counterclockwise. Particles of ore 2 with a size of less than 1 mm spill out under the conveyor mesh 1, fall on a vibrating chute (not shown in Fig. 1) and are removed

- 3 037602 from further processing.

The air flow in chambers 3 is selected in such a way that in the first separation chamber a product is released, represented by phlogopite plates with a thickness of less than 0.1 mm, and in the second chamber, grains with a thickness of up to 1 mm are released. The material remaining on the conveyor is represented by grains of crushed stone, which can be used for construction purposes. The capacity of the experimental technological line is up to 20 t / h.

Example 2.

Consider the separation of construction crushed stone. The task is to obtain a stable quality of crushed stone containing a small amount of weak grains having a flat shape (flaky grains). The pneumatic enrichment process was carried out on a pilot plant shown in FIG. 1. During processing, the raw material is crushed and classified into machine classes, and crushed stone of 5-10 and 10-20 mm classes, most often used in road construction, is sent for processing, each of which is processed separately. Particles with a size of 5-10 mm are fed to a belt conveyor 1, with a cloth made of a mesh with a mesh of 3 mm and a width of 1000 mm, moving at a speed of 1.0-2.0 m / s, above which one chamber 3 is installed, with a conical base 4 equal to conveyor width - 1000 mm. The cylindrical part of the chamber has a diameter of 1500 mm and a height of 1600 mm. The chamber is connected to the gravity settling chamber 9 with a top base diameter of 2800 mm, a bottom base of 2000 mm and a height of 3700 mm. Particles of crushed stone with a size of less than 3 mm, which remained in crushed stone of class 5-10 due to the impossibility of their complete removal, wake up under the conveyor mesh 1, fall on the vibrating chute (in Fig. 1 it is not shown conventionally) and are removed from further processing. Air flows 6 and 17 in the separation chamber 3 are selected in such a way that a product with a flat flaky shape is released in the chamber 3, and a product represented by grains with a shape close to cubic remains on the conveyor mesh 1. The capacity of the experimental processing line is up to 100 t / h.

Crushed stone of 10-20 mm class is processed on a similar plant, characterized in that the mesh size of the conveyor 1 mesh is 5 mm.

Example 3.

Consider the separation of household waste. In the process of human activity, large volumes of solid household waste are generated. They contain both organic waste and recyclable materials: glass, plastics, paper, cardboard, etc. When processing solid waste, the first stage provides for the removal of small impurities with a particle size of 40 mm or less. They are mainly represented by organic waste and cullet and go for further washing. Material larger than 40 mm is fed to a shredder with a blade width of 20 mm, in which flat material is cut into strips 20 mm wide or crushed into particles of the same size. Further, all the material is fed to the belt conveyor 1 with a canvas made of a mesh with a mesh of 10 mm, a width of 500 mm and moving at a speed of 0.5-1.5 m / s, above which two cylindrical chambers 3 with conical bases 4 equal to conveyor width 500 mm. The cylindrical part of the chamber has a diameter of 1200 mm and a height of 2000 mm. Each of the chambers is connected to its own gravity settling chamber 9 in the form of an inverted truncated cone with a diameter of the upper base of 2400 mm, the lower base of 900 mm and a height of 3200 mm. Each chamber has a design that provides the formation of two oppositely directed vortices 15 and 17. Particles of raw materials with a size of less than 10 mm spill under the conveyor mesh 1 and fall on a vibrating chute (not shown in Fig. 1), which removes the product from under the conveyor 1. The air flow in the chambers is selected in such a way that in the first chamber a product is released, represented by thin materials, such as films, fabrics, paper, plastic from bottles, and in the second chamber thicker stripes are released, which are mainly represented by cardboard. The material remaining on the conveyor is represented by cuboid grains, which are fed for further processing. The resulting products are then briquetted and used as fuel or raw materials for the chemical industry. The capacity of the experimental technological line is up to 4.5 t / h.

Thus, the inventive method makes it possible to effectively carry out pneumatic separation of particles from various mineral and technogenic raw materials that differ in their shape.

Claims (6)

CLAIM 1. A pneumatic method for separating mineral and technogenic raw materials in the form of particles, including placing the processed raw materials on an air-permeable surface made in the form of a conveyor, passed below the level of the lower base of the separation chamber, in which a volumetric pseudo-boiling layer of particles of a given density is formed by choosing the air flow rate, in particles of a lower density enter and freely pass through it, and then by an ascending air flow are transferred from the vertical chamber to the gravitational settling chamber, characterized in that an additional air stream tangentially oriented to the chamber wall is directed into the separation chamber, creating auxiliary vortex flows at the - 4 037602 nok and the lower base of the chamber, after which particles of a flat, needle-like or filamentary shape are picked up by an ascending air flow and transferred to a gravitational settling chamber, in which one or more counter-directed vortex flows are created, which precipitate particles in the chamber, from where they are then removed ... 2. The method according to claim 1, characterized in that an additional tangentially oriented air jet is supplied through a tangential nozzle, which is installed with the possibility of changing its position in the vertical plane. 3. The method according to claim 1, characterized in that the speed of the additional tangentially oriented air jet is selected experimentally for each separated fraction of particles. 4. The method according to claim 1, characterized in that for the simultaneous separation of various fractions of particles of a flat, needle-like or filamentary shape, several separation chambers are installed in series, in each of which individual parameters are selected for the selection of particles of a given shape and dimensions, with each chamber connected with its own gravity settling chamber. 5. The method according to claim 1, characterized in that the particles deposited on the walls of the gravity settling chamber are removed by a contact method, for example by mechanical scrapers. 6. The method according to claim 1, characterized in that the particles deposited on the walls of the gravitational settling chamber are removed by a non-contact method, for example by exposure to an air stream.