RU2338595C2 - Screening method for fine material by density and concentrator for its implementation - Google Patents

Abstract

FIELD: processes; mining.

SUBSTANCE: screening method by density of fine unsized material with extraction of concentrate and tails includes classification and separation in centrifugal field. Unsized fine material is fed as pulp under pressure not less then 0.05 MPA into feeding device of centrifugal separator, implemented in the form of hydrocyclone. Sands of hydrocyclone are directed inside of conical rotating bowl, and discharge after blending with condensing water or compressed air, in the form of emulsion, is fed into accumulation zone and concentrate discharge. Feeding of these compounds depending on chosen mode can be implemented under pressure created by bowl rotation or by compressed air, permanently or pulsed and cyclical, with emulsion receiving and formation in accumulation area of semi-boiling medium of reduced viscosity and density. Method is implemented in centrifugal concentrator, including driver, bowl connected to hollow control shaft, body with circular section, facilities for charging and discharging of separation products, feeding of compressed air, condensing and wash water. Concentrator is outfitted by conglobated disk and mixing chamber, installed on the end of hollow driving shaft and connected to emptying fitting of feeder, implemented in the form of hydrocyclone with sand neck located inside of internal hollow shaft of discharging device, under which it is installed conglobated disk, rigidly bound to bowl and forming with it divided by blades ring channel, communicating to mixing chamber.

EFFECT: increasing of hard-cleaning heavy metals and minerals extraction and reduction of investment and operating costs.

4 cl, 2 dwg

Description

The invention relates to the process of separation (concentration) of fine-grained materials by dividing them by density in the field of action of centrifugal and gravitational forces.

The purpose of the invention is to increase the efficiency of extraction of heavy metals and minerals from unclassified pulp while reducing capital and operating costs associated with their processing.

This is achieved by preliminary classification of the pulp in the loading device of the concentrator and the direction of the material of two classes of fineness into the zones of the concentrator with different hydrodynamic separation conditions, including various parameters of centripetal acceleration, viscosity and effective density of the separating medium.

A known method of separating fine-grained material by density (see analogues RU 2080933 C1, 06/10/1997; RU 2245740 C1, 10/02/2005) in the field of action of centrifugal and gravitational forces, including classification on hydraulic screens and density separation in centrifugal separators (concentrators) with the allocation of the heavy fraction (concentrate) and light fraction (tails).

The disadvantage of this method is that its implementation requires several (at least three) separation devices, which complicates the technological scheme, increases metal consumption and energy intensity, worsens specific technical and economic indicators, reduces the cost of processing.

A known method of separating unclassified material, including the supply in the form of pulp of the source material inside a rotating bowl, where under the action of centripetal accelerations acting on particles of minerals, they are separated by density and size.

Light large and small heavy particles are discharged through the annular space on top of the grooves (grooves filled with concentrate) located on the inner surface of the rotating bowl.

One of the disadvantages of this method and device, implemented in a Knelson concentrator and other concentrators of a similar purpose, operating on this principle, is the low separation efficiency of fine particles (less than 50 microns), which is explained by their washing out by trickles of fluidizing water supplied to the concentrator from a variety of small holes for loosening a concentrate bed formed inside annular grooves located on the inner walls of a rotating bowl (see A. Bogdanovich, “Intensification of gravitational processes enrichment in centrifugal fields. - Ore dressing, 1999, No. 1-2, p. 33-35).

Moreover, the presence of a large number of small holes (⌀1.6-2 mm), through which water can be supplied from natural reservoirs, leads to clogging of these holes with solid inclusions (algae, sand, etc.).

Known hubs (see patents RU No. 21114700, 2132737, 2132738) with a floating bed, in which there are no holes for supplying fluidizing water and loosening a concentrated bed. Their distinctive feature is a floating concentrate bed, which is formed during the rolling in of an elastic rotating bowl with ring concentrate grooves along its compressing rollers.

This design of the concentrator allows you to work on untreated water, reduce its consumption and better remove fine particles of heavy minerals. But the unloading of the heavy fraction (concentrate) from the grooves is carried out manually, which requires stopping the entire technological thread and leads to a decrease in its productivity.

Serious drawbacks in the design of an elastic bowl include its very low durability, since operation under high-frequency, alternating loads leads to its destruction as a result of fatigue wear of the bowl material itself.

Therefore, a hub with a floating bed, despite the fame, has not yet found successful use and can only be used in laboratory conditions.

A known apparatus (see patent RU 2238149, C2), which combines three methods of gravitational enrichment (separation) - centrifugal, jigging and separation in tapering channels.

One of the disadvantages of combining these methods of separating unclassified material and a device for their implementation is that none of the three methods of separation can be fully implemented. So, for example, the troughs installed along the forming bowl facilitate mixing of the light fraction with small grains of the heavy fraction in the discharge zone, which is carried out continuously, which leads to the loss of fine particles of the heavy fraction leaving with the drain and a decrease in the useful area of the sieve, which determines the productivity of the machine, and the presence of several sequentially working diaphragms, although it increases the total frequency of oscillations along the camera, but it causes the phenomenon of wave interference, contributing to the unevenness of the pulsations, which reduces a technological effect separation by depositing.

The possibility of effective separation in rotating troughs located perpendicular to the plane of rotation is also questionable.

In view of the foregoing, the most advanced centrifugal apparatus that implements a method for separating fine-grained material by density with separation of concentrate and tailings is the Falkon concentrator (see US Pat. No. 6,796,934 B1), adopted as a prototype, different from the centrifugal type concentrators described above in that the discharge concentrate (heavy fraction) is carried out automatically and periodically with the help of pneumatic valves installed in the holes of the annular grooves, where the concentrate settles and fluidizing water enters. Otherwise, this concentrator has the same structural and operational drawbacks as the well-known Knelson apparatus.

In addition, numerous valves installed around the periphery of the bowl, when working on dirty water, are also able to clog and lead to a violation of the separation process and the need for stops to clean or filter them.

A common disadvantage of the above methods for separating unclassified fine-grained material by density, as noted above, is the low efficiency of separation of fine particles (less than 50 microns) in centrifugal concentrators of the "classifying type", which is associated not only with the supply of fluidizing water washing thin particles of the concentrate, but also with methods for loading source material and unloading separation products.

When unclassified material is fed along the axis of rotation inside the bowl around its axis, a stagnant zone is formed in which the increase in the speed of particle movement in a spiral and in the radial direction occurs relatively slowly and is proportional to the mass of the particle, its rotational speed squared and the shear resistance determined by the viscosity of the separating medium.

Therefore, in the stagnant central zone there is an accumulation of fine particles, as a result of which the viscosity of the separating medium increases, which contributes to their retention and reduce the efficiency of the separation process.

During continuous unloading of the light fraction along the large perimeter of the bowl, an intense upward flow arises in it, where the pulp volume is carried away, where the separation process is hindered by the above reasons, which leads to loss of concentrate and industrial product with the discharge of the light fraction.

These shortcomings can be partially eliminated by supplying a classified (calibrated) material to the concentrator and for each size class to select the optimal hydrodynamic separation mode (bowl rotation speed, density and viscosity of the separating medium), but at the same time it will be necessary to double the number of separating devices (concentrators) and introduce into the technological scheme a classification apparatus (hydrocyclone, spiral or hydraulic classifiers), which will entail an increase in capital , Operating costs will increase the cost of the enrichment process and do not solve the problem of trapping fine particles heavy fraction.

An object of the invention is a method of increasing the extraction of heavy metals and minerals by reducing the minimum size of effectively captured grains and increasing specific productivity by expanding the technological and functional capabilities of the device (concentrator), which can significantly simplify the process flow chart and reduce capital and operating costs associated with the separation process , increase hub performance.

In view of the foregoing, the closest to solving the problem is a method for separating fine fractions of heavy minerals in centrifugal fields during counter injection, which is implemented in a Falkon concentrator with automatic unloading of the concentrate (see US patent 6796934 B1), adopted as a prototype.

Advantages and disadvantages of this invention are described above.

The task posed involves the elimination of these disadvantages of the prototype and is solved by the fact that unclassified material is fed into a centrifugal concentrator in the form of pulp under a pressure of at least 0.05 MPa through a centrifugal loading device configured to carry out preliminary classification, the sands of which are directed into the concentrator by axis, and discharge after mixing with fluidizing water under pressure created by the blades of a rotating bowl, or compressed air in the form of an emulsion, is supplied I am in the zone of accumulation and unloading of the concentrate, where centrifugal forces and centripetal accelerations with an intensity of not less than 50 g act, separated by a partition from the zone of unloading of the light fraction, where the intensity of accelerations does not exceed 10 g, and the pulp-air mixture formed during mixing with air can be pulsed and cyclically with the possibility of the formation of a pulsating pseudo-boiling medium in the concentrator of reduced density and viscosity, and the concentrate is unloaded in an automatic mode and period by opening, by means of an actuator, an annular gap formed in the concentrate discharge zone along the perimeter of the larger base of the bowl.

The technical problem of the device (concentrator) is solved in that the centrifugal concentrator, including a bowl connected to the hollow drive shaft, a housing with annular compartments, devices for loading and unloading separation products, compressed air, fluidizing and flushing water, is characterized in that it is equipped with a mixing chamber mounted on the end of the hollow shaft of the drive and connected to the drain pipe of the loading device, made in the form of a hydrocyclone with a sand nozzle located inside the hollow shaft a device by which the spherical Tarel mounted rigidly associated with a cup and forming with it an annular passage for communication with the mixing chamber.

A concentrator designed to solve the technical problem is also characterized in that the device for unloading separation products is made in the form of a friction coupling half, with the possibility of rotation and axial movement, and contains a friction disk with a nozzle separating the concentration and discharge zone of the heavy fraction (concentrate) from a light fraction unloading zone, inside which there are windows and blades connecting it to the hub and the hollow axis, mounted in a spring-loaded bearing housing mounted on the diaphragm me and kinematically connected with the actuator.

The solution of the technical problem also contributes to the fact that the device for loading and unloading separation products, compressed air, fluidizing and flushing water are equipped with actuators and interconnected timers.

In Fig.1, 2 shows one of the possible options for a hub that implements the proposed method.

The concentrator includes a loading (and classifying) device 1, a housing 2 with annular compartments for receiving separation products, an unloading device with a friction disk 3, a nozzle 4, an elastic element 5, a bearing housing 6 and a hollow shaft 7 connected to the disk by the blades 8 forming the windows " D "for unloading light fractions, bowl 9, drive 10 with a hollow shaft 11, mixing chamber 12, air pipe 13, stand 14, spring 15, actuator 16 with rod 17, air manifold 18, control devices 19, ribs 20, nozzles unloading lay down Coy and heavy fractions, respectively 21 and 22, the supporting frame 23, el. engine 24, a device 25 for supplying flushing water to the stuffing box, the diaphragm 26, the plate 27.

The work of the proposed device (hub) is as follows.

The feed (unclassified material) in the form of pulp is supplied, for example, by a pump (at an inlet pressure not lower than 0.05 MPa) to the loading (and classifying) device 1, made in the form of a hydrocyclone, the sand nozzle of which is lowered inside the hollow shaft 7, and the drain pipe is connected to the mixing chamber 12.

Under the influence of centrifugal forces in the loading device of the hydrocyclone, the initial pulp is classified. Sands (large fraction) through the sand nozzle are directed down the shaft 7 of the unloading device and, in contact with the plate 27 rotating by the electric motor 24, are moved to the periphery of the plate in the annular zone "B", limited by the inner wall of the bowl 9, by the disk 3 and branch pipe 4. An elastic ring 5 with springs 15 acting on the bearing housing 6 of the unloading device, made in the form of a friction coupling half, is pressed against the inner wall of the bowl 9 and forms a friction gear with it, silver stvom which bowl rotation is transferred to the discharge unit. The heavy fraction accumulates in zone "B" and is cleaned with a reverse (counter) flow, which is sent here from the mixing chamber 12, where the discharge of the hydrocyclone (loading device) is mixed with fluidizing water and through the annular slot "D" (see figure 2) with using the blades 20, installed between the bowl 9 and the plate 27, is fed in the form of a mixture of liquefied pulp, or an emulsion formed by mixing it with compressed air, into the zone "B", where the intensity of centripetal accelerations is many times higher than in the loading zone, and should be at least 50g. This value is due to the fact that a noticeable separation of fine fractions (less than 20 μm), as shown by numerous tests of centrifugal apparatuses of various types, including the ones described above, begins with such a hydrodynamic regime of the separating medium. Fine particles of the heavy fraction are separated from the liquefied pulp, or emulsion, and remain in zone "B". This is facilitated by the fluidized (boiling) state of the separating medium formed in this zone when a pulp-air mixture (emulsion) is supplied to it, the density and viscosity of which is lower than the discharge of the hydrocyclone, and can be regulated over a wide range, which is achieved and regulated by the supply of fine air into it through an air pipe 13 connected to an adjustable actuator, providing the possibility of both constant and pulsating supply of compressed air for the implementation of bubbling in the zone "B" and prevent Azania dense concentrate bed.

Grains of light fraction that came here from the mixing chamber together with the stream of liquefied pulp or emulsion, under the influence of high-speed pressure, pass under the nozzle 4 and are discharged through the window "D" (see figure 2) through the disk 3 into the outer annular compartment of the housing 2, entraining followed by a light fraction of sand, which circulates in the plate 7. Blades 8 contribute to the intensification of unloading of the light fraction.

The heavy fraction (concentrate) is unloaded periodically (cyclically) as it accumulates in zone “B”. Figure 2 shows the position of the discharge device at the time of unloading of the concentrate.

By means of an actuator made, for example, in the form of an electromagnet with a thrust 17, a connected time relay with other actuators and relays that ensure the hub operates in automatic mode, the friction coupling is lifted, as a result of which an annular gap is formed between the cup 9 and the elastic ring 5 "G" (see figure 2), in which the heavy fraction from zone "B" is discharged into the inner annular compartment of the housing 2 and then through the nozzle 22 leaves the concentrator for further enrichment operations, and the soft fraction through the nozzle 21 is sent to the dump or regrinding and subsequent enrichment operations.

The design of the concentrator also provides for the possibility of operation of the oscillation mode during continuous or periodic unloading of the heavy fraction.

To do this, the compressed air through the fitting 28 is directed into the chamber "B", under the pressure of the compressed air, the elastic diaphragm 26 connected to the bearing housing 6 and the coupling half of the unloading device rises and opens the annular slots "E" and "G" (see figure 2 )

When opening the gap "E", air is released from the chamber "B", the pressure in it drops, the diaphragm 26 and the unloading device are lowered. With a constant supply of compressed air to chamber "B", the unloading device continues to operate as a non-return valve in the oscillation mode, the frequency and amplitude of which depend on the pressure and volume of compressed air supplied from the network.

The implementation of the oscillation mode (by analogy with jigging) is also possible in the case of connecting instead of an electromagnet 16 of an electromagnetic valve or vibrator.

The above information indicates the following conditions are met when using the claimed invention:

- the method and means of its implementation, implemented in the device, are intended for use in mineral processing, namely for centrifugal wet separation of mainly small and thin particles of metals or their minerals by density, as well as for separation of particles with a small difference in density;

- for the claimed method and device in the form as described in the independent clause of the claims, the possibility of their implementation using the means and methods described and known prior to the priority date is confirmed;

- the advantage of the invention compared with the known analogues and prototype is that when it is implemented, it is provided:

- expanding the technological capabilities of the centrifugal method of separating the material by density, by increasing the extraction of the finest particles of the concentrate by changing the hydrodynamic separation mode by directing a liquefied or fluidized stream containing fine fractions of the enriched material directly into the accumulation zone of the heavy fraction, where centrifugal forces and accelerations intensities above 50g, at which the thin particles of the heavy fraction remain in the zone of its discharge and do not leave with a light fraction, since the drain windows are displaced to the center of the bowl and are located in the zone of action of centrifugal forces and accelerations, the intensity of which does not exceed 10 g, and the pressure head arising in a liquefied or fluidized (boiling) flow of medium acting in the direction of unloading of the light fraction, cannot overcome centrifugal forces, because it has a relatively low energy, since the density and viscosity of the medium forming the flow are relatively small (due to its fluidized or fluidized state);

- expanding the functionality of the device (hub) that implements the proposed method by:

- combining in one device (concentrator) the functions of the classifying and separating devices;

- the possibility of adjusting the density and viscosity of the separating medium in the apparatus;

- separating the zone of accumulation and unloading of the heavy fraction from the unloading zone of the light fraction, which allows you to fundamentally change the hydrodynamic mode of operation of the centrifugal apparatus and carry out the separation process, combining the action of centrifugal forces and the counter velocity head, facilitating the cleaning of the heavy fraction by expelling the light fraction from the separation zone, and when necessity, and industrial product grains;

- creating conditions, using simple automation tools for automatic operation of the concentrator according to a given sequence diagram, providing the optimal separation mode determined by laboratory methods;

- providing conditions for the accumulation and automatic unloading of the heavy fraction of a wider particle size range than in existing centrifugal devices due to the possibility of changing the flow dynamics, adjusting the density and viscosity of the separating medium in the separation zone;

- realizing the possibility of the concentrator working in the oscillation mode during continuous or periodic unloading of the heavy fraction, combining separation methods by depositing, centrifugal separation and separation in special media (class B03B 5/44).

An advantage of the invention also lies in the fact that with this enrichment method (density separation) and a device for its implementation, the technological scheme of the apparatus circuit, its energy consumption, metal consumption and installation dimensions are greatly simplified, which allows to reduce the cost of processing mineral or industrial raw materials.

Claims (4)

1. The method of separation by density of fine-grained unclassified material with the separation of concentrate and tailings, including classification and separation in a centrifugal field, characterized in that the unclassified fine-grained material is supplied in the form of pulp under a pressure of at least 0.05 MPa to the loading device of a centrifugal separator, made in the form of a hydrocyclone, the sands of which are directed inside a conical rotating bowl, and the discharge, after mixing with fluidizing water or compressed air, in the form of an emulsion, is fed into the zone on filling and unloading the concentrate, where centrifugal forces and centripetal accelerations with an intensity of not less than 50 g act, and the supply of these mixtures, depending on the selected mode, can be carried out under pressure created by rotation of the bowl or compressed air, continuously or pulse and cyclically, with the possibility of obtaining emulsions and formations in the accumulation zone of a concentrate of a pseudo-boiling medium of reduced viscosity and density. 2. A centrifugal concentrator including a drive, a bowl connected to the hollow drive shaft, a housing with annular compartments, devices for loading and unloading separation products, compressed air, fluidizing and washing water, characterized in that it is equipped with a spherical plate and a mixing chamber installed at the end of the hollow shaft of the drive and connected to the drain pipe of the loading device, made in the form of a hydrocyclone with a sand nozzle located inside the hollow shaft of the unloading device, under which lena spherical Tarel rigidly associated with a cup and forming with it an annular channel divided blades communicating with the mixing chamber. 3. The concentrator according to claim 2, characterized in that the device for unloading the separation products is made in the form of a friction coupling half, with the possibility of rotation and axial movement, and contains a friction disk with a nozzle separating the concentration zone of the heavy fraction from the discharge zone of the light fraction, inside of which there are windows and blades connecting it with the hub and the hollow axis mounted in a spring-loaded bearing housing, mounted on an elastic diaphragm and kinematically connected with the actuator. 4. The concentrator according to claim 2 or 3, characterized in that the devices for loading and unloading separation products, compressed air, fluidizing and flushing water are equipped with actuators and interconnected timers.

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