RU2301112C1 - Method for grinding of mineral deposits and cavitational disperser for effectuating the same - Google Patents

Abstract

FIELD: mining industry, in particular, fine grinding of mineral deposits to prepare it for concentration process.

SUBSTANCE: method involves dosed feeding of aqueous suspension of mineral raw material into cavitational disperser and grinding; breaking-down grains of useful component by exposing to hydraulic percussion and cavitational pulses at natural grain and rock cohesion zones; controlling cavitational pulse frequency by changing cartridges with resonators secured therein and adjusted for required frequency; additionally controlling cavitational pulse frequency by regulating feeding pressure of mineral raw material aqueous suspension delivered into disperser. Disperser used in the process is of direct-flow type and consisting of hollow rotor with blades fixed on its internal surface, partition positioned at rotor end side opposite to rotor inlet branch pipe, perpendicular to axis of rotation of rotor, and equipped with openings, and stator positioned adjacent to rotor end adjoining to cavitational chamber. Stator has partition with openings which are aligned with rotor partition openings upon rotation of rotor. Regardless of controlling cavitational pulse frequency, hydraulic percussion pulse frequency is to be controlled.

EFFECT: increased efficiency in grinding of mineral raw material and reduced adverse effect of abrasion wearing of main parts of disperser upon its service life.

5 cl, 3 dwg

Description

The technical solution relates to the mining industry and is intended for fine grinding of minerals in preparation for enrichment.

A known method of grinding refractory ores, implemented in the method of flotation of refractory copper ores according to the patent of the Russian Federation No. 2151010, class. B 03 D 1/00, publ. in BI No. 17 for 2000, which includes the dosed supply of an ore-water suspension and grinding of ore grains in a ball mill with the opening of grains of useful components.

The disadvantage of this method is the relatively low efficiency of grinding ore due to the long duration of the grinding grinding cycle in a ball mill and the large yield of sludge fractions that go to waste.

The closest in technical essence and the set of essential features is a method of grinding refractory ores (RF patent No. 2203738, 02 C 19/00, published in BI No. 13 for 2003), which includes a dosed supply of a suspension of water-ore and grinding it into cavitation dispersant with the opening of mineral grains by natural defects by the sequential action of hydroshock loads and cavitation pulses formed by the expansion of the flow channel and oscillations of the resonators with the frequency of natural vibrations of the ore particles and The pressure of the cavitation pulse frequency by changing the yokes with fixed to them resonators tuned to the desired frequency.

The disadvantage of this method is the limited regulation of the frequency of hydraulic shock loads, which is strictly dependent on the rotational speed of the rotor, which negatively affects the accuracy of tuning the frequency of hydraulic shock loads, as a result of which the efficiency of grinding of ore is reduced due to non-compliance with the conditions of resonant exposure of useful components to grains. The flow rate of the suspension jet from the rotor holes is also strictly dependent on its rotation frequency, which limits the limits and accuracy of controlling the frequency of cavitation pulses, as a result of which the ore grinding efficiency is reduced due to non-compliance with the resonant effect of useful components on the grains. For each type of mineral, a cavitation dispersant with individual geometric parameters is required.

Known rotary apparatus hydropercussion (AS USSR No. 1586759, 01 F 7/12, publ. In BI No. 31 for 1990), comprising a housing inside which a rotor and a stator are concentrically mounted with slots in the side walls, and the slots in the rotor are made in the form of subsonic nozzles, tapering towards the stator, the slots of which are made expanding towards the body and have concave surfaces.

A disadvantage of the known rotary apparatus of hydropercussion is the strictly determined frequency of cavitation pulses, which is determined by the shape of the cracks in the walls of the rotor and stator, which negatively affects the accuracy of tuning the frequency of hydropercussion pulses, as a result of which the ore grinding efficiency is reduced due to non-observance of the resonant effect on the grain of useful components. The abrasive wear of the working surfaces of the rotor and stator from the effects of hydroshock pulses also leads to the fact that the conditions of the resonant effect on the grains of useful components are violated and, as a result, the efficiency of ore grinding is reduced.

The closest in technical essence and combination of essential features is a cavitation dispersant (RF patent No. 2203738, 02 02/19/00, published in BI No. 13 for 2003), comprising a housing inside which a stator is installed with slots in the side walls, expanding toward the body, having concave surfaces, a rotor in which slots are made in the form of subsonic nozzles, tapering towards the stator, which can be combined with the stator slots during rotation of the rotor, and the working chamber, while the number of slots in the rotor and stator varies o, and in the working chamber mounted coaxially with the slots of the stator adjustable oscillation frequency resonators.

A disadvantage of the known cavitation dispersant is the limited regulation of the frequency of hydroshock pulses, which is strictly dependent on the rotational speed of the rotor, which negatively affects the accuracy of setting the frequency of hydroshock pulses, which reduces the grinding efficiency of the ore due to inaccurate observance of the resonant effect on the grain of useful components. The flow rate of the suspension jet from the rotor holes is also strictly dependent on its rotation frequency, which limits the limits and accuracy of the regulation of cavitation pulse frequencies, as a result of which the ore grinding efficiency is reduced due to non-compliance with the resonant effect of useful components on the grains. For each type of mineral, a cavitation dispersant with individual geometric parameters is required. In addition, the stator material of the cavitation dispersant has high abrasive wear from exposure to cavitation pulses, which significantly reduces the life of the cavitation dispersant, increases repair costs, leads to equipment downtime and, therefore, reduces the efficiency of grinding minerals.

The technical task is to increase the efficiency of grinding minerals by increasing the accuracy and expanding the limits for regulating the frequency of hydroshock and cavitation pulses and reducing the negative impact of abrasive wear on the life of a cavitation dispersant due to more precise tuning to the resonant grinding mode.

The problem is solved in that in the method of grinding minerals, comprising dosing the aqueous suspension of minerals into a cavitation dispersant and grinding it with opening the grains of the useful component by the resonant action of hydroshock and cavitation pulses along the zones of natural adhesion of these grains with the rock, controlling the frequency of cavitation pulses due to change of clips with resonators fixed to them, tuned to the desired frequency, according to the technical solution, additionally carry out adjusting the frequency of cavitation pulses due to the regulation of the pressure of supplying an aqueous suspension of minerals to the dispersant, made straight-through and consisting of a hollow rotor with blades on the inner surface, and installed from the opposite end of the inlet pipe of the rotor end, perpendicular to the axis of rotation of the rotor, a partition with holes and from the stator, made from the end adjacent to the cavitation chamber, with a partition having holes that are compatible with the holes of the rotor during rotation of the latter, while independently mo of cavitation pulse frequency control performed hydropercussion frequency control pulses.

The problem is solved by the fact that the cavitation dispersant, including the housing, inlet and outlet pipes, a stator with holes expanding towards the cavitation chamber, installed in it and tuned to the frequency of natural vibrations of the mineral particles in the suspension, cavitation pulse resonators, a rotor with a drive, blades and holes in the form of subsonic nozzles, tapering towards the stator holes, made with the possibility of combining them when the rotor rotates with the stator holes, according to the technical solution about n made straight-through, for which the rotor is made hollow, the blades are mounted on its inner surface, while a partition is installed from the opposite end of the rotor end, perpendicular to the axis of rotation, and these rotor holes are made in its partition, and the stator is equipped with an end face adjacent to cavitation chamber, a partition in which these stator holes are made.

Since the aqueous suspension of minerals (hereinafter referred to as the suspension) is supplied through the inlet to the cavitation dispersant under pressure, the flow rates of the suspension are V ₁ until the holes in the rotor overlap and after their V _{0 is} closed in the well-known formula N.E. Zhukovsky depend on the pressure and do not depend on the rotor speed. This allows, regardless of the rotor speed, to control the speed V _{1 of} the suspension flow into the rotor holes by changing the pressure in the system and thereby regulate the force P of the hydroshock pulses

P = ρ (V ₁ -V ₀ ) s, N / m ² ,

where ρ is the density of the suspension, kg / m ³ ;

V ₁ and V ₀ are the flow rates of the suspension before the holes in the rotor overlap and after the overlap, respectively, m / s;

C is the speed of sound propagation in suspension, m / s.

Since in the free flow there are oscillations of the suspension with a frequency

, Гц,

Hz

where K is the coefficient of proportionality, depending on V and h;

V is the flow rate of the suspension stream from the rotor hole, m / s;

h is the distance between the baffle of the rotor and the resonator, m,

then by changing the pressure in the system, the frequency of cavitation pulses can also be independently controlled due to a corresponding change in the velocity V of the jet of suspension from the rotor hole in the direct-flow mode of operation of the cavitation dispersant.

Thus, when dosed feeding into a direct-flow cavitation dispersant, mineral suspensions under pressure and as a result of independent control of the frequency of hydroshock pulses (by changing the rotor speed) and cavitation pulses (by adjusting the pressure and changing resonator settings in the cavitation chamber), it becomes possible improving accuracy and expanding the limits of regulation of the force and frequency of hydroshock and cavitation pulses. As a result, the efficiency of grinding minerals increases. It becomes possible to adjust the cavitation dispersant to the conditions favorable for grinding minerals of various properties (for example, sulfide ores or coal) while maintaining their high grinding efficiency.

The direct-flow design of the cavitation dispersant, when the rotor is hollow and the blades are mounted on its inner surface, and from the opposite end of the rotor inlet there is a baffle perpendicular to the axis of rotation, while these rotor holes are made in its baffle, the stator is equipped with an end face adjacent to the cavitation the chamber, the partition, and the stator holes are made in its partition with the possibility of combining them when the rotor rotates with the indicated rotor holes most easily allows for stignut resonant mode destruction of mineral particles.

The condition for the resonant rupture of mineral particles in suspension is the equality

f _cf = f _p

where f _p is the oscillation frequency of the cavitation pulse resonators, Hz.

To adjust the frequency f _{p of} cavitation pulse resonators to the frequency f _{h of} natural vibrations of mineral particles in the suspension and to fulfill the condition f _p ≈ f _{h, we} use the dependence

where α is the coefficient of proportionality (for the console method of fastening the resonators α = 0.162);

t is the thickness of the resonators, m;

l is the length of the cantilever part of the resonators, m;

E is the modulus of elasticity of the material of the resonators, MPa;

ρ is the density of the suspension, N / m ³ .

According to the proposed technical solution, it becomes possible to more accurately adjust the resonance regime of grinding minerals (f _p ≈ f _h ) by varying the parameters V, h, E, t and l in the above formulas by replacing the holder with cavitation pulse resonators fixed to it (with a rough tuning to the type of mineral) and a smooth change in the pressure at the input of the cavitation dispersant and rotor speed (with fine tuning). This increases the efficiency of grinding minerals and reduces the negative impact of abrasive wear on the life of a direct-flow cavitation dispersant due to more accurate tuning to the resonant grinding mode.

It is advisable that the rotor drive is independent and in communication with the rotor by means of a speed variator pulley.

In this case, the change in the rotor speed is most easily achieved, as a result of which the efficiency of grinding minerals is further increased and the negative impact of abrasive wear on the life of the cavitation dispersant is reduced by increasing the accuracy and expanding the frequency limits of hydraulic shock and cavitation pulses and more accurately adjusting to the resonant grinding mode .

It is also advisable to carry out the rotor drive built-in when the rotor serves as the anchor of the electric motor, and the stator serves as the stator of the electric motor.

This achieves a smooth change in the rotor speed, which further increases the efficiency of grinding minerals and reduces the negative impact of abrasion on the life of the cavitation dispersant by increasing the accuracy and expanding the frequency limits of hydraulic shock and cavitation pulses and more accurately adjusting to the resonant grinding mode.

It is advisable to make the stator baffle removable and / or install with the possibility of movement along the longitudinal axis of the stator and fixation relative to the latter by means of an adjustment element, for example, an elastic ring.

The possibility of replacing and / or moving the stator baffle along its longitudinal axis (without dismantling it) with fixing relative to the stator by means of an adjusting element allows to increase the life of the cavitation dispersant due to the possibility of compensating for abrasive wear by adjusting the working gap between the rotor and stator and, therefore, increases the grinding efficiency mineral due to lower equipment repair costs and reduced technological downtime.

The essence of the technical solutions is illustrated by examples of specific performance and drawings, where figure 1 shows the technological scheme of ore grinding by the proposed method; figure 2 is a schematic diagram of a cavitation dispersant with an independent drive containing the simplest speed variator, and figure 3 is a cavitation dispersant with a built-in drive in which the hollow rotor is the armature of the electric motor, and with a removable stator baffle.

The proposed method (figure 1) is implemented using the proposed cavitation dispersant as follows. Dosed components of the suspension of minerals are fed into the repulpator 1 and then pump 2 into the specified dispersant 3, in which the particles of minerals are mined in suspension by natural defects and the grains of useful components are opened from intergrowths by the resonant action of hydroshock and cavitation pulses along the zones of natural adhesion of these grains with breed. The treated suspension is fed into the tank 4, and then through the pipeline 5 for enrichment (for example, flotation).

The cavitation dispersant is made direct-flow (hereinafter the dispersant) and consists of a housing 6 (FIG. 2), to which a stator 7 is fixed, having a partition 8 at the end, perpendicular to the axis of rotation of the rotor 9. In the partition 8 of the stator 7 holes 10 are made, expanding towards the cavitation chamber 11, in which cavitation pulse resonators 12 (hereinafter referred to as resonators 12) mounted on a clip 13 are mounted. Resonators 12 are tuned to a frequency f _p close to the frequency f _{h of} natural vibrations of the mineral particles (the condition f _p ≈f _{h is} fulfilled). The rotor 9 is hollow and blades 15 are mounted on its inner surface 14. During rotation, the rotor 9 is supported by bearings 16. With one of its ends, the rotor 9 is in communication with the inlet pipe 17. The tightness of the inner cavity of the rotor 9 is achieved by installing glands 18. On the opposite end of the inlet pipe 17 the rotor 9 has a partition 19 perpendicular to the axis of rotation of the rotor 9 and adjacent to the partition 8 of the stator 7. In the partition 19 of the rotor 9 holes 20 are made in the form of subsonic nozzles, tapering towards the holes 10 of the stator 7. Holes 10 and 20 races laid in such a way that when the rotor 9 is rotated, they have the ability to combine with each other.

The rotor drive 9 can be independent and communicated with its outer surface 22 by means of a pulley 23 (Fig. 2) of a simple variator for controlling the rotation frequency with a V-belt 24, by which the pulley 23 of the rotor 9 is connected to the pulley 25 on the axis of the electric motor 26.

The rotor 9 drive can be built-in when the rotor 9 serves as an electric motor armature and the stator 7 serves as an electric motor stator: on the outer surface 22 of the rotor 9 sections of the armature winding 27 are fixed (Fig. 3), which in conjunction with the stator winding 28 create an electromotive force.

The dispersant (figure 3) may have a removable partition 8 of the stator 7, which is mounted with the possibility of movement along the longitudinal axis of the stator 7 and fixation on the stator 7 by an adjustment element 29, for example, an elastic ring.

Dispersant works as follows. Prepared in the repulpator 1 (Fig. 1), a suspension containing minerals and water in the required proportions is fed into the inlet pipe 17 of the dispersant 3 (Figs. 2, 3). The pressure created by the pump 2 (figure 1). The blades 15 mounted on the inner surface 14 of the rotor 9 further increase the pressure head of the suspension flow, providing the necessary flow velocity V ₁ to the holes 20 in the baffle 19 of the rotor 9. When the rotor 9 is rotated at a given angular velocity, the suspension is able to flow through the holes in a pulse mode 20, made in the form of tapering subsonic nozzles, into the holes 10 in the partition 8 of the stator 7. The flow rate of the suspension at the moment of closing the holes 20 by the partition 8 of the stator 7 when the rotor 9 rotates sharply decreases to eniya V _0, whereby the water hammer occurs and creates a compressive force F hydropercussion impact pulses to a particle of mineral in suspension. At the moment of the next alignment of the holes 20 of the rotor 9 and the holes 10 of the stator 7, the mineral particles experience tensile deformations when the suspension leaves the holes 10, expanding towards the cavitation chamber 11. The mineral particles are subjected to the tensile action of cavitation pulses created by the resonators 12. Since the resonators 12 tuned to a frequency f _p close to the frequency f _{h of} natural vibrations of mineral particles in the suspension, the operating mode (f _p ≈f _h ) in the cavitation chamber is maintained re 11.

Using the variator, the change in rotor speed 9 is most easily achieved, which further increases the efficiency of grinding minerals by increasing the accuracy and expanding the limits of frequency control of shock and cavitation pulses. The negative impact of abrasive wear on the life of the dispersant is also reduced due to a more accurate adjustment to the resonant grinding mode.

In a disperser with a built-in drive (Fig. 3), the rotor 9 serves as an electric motor armature, and the stator 7 serves as an electric motor stator, while a smooth change in the rotational speed of the rotor 9 is possible, which also further improves the efficiency of grinding minerals by increasing the accuracy and expanding the limits of frequency regulation hydropercussion and cavitation impulses. The negative impact of abrasive wear on the life of the dispersant is reduced due to a more accurate adjustment to the resonant grinding mode.

The partition wall 8 of the stator 7 can be made removable and / or mounted with the possibility of moving along the longitudinal axis of the stator 7 and fixation relative to it by means of the adjusting element 29. Due to this, an increase in the efficiency of grinding of minerals is achieved as a result of more accurate tuning of the dispersant to the resonant grinding mode and / or due to the possibility of compensating for the abrasive wear of the partition 8 of the stator 7 by its longitudinal movement and fixing by means of an adjusting element 29, for example, an elastic ring, when adjusting the working gap between the rotor 9 and the stator 7, which reduces the cost of repairing equipment and reduces technological downtime.

Thus, grinding in the dispersant 3 (Fig. 1) involves the suspension of a mineral with the opening of the grains of useful components by the resonant action of hydroshock and cavitation pulses along the zones of natural adhesion of these grains with the rock. The presence of intergrowths contributes to the selectivity of the places of destruction and better disclosure of mineral grains. The crushed product through the outlet pipe 21 (figure 2, 3) of the dispersant 3 enters the tank 4 (figure 1) and then through the pipeline 5 for enrichment (for example, flotation).

The use of the proposed solutions, as shown by experiments, can increase the efficiency of grinding minerals by 10-15%, and reducing the negative impact of abrasive wear on the main parts of the dispersant allows you to increase its resource by 2-3 times.

Claims (5)

1. A method of grinding minerals, comprising the dosed supply of an aqueous suspension of minerals into a cavitation dispersant and grinding it with opening the grains of the useful component by the resonant action of hydroshock and cavitation pulses along the zones of natural adhesion of these grains with the rock, controlling the frequency of cavitation pulses by changing the cages with fixed on them resonators tuned to the desired frequency, characterized in that they additionally control the frequency of the cavitation and pulses due to the regulation of the pressure of supplying the aqueous suspension of minerals to the dispersant, made straight-through and consisting of a hollow rotor with blades on the inner surface, and installed from the opposite inlet pipe of the rotor end, perpendicular to the axis of rotation of the rotor by a partition with holes, and from the stator, made from the end adjacent to the cavitation chamber, with a partition having holes that are compatible with the holes of the rotor during rotation of the latter, while independently of controlling the frequency of cavitation onnyh pulse frequency control performed hydropercussion pulses. 2. Cavitation dispersant, which includes a housing, inlet and outlet nozzles, a stator with holes expanding towards the cavitation chamber, installed in it and tuned to the frequency of natural vibrations of the mineral particles in the suspension cavitation pulse resonators, a rotor with a drive, blades and holes in the form subsonic nozzles tapering towards the stator holes, made with the possibility of combining them when the rotor rotates with the stator holes, characterized in that it is straight-through, for which the otor is made hollow, and the blades are mounted on its inner surface, while a partition is installed from the opposite end of the rotor end inlet perpendicular to the axis of rotation, and these rotor holes are made in its partition, and the stator is provided with a partition from the end adjacent to the cavitation chamber, in which said stator holes are made. 3. The dispersant according to claim 2, characterized in that the rotor drive is independent and communicated with the rotor by means of a speed variator pulley. 4. The dispersant according to claim 2, characterized in that the rotor drive is built-in, the rotor serves as the armature of the electric motor, and the stator serves as the stator of the electric motor. 5. Dispersant according to one of claims 2 to 4, characterized in that the stator baffle is removable and / or mounted with the possibility of movement along the longitudinal axis of the stator and fixation relative to the latter by means of an adjusting element, for example, an elastic ring.

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