RU2507007C1 - Method of extraction of selected minerals from ore pulps by pressure flotation and device to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to concentration of minerals by flotation, particularly, for extraction of sliming mineral polymetallic ore pulps, for example, for extraction of valuable metals from slimes and can be used for concentration of fine and superfine ingrained polymetallic ores. Method of extraction of selected minerals from ore pulps by pressure flotation comprises processing of the pulp by flotation reagents for hydrophobisation of mineral particle surface and water saturation with air under pressure. Prepared conditioned pulp is thoroughly mixed with air-saturated water at barometric pressure while produced mix is processed by stream of air bubbles of flotation sizes generated nearby flotation chamber bottom.

EFFECT: higher efficiency of pressure flotation.

10 cl, 8 dwg

Description

The invention relates to the beneficiation of minerals by flotation, in particular for the extraction of slurry minerals from polymetallic ores from pulps together with known flotation methods or independently, for example, for the extraction of precious metals from gravity dressing tailings. In addition, this invention can be used to enrich finely and finely disseminated polymetallic ores.

Method for extracting selected minerals from ore pulps by pressure flotation

The flotation method is based on the elementary act of adhesion of hydrophobized particles of selected minerals to air bubbles created in the pulp by their collision, the resulting particle-bubble aggregates floating under the influence of Archimedean force in the form of foam with the subsequent discharge of this foam into the foam collector. Foam is dehydrated, turning into a concentrate of recoverable minerals, and the chamber product - depleted pulp - is discharged in the form of flotation tailings into the tailings [1].

In this case, using a rich range of known flotation reagents, the pulp is treated before flotation with the required flotation reagents, converting particles of selected minerals into floatable hydrophobic particles, and particles of other minerals are converted to non-floatable hydrophilic, easily wettable particles.

Then, dispersing atmospheric air in one way or another in the pulp, conditions are created for the hydrophobized particles to stick together with the air bubbles created in the pulp. Adhesion of hydrophobized particles to the bubbles and their retention on the surface of the bubble occurs under the action of the van der Waals forces of intermolecular interaction existing on the surface of the particle and the bubble in the form of the free energy of the surface created by the uncompensated forces of molecules and atoms lying on this surface.

The action of the van der Waals forces begins to appear at a distance of 1000 pm (picometers 1 * 10 ^-12 m), and their maximum effect occurs at a distance of 500 pm, but the further repulsion of the reacting particles is counteracted by the repulsion of the electrons of the molecules of the converging particles [2].

The approach of particles to the bubble is prevented by hydration layers on the surface of the particle and the bubble. On the bubble and on the hydrophobized particle, these layers are thin, but, nevertheless, they prevent the particle from reaching the field of action of the van der Waals forces. To overcome this obstacle, the particle is imparted motion and, due to the inertial forces of motion that have arisen, the particle is able to collide with the bubble and break through the hydrated layers of the bubble and particles and enter the zone of action of the van der Waals forces. According to reports, to keep the particle on the bubble, it is enough to stay the particle in the zone of action of the van der Waals forces for 0.01-0.001 seconds.

As the mass of hydrophobized particles decreases to sizes less than 0.05 mm, the inertial forces of such particles weaken and it becomes more difficult to break through the hydration layers and the elementary act of flotation of such small particles does not occur, therefore, they do not float. It should be noted that the crushing and grinding of ores is carried out in order to liberate the extracted minerals from the waste that has grown together with them, and the finer the ore is crushed, the greater the proportion of minerals that is free. This is especially important in the enrichment of finely disseminated and especially finely disseminated ores.

For the reasons stated above, over-crushed particles, which have a low mass and, accordingly, a low inertial force, are unable to break through the hydration shells and connect to the bubble, i.e. are unable to perform the primary elementary act of flotation, therefore, they do not float and even complicate the flotation of particles of optimal sizes.

At the same time, the flotation of such particles is especially important in the enrichment of, for example, gold-containing sands, in which a significant part of the noble metals is in the form of small particles less than 0.05 mm in size, which cannot be recovered by either gravity or flotation methods. Therefore, a number of sources indicate that during the enrichment of such sands up to 50% of the gold contained in them is not extracted and goes into tails. It is for such deposits that a flotation method is required in which air bubbles would selectively combine with such small particles and carry them out into the foam layer.

In the first half of the 20th century, an attempt was made to use the flotation method for wastewater treatment, but the result of their treatment was very low. When analyzing the reasons for such a low degree of wastewater treatment by classical flotation, it was concluded that the size of the flotation bubbles was from 1 to 6.4 mm, as it turned out, was ten times larger than the size of the pollution particles. To reduce the size of the bubbles to a size approaching the size of the particles of contamination, mechanical dispersion of air in wastewater was impossible even theoretically. Then they remembered Henry's law, discovered by William Henry in 1803 [2, 3]. According to this law, the solubility of gases in liquids, including air in water, is directly proportional to the pressure of this gas over the liquid, i.e. how many times the pressure increases, the number of times the solubility of gas or air in water increases in comparison with its solubility in water, at the same temperature at atmospheric pressure.

When the pressure decreases, the solubility of the gas decreases and the aqueous solution of air obtained under pressure is supersaturated with air and unstable at atmospheric pressure. Therefore, excess air spontaneously (spontaneously) begins to move from the solution phase to the gas phase. This phase transition occurs in the form of tiny bubbles, the nuclei of which can selectively form on hydrophobic particles of pollution, and grow on them as a result of diffusion of air from the adjacent solution. This occurs by shifting water molecules from this hydrophobic surface. And if there are not enough particles of pollution, then the bubbles will begin to stand out in the volume of water. This is due to the fact that water molecules adjacent to it on a hydrophobic surface are loosely bound to it, and the nuclei of bubbles formed on this surface easily shift them, spending little energy. In contrast, when air nuclei appear in the volume of water and grow, they have to break rather strong bonds of the polar water molecules with each other, spending much more energy. In other words, the work done by air nuclei on a hydrophobic surface is much less than the work of creating a gas cavity in the volume of water. That is why air bubbles are energetically more profitable to form selectively on the hydrophobic surfaces of impurity particles than in the volume of water.

On this basis, a method for flotation of contaminant particles was created, implemented in a patented device for wastewater treatment by pressure flotation [4]. In this method, the wastewater was saturated with air under pressure created by two rotary-type pumps connected in series. The first pump sucked in water and a metered amount of air, and the second pump mixed water and air, simultaneously increasing the pressure, i.e. saturated the wastewater at a pressure regulated by a pressure regulator such as a safety valve. Saturated water through the pressure regulator was discharged into an open flotamok, where the pressure decreased to atmospheric and the process described above occurred. The resulting particle – bubble aggregates, under the action of Archimedean force, floated into the foam layer discharged into the foam collector, and clarified water from the bottom nozzle was discharged by gravity through a siphon. The disadvantage of this method was that the rotary pumps dispersed the particles of contaminants, and this reduced their floatability. In addition, the rotors of the pumps were salted and fibrous impurities were wound on them, which reduced their performance. To top it off, the rate of emergence of the formed particle - bubble aggregates was very low.

Later, these shortcomings were eliminated in the created new method used in the new device for wastewater treatment by pressure flotation, protected by a patent for a utility model [5]. According to this method, part of the purified water was saturated in the saturation block with air, which was then mixed with waste water in the ejector, and the resulting mixture was floated in a flotation chamber, in which the flow of the floated mixture was organized from the bottom up, facilitating and accelerating the floating of impurities into the foam layer.

The disadvantage of this method for its use in the process of extracting thin hydrophobic particles of minerals from ore pulp by pressure flotation is its inability to float ore pulp in this state.

Leading specialists in the field of flotation I. Sven-Nelson and V.I. Klassen [6, 7] established that during the operation of mechanical flotation machines in the pulp significant pressure drops are created and areas with high and low pressure arise.

In accordance with Henry's law, in areas with high pressure, air dissolves in the pulp, and in areas with low pressure it is released from the pulp in the form of tiny nuclei of bubbles that appear on the hydrophobic surface of small particles. These bubbles on the surface of the particles act as highly hydrophobic protrusions, which "catalyzes" the adhesion of these particles to the surface of larger bubbles, facilitating their ascent and thereby increasing the speed of flotation. But the most important fact is the fact that the particle — the bubble — has such formation of aggregates. It has a flotation for small inertialess particles that are not able to adhere independently to flotation-sized air bubbles.

Such particles have a hydrophobic surface, have a developed surface, therefore there is a high probability of release of air dissolved in water on their hydrophobic surface, and this facilitates their adhesion to large transporting bubbles.

The described properties of the deposition of nuclei of air bubbles dissolved in a pulp on small particles with a hydrophobic surface formed the basis for the creation of flotation machines with variable pressure: vacuum and so-called compression. In the first case, the evacuation method was used, and in the second, air was dissolved in the pulp under pressure [8]. Then the pressure was reduced in the pulp, air microbubbles appeared on the hydrophobic surface of the particles, contributing to the removal of minerals to the surface of these particles in the foam layer. However, due to great structural difficulties, both methods have not found practical application in flotation ore processing.

The main difficulties and shortcomings in the methods for creating air microbubbles due to the active mixing of the pulp are the too low specific yield of these bubbles, and in the proposed method of evacuation of flotation, especially with the required high productivity of flotation machines, the increase in the specific yield of bubbles turned out to be practically impossible. The same difficulties arose in the hardware design of compressor machines. Firstly, the passive process of saturating the pulp with air without mixing it is very long, and secondly, the volume of flotation machines operating under pressure cannot be small, and with the required multiplication of the volume of the apparatus by a pressure reaching 1000 dm ³ * kg / cm ² , it falls under the strict control of the control department "Kotlonadzor", which requires special operating conditions for such equipment, upon reaching the specified parameter 1000 dm ³ * kg / cm ² .

Of these methods, only the so-called compression method has found application, but not in enrichment, but for wastewater treatment under the name “pressure flotation” described above. We calculated that certain elements of the pressure flotation method can also be used in the flotation ore concentration processes.

As is known, the classical flotation method is based on the implementation of the primary flotation act, which consists in the formation of a lung, a particle - bubble aggregate floating up in the pulp. This aggregate results from the collision of particles of selected minerals with an air bubble. With sufficient inertia, the particle breaks through thin hydrate layers on its hydrophobized surface and on the surface of the bubble and, having reached the region of action of the van der Waals forces, is fixed on the bubble, forming a particle-bubble pop-up aggregate.

But if this particle is small and does not have the inertia sufficient to perform the elementary act of flotation, then, as described above, it does not float and remains in the depleted ore pulp - chamber product, which is transported to the tailing dump together with non-flotated particles of minerals.

Thus, the proposed method for the extraction of hydrophobized minerals from ore pulps by pressure flotation is the implementation of an elementary act of flotation, but a method fundamentally different than in classical flotation.

In the proposed method, the formation of an elementary act of flotation (particle-bubble aggregate formation) is carried out not by the collision of a hydrophobic particle with a bubble, but by the appearance of a tiny nucleus of an air bubble on its surface and its growth on this surface due to diffusion of air from an adjacent aqueous solution saturated with air - mixtures of saturated water with the aqueous phase of the pulp. Spontaneously diffusing out of this supersaturated solution, air creates the required particle-bubble aggregate. That is why for the proposed method of enrichment by pressure flotation, the size of the extracted hydrophobic particles does not matter much, this is the fundamental difference between the proposed method and the classical flotation method based on the collision of hydrophobic particles with an air bubble.

In order to eliminate the identified shortcomings in the described methods of flotation extraction of minerals from ore pulps, a new technical solution is proposed, devoid of these shortcomings.

The claimed technical result of the proposed method consists in the selective extraction of hydrophobized particles of selected minerals not recoverable by known flotation methods. This technical result is based on the use of the following significant distinguishing features.

Water, saturated with air at elevated pressure, has a concentration of air, according to Henry's law, is so many times greater than atmospheric, how many times the pressure applied during saturation was greater than atmospheric.

When ore ore pulp is mixed with saturated water under atmospheric pressure, the solubility of air in water decreases, so the resulting mixture of saturated water with the aqueous phase of the pulp is supersaturated with air and part of it in the mixture becomes redundant and spontaneously passes from the solution phase to the gas phase, first in the form of tiny embryos. It is energetically more profitable for these nuclei to form particles of hydrophobized minerals on the hydrophobic surface by shifting water molecules weakly bound to this surface without a large expenditure of energy. Moreover, the formation of air cavities in the volume of water created by the released air is associated with significantly greater energy expenditures for breaking strong bonds between polar water molecules when creating these cavities in the form of air bubbles. Therefore, first of all, the process of nucleation of air bubbles occurs on the hydrophobic surface of hydrophobized minerals, which is associated with much lower energy costs for the shift of water molecules weakly bound to it from this surface. In almost the entire volume of the obtained mixture of pulp with saturated water, air diffuses from the solution adjacent to the surface of hydrophobic particles scattered in the volume of the pulp. In this case, nuclei of bubbles arise on the hydrophobic surface, which grow due to diffusion of air from the adjacent solution, forming particle-bubble aggregates. The described is carried out only if the prepared conditioned pulp is thoroughly mixed with saturated water so that a layer of air-saturated aqueous phase is adjacent to each hydrophobic particle. To this end, the first independent claim provides a distinctive essential feature: "... prepared conditioned pulp with hydrophobized particles of selected minerals is thoroughly mixed with water saturated with air at atmospheric pressure ...". Due to their small size, these aggregates have a disappearing low ascent rate. To increase this speed, they must be attached to larger transport bubbles. Fortunately, air bubbles adhering to particles are ideal hydrophobic protrusions to which large flotation-sized air bubbles created in flotation machines easily adhere. That is why the second distinctive essential feature “with the subsequent processing of the pulp by the current of air bubbles of transport sizes” was introduced into the first independent point.

The sign of the second dependent clause is formulated as: "sewage from the tailings, purified from suspended particles, is saturated with air." This paragraph clarifies that it is not pure water that is saturated with air, but wastewater draining from tailings that contains residues of flotation reagents harmful to the environment and if this wastewater is discharged into the environment without treatment, serious harm will be done to nature. Thus, three tasks are solved at once: 1 - environmental protection, 2 - saving of flotation reagents due to the use of their balance in wastewater and 3 - organization of recycled water supply, which dramatically reduces the need for production in clean water.

An insignificant sign of the third dependent clause is “a layer of foam on the surface of the pulp with extracted particles of selected minerals is washed with a small amount of water before dumping it into the foam collector”. This feature is designed to remove non-floated hydrophilic particles mechanically captured by air bubbles from the pulp from the foam layer, which is necessary to increase the content of extracted components in the resulting concentrates.

And finally, the fourth dependent clause containing an insignificant attribute indicating the permissible minimum volumetric ratio of saturated water to a unit volume of pulp equal to at least 0.1: 1.0. This is based on the calculation, which shows that after flotation, the air concentration in the pulp still exceeds 50% of its solubility in water at atmospheric pressure. In this case, the energy is still sufficient for the formation of a microbubble on the surface of the hydrophobic particle. This will allow more complete extraction of the specified components from the pulp. However, for the breaking of intermolecular bonds during the formation of air bubbles in the volume of water this energy will not be enough. And the optimal ratio of saturated water to pulp is determined empirically by the obtained maximum extraction of emitted components when the ratio of saturated water to pulp changes.

Compared to the classical flotation method, the pressure flotation method is also based on the creation of a particle-bubble pop-up aggregate. However, the principle of creating this unit is completely different.

It is based on the appearance of an air bubble embryo selectively on the hydrophobic surface of particles of selected minerals. In this case, the particle size does not matter, it can be both of flotation size and disappearing of small, commensurate with the nuclei of micron sized bubbles. These air bubble germs can occur in an air-conditioned ore pulp if mixed with water that is pressurized with air under pressure. If this mixture is produced at atmospheric pressure, then, according to Henry's law, the solubility of air in water decreases and the aqueous solution is supersaturated with air.

The supersaturated state of this solution is unstable and it tends to an equilibrium state by the transition of excess air from the state of the solution to the free gas phase. This phase transition occurs spontaneously (spontaneously) in the form of tiny nuclei of bubbles. These vesicles have two pathways of origin in the pulp. They can form in the volume of the aqueous phase of the pulp. In this case, the emerging bubbles have to break rather strong bonds between the polar water molecules with each other, spending considerable energy on this to create a gas cavity in the water volume of the air bubble.

But there is a second, easier way: nuclei of bubbles can occur on the hydrophobic surface of the extracted particles of minerals in the pulp. In this case, they will not have to break the strong bonds of water molecules with each other, but simply move water molecules from the hydrophobic surface that are loosely bound to this surface. From an energetic point of view, the work performed by the nucleus of a bubble arising on the hydrophobic surface of a particle and the subsequent growth of a bubble on this surface due to diffusion of air from an adjacent supersaturated solution are incommensurably less than the work that is expended on the occurrence of an air bubble in the volume of water.

As you know, the processes that have arisen are directed towards the least energy consumption. In this case, the emergence of nuclei of air bubbles on a hydrophobic surface is preferable in relation to energy costs. Therefore, it is in this direction that the process of air evolution from saturated water takes place, the nucleation of the bubble on the hydrophobic surface of the hydrophobized particles of selected minerals is fixed and grown. This process of spontaneous fixing of bubbles on the hydrophobic surface of particles of selected minerals is essentially an elementary act of flotation, only created by another method called the “pressure flotation method”. This elementary act of flotation does not depend on the sizes of hydrophobized particles, which can be either ordinary flotation sizes or sizes of slurry inertialess particles.

Pressure flotation can, in principle, continue as long as the free area of the hydrophobic surface and the remainder of the aqueous solution saturated with air remain in the pulp. Only with a decrease in this area of the free hydrophobic surface of the particles of minerals can a more energy-intensive process of the appearance of air bubbles in the volume of the aqueous phase of the pulp begin. In this regard, the process of mixing the conditioned pulp with water, saturated with air, must be thorough so that the resulting mixture of saturated water with the aqueous phase of the pulp is distributed throughout the volume of the pulp. However, due to the small size of the particle-bubble aggregates formed during this process, which have a disappearing low ascent rate, the pulp must be carefully treated with a stream of air bubbles of transport dimensions.

The presence of strongly hydrophobic protrusions in the form of created aggregates in the form of air bubbles fixed on the surface of hydrophobic particles facilitates the fixation of these aggregates on the surface of transport bubbles. It is possible that the number of mini-units mounted on the transport bubble will be more than one.

The device is intended for the practical implementation of the method of extracting selected minerals from ore pulps by pressure flotation.

Common to all modern designs of flotation machines is the use as a working tool of air bubbles generated in the ore pulp in one way or another.

As a rule, the mineralization of these bubbles (their adhesion to hydrophobic particles of minerals) is carried out by direct collision of particles of minerals with bubbles. The particle – bubble aggregates formed, due to a density lower than that of the pulp, float to the surface of the pulp under the action of an Archimedean force, forming a foam layer. This layer is discharged into the foam collector, and the depleted pulp — the chamber product — is removed in the form of flotation tails. So that particles of selected minerals adhere to the bubbles, their surface is pre-hydrophobized by special treatment with the required flotation reagents, i.e. condition. At the same time, particles of selected minerals are made hydrophobic, and the remaining particles in the pulp are converted to hydrophilic - not floated, because they do not stick to bubbles.

Classification of flotation machines is most often carried out depending on the method of pulp aeration, i.e. from a method of dispersing air in a pulp volume. On this basis, machines are divided into: mechanical, in which the pulp is mixed with air suction and dispersion, carried out by an impeller (paddle mixer) of various designs; pneumatic, in which the mixing and aeration of the pulp is carried out by compressed air supplied to the pulp through special nozzles or through porous partitions; pneumomechanical, in which air is supplied from the blower, and the pulp is mixed and air is dispersed by an impeller; pneumohydraulic with self-aeration or dispersion of forced air by various hydraulic devices.

The most widespread are mechanical, pneumomechanical and pneumatic flotation machines.

Analogs of the proposed device are pneumatic flotation machines, among which close analogues are pneumatic column type machines. These machines are vertical columns of circular or rectangular cross-section. They air-conditioned pulp is fed into the chamber of the flotation machine through a pipe located slightly above the middle of the column. [8].

For example, in the columnar pneumatic flotation machine shown in FIG. 1, a circular cross-sectional type with a diameter of 1-1.8 m and a height of 7 to 12 m has a housing 1 in which a pipe 2 is located at a level above the middle, connected to a mixer 3 for ore ore conditioning pulp flotation reagents.

At the bottom of the column there is a porous diffuser 4 connected to the receiver 5 with compressed air. At the outlet of the column there is an outlet valve 6, which regulates the level of pulp in the column, connected to a discharge pipe 7 transporting the depleted chamber product to the tailing dump. In the upper part of the column 1 there is a nozzle 8 for removing the foam product and a clean water pipe 9, which has spray nozzles 10 in the column above the foam layer for washing the foam.

The flotation machine operates as follows:

The initial ore pulp is conditioned by flotation reagents in mixer 3 to hydrophobize particles of selected minerals to flotate them and hydrophilize particles of other components to prevent their flotation. The conditioned pulp is fed through pipe 2 into the chamber of the flotation machine. Here, the pulp particles move under the action of gravity down, and a stream of bubbles pops up towards them, generated by the porous diffuser 4 at the bottom of the column, which is fed by compressed air from the receiver 5. During the movement of the pulp particles down, they hit the ascending air bubbles and stick to them if they have a hydrophobic surface created in a mixer for particles of selected minerals. The remaining particles having a hydrophilic surface do not adhere to air bubbles, i.e. Do not float and continue to move down. In contrast, particles sticking together with air bubbles form a light aggregate that, under the action of Archimedean force, floats to the surface of the pulp into the foam layer. This layer is often contaminated with non-floated hydrophilic impurities, mechanically entrained by bubbles. These impurities dilute the isolated foam product with recoverable components - a concentrate.

To prevent this, the foam layer is washed with clean water from the pipe 9 with sprays before it is discharged into the pipe 8. The depleted chamber product is discharged through the valve 6, which regulates the pulp level in the column, into the pipe 7 transporting the chamber product to the tailing dump or to another control flotation machine flotation.

The drawback of most column flotation machines, and this, in particular, was the poor performance of air dispersants installed at the bottom of the column, which were often clogged with pulp particles or produced too large bubbles that poorly floated small particles of recoverable minerals. Despite this, column-type flotation machines have a number of advantages over other types of flotation machines. They do not have elements moving in the abrasive environment of the pulps, the columns occupy several times less working area in comparison with other types of machines. They are relatively easy to automate, have low metal consumption and are economical to operate.

However, a significant factor hindering the use of this promising column type of flotation machines was their relatively low private (operational) recovery. Understanding this, in 1993, after extensive research, Svedala CISA (subsequently MetsoMinezals) began production of dispersants based on the patented MICROCEL ^TM technology [9]. Created dispersers of a new design - aerator reactors, called static mixers, increased private recovery to a level comparable to pneumomechanical flotation machines. The use of upgraded column flotation machines MICROCEL ^TM allowed to increase the extraction of selected minerals and at the same time improve the quality of the resulting concentrate. In addition to this, it became possible to dramatically increase the productivity of flotation machines with column diameters increased to 4.6 m.

The distinctive features of the created MICROCEL ^TM flotation machines ^, according to the owners of this technology, include the following:

1. Dispersion of air into very small bubbles - up to 0.4 mm, which allows the extraction of particles of minerals of small classes [but not fine particles].

2. The degree of interaction of particles with bubbles sharply increases - an elementary act of flotation that occurs in statistical mixers.

3. Strengthening the interaction of mineral particles with flotation reagents due to the operation of the recirculation pulp pump available in the flotation machine.

4. Static mixers allow you to control the size of the created bubbles in the range from 1.2 to 0.4 mm when changing the number of working mixers by simply turning them off.

According to the authors, the advanced column flotation machines MICROCEL ™ are successfully operated at the world's leading mining enterprises.

In Russia, the official partner of MetsoMinerals is TVELL LLC, which distributes MICROCEL ^TM column flotation machines in the Russian Federation and their implementation in mining enterprises.

Based on the fact that, from the existing designs of flotation machines, this column photographic machine in most respects coincides with the device that we are presenting for patenting, we took it as a prototype and give its description.

This MICROCEL ^™ column type flotation machine is shown in FIG. 2. This machine includes a housing 11, an air-conditioned pulp supply pipe 12 located above the middle of the column, an air ring collector 13 at the bottom of the column, a static air dispersing mixer 14 connected to the air ring collector 13, a recirculation pulp pump 15, the discharge pipe of which connected to the pulp ring collector 16. In the upper part of the column there is a pipe 17 for the exit of the foam product, a pipe 18 for supplying clean water, to which splashes are attached inside the column (they are not visible), washing water layer of foam. At the bottom of the column there are shut-off valves 19 for each static mixer, which enable the operation of the mixers to change the size of the bubbles. In the upper part of the column there is a pulp level control unit 20 in the column connected to the pulp discharge valve 21.

This device works as follows:

The conditioned pulp, which is fed from a mixer (not shown in the figure), where ore pulp is treated with flotation reagents to hydrophobize the surface of the particles of selected minerals, is fed into the pipe 12. The pulp is distributed over the cross section of the flotation chamber pipe and moves down. Toward it rises the flow of air bubbles created by static dispersant mixers 14. At the same time, hydrophobized particles of minerals with inertia of impact hit the rising bubbles, break through the hydration shells and, having reached the zone of action of the van der Waals forces, are attracted to the bubble, performing an elementary act of flotation. Moreover, the smaller the particle, which still has inertia, the smaller should be the bubbles produced by static mixers. To a certain extent, the design of dispersant mixers allows the bubble size to be reduced to 0.4 mm using static mixers 14. This allows particles to be floated larger than 0.05 mm. But with a decrease in particle size to 0.05 mm and less, they turn out to be practically inertialess and incapable of breaking through hydration shells in a collision with air bubbles, therefore such particles of minerals are not able to perform an elementary flotation act and swallow. But large and small hydrophobized particles of minerals, capable of sticking to air bubbles, under the influence of Archimedean force rise up into the foam layer on the surface of the pulp. When the particle – bubble aggregates obtained in the pulp rise, they, to a certain extent, mechanically capture non-floated hydrophilic particles of impurities, dragging them into the foam layer. Therefore, in columned flotation machines, an operation for washing the foam layer on the surface of the pulp with clean water is provided. To do this, clean water is supplied through the pipe 18, which rinses with a spray and, to a certain extent, removes trapped impurities from the foam layer. The washed foam is poured over the threshold, flows from the nozzle 17 and is sent to dehydration and drying to obtain a concentrate of selected minerals. During the operation of the flotation machine, it is required to maintain a stable pulp level in the chamber, this is done using the pulp level control unit 20 connected to the chamber product relief valve 21. In practice, the block 20 matches the supplied volume of the conditioned pulp with the volume of the chamber product discharged from the flotation column. The recirculation pulp pump provided in the flotation machine allows flotation of the same pulp volume repeatedly, performing the function of control flotation of the chamber product (flotation tailings). To do this, during pump operation, the pulp is sucked from the space under the static mixers, where the flotation tailings are practically located, and sent through the discharge pipe to the pulp ring collector 16. From this collector, the pulp is distributed evenly in the pulp layer above the bubble generators 14 through the openings in it and secondarily processed by a stream of bubbles, for flotation of non-flotated hydrophobic particles.

The disadvantage of this column type flotation machine is its inability to extract fine inertialess particles of useful minerals from ore pulp.

In our device for extracting selected minerals from ore pulps by pressure flotation, a well-known water saturator with air at high pressure [5], a contact pulp mixer with flotation reagents [8, p. 145] and the above-described column flotation machine shown in Fig. 2 are used .

The waste water saturator is shown in FIG. 3. It consists of a housing 22, a waste water supply pipe 23 connected through a waste water flow valve 24, a waste water flow meter 25 connected to an air supply system consisting of an air flow valve 26 and an air flow meter 27. The resulting mixture of water and air is connected a pipe with a suction pump 28 of a rotor type, which is connected by its pressure pipe to the suction pipe of a pump-saturator 29, also of a rotor type. The pressure port of the pump - saturator is connected to the pressure regulator valve 30 of the type of safety valve. The output of the pressure regulator is connected to the supply pipe of the saturated water 31.

A water water saturator operates as follows.

Wastewater flows through a pipe 23 to a valve 24, which controls the flow rate of the supplied water according to the reading of the wastewater flow meter 25. The water supply system is connected to the atmospheric air supply system, consisting of a valve 26 that regulates the supply of atmospheric air to the incoming wastewater according to the air flow meter 27. The ratio between the supplied air volume and the incoming wastewater volume is determined by the solubility of air in water at a given temperature and pressure, created by a saturator pump. So, for example, at a temperature of plus 25 ° C and a pressure of 0.6 MPa, the ratio of air to water should be no more than 120 dm ³ per 1 m ^{3 of} water in order to avoid deterioration of the operation of the pumps. A mixture of water and air entering the suction pipe of pump 28 is mixed with a pump rotor, where the air is partially dissolved in water. Then this mixture enters the suction pipe of the pump-saturator 29, where the pump rotor actively mixes the mixture of water and air and at the same time increases the pressure of the mixture to a value regulated by a pressure regulator, for example, to a pressure of 0.6 MPa. When the mixture of water and air is mixed intensively by the pump rotors, while the pressure is increasing, air quickly passes from the gas phase to the phase of its solution in water during the passage of the resulting air-water mixture through two pumps. The resulting saturated water from the valve of the pressure regulator 30 under pressure enters the pipe 31, transporting this saturated water to its place of consumption.

Figure 4 presents the contact tank mixer pulp with flotation reagents. The contact tub has a cylindrical body 33, which is equipped with a pipe 32 for supplying a mixture of the initial pulp with flotation reagents. A shaft 34 is mounted in the center of the tub with an axial type mixer 35, which are located in the hollow pipe 36 with holes 37. The shaft 34 is equipped with an electric motor 38, and the contact tub is equipped with a drain pipe in the upper part 39 for transporting the finished conditioned pulp to the flotation machine.

Contact tank mixer works as follows.

The initial mixture of pulp with metered flotation reagents enters the pipe 32, through which it is poured into the hollow pipe 36. When the shaft 34 is rotated, an axial-type mixer 35 mounted on it moves the pulp upwards of the hollow pipe 36, and the pulp is poured out of the holes 37. Then, the pulp mixer 35 again fed up and poured from the openings 37 into the vat cavity. For several such cycles, flotation reagents are fixed on the surface of selected minerals, hydrophobizing their surface. With this conditioning of the pulp, new batches of pulp are poured into the vat, which displaces the finished pulp, pouring through the drain threshold into the pipe 39, from where it is transported to the flotation machine.

The proposed device, for the practical implementation of the above method of extracting selected minerals from ore pulps by pressure flotation, is presented in figure 5. This device includes the known pneumatic column flotation machine shown in FIGS. 1 and 2, a pressurized water water saturator, shown in FIG. 3, and a known pulp contact tank mixer with flotation reagents, shown in FIG. 4.

The final technical result of the proposed device for the practical implementation of the method of extracting minerals from ore pulps by pressure flotation is as follows:

1. Thorough mixing of conditioned pulp with water, saturated with air, providing a mixture of the aqueous phase of the pulp with saturated water, adjacent to hydrophobic particles in the entire volume of the pulp.

2. The second technical result consists in a sharp increase in the ascent rate of the formed microaggregates of the particle - bubble having a vanishingly low ascent rate.

The receipt of these technical results provides the following distinctive essential features of the fifth independent paragraph:

 1. The known pneumatic flotation machine of the column type is equipped, at the inlet of the conditioned pulp, with a jet mixer of this pulp with water, pressurized with air, followed by further mixing with a shelf mixer.

 2. For a sharp increase in the ascent rate of the formed particle-bubble microaggregates, the resulting mixture of pulp with saturated water is treated with a stream of transport bubbles in a flotation chamber using a tubular perforated distributor of the resulting mixture over a stream of transport bubbles. Such a double mixing of a mixture of conditioned pulp with water suaturated under pressure with air ensures the formation of macro- and microaggregates of a particle-bubble in the entire volume of the pulp, and processing of this pulp mixture with a stream of transport bubbles in the middle part of the flotation chamber leads to the attachment of these units to transport bubbles that carry them to the surface of the pulp in the foam layer.

In the sixth paragraph, depending on the fifth, an insignificant sign is specified that clarifies the structure of the jet mixer, which is an annular pipe, on the inside of which there are fixed expanding nozzles with an inclination towards the rotation of the pulp mixture in the ring and a pipe supplying the saturated water to the ring under pressure from the saturator .

In the seventh paragraph, depending on the sixth, it is specified that the annular tube of the jet mixer is fixed in a cylindrical insert with flanges, with the help of which this insert is connected through the sealing gaskets to the upper feed pipe of the conditioned pulp and to the lower pipe in which the shelf mixer is located. This provides double mixing of the pulp with saturated water.

Dependent clause 8 indicates an insignificant sign clarifying that for a higher intensity of the jets of saturated water leaving the nozzles, it is necessary that the sum of the gaps in these nozzles be less than the cross-sectional area of the pipe that leads the saturated water to these nozzles.

In dependent clause 9, an insignificant feature is specified regarding the shelf mixer device, which consists of metal shelves fixed in a removable frame at an angle of 45 ° with a variable inclination of the shelves to each other. This structure of this mixer enhances the degree of mixing of the mixture of pulp with saturated water due to the zigzag movement of the pulp with the aqueous phase of saturated water, from which an excess of dissolved air is formed in the form of nuclei of bubbles deposited on the hydrophobic surface of particles of selected minerals with the formation of an elementary act of flotation.

And finally, in the tenth dependent paragraph of the formula, an insignificant sign is specified, which consists in the fact that for better contact of the formed microaggregates, a particle - a bubble with transport air bubbles generated in the lower part of the flotation chamber, the distributor of the mixture of pulp with saturated water supplied to the flotation chamber is made the shape of a tubular ring with a diameter of 1.5-2 times smaller than the diameter of the cell, the cavity of which is connected in diameter by a segment of a perforated pipe. Moreover, the entire lower side of this structure is perforated with holes twice as large as pulp particles, with the holes tilted in different directions.

This design of the pulp distributor ensures uniform distribution of the pulp mixture over the flow of transport bubbles, which intensifies the encounter between the formed particle micro-aggregates - a bubble with transport bubbles that carry these aggregates to the surface of the pulp in the foam layer, i.e. separation of floated particles from related impurities.

To clarify the application material, the following figures are attached, showing known devices used for the operation of the claimed device, and the device itself:

Figure 1. Column-type pneumatic flotation machine (general view).

Figure 2. Advanced column flotation machine brand "Microcel-TM".

Figure 3. Famous wastewater saturator.

Figure 4. Known contact pulp mixer with flotation reagents.

Figure 5. The design of the proposed device for the practical implementation of the method of extracting selected minerals from ore pulps by pressure flotation.

6: a) a jet mixer (key 41); b) the housing of the jet mixer (pos. 55) with flanges.

 7. An annular perforated distributor of pulp mix with saturated water in a flotation chamber (bottom view).

 Fig. 8. Column type laboratory pneumatic flotation machine.

The proposed device, intended for the practical implementation of the above method of ore dressing by pressure flotation, includes the well-known pneumatic flotation machine of the column type shown in Figs. 1 and 2, the known saturator of water under pressure air shown in Fig. 3, and the known pulp contact mixer with flotation reagents described above.

Figure 5 presents the design of the proposed device. This device includes a cylindrical body 40, a jet mixer 41 for mixing the conditioned pulp from the mixing tank (Fig. 4) with water, pressurized with air, in a known saturator (Fig. 3). The jet mixer 41 is connected to a shelf mixer 42, which is connected at the inlet to the column with a perforated distributor 43 of a mixture of pulp and saturated water in a photocamera above a stream of bubbles generated by dispersant 44 at the bottom of the column, powered by compressed air from the receiver 45. At the top of the column is provided a pipe 47 supplying clean water to the spray 48, irrigating a layer of foam 46 on the surface of the pulp, which is discharged into a foam collector 49, from which the foam product is discharged from the discharge pipe 50. In the flotation chamber, at the surface level STI pulp installed position sensor 51 pulp level associated with the pulp level control unit 53 which is connected with the valve chamber 52 discharge the product. Fig. 6, a shows a section of a jet mixer 41, consisting of an annular pipe 54, on the inside of which expandable nozzles 56 are fixed with an inclination of 45 °, the annular pipe 54 is connected to a pipe 58, which supplies the saturated water from the tube 31 of the saturator (see Fig. .3). The annular tube 54 of the jet mixer (see Fig. 6, a) is fixed in a cylindrical housing 55 with flanges (see Fig. 6, b), with which the housing 55 is connected through a sealing gasket 60 to the upper pipe 58, which feeds the conditioned pulp from the drain pipe 39 of the contact tank mixer (see figure 4), and the lower flange of the housing 55 is connected through a sealing gasket 60 to the pipe 59, in which the shelf mixer 42 is fixed. The pipe 59 with the shelf mixer 42, consisting of metal shelves fixed in frame with a variable inclination of 45-50 ° to each other y, is connected to the perforated distributor 43 of the mixture of pulp with saturated water, located in the center of the photocamera above the stream of air bubbles created by the air dispersant 44 (see Fig. 5). This pulp mix dispenser is shown in FIG. 7 (bottom view). It consists of an annular pipe 61, the inner cavity of which is connected along the diameter of the ring by a segment of the perforated pipe 62. The bottom side of the distributor pipes, as can be seen in Fig. 7, is perforated with holes with a diameter of 2.5-3 mm, sufficient for the passage of pulp particles.

The diameter of the pipe ring 61 is 0.5-0.7 of the diameter of the column of the flotation machine, which is enough to place this distributor above the flow of air bubbles in the middle of the cross-sectional area of the column.

The proposed device operates as follows.

The pulp is treated with flotation reagents in a contact mixing tank (Fig. 4), where the particles of selected minerals acquire a hydrophobic surface, and the other hydrophilic properties enhance the remaining pulp particles, i.e. create conditions under which air bubbles will stick only to the hydrophobic particles of selected minerals and carry them to the surface of the pulp, and the remaining hydrophilic particles, without sticking to the bubbles, remain in the pulp, which, after flotation of hydrophobic particles of selected minerals, is discharged to the tailings, and from the foam product receive a concentrate of selected minerals. After such conditioning, the pulp enters from the drain pipe 39 of the contact tank (see FIG. 4) into the pipe 58 (FIG. 6, b) supplying the jet mixer 41 (FIG. 5) with the conditioned pulp. And through the inlet pipe 57 of the annular pipe 54 of the mixer (Fig. 6, a), saturated water flows from the outlet pipe 31 of the saturator (Fig. 3) under pressure with a flow rate of at least 0.1 m ³ per 1 m ^{3 of} pulp and this water rushes from expanding nozzles 56 (FIG. 6) to the conditioned pulp stream in the housing 55 of the jet mixer 41. Under the influence of these jets, the pulp stream is twisted and the jets of saturated water process the rotating pulp stream from all sides and into the depth of the stream.

Such intense interaction of the pulp stream with jets of saturated water sharply enhances their mixing. The resulting mixture of pulp with saturated water enters the shelf mixer 42. Here, this pulp mixture performs a zigzag movement, overflowing from shelf to shelf, which lengthens its path and contributes to even better mixing of the saturated water with pulp. Due to such intensive mixing, the saturated water mixes well with the aqueous phase of the pulp and is in the particles of selected minerals adjacent to the hydrophobized surface in the entire volume of the pulp. As a result of such a close arrangement of the aqueous phase supersaturated with air to the hydrophobic surfaces of the particles, excess air from the solution phase begins to spontaneously (spontaneously) transfer to the gas phase in the form of nuclei of bubbles on these hydrophobic surfaces. It is energetically more profitable for these bubbles to sit on the hydrophobic surface of the particles, easily shifting water molecules weakly bound to this surface from it, than to form an air cavity in the volume of water by breaking fairly strong bonds of polar water molecules with each other.

Due to the diffusion of air from the supersaturated aqueous phase of the pulp surrounding the hydrophobic particle, the nucleus that arises grows and turns into an air bubble. Thus, an elementary act of flotation occurs and, unlike classical flotation, it does not require the collision of particles with a bubble, but only the presence of an aqueous solution saturated with air in the surrounding water particle is required. The fundamental difference between pressure flotation and classical flotation is that for this flotation the size of the mineral particle does not matter, but the presence of a hydrophobized surface of this particle is of decisive importance. It is to this result that the described two-stage process of mixing saturated water with pulp first occurs in a jet, and then in a shelf mixer.

Further, the pulp mixture with the particle-bubble aggregates arising in it, including microaggregates, enters the distributor of the obtained pulp mixture by the cross-sectional area of the stream of air transport bubbles floating in the pulp in the central part of the photocamera.

Processing the pulp mixture with a stream of such air bubbles of flotation size is necessary for lifting the particle-bubble microaggregates that have arisen to the pulp surface, which have a vanishing low ascent rate.

With this treatment, hardly floating microaggregates, meeting with large bubbles, adhere to them and are carried by them to the surface of the pulp into the foam layer. The adhesion of these aggregates to the transport bubbles is facilitated by the presence of highly hydrophobic protrusions in the form of small air bubbles, which adhere easily to large bubbles. It is possible that not only one, but also several microaggregates can stick to one transport bubble. In principle, larger particle-bubble aggregates can adhere to transport bubbles, which speeds up their ascent.

To increase the likelihood of meeting these units with transport bubbles, as described above, the pulp mixture distributor in the stream of air bubbles is made in the form of a tubular ring 61, the inner cavity of which is connected in diameter by a perforated pipe section. The diameter of this ring is less than the diameter of the cylindrical flotamochka and is 0.5-0.7 of its diameter, which corresponds to the diameter of the flow of transport bubbles in the center of the flotamochka.

The lower side of this distributor, facing the flow of bubbles, is perforated by multidirectional holes with a diameter of 1.5-2 times larger than the maximum particle size of the pulp.

Such a structure of the pulp distributor allows one to obtain multidirectional jets of the supplied pulp mixture, which increases the likelihood of encountering microaggregates introduced by the pulp jets with transport bubbles.

The experiment was performed on the created laboratory pneumatic flotation column type flotation machine with a diameter of 1 dm (0.1 m) and a height of 16 dm (1.6 m), shown in Fig. 8, using a sample of the stagnant tailings of flotation-gravity processing of gold-sulfide ores of the Alexandrovsky deposit at Davendinsky enrichment plant of Transbaikalia.

1. Equipment: laboratory pneumatic flotation machine column type, shown in Fig.8.

The flotation machine is equipped with a series-connected jet (41) and shelf (42) mixers of conditioned pulp supplied to the flotation machine (40). In addition, the column is connected to an ore pulp mixer with flotation reagents (62) and to a water saturator with air under pressure (63). The dispersant (44) installed in the bottom of the column is used in the form of an aquarium aerator (66) equipped with a control valve (68). The foam layer (46) on the pulp surface was washed with tap water from a plastic tube (47) with sprinklers (48) and equipped with a valve (67) that regulates the flow of water from the plumbing system. The pulp level was controlled using a siphon system (65) for discharging the chamber product as the conditioned pulp was supplied through the system of jet and shelf mixers. The conditioned pulp was supplied from a pulp mixer with reagents with a capacity of 0.6 m ³ , equipped with a mixer, through a hose equipped with a pulp flow control valve (62b), a shut-off valve (62a).

2. Pulp conditioning with flotation reagents.

Air conditioning of the pulp was carried out in a mixer with a capacity of 0.6 m ³ equipped with a propeller stirrer.

The following flotation reagents were used for conditioning:

2.1 Butyl potassium xanthate, 2nd grade (85% aqueous solution with a flow rate of 150 g / t) in the form of a 5% working solution.

2.2 Reagent IM-50 (hydroxamic acids C ₇ O ₈ ), marketable 7% -9% aqueous solution of sodium salts of hydroxamic acids. Working solution - 2% aqueous solution. Consumption IM-50-90 g of a 100% product per 1 ton of solid.

2.3 Pine oil (a mixture of terpene alcohols with aromatic hydrocarbons). The main component is terpenol. Consumption - 80 g / t.

3. Conducting the enrichment process in a laboratory setup. 3.1 Composition of the stale tails of the Davendinsky factory (see table 1.2).

Table 1 Screen analysis of stale tails Size classes, mm Class yield,% 0,074 31.21 0,063 11.78 0.05 4.72 0.04 2,56 -0.04 49.73 TOTAL one hundred

table 2 Results of phase analysis of stale tails Forms Gold content gold g / t % Free 0.18 41.86 In intergrowths 0.12 27.91 In sulfides 0,07 16.28 In quartz 0.06 13.95 Source tails 0.43 one hundred

As can be seen from the table. 1, the main fraction of particles in the stale tails is represented by the fineness class less than 0.04 mm - 49.73% and 0.074 mm -31.21%.

The main form of gold in stale tails, according to the table. 2: gold in free form - 41.86%, in intergrowths - 27.91% and in sulfides - 16.28, which amounts to more than 86%. This fraction of gold is recovered by flotation.

In quartz, gold can be partially extracted if the fraction of its free surface is significant.

Thus, the amount of gold recovered in stale tails, the particle size of which is 50%, according to the table. 1, less than 0.04 mm is about 90%. This gold belongs to a very thin class of fineness, the gold of which is not recovered by classical flotation.

3.2 Composition of conditioned pulp.

600 dm ³ (0.6 m ³ ) of conditioned pulp of 40% solid and 60% liquid phase was prepared. The pulp density was 1380 kg / m ³ . According to available data, the gold content in the used tailings in the process is 0.43 g / t.

Based on this, 1 m ^{3 of the} prepared pulp of the solid phase contains, at a density of 1380 kg / m ³ and a phase ratio of 40% solid, 60% liquid:

$$X=\frac{1380}{\mathrm{one\; hundred}}*40=552\mathrm{to}g$$

In this mass of tails (containing - 0.43 g / t gold), the amount of gold is

$$X=\frac{0.43}{1000}*40=0.237\mathrm{to}g$$

3.3 Flotation process parameters:

- the feed rate of the pulp in the photocamera was - V = 1.2 cm / s;

- the flow rate of the conditioned pulp was Q = 0.1 dm ³ / s;

- the air supply to the dispersant was - (0.2-0.3) dm ³ / s;

- the supply of tap water for washing the foam product was

- 2.8 dm ³ / min or 141 dm ³ / h;

- the supply of saturated water to the jet mixer was - (36-50) dm ³ / h.

Flotation was carried out for 1.5 hours. During this time, 540 dm ^{3 of} conditioned pulp from a mixer was passed through a flotation machine, which contained 300 kg of solid phase. During flotation, two medium samples were taken: one of the incoming conditioned pulp, the second from the discharged chamber product (spent pulp). Samples were filtered through a “red ribbon” filter (large-pore paper filter), dried, and given to a test assay to establish their gold content. According to assay data, 0.44 g / t of gold was found in the dried precipitate sample of the initial conditioned pulp, and (0.049-0.050) g / t of residual gold was found in the dried spent pulp sample (chamber product). According to these data, the gold recovery amounted to 0.44 g / t - 0.049 g / t = 0.391 g / t, which is 88.86% of 0.44 g / t of the maximum possible amount of extraction from the thin size class.

In the flotation process, a gold concentrate was obtained from the washed and dried foam product. The mass of this concentrate was 17 kg. In relation to the initial mass of stale tails contained in the processed pulp volume (540 dm ³ ) - 300 kg, the yield of the obtained concentrate is 5.7%. A dried sample of this concentrate was sent to perform an assay. According to assay data, 6.5 g / t of gold was found in this sample. When the gold content in the initial tails was 0.44 g / t, the concentration of gold in the concentrate was 6.5 g / t / 0.44 g / t = 14.8 (times).

When cleaning this concentrate by pressure flotation, the increase in the gold content in the obtained concentrate, presumably, can increase by the same factor, for example, by 14 times, and then the gold content in the concentrate will increase to 90 g / t. The resulting flotation concentrates can be stored and periodically cleaned, directing the tailings to the main flotation in order to achieve the required gold content in the marketable product.

As you know, all gravity and flotation methods of ore dressing are based on the use of the kinetic component.

In gravitational enrichment, this kinetic component is expressed in the movement of particles of minerals, depending on their density and speed.

In the case of flotation enrichment, this kinetic component is expressed in the inertial motion of the hydrophobized particles of minerals during the implementation of the elementary act of flotation - impact on the air bubble and sticking to it.

In all these cases, the size of mineral particles plays a decisive role. With a decrease in the particle size, their kinetic component decreases, the particles become inactive and unable to perform the elementary act of flotation, as a result of which the floatability of such particles, under other conditions being equal, disappears, the enrichment of such pulps ceases.

In our proposed technical solution for the extraction of selected hydrophobic particles there is no kinetic component, because the formation of a flotation particle-bubble aggregate is carried out by a different, new method - pressure flotation. For this method, the size of the recoverable particles does not matter, but the degree of hydrophobicity of their surface matters; the method is based on other physicochemical principles. To do this, ore pulp is thoroughly mixed at atmospheric pressure with water, saturated with pressure air. According to Henry's law, with increasing gas pressure above the surface of a liquid, its solubility in a liquid, such as air in water, increases proportionally. If such saturated water is mixed with pulp at atmospheric pressure, then with a decrease in pressure the solubility of air also decreases, the solution is unstable in a supersaturated state. In this case, excess air spontaneously begins to pass from the state of the solution to the free gas phase. This transition occurs in the form of tiny nuclei of bubbles. There are two ways for these nuclei: the first way is the formation of nuclei in the volume of water, by breaking fairly strong bonds of the polar water molecules with each other, with the formation of an air cavity, which is associated with significant energy consumption; the second way is the formation of nuclei of bubbles on the hydrophobic surface of particles, where these nuclei easily displace water molecules from surfaces with which they are also weakly bound. Due to the diffusion of air from the supersaturated solution surrounding the particle, the nucleus of the bubble grows, turning into a particle-bubble aggregate. Due to the fact that a small particle turns into a small aggregate, which has a vanishing low ascent rate in the pulp under the action of Archimedean force, it must be equipped with a transport bubble. To do this, the pulp with such aggregates must be treated with a stream of transport bubbles, to which these small aggregates adhere quite easily due to the presence of highly hydrophobic protrusions in the form of air bubbles on the surface. Thus, conditions are created for the formation by all hydrophobic particles of the pulp of the flotated particle-bubble aggregates without the use of the kinetic component. To do this, create saturated water, hydrophobize the surface of the particles of selected minerals, and thoroughly mix the saturated water with conditioned pulp, which is then treated with a stream of transport bubbles. This is the essence of the technical proposal for patenting.

It seems to us that the proposed technology will find wide application for the enrichment of large accumulated volumes of tailings of gravitational and flotation enrichment and for the extraction of thin components of ores at existing enterprises.

A prominent scientist geologist Shilo Nikolai Alekseevich, who devoted his many years of research to the study of a variety of placers, including gold placers in Yakutia, in his monograph [10] reports that ancient alluviums containing placers with large reserves of gold of fine size classes are common in Yakutia "... However their exploration, and, moreover, development, is possible only with the availability of advanced technologies. Without solving this problem, the entire area where alluvial deposits containing fine gold are concentrated, whose reserves can be estimated in hundreds of tons, cannot be put into industrial circulation ... ”

It seems to us that the technical solution we are proposing can be considered as a “perfect technology” required for the development of these ancient placers in Yakutia (and not only) containing fine gold and particles of other useful minerals, because the lower particle size limit is not limited to our technical solution.

The list of positions in the figures:

Figure 1. Column type pneumatic flotation machine:

1 - flotation machine housing

2 - pulp conditioning pipe

3 - contact tank pulp mixer with flotation reagents

4 - porous air dispersion diffuser

5 - receiver of compressed air

6 - outlet valve discharge chamber product (pulp level controller) "

7 - pipe for dumping the chamber product in the reservoir

8 - pipe for the discharge of foam product

9 - pipe for supplying clean water

10 - sprayed for washing foams

Figure 2. Pneumatic column flotation machine brand "Microcel-TM":

11 - flotation machine body

12 - pulp conditioning pipe

13 - air ring collector

14 - static mixer dispersant

15 - recirculation pulp pump

16 - pulp ring collector

17 - pipe discharge foam product

18 - pipe supply clean water

19 - shut-off valve of static mixers

20 - pulp level control unit

21. - valve discharge chamber product (flotation tailings)

Figure 3. Wastewater saturator:

22 - saturator body

23 - sewage pipe

24 - waste water flow valve

25 - wastewater flow meter

26 - air flow valve

27 - air mass meter

28 - suction pump

29 - saturator pump

30 - valve pressure regulator

31- pipe supply of saturated water

Figure 4. Contact pulp mixer with flotation reagents:

32 - pipe feed camp pulp with flotation reagents

33 - cylindrical tank body

34 - shaft

35 - axial type mixer

36 - hollow pipe

37 - holes in the pipe

38 - electric motor

39 - drain pipe air-conditioned pulp

Figure 5. Device for extracting fine fractions of selected minerals from ore pulps by pressure flotation:

40 - column car body

41 - jet pulp mixer with saturated water

42 - shelf mixer

43 - distributor of pulp mixture with saturated water in the volume of pulp

44 - air dispersant at the bottom of the camera

45 - receiver with compressed air

46 - layer of foam

47 - pipe with clean water

48 - sprayed for washing foam

49 - foam collector

50 - foam discharge pipe 51.- pulp level sensor

52 - valve discharge chamber product

53 - pulp level control unit

6. Jet Mixer:

54 - annular tube

55 - housing of the jet mixer

56 - expanding nozzles

57 - supply pipe of saturated water

58 - pipe air-conditioned pulp

59 - shelf mixer pipe

60 - sealing gasket between the flanges

7. The pulp mixture distributor in the flotation chamber, pos. 4 (in plan - the bottom side of the distributor):

61 - holes in the pipe of the pulp mixture distributor with a diameter of 3.0 mm R ₁ - diameter of the distributor valve valve of the chamber product discharge valve - diameter of the column flotation machine Ratio R ₂ : R ₁ = 1.5-2.0

Fig. 8. Laboratory column flotation machine and its equipment:

62 - pulp mixer with reagents (a - shut-off valve, b - control valve)

63 - saturator

64 = compressor

65 - siphoning device for dumping the chamber product

66 - aquarium aerator

67 - valve regulating the supply of wash water

68 - valve regulating the air supply

62 (a) - shutoff valve for pulp

62 (b) - valve regulating the supply of pulp.

Bibliography

1. Abramov A.A. Flotation enrichment methods. Textbook for students challenge in the specialty "Mineral processing" .- M .: Nedra, 1984. 383 p.

2. Limus Pauling, Peter Pauling. Chemistry. Per. from English V. Sakharova. Ed. Karapeiyana M.M. - M.: Mir, 1978, p. 246.

3. Kireev V.A. Course of physical chemistry. M., State. scientific and technical. publishing house chemical literature, 1955, p. 389.

4. Patent No. 2155716. Publ. September 16, 2000 Bull. Number 25.

5. Patent No. 87159 for utility model. Publ. September 27, 2009 Byul. Number 27.

6. Glembotsky V.A., Klassen V.I. Flotation methods of enrichment M., Nedra, 1981

7. Klassen V.I., Mokrousov V.A. Introduction to flotation theory. M., Gosgortekhizdat, 1959

8. Shalaev V.P. The basics of mineral processing. Allowed Min. higher and secondary specialist. Education of the USSR as a textbook for university students enrolled in the specialty "Economics and organization of mining." M., Nedra, 1986, 120 pp.

9. Website on the Internet:.

10. Shilo N.A. The doctrine of placers. Theory of placer ore formations and placers. Vladivostok, Dalnauka, 2002, 473 pp.

Claims (10)

1. A method of extracting selected minerals from ore pulps by pressure flotation, comprising treating the pulp with flotation reagents to hydrophobize the surface of the particles of the selected minerals, saturating the water with air under pressure, characterized in that the prepared conditioned pulp is thoroughly mixed with water saturated with air at atmospheric pressure and the resulting pulp mixture with Saturated water is treated with a current of flotation-sized air bubbles. 2. The method according to claim 1, characterized in that the air is saturated with waste water from the tailings, cleaned of suspended particles. 3. The method according to claim 1, characterized in that the foam layer on the surface of the pulp with the extracted particles of selected minerals is washed with a small amount of water before discharge. 4. The method according to claim 1, characterized in that the volumetric ratio of saturated water to the pulp during their displacement cannot be less than 0.1: 1. 5. A device for extracting selected minerals from ore pulps by pressure flotation includes a column-type pneumatic flotation machine, an initial pulp mixer with flotation reagents and a pressurized water saturator, characterized in that the column flotation machine, at the inlet of it is conditioned pulp, is equipped with a jet pulp mixer with water, saturated with air under pressure, and sequentially with a shelf mixer, and in the chamber of the flotation machine, a perforated distributor of the mixture supplied by the pulp is fixed over the outflow of air bubbles generated at the bottom of the camera. 6. The device according to claim 5, characterized in that the jet mixer includes an annular tube with expanding nozzles mounted on the inner surface of the ring with an inclination in the direction of rotation of the pulp mixture, and a pipe supplying water to the annular pipe, pressurized with air. 7. The device according to claim 6, characterized in that the annular pipe is fixed in a cylindrical insert with flanges, with which the insert is connected to a pipe supplying an air-conditioned pulp, and in series with a shelf mixer. 8. The device according to claim 6, characterized in that the sum of the areas of the gaps of all nozzles fixed in the annular pipe should be less than the cross-sectional area of the pipe supplying the saturated water to the annular pipe. 9. The device according to claim 5, characterized in that the shelf mixer consists of metal shelves fixed in the frame at an angle of 45-50 ° with a variable inclination to each other. 10. The device according to claim 5, characterized in that the perforated distributor of the pulp mixture fed into the chamber of the flotation machine has an annular shape with a diameter of one and a half to two times less than the diameter of the flotation chamber and a segment of the perforated pipe connecting the inner cavities of this ring in diameter.

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