RU2737299C1 - Ejector-vortex aerator for flotation machine - Google Patents

Abstract

FIELD: technological processes; mining.

SUBSTANCE: present invention relates to processing of minerals, in particular, to purification of potassium pulps from insoluble residue (IR) using hydrocyclones and pneumatic floatation machines. Ejector-vortex aerator for flotation machine includes hydrocyclone, drain chute, pipeline for hydrocyclone drainage transportation to flotation machine, on the initial section of which there is a point for supply of floatation reagents (collectors and foaming agents), and nipples for supply of pulp-air mixture from the pipeline into flotation chambers. Difference between the levels of the hydrocyclone drain flute arrangement and the pulp mirror in the flotation cell and loss of pressure in the pipeline have such values, at which pulsed-air mixture under acceleration at the pipeline outlet is accelerated to speed of 7–20 m/s.

EFFECT: technical result is increase in selectivity of flotation process and extraction of specified mineral component.

1 cl, 1 tbl, 3 ex, 2 dwg

Description

The invention relates to the field of mineral processing, in particular to the purification of potash slurries from insoluble residue (HO) using hydrocyclones and pneumatic flotation machines.

At potash enrichment plants, at the first stage of mechanical extraction of HO, either one or two stages of hydrocyclones are used, the discharge of which is directed to the next stages of obtaining waste sludge corresponding to the following regulatory standards, namely: the mass fraction of HO in the solid phase must exceed 60%, and the mass fraction the proportion of KCl should be less than 10%. At sylvinite processing plants, a scheme is widespread, in which pneumatic flotation machines (MPGS) with tubular rubber aerators are used to extract NW from the discharge of hydrocyclones / Yu.B. Rubinstein, V.I. Melik-Gaikazyan, N.V. Matvienko, S.B. Leonov, Foam separation and column flotation - M: Nedra, 1989, p. 82-83, 276-278 /. Tubular aerators ensure high saturation of the flotation cell volume with optimal sized air bubbles.

The disadvantages of rubber tubular aerators are the rapid wear of rubber, an increase in the diameter of the holes and an increase in uneven aeration during operation. Due to the unstable operation of tubular rubber aerators at sylvinite processing plants, there is a regular violation of regulations, which manifests itself in the fact that in the solid phase of the foam product MPGS, the mass fraction of HO is on average less than 50%, and the mass fraction of KCl on average exceeds 15%. Ejector aerators are devoid of these disadvantages, in which air is supplied into the pulp flow and dispersed by the energy of the moving jet.

The closest in technical essence to the proposed ejector-vortex aerator for a flotation machine is an installation for the extraction of surface active substances (surfactants) from wastewater / USSR author's certificate No. 789403, class. C02F 1/38. В04С 5/107 / containing a flotation chamber and a pressure hydrocyclone, the sands of which concentrate mechanical impurities, and the drain is a water-air mixture prepared for surfactant flotation. In the area of the air column of the hydrocyclone, the pressure is below atmospheric, therefore, air is ejected from the atmosphere through the air tube installed in the area of the air column. The mixing of the air dispersed by ejection with the upward flow of the pulp takes place in the drain pipe of the hydrocyclone and in a special drain chamber.

The disadvantage of the known installation is the limited scope, which manifests itself in the absence of the possibility of using it for effective flotation from the discharge of hydrocyclones of fine fractions of mineral raw materials. This disadvantage is mainly due to the fact that the diameter of the air bubbles in the feed of the flotation chamber of the installation for the extraction of surfactants from wastewater significantly exceeds the optimal limits for bubble mineralization with fine fractions of mineral raw materials of 20-500 μm.

The size of the bubble significantly affects the intensity of all flotation sub-processes. The hydraulic coefficient of the capture of a mineral particle by an air bubble, on which the extraction of the useful component depends, and the probability of particle fixation on the bubble, which determines the selectivity of the process, decrease with an increase in the average bubble diameter.

The aim of the invention is to increase the selectivity of the flotation process and increase the extraction of a given mineral component into the foam product of the flotation machine, which is fed with a slurry-air mixture from an ejector-vortex aerator, including a hydrocyclone, a drain chute, a pipeline for transporting the discharge of the hydrocyclone to the flotation machine and pipes for supplying the slurry mixtures from the pipeline to the flotation cells.

The specified purpose for the flotation machine, which is fed with the slurry-air mixture from the ejector-vortex aerator, is achieved by the fact that the slurry-air mixture of the hydrocyclone discharge is conditioned with surfactants (collectors and frothers necessary for the flotation process) and before being fed into the flotation chamber under the influence of gravity accelerates in the pipeline to a speed of 7-20 m / s. For additional dispersion of air bubbles at the exit from the pipeline inside the flotation chamber, it is advisable to install a nozzle with a baffle plate.

Figure 1 (Fig. 1) shows a pressure hydrocyclone 1 with a drain chute 2, from which the slurry-air mixture through the pipeline 3 through the slurry divider 4 enters through the branch pipe 5 into separate flotation chambers 6, which have a nozzle installed at the end of the pipe 5 and a baffle plate, as well as foam chutes 7 for collecting the concentrate and an unloading device for removing the chamber product 8. At the initial section of the pipeline 3, there is a supply point for flotation reagents, which are also necessary to obtain air bubbles of the optimal size.

Elements 1-3 together form an ejector-vortex aerator. The pneumatic flotation machine, which is fed with the slurry-air mixture from the ejector-vortex aerator, operates as follows.

The initial pulp is supplied under pressure to the feed of the hydrocyclone 1. Due to the rotational movement of the pulp in the area of the air column of the hydrocyclone, a vacuum is created, therefore air is ejected there from the atmosphere through the drain pipe. In order to provide conditions for air ejection into the air column zone, the hydrocyclone drain pipe must work with an incomplete section.

The pulp-air mixture from the drain chute 2 enters the pipeline 3, in which it is conditioned with flotation reagents and, under the influence of gravity, accelerates to a speed of 7-20 m / s. With an increase in the velocity of the jet, a developed boundary layer is formed in the pipeline near it, moving with it. The conditions for accelerating the slurry-air mixture to a given speed are provided due to the corresponding height difference between the level of the location of the discharge chute of the hydrocyclone 2 and the slurry mirror in the flotation chamber 6.

When determining the required difference between the levels of the location of the drain chute 2 and the flotation chamber 6, on the basis of known regularities, one should take into account the loss of pulp pressure in the pipeline 3, which significantly depends on its diameter, as well as the number of elbows and nozzles on it. Each elbow and each nozzle on the pipeline 3, on the one hand, lead to a certain loss of pressure of the slurry-air mixture, but on the other hand, they contribute to the formation of vortices and increase the dispersion of air bubbles. The dispersion of air in the drain pipe of the hydrocyclone 1, the drain chute 2, the pipeline 3, the slurry divider 4 and the branch pipe 5 occurs precisely under the influence of the vortex flows of the slurry.

The supply of surfactants to the pipeline 3 is a prerequisite for obtaining air bubbles of the optimum size for the flotation process. Surfactant adsorption reduces surface tension, which reduces the likelihood of bubble coalescence. The addition of a surfactant to the slurry-air mixture typically reduces the average bubble diameter due to the smaller initial bubble size and the prevention of coalescence. In addition, due to the supply of reagents in the pipeline 3, there is not only more efficient dispersion of air bubbles, but also their partial mineralization.

Installed in the flotation chamber at the outlet of the branch pipe 5, the nozzle and the baffle plate also contribute to the formation of vortices and increase the dispersion of air bubbles, therefore, if installed, they will be an additional part of the ejector-vortex aerator 1-3. To eliminate the useless loss of pressure, the design parameters of the nozzle installed on the branch pipe 5 and the level of the baffle plate are determined so that the speed of the slurry-air mixture does not increase when passing through the nozzle.

Thus, a necessary and sufficient condition for increasing the extraction of a given mineral component into the foam product of the flotation machine, which is fed with the discharge of the hydrocyclone, and for increasing the selectivity of the flotation process, is the optimization of the dispersed composition of air bubbles in the ejector-vortex aerator due, firstly, conditioning the slurry-air mixture of discharge of hydrocyclones with flotation reagents and, secondly, accelerating the slurry-air mixture to a speed of 7-20 m / s. Moreover, the higher the speed of the slurry-air mixture before feeding into the flotation chamber, the higher the efficiency of the flotation process of fine fractions of the mineral component.

Example 1.

At the sylvinite processing plant, in one of the chambers of the deep foam separation machine (MPSG), instead of rubber tubular aerators, an ejector-vortex aerator 1-3 was installed, and an airlift was also mounted as an unloading device. At the end of pipe 3, a nozzle and a baffle plate were installed. The results of industrial operation of a pneumatic flotation machine for extracting HO from the discharge of hydrocyclones, shown in Fig. 1, with the difference between the levels of the location of the discharge chute of the hydrocyclone of the second stage of mechanical de-sludging 2 and the mirror of the flotation chamber 6 (H) equal to 9 meters, are presented in Table 1. With these Under conditions, the slurry-air mixture of the hydrocyclone discharge was accelerated to a speed of more than 7 m / s before being fed into the flotation chamber.

Table 1 shows the values of KCl and HO into the foam product achieved during industrial operation, as well as the process selectivity. The index of selectivity of the slurry flotation process was calculated as the ratio of the difference between the values of recovery into the frothy product of HO and KCl to the value of recovery into the frothy product of HO. For comparison, Table 1 shows the performance indicators of the reference process of sludge flotation in the MPSG.

Replacement of the aerator in the MPSG chamber ensured a high selectivity of the NDF flotation process from the discharge of hydrocyclones 0.941 versus 0.742 in the reference MPSG. The low value of HO recovery into the foam product equal to 13% is explained by the fact that most of the air bubbles in the feed to the flotation cell had a diameter exceeding the optimal size of 20-500 microns.

Example 2.

The results of industrial operation of the improved two-chamber MPSG in the slurry flotation circuit shown in Fig. 1 are presented in Table 1. In the improved MPSG chambers, a reconstruction similar to that described in example 1. Unlike the machine described in example 1, the difference between the levels of location the drain chute of the hydrocyclone of the first stage of mechanical de-sludging 2 and the mirror of the flotation cell MPSG 6 were equal to 21 meters. Increased by 12 meters the difference between the cyclone and the improved chambers of the MPSG ensured the acceleration of the slurry-air mixture of the hydrocyclones discharge to a speed of about 20 m / s, due to which the extraction of HO into the foam product increased in comparison with example 1 from 13% to 46.6% with high selectivity flotation process (0.937).

An increase in the extraction of fine fractions of HO into the foam product, provided that the flotation process is highly selective, is achieved by saturating the pulp in the flotation chamber with smaller air bubbles of the optimal size of 20-500 microns, the mineralization of which is high.

Example 3.

The results of industrial operation in the operation of slurry flotation of the three-chamber MPSG, which was improved according to the scheme shown in Fig. 2, are presented in Table 1. In the improved MPSG chambers, a reconstruction similar to that described in example 1 was performed. the first stage of mechanical de-sludging 2 and the improved flotation cell MPSG 6 was equal to 21 meters, and between the level of the location of the drain chute 9 of the hydrocyclone 10 of the second stage of mechanical de-slugging and the improved flotation cell MPSG 6 was 9 meters.

The combined supply of 4 overflows of two hydrocyclones located at different levels to the slurry divider created favorable conditions for coalescent flotation of fine fractions of HO with large and small bubbles at the same time. Large vesicles are known to carry out transport functions for highly mineralized small vesicles. Compared with the process of slurry flotation in the machine presented in example 2, due to coalescence flotation, the selectivity of the flotation process slightly decreased from 0.937 to 0.921, but the recovery of HO increased from 46.6% to 50.9%.

Thus, the industrial application of the ejector-vortex aerator 1-3 provided an increase in selectivity and an increase in the recovery of ND from the discharge of hydrocyclones in the process of slurry flotation in comparison with the use of MPSG with a rubber tube aerator. At the same time, to further increase the recovery of HO, it is possible to equip the MPSG with aerators of both types simultaneously.

Claims (1)

Ejector-vortex aerator for a flotation machine, including a hydrocyclone, a drain chute, a pipeline for transporting the discharge of a hydrocyclone to the flotation machine, at the initial section of which there is a supply point for flotation reagents (collectors and foaming agents), and nozzles for supplying the slurry-air mixture from the pipeline to the flotation chambers, characterized in that in order to increase the selectivity of the flotation process and the extraction of a given mineral component, the difference between the levels of the location of the hydrocyclone drain trough and the slurry mirror in the flotation chamber and the pressure loss in the pipeline have such values at which the slurry-air mixture under the action of gravity at the outlet from the pipeline accelerates to a speed of 7-20 m / s.

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