Magneto-centrifugal flotation cell for concentrating materials which reduces water consumption and method of use

Abstract

The invention relates to a magneto-centrifugal flotation cell for ore concentration which reduces water consumption. A disadvantage of conventional flotation cells is the use of a large amount of water, some flotation cells requiring at least 60% water. The present invention uses ore pulp with increased density and viscosity, owing to the application of an axial magnetic field, wherein the Lorentz force, which is the force exerted by an electromagnetic field that receives a charged particle or an electrical current, can be used. The solution is a cell which, in addition to the forces that usually act on conventional flotation cells, uses external forces which, in principle, produce synergy in the separation of ore particles that have different gravitational and magnetic properties.

Claims

1. A magnetic-centrifugal flotation cell for the concentration of ore that reduces water consumption, made up with a tubular container (2) acting as a chamber to process ore slurry and elements to provide a magnetic field, wherein said tubular container (2) comprises: a first segment (19) generating turbulent bubbles; a second segment (20) with a stabilized bubbles flow; one end where a first face (11) is found, with at least one air entrance (4), and, at one side of said tubular container and close to said face (11) has an ore feed entrance (3); a second end where a second face is found (12), with one concentric material exit (6), and, at a side close to said face (12), a lateral eccentric exit (5) is found; elements to generate an axial magnetic field located at the external perimeter of the tubular container (2); a cover (14) that encloses said elements to generate an axial magnetic field (10).

2. The magnetic-centrifugal flotation cell, according to claim 1, wherein the elements used to generate an axial magnetic field (10) are only located at a perimeter where the second segment (20) with the stabilized bubble flow is found (2).

3. The magnetic-centrifugal flotation cell, according to claim 1, wherein the elements used to generate an axial magnetic field (10) are found along an entire perimeter of the tubular container (2).

4. The magnetic-centrifugal flotation cell, according to claim 3, wherein the cover is located outside and all along the cover of the tubular container (2).

5. The magnetic-centrifugal flotation cell, according to claim 1, wherein the elements used to generate an axial magnetic field (10) are a coil (13) and a power supply (18).

6. The magnetic-centrifugal flotation cell, according to claim 5, wherein the cover it is placed outside a mantle of the tubular container (2), covering the coil at the second segment (20).

7. The magnetic-centrifugal flotation cell, according to claim 1, wherein the elements used to generate an axial magnetic field (10) are permanent magnets.

8. The magnetic-centrifugal flotation cell, according to claim 7, wherein the permanent magnet is neodymium.

9. The magnetic-centrifugal flotation cell, according to claim 1, wherein the tubular container it has a plurality of air entrances (4).

10. The magnetic-centrifugal flotation cell, according to claim 9, wherein the tubular container has four or more air entrances (4).

11. The magnetic-centrifugal flotation cell according to claim 1, wherein the tubular container has a generally horizontal orientation.

12. A magnetic-centrifugal flotation process for the concentration of ore that reduces water consumption, which is made up of a tubular container (2) acting as a chamber to process an ore slurry and elements to provide a magnetic field, wherein the process comprises the steps of: a) inputting ore slurry through an ore feeding entrance; b) inputting air through at least one air feeding entrance; c) generating a first segment in the tubular container with turbulent bubbles; d) generating a second segment in the tubular container with a stabilized flow of bubbles; where heavier particles of the ore flow eccentrically while light particles of the ore are transported by a concentric axis of the tubular container; e) generating an axial magnetic field using the elements that provide the magnetic field, which acts as a magnetic force on the particles; and f) recovering the ore at a lateral eccentric exit and a concentric ore exit.

13. The magnetic-centrifugal flotation process according to claim 12, wherein the at least one air feeding entrance is at a first face on one end of the tubular container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The attached drawings are included to provide a greater understanding of the invention and constitute a part of this description and help to explain its principles.

(2) FIG. 1 shows a first experimental schematic of this invention.

(3) FIG. 2 shows a second experimental schematic of the flotation cell in this invention.

(4) FIG. 3 is the rear view of a magnetic flotation cell mode in this invention.

(5) FIG. 4 is the rear view of a magnetic flotation cell mode in this invention with the cover that protects the coil.

(6) FIG. 5 is the front view of a magnetic flotation cell mode in this invention.

(7) FIG. 6 is the front view of a magnetic flotation cell mode in this invention with the cover that protects the coil.

(8) FIG. 7 shows the arrangement of the equipment used in the experimental validation of the magnetic flotation cell in this invention.

(9) FIG. 8 shows a chart with recovery vs copper grade considering the tangential outflow.

(10) FIG. 9 shows a chart with recovery vs grades observed in both outflows (central and tangential).

DESCRIPTION OF THE INVENTION

(11) This invention refers to a magnetic-centrifugal flotation cell for the concentration of ore that reduces water requirements. The operation of this flotation cell will be explained based on the attached drawings and the theoretical principles of the phenomena that take place inside the same.

(12) In the first place, it is accepted that the impact of centrifugal effects habitually brings together mass separation (density and size, because mass is proportional to the product of density times the size to the cube) of particles, where the particles with a greater mass, in principle, will move eccentrically while the lighter particles will be initially transported by the concentric axis of the cylinder or the eddy located at the center of the tube. This commonly observed motion of particles is subsequently modified by the magnetic field applied that exacerbates the separability of semiconductor material of the sulfide type. It is expected that the movement of bubbles and particle-bubble aggregates towards the external mantle prevents coalescence and promotes the dispersion of the gas phase because the bubbles will experience shear stresses that will help gas dispersion.

(13) FIGS. 1 and 2 show an experimental schematic of the magnetic flotation cell (1) of this invention. The magnetic flotation cell (1) is made up by a hollow tubular container (2), whose length is greater than its width and its inside holds a first segment (19) that generates bubbles in a turbulent medium with the coming together of the air and ore slurry flows and a second segment (20) where the bubble flow is stabilized and the heavier particles flow eccentrically while the lighter particles will be transported by the concentric axis of the tubular container (2).

(14) One of the ends of the tubular container (2) holds a first face (11) and the other end holds a second face (12). The air entrances (4) are found in the first face (11) and on the side of the tubular container mantle (2) and the ore entrance (3) is located close to the air entrances (4). The material eccentric lateral exit (5) is found close to the second end and perpendicular to the symmetry axis of said tubular container (2), which may or may not follow the flow mainly governed by the helicoidal motion of the complex fluid. The material concentric exit (6) is placed on the second face (12). The axial magnetic field (10) is found around the tubular container (2) and positioned towards the turbulence area, close to the second face (12).

(15) The axial magnetic field (10) in the first embodiment of the invention is provided by a coil (13) with its respective power supply and, alternatively, permanent magnets may be used in order to avoid the electric energy expense at the coil (13).

(16) Experiments were conducted on the basis of the preceding scheme and the first embodiment of the invention, whose results indicate that the eccentric lateral exit (5) displays foam similar to the foam seen in conventional concentrate flotation cells with watery slurry, preliminarily indicating that particulate matter containing valuable material was obtained at this exit. This indicated that the centrifugal effect, the magnetic effect, or both, when air comes into the system as shown in FIG. 1 (please note that the ore feeding entrance (3) is very close to the air entrances (4) allowing a kind of gas suction at this point), have an ore concentration effect, a symptom indicating that the invention allows separation similar to a conventional flotation cell. In addition, setting aside some out of trend points it is possible to see that the recovery and grade curve behaves very similarly to a state-of-the-art classical flotation cell.

(17) As shown in FIGS. 1 and 2, the ore slurry enters the magnetic flotation cell (1) through the ore feed entrance, encountering the air that comes in through the air entrances (4) in order to make up the bubbles. Having flowed through a part of the segment of the tubular container (2), the current stabilizes and the particles are separated by their mass, where the heavier particles (8) will move eccentrically outwards, generating a vector (9) perpendicular to the symmetry axis of the tubular container (2), leaving the cell through the eccentric lateral exit (5), while the light particles will be transported by the concentric axis of the tubular container (2) and will leave the cell with a current (7) through the concentric material exit (6).

(18) As already indicated, an axial magnetic field (10) is applied to the flotation cell. Thus, it is possible to analyze the Lorentz force, to determine how a magnetic force acts on a particle with charge q as shown in Equation 1.
F=q[E+vxB]  (1)

(19) where q is the charge, E represents the electric field, v is the particle velocity, and B is the magnetic field.

(20) The experiments were conducted with continuous current so that the effect of the electric field is negligible. Equation 1 becomes Equation 2.
F=q[vxB]  (2)

(21) The force on particle (8) increases with the increase of the magnetic field obtained using electric current, which may involve an expense, particularly at high capacity ore treatment industrial levels.

(22) Since ore particles exhibit a low charge, it is necessary to increase their velocity. In this apparatus, this is achieved using the centrifugal effect on the particles along the tubular container (2).

(23) In short, it is possible to conclude that the position of the axial magnetic field (10) causes particles, bubbles, and/or particle-bubble aggregates slightly charged by their tangential motion velocity and the field direction to move eccentrically and be recovered in tangential exits.

(24) One of the preferred modes of this invention is shown in FIGS. 3 to 6, where a hollow tubular container (2) acts as a chamber to process mineral slurry. At one end, an air entrance (4), preferable four, and, perpendicular to the air flow, the tubular container (2) has an ore feed entrance (3). At the other end where the second face is located (12), the tubular container (2) has a concentric material exit (6) and, very close to it and perpendicular to the symmetry axis, an eccentric lateral exit (5) is found. Referring to FIGS. 4 and 6, the magnetic flotation cell has a cover (14) to protect the coils (13) that generate the axial magnetic field (10) for the magnetic flotation cell (1).

(25) In another embodiment, the cover (14) may also be used to protect permanent magnets that provide an axial magnetic field (10).

(26) The cover (14) is placed outside the mantle of the tubular container (2), covering the coil in the second segment (20) as shown in FIGS. 4 and 6. If the coil is placed along the entire tubular container (2), then the cover (14) must also be placed along the entire tubular container (2).

(27) As already mentioned, the tubular container (2) has a flow segment (19) with the entrance of ore and air, so that this segment becomes a turbulent zone where bubbles are formed. Likewise, the tubular container (2) has a second segment (20) with the eccentric lateral exit (5) and the materials concentric exit (6), where the flow of bubbles is stabilized and the heavier particles flow eccentrically while the light particles will be transported by the concentric axis of the tubular container (2).

(28) Since the slurry flow in the second segment (20) of the tubular container (2) is relatively more stable, with and eddy flow and a concentric flow, it is in this segment where it us useful to install the coil (13), given that the axial magnetic field exercises its effect on an ordered flow of particles.

(29) Although the preceding condition is quite reasonable, it is not proper to dismiss having a short turbulent first segment (19) and a longer stability segment in an eddy flow and a concentric flow, so that the coil (13) may cover the entire tubular container (2). The same would happen if permanent magnets are used to generate the axial magnetic field (10).

(30) The axial magnetic field for the tubular container (2) may also be generated with permanent magnets. It is well known that using coils (13) demands electric current, which may limit the large-scale application of the invention. The permanent magnets may be made of neodymium or something similar.

EXPERIMENTAL EXAMPLE

(31) FIG. 7 shows the experimental system used herein. Into an agitated tank (15) was introduced a slurry from a mining site with a 50% content of solids and a copper grade around 0.8%. Using a peristaltic pump (16), the slurry is taken towards the flotation cell (1) coming in through the ore feed entrance (3), where the cell may work with or without an axial magnetic field and generating, in any case, 2 products: C1: central flow and S1: tangential exit flow. In order to generate the bubbles, there is a pressurized air generator (17) and air is injected to the tubular container (2) through the air entrances (4). The flotation cell may operate horizontally or vertically with the ore being fed from above or from below when operating vertically.

(32) The field intensity used herein was approximately 0.001 T using 2 Amp direct current and a copper wire solenoid with approximately 500 turns in a segment approximately 20 cm long. The electric energy was provided by an 18 volt power supply.

(33) Table 1 shows the experiments carried out.

(34) TABLE-US-00001 TABLE 1 Set of Experiments Experimental Run Tube Orientation Axial Magnetic Field P1 Horizontal No P2 Top vertical feed No P3 Bottom vertical feed No P4 Horizontal Yes P5 Top vertical feed Yes P6 Bottom vertical feed Yes

(35) The samples were taken at both exits of the apparatus and sent to an automated mineralogical analysis using QEMSCAN®. In order to reconcile the copper grades, the feed was backcalculated, and the recoveries were estimated.

Results

(36) The recovery results for each one of the elements measured using the QEMSCAN® technique are shown in Table 2.

(37) TABLE-US-00002 TABLE 2 Recovery of each element in each experiment Experiment No. Element P1 P2 P3 P4 P5 P6 Al 10.3 49.1 60.6 57.7 65.5 53.4 B 8.3 40.0 75.0 40.0 60.0 66.7 C 15.3 33.3 60.0 50.0 55.6 33.3 Ca 9.4 44.9 59.4 54.5 59.5 51.4 Cu 19.3 52.1 27.0 22.4 20.8 49.0 F 11.8 53.3 61.5 70.0 66.7 46.7 Fe 18.8 57.8 29.5 29.9 22.6 50.3 H 9.9 47.4 62.5 60.0 66.7 52.9 K 10.8 46.7 60.9 59.9 64.2 51.6 Mg 10.1 44.8 61.8 57.6 60.5 52.2 Mo 23.2 69.2 17.6 40.0 0.0 18.2 Na 9.3 50.2 59.0 55.8 63.8 56.3 O 9.7 48.1 60.0 58.2 63.4 50.0 P 8.3 42.9 42.9 45.5 55.6 50.0 S 18.9 57.4 29.6 28.9 22.1 49.9 Si 9.6 48.5 59.8 58.7 63.4 49.3 Ti 9.3 47.1 63.2 50.0 56.5 54.5 Zn 100.0 50.0 0.0 40.0 0.0 100.0 Rm (%) 10.8 13.6 40.9 10.5 16.4 38.5

(38) It may be seen that copper recovery ranges between approximately 19% and 52% and it is difficult to get these recoveries in conventional cells with a 50% of solids. Therefore it is possible to claim that this magnetic flotation cell considerably brings down water requirements. The maximum observed recovery ranged approximately between 10%, the customary value in rougher cells, and 40%.

(39) As expected, the recovery vs copper grade relationship has a behavior like the one observed in conventional cells, as shown in the recovery vs copper grade chart that only considers the tangential exit in FIG. 8.

(40) The copper enrichment ratios range between 2 and 15, also observed in conventional cells with lower percentages of solids (30% and less).

(41) FIG. 9 shows recovery vs copper grades considering both the center exit and the tangential exit of the magnetic flotation cell. It may be seen that the best experimental condition, allowing the maximum grade differences between both exits corresponds to experiment P4 with the equipment in a horizontal position and using the axial magnetic field.

CONCLUSION

(42) The magnetic flotation cell invention obtains important recoveries and grades compared to those observed in conventional flotation cells operating with 50% of solids. Preliminarily, the best experimental condition was achieved working with the new cell in a horizontal position with the application of a magnetic field. In only one run, this condition obtains enrichment ratios above 10% and recovery ratios above 20%. In theory, it may be expected that the cell should also allow working with up to approximately 70% of solids.