FI115699B - Method and apparatus for separating into foam and using a spiral rotor screw - Google Patents

Abstract

In a froth flotation method and apparatus, a thick slurry is formed from a coarse-grained material and flotation chemicals. The slurry is prepared substantially without producing sludge in the slurry. In a flotation separator (2), a liquid phase is provided and a froth phase is arranged on the surface of the liquid phase. The slurry is fed into the froth phase, with the result that hydrophobic particles are caught in the froth, to be removed as a froth overflow, while hydrophilic particles sink through the froth into the liquid phase below it, to be removed as an underflow. In the preparator (1), the slurry is brought into a flowing motion with an axial vertically circulating flow pattern. The preparator (1) used is a helical rotor mixer.

Description

115699 Foam Separation Method and Apparatus, and Operation of a Rotary Rotary Mixer

FIELD OF THE INVENTION

The invention relates to a method as defined in the preamble of claim 1. The invention further relates to apparatus as defined in the preamble of claim 9. The invention further relates to the use of a helical rotor-10 mixer as defined in claim 19.

BACKGROUND OF THE INVENTION

The present invention relates to a foam separation process and system known as Separation In Froth (SIF), which is intended for the enrichment of coarse minerals and typical separation techniques for recycling technology. The SIF method and a preferred SIFI foam erofcus device have been described e.g. in WO 20 00/51744.

From literature it is known that the first; once, directing the slurry directly to the foam pointed out:; Malinovsky, V.A. (1961) Selective recovery of:: hydrophobic and hydrophobic particles and some sur-

\ 25 face active agents by separation in froth. ”DAN SSSR

141.420-423. Further, SIFs are known from US 3,434,596, US 4,274,949, US 4,469,591 and US 3,815,739.

The Separation In Froth (SIF) method is based on the separation of materials in the foam phase. Essential in the process is the direct introduction of the powdered and chemical treated feed in a SIF flotation device. foam. In this way, hydrophobic particles will adhere to the foam and migrate away from the foaming device, while hydrophilic particles will pass through the foam to the underlying slurry layer. In this case, 2 115699 gives the excess to be removed with the foam phase and the under solution from the solution below. The separation thus takes place entirely in the foam phase, where the residence time is usually only in the order of 10 s.

The SIF method differs substantially from the conventional flotation methods, in which the contact between the particles and the bubbles is created in the slurry and the rise of the particles with the air bubbles in the foam layer is a critical step for grain size. SIF method 10 can distinguish particles that are considerably coarser than conventional foaming depending on the surface properties of the material, particle shape and density. Depending on the mineral, the maximum grain size of the concentrate is about 3 mm. In mineral enrichment, the SIF-15 method is preferably suitable for the treatment of coarse fraction classification (screen, cyclone) of refining circuits and generally for cases where the material is already finely divided in coarse grain size.

An advantage of the SIF process is that the processes can be substantially simplified and savings in refining energy can be achieved because of the large grain size of the material and in chemical consumption because the process '' uses smaller quantities of wax bleaching chemicals than conventional processes. Still in a short SIF device, the | : Because of the 25 hours, the process is fast.

In the SIF process, it is preferable to use a high slurry density which is generally in the order of 50-70%.

For this reason, the slurry is usually pre-thickened, for example by means of a spiral classifier. In some cases, the let-30 density is naturally high enough so that no pre-thickening is required.

'···' Problems with the known SIF method are related to the preparation of a thick slurry using foaming chemicals; with me. The purpose of the training is to put the chemicals on the surface of the minerals. It is known in the art to use a * * drum trainer as a '' trainer in the SIF process. The drum trainer has been used

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3 1 1 5699 because the mixing properties of conventional dampers are generally unsuitable for use at said high slurry densities because of the high local mixing energy they tend to generate, which in many ways impairs the operation of the SIF process. Therefore, until now, the only viable way has been to use a drum-type mixer for coaching, which, due to its low rpm, has low mud formation.

The drum of a drum mixer is usually a cylindrical container arranged to be rotated about its substantially horizontal central axis. Fixed agitator disks are provided on the inner wall of the drum to enhance agitation. There are 15 continuous drum mixers. The slurry to be mixed is fed to the drum at one end and removed at the other end. The flow pattern of the slurry in the trainer is so called. plug-flow pattern.

The problem is that the drum mixer is a bulky device that requires a lot of floor space. This is a problem 20, especially in existing concentrator production facilities, where processes are being upgraded to SIF but the buildings are not * wanted to be expanded for this purpose. In addition, the drum trainer drum *. ·. · Can only be partially filled, since, as a rule, about two thirds of its interior space must be left empty. Thus, about 30% of the drum filling is poor. A further problem is that the coaching time is relatively long.

... PURPOSE OF THE INVENTION

The object of the invention is to eliminate the above disadvantages.

··! In particular, it is an object of the invention to provide a foam separation method and apparatus in which the die is as small as possible.

»» 4 115699

It is a further object of the invention to provide a foam separation process and apparatus wherein the slurry preparation time is as short as possible.

SUMMARY OF THE INVENTION

The foam separation process according to the invention is characterized by what is set forth in claim 1. Further, the foam separation apparatus according to the invention is characterized by what is set forth in claim 10. The use of a helical rotor mixer is characterized in claim 19.

According to the invention, in the process step of the method, the slurry is brought into a flow having an axial-vertical vertical circular flow pattern.

According to the invention, the damper in the apparatus is a helical rotor mixer.

An advantage of the invention is that the damper which produces the said flow pattern, in practice a helical rotor 20 mixer, is only slightly bulky in the upright position. Existing concentrators can be applied to the SIF-T. process without additional construction. The filler rate of the valve used is high because the hopper mixer tank is preferably filled completely !!. ' 25 slurries to be coached. The residence time of the slurry in the diluent is short so that the SIF process coaching step can be substantially accelerated.

In one embodiment of the method, an axial vertical rotational flow is formed by a helical rotor rotary mixer 30 having a circular cross-section rotating a vertical central axis of rotation at a constant radius distance; ; double helix rotor with hose.

** In one embodiment of the method, the pitch of the helical tubes 35 is selected to be between 15 ° and 50 °.

5, 115699

In one embodiment of the method, the particle size of the coarse-grained material is selected to be no more than about 3 mm.

In one embodiment of the method, the slurry is formed to a slurry density of 50-70%.

In one embodiment of the method, the slurry is thickened prior to coaching.

In one embodiment of the method, the efficiency of mixing is controlled by varying the rotational speed of the helical rotor 10, whereby the flow rate of the circulating flow is changed.

In one embodiment of the method, the speed of rotation of the helical rotor is controlled such that the flow rate is up to 2.0 m / s, preferably up to 1.0 15 m / s.

In one embodiment of the apparatus, the trainer comprises a container having an interior space limited to the side by a cylindrical vertical side wall and a downwardly planed base. The double helix rotor 20 is centrally arranged in the interior of the container. The power unit is arranged to rotate the double helix rotor at a predetermined rotation speed. Inside the container, the sidewall has a plurality of elongated vertical flow defects extending from the sidewall to the center axis of the container.

:: In one embodiment of the apparatus, the twin-screw rotor includes a vertical shaft connected to the power unit. Two identical spiral tubes of circular cross-section, ··. 30 is mounted on the shaft with support arms opposite each other symmetrically at a radius from the axis.

In one embodiment of the apparatus, the helix tubes have a pitch angle of 15 ° to 50 °.

In one embodiment of the apparatus, the rotor has a diameter of 0.5-0.8, preferably 0.65-0.7 times the inside diameter of the container.

6, 115699

In one embodiment of the apparatus, the diameter of the double-helical rotor is 0.5-0.8, preferably 0.65-0.7 times the inside diameter of the container.

In one embodiment of the apparatus, the helical-5 tubes rotate the vertical axis 1/2, 5/8, 2/3, 3/4, 7/8 or 1 turn.

In one embodiment of the apparatus, the diameter of the helical tubes is 0.04 to 0.07 times the diameter of the rotor.

10 In one embodiment of the apparatus, the width of the flow disadvantage is 1/12 to 1/9 times the inside diameter of the container.

In one embodiment of the apparatus, there is a circumferential gap between the flow disadvantage and the container wall having a width of 0.01 to 0.04 times the inside diameter of the container.

In one embodiment of the apparatus, the number of flow disadvantages is 3 to 12, preferably 6 to 8.

2 0 LIST OF PHOTOS

In the following, the invention will be described in detail by means of specific embodiments with reference to the accompanying drawing, in which * »·! Figure 1 shows a schematic diagram of a prior art SIF- * * · * 25 process, * »Figure 2 shows a SIF process according to the invention, · · and Figure 3 shows a sectional view of Figure 2 SIF-1 ' » '; 30 process coach.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 illustrates a prior art SIF process of 50 to 70% of a coarse-grained material having a particle size of about 35 to about 0.1 to 3 mm initially thickened with a thickener 17 which is a pre-spiral classifier. .

The thickened slurry is then fed to a trainer 1, where the slurry is substantially prepared without forming a sludge, i.e. so that the particles do not grind into finer fractions. As mentioned above, the prior art employs as a trainer 1 a drum roller whose training drum rotates about a horizontal axis. From the training drum, the slurry is fed through a feeder 3 to a foam separation device 2 having 10 foam phases and a liquid phase under the foam phase. The slurry is fed to the foam separator 2 so that it enters directly into the foam phase, whereby the hydrophobic particles adhere to the foam and can be removed from the apparatus as a foam overflow by the first discharge means 154.

The SIF process of the invention shown in Figure 2 is similar to the process of Figure 1, the description of which is referred to, but differs only with respect to diluent 1. Here, the coaching is carried out with a low-volume, helical rotor trainer where the helical rotor can slurry; : under the vertical axial flow.

*,: 25 Characteristic of this mixing arrangement is the relatively large size of the helical rotor trainer. It-se rotor covers 25 to 55% of the total capacity of the trainer, "... and preferably 35 to 45% of this volume. The effective volume is the volume remaining inside the vir-30s. The size: * 'is so large that the mixer, with this direction of rotation elevating, provides a circulating flow which flows upwardly and downwardly in the center of the diluent. The circulating flow is strongly directed towards the bottom of> 35 ti and rotates with the coil mixer lower supports t «· ' '' towards the ring to turn here near the bottom 8 115699 upwards. Correspondingly, the circulation current flowing near the surface turns towards the center and here downwards from the vicinity of the surface. According to our invention, using a large lifting mixer having the structure described below and a dampener adapted to the size and use of the mixer, a very uniform mixing of the slurry volume of the entire trainer is achieved.

The stirring intensity is adjusted to vary the rotational speed of the helical rotor mixer, which directly affects the flow rate of the circulating flow and thus the turbulence present. The intensity of uniform mixing can be adjusted over a wide range due to e.g. just the size of the mixer and the build-15 of tea. There is no actual lower limit of flow with a practical upper limit of 1.5 to 2.0 m / s. However, the re-mixing time is quite short even at significantly lower flow rates. In most coaching cases, it is appropriate to lower the circulation flow below 1.0 m / s to between 0.2 m / s and 0.6 m / s, which has been found to provide sufficient mixing. The mixing is improved by the fact that the circulating currents • f * '·' 'exhibit short-circuiting currents caused by the support f, · j from the mixer shaft to the helix tubes of the mixer.

:: In SIF coaching, it is important to avoid a lie; decomposition, that is, solidification of the solid by local agitation. As discussed below, the helical rotor of the present invention used as a mixer is of such a design as to minimize the grinding effect.

; 'The rotor is constructed of circular tubes and is shaped as a symmetrical double helix whose pitch angle directly influences the mixing angle of the slurry. The above-mentioned li-! In particular, the relatively large size of the helical rotor greatly reduces sludge grinding, precisely due to the absence of locally vigorous mixing. The mixing remains uniform and restrained even as the size of the coach increases, which would not be possible with a smaller mixer rotating in a limited volume of mold. By way of example, this can be seen by observing how the peripheral speed of a jug mixer increases as the size of the coach increases as. the diameter of the coil mixer is 70% of the diameter of the coil. When the peripheral speed 10 is between 2.2 m / s and 4.0 m / s in a 10m3 trainer and 2.5 m / s and 4.5 m / s in a 50 m3 trainer, the interval is 3.0 m / s and Correspondingly, 5.2 m / s is sufficient in a 300 m3 large coach. It should be noted that in said coach volumes, for example, peripheral velocities of 3.0 to 15 m / s, 3.5 m / s, and 4.0 m / s give the same average mixing intensity when taken into account as a whole in the coach volumes.

In coaching, it is important that the contents of the coach are uniformly mixed throughout so as to prevent bsa feed from passing through the coach in an incompletely agitated flow. This will result in inadequate training, which means that • • ·! . transit chemicals not properly targeted / mineral surfaces. According to our invention, this situation: The prevention of the occurrence is ensured by the introduction of a controlled surface feed for upcoming slurry * *, * 'and coaching chemicals. The most recommended method: is to feed this slurry and chemicals upstream to the surface of the diluent, the slurry on one side and the chemicals on the other side, with the feed points positioned symmetrically or almost symmetrically with respect to each other. The best feed points are located in the vicinity of the vertical flow drawbacks near these inner edges and preferably obliquely in the radiator direction of the trainer: ·. 35 against the direction of rotation of the helical mixer.

'* »At these points, the surface flow is particularly strong and spiraling towards the center. Using this 115699 feed system, the feeds meet in the center of the mill and are absorbed from the surface while mixing with each other in a continuous flow to the bottom. In fact, this feed method raises the performance of the valent 5 from the performance of a conventional "back-mixed" reactor, since no part of the feeds can be corrected directly or almost directly out of the train. It should also be noted that for vertical reasons, the number of vertical flow hazards is already 6-8, which allows for the addition of more chemicals, if necessary, in the vicinity of the adjacent flow hazards.

i

The correct type and fully developed surface flow is achieved when the helical rotor does not extend to 15 surfaces. It is desirable that the upper ends of the rotor extend to a surface distance of 30 to 90 cm from the tank cover, depending on the size of the trainer. It should be noted that the bottom clearance of the helical rotor is of the same order as the surface distance, but often less than 20 pi, but not less than half that surface distance. The structure of the helical rotor mixer 1 is illustrated in more detail in Figure 3.

; Figure 3 shows the SIF process trainer 1 of Figure 2. The coach 1 includes a container 6 having an interior space • «• M: 25 7 bounded to the side by a cylindrical vertical side wall 8 and downwardly by a bottom 9. arranged centrally in the interior 7: to be rotated by the power unit 11. From the side walls 8 of the container 6 towards the interior 7 there is a plurality of longitudinal vertical flow deficiencies 12, 'V, 30'.

The twin-screw rotor 10 includes a vertical shaft 13 connected to a power unit 11. In addition, the rotor 10 comprises two identical helical tubes: 14, 15, i.e. the aforementioned helix tubes, which are circular in cross-section and fixed to the vertical shaft 13 by support arms 16. opposed symmetrically to each other at -'M1 radius from the axis. The diameter of the double helical rotor 11 115699 10 is relatively large relative to the diameter of the coach, generally 0.5 to 0.8 times the diameter of the coach, and preferably 0.65 to 0.70 times the diameter of the coach.

In the example of Figure 3, the two mutually symmetrical helix tubes 14, 15 rise by half a revolution around the axis 13, with an angle of incidence of between 30 ° and 40 °, which is advantageous for fluidizing the solid. However, the trainer can be increased in proportion to its diameter, thereby increasing the height of the helical rotor in accordance with the aforementioned surface distance recommendation. It is preferable to remain within the aforementioned elevation fork and accordingly continue to rotate both helix tubes about its axis 15. Depending on the shape of the trainer, said helix tubes 14, 15 rotate shaft 13, for example 5/8, 2/3, 3/4, 7/8 or one complete revolution, whereby the height of the trainer at the same time increases almost twice its diameter as shown in FIG.

Hl 2 0 to »(relative to. The lowering of the coach can also be done in a similar manner by introducing helical rotors whose helix tubes rotate, for example, · 3/8 turns around their axis.

*, v With low risk of splashing, vigorous mixing may be used, whereby one alternative is to steepen the pitch of the rotor helix tubes, for example between 40 ° and 50 °. For example, helix tubes that make 3/8 turns around their axis bring coaching into this category. In this case,. 30 training is enhanced by the large number of vertical barrier plates, for example, 8.

; * The diameter dh 'of the rotor helix tubes 14, 15 is preferably 0.04 to 0.07 times the diameter d of the rotor itself. The same applies to the lower support arms of the helix tubes, which follow the bottom profile of the trainer at a constant distance. The other support arms, divided on the basis of strength analysis, are inclined towards the shaft, preferably at an angle of 60 ° to the shaft. Correspondingly, the upper support arms are lower relative to the axis, preferably also at an angle of 60 °, so that the arms do not rise above the upper ends of the helix tubes. Mentioning the size of 5 is that there are usually 3-5 support arms per helix tube in a semicircular spiral mixer. One useful angular view from below is, for example, 0 °, 30 °, 70 °, 110 ° and 150 °, with five supports per helix tube.

The vertical flow defects 12 have a width of 1/12 to 1/9 of the diameter of the coach, preferably of the order of 1/10 of that diameter. Vertical flow defects are installed near the inner surface of the cylindrical side wall 8 of the container 6 so that a circumferential gap s of 0.01 to 0.04 times the diameter D of the coach, preferably 0.02 times the diameter of the coach, remains between the inner surface of the barrier 12 and 15. The number of flow disadvantages 12 is 3 to 12, preferably 6 to 8.

In the embodiment of Figure 3, the helical tubes 14, 15 20 include a first helical tube 14 having an upper end 18 and a lower end 19, and a second helical tube 15 having an upper end 20 and lower end 21. The upper end 18 of the first helical tube 14 and same mass in the first horizontal plane of the Ti rotor: 25 on the opposite sides of the 13 backs. The lower end 19 of the first helical tube 14 and the lower end 21 of the second helical tube 15 are in the same second horizontal plane T2 of the rotor stop ···. on opposite sides of axle 13. The upper end 18 of the first helical tube 14 and the second helical tube 15. The lower ends 21 30 are on the same first vertical line Lj.

The lower end 19 of the first helical tube 14 and the upper end 20 of the second tongue-and-groove tube 15 are on the same second vertical line L2 which is opposite to the first vertical line L1 of the rotor axis.

35 *> · 13 115699

TEST EXAMPLE

1. SIF Process Preparation Drum Mixer The process input was a phosphate concentrate waste, the 5 coarse fractions of which were separated by cyclone classification. The solids content of the slurry was about 60%. The viscous slurry was fed to the feeder and further fed to the SIF. The process input was 29.5 t / m2h, expressed as a ratio of the active foam surface area of the SIF cell. The residence time in the training drum was 8 min.

The process results were as follows: _Mass% __ P205 content (%)

Feed_ 100.0_ 1.02_

Concentrator__13,5__5,95_ Waste__86,5__0,25 ___ 15 2. Coil Rotor Mixer for SIF Process The process input was phosphate concentrate waste which. the crude fraction was separated by cyclone classification. The solids content was 65%. The viscous slurry was fed to the feeder and further fed to the SIF. The solids input was 38.7 t / m2h. The effective residence time was approximately 4.5 min.

* * »·

The results were as follows: 25 ___ _Mass% __ P205 content (%)

Feed_100,0_ 0.56_

Concentrate__13,0__2.88_ ···: '[Waste_87,0_0,21_ · ** ,, Test Examples 1 and 2 show that in the SIF process with a rotor rotor mixer, the P205 concentration was slightly lower than that of the drum mixer. in the process (0.21% vs. 0.25%). However, the P205 content of the final waste product is the most important value in the overall process, so even a slight change in the P205 content of the waste is significant. In addition, it should be noted that in the example of a helical rotor mixer, the P205 content of the feed is only about half that of the feed to the drum mixer.

The residence time in the helical rotor trainer was 10 4.5 min vs. 8 min in the drum trainer. The result shows that the agitator rotor training mixing efficiency is better or at least as good as in the drum coaching.

The invention is not limited to the above embodiments only, but many modifications are possible within the scope of the inventive idea defined by the claims.

Claims (19)

115699 A foam separation process for enriching minerals from a coarse-grained material, comprising: 5. forming a viscous slurry of the coarse-grained material and foaming chemicals; as foam overflow, and hydrophilic particles sink through the foam into the underlying liquid phase for removal, characterized in that the slurry is subjected to a flow having an axial vertical circulation pattern. Method according to Claim 1, characterized in that an axial vertical rotary flow 20 is formed by a twin screw helix rotor with two helical coils rotating in a constant radius distance with a helical rotor mixer having a constant radial center of rotation. : 25 Method according to Claim 2, characterized in that the pitch angle of the helical tubes: the helix is selected from 15 ° to 50 °. Method according to one of Claims 1 to 3, characterized in that the curved granular material is selected to have a particle size of not more than about 3 mm. A process according to any one of claims 1 to 4, characterized in that the slurry is formed at a slurry density of 50-70%. Method according to one of Claims 1 to 5, characterized in that the slurry is thickened before coaching. 115699 Method according to one of Claims 1 to 5, characterized in that the efficiency of mixing is controlled by changing the rotational speed of the helical rotor, whereby the flow rate of the circulating flow is changed. A method according to claim 7, characterized in that the rotational speed of the helical rotor is adjusted so that the flow rate is not more than 2.0 m / s, preferably not more than 1.0 m / s. A foam separation apparatus for enriching minerals from a coarse-grained material, including an attenuator (1) for preparing a slurry of coarse-grained material and foaming chemicals; a foam separator (2) having a foam phase and a liquid phase; feeding means (3) for feeding the slurry into the foam phase; first outlet means (4) for removing foam overhead and second outlet means (5) for removing slurry as a slurry from the liquid phase, characterized in that the damper (1) is a helical rotor mixer. Apparatus according to Claim 9, characterized in that the trainer (1) comprises a v 'container (6), the interior space (7) of which is limited by: to the side a cylindrical vertical sidewall · ;; 25 m (8) and downward bottom (9), - a double helical rotor (10) centrally arranged in the interior (7), a power unit (11) for rotating the dual helical rotor (10), and a plurality of elongated vertical, flow problems (12) projecting from the side wall (8) towards the central axis. : V. Apparatus according to claim 10, characterized in that the twisted-coil rotor T 35 (10) comprises a V: - a vertical axis (13) connected to the power unit (11), 115699 - two identical helical tubes (14, 15). ), which are circular in cross section and fixed to the vertical axis (13) by means of support arms (16) facing each other symmetrically at a radial distance from the axle-5. Apparatus according to Claim 11, characterized in that the helix tubes (14, 15) have a pitch angle of 15 ° to 50 °. Apparatus according to one of claims 10 to 12, characterized in that the diameter (d) of the double helical rotor (10) is 0.5-0.8, preferably 0.65-0.7 times the container (6). inner diameter (D). Apparatus according to one of Claims 11 to 13, characterized in that the helical tubes (14, 15) rotate the vertical axis (13) by 1/2, 5/8, 2/3, 3/4, 7/8 or 1 turn. Apparatus according to one of Claims 11 to 14, characterized in that the diameter (dh) of the helical tubes (14, 15) is 0.04 to 0.07 times the diameter (d) of the rotor (10). Apparatus according to one of claims 11 to 15, characterized in that the flow (Y) has a width (L) of the barrier (12) of 1/12 to 1/9 times the inside diameter (D) of the container (6): 25 ). , ···. The process of any one of claims 11 to 16! Apparatus characterized in that between the flow drawback (12) and the wall (8) of the container (6) there is a '··' foam having a width (s) of 0.01 to 0.04 times that of the container 30 (6). ) inside diameter (D). ,:! 1 Apparatus according to one of Claims 11 to 17, characterized in that the number of flow disadvantages (12) is 3 to 12, preferably 6 to 8. Use of a helical rotor mixer as a SIF process preparer comprising forming a s-J slurry from coarse-grained material 115699 and flotation chemicals, slurry preparation with a helical rotor mixer substantially without forming a slurry, liquid phase and foam phase, adhere to the foam for removal as a foam overlay, and hydrophilic particles sink through the foam into the underlying liquid phase for removal as a foam. 1 I I I 115699