Flotation cell
阅读说明:本技术 浮选池 (Flotation cell ) 是由 P·伯克 S·施密特 A·林内 J·托米嫩 V·瓦尔纳 A·佩尔托拉 于 2019-08-01 设计创作,主要内容包括:本发明公开了一种浮选池(1),其用于处理悬浮在浆料中的颗粒以及用于将浆料分离成底流(400)和溢流(500)。浮选池包括:浮选槽(10),浮选槽具有中心(11)、周边(12)、底部(13)和侧壁(14);围绕浮选槽的周边(12)的流槽(2)和流槽缘(21)。浮选槽(10)还包括用于将浆料进料(100)引入至浮选槽中的喷射管(4),喷射管包括入口喷嘴(41)、用于加压气体的入口(42)、长形腔室(40)和出口喷嘴(43)。出口喷嘴设置在距流槽缘的竖直距离(L<Sub>5</Sub>)处,所述竖直距离(L<Sub>5</Sub>)为至少1.5m。另外,公开了浮选线及浮选线的用途。(A flotation cell (1) for treating particles suspended in a slurry and for separating the slurry into an underflow (400) and an overflow (500) is disclosed. The flotation cell includes: a flotation cell (10) having a center (11), a perimeter (12), a bottom (13), and a sidewall (14); a launder (2) and a launder rim (21) around the perimeter (12) of the flotation cell. The flotation cell (10) further comprises a jet pipe (4) for introducing a slurry feed (100) into the flotation cell, the jet pipe comprising an inlet nozzle (41), an inlet (42) for pressurized gas, an elongated chamber (40) and an outlet nozzle (43). The outlet nozzle is arranged at a vertical distance (L) from the edge of the launder 5 ) The vertical distance (L) 5 ) Is at least 1.5 m. Furthermore, a flotation wire and the use of a flotation wire are disclosed.)
1. A flotation cell (1) for treating particles suspended in a pulp and for separating the pulp into an underflow (400) and an overflow (500), the flotation cell comprising:
a flotation cell (10) comprising a center (11), a perimeter (12), a substantially horizontal flat bottom (13), and a side wall (14); and
a launder (2) and launder rim (21) around the perimeter (12) of the flotation cell (10); the flotation cell having a height (H) measured as the distance from the bottom (13) to the launder rim (21), characterized in that the flotation cell further comprises a jet pipe (4) for introducing a slurry feed (100) into the flotation cell, the jet pipe comprising:
an inlet nozzle (41) for feeding a slurry feed (100) into the injection pipe;
an inlet (42) for a pressurised gas to which the slurry feed is subjected as it is discharged from the inlet nozzle;
an elongate chamber (40) arranged to receive a slurry feed under pressure; and
an outlet nozzle (43) configured to restrict flow of slurry feed from the outlet nozzle and to maintain in the elongated chamberThe slurry feed is under pressure; and the outlet nozzle is at a vertical distance (L) from the edge of the runner5) Is arranged inside the flotation cell, said vertical distance (L)5) Is at least 1.5 m.
2. The flotation cell according to claim 1, characterized in that the outlet nozzle (43) is configured to generate a supersonic shock wave in the slurry feed (100), the supersonic shock wave inducing the formation of flotation bubble-particle agglomerates.
3. Flotation cell according to claim 1 or 2, characterized in that the vertical distance (L) of the outlet nozzle (43) from the launder edge (21)5) Is at least 1.7m and the outlet nozzle is at a distance (h) from the bottom (13) of the flotation cell (10)1) Is at least 0.4 m.
4. A flotation cell according to any one of claims 1 to 3, characterized in that the height (H) of the flotation cell (10) is at most 20% lower at the periphery (12) of the flotation cell than at the center (11) of the flotation cell.
5. The flotation cell according to any one of claims 1 to 4, characterized in that the vertical distance (L)5) Ratio (L) to the height (H) of the flotation cell5H) is 0.9 or less.
6. Flotation cell according to any of claims 1 to 5, characterized in that the outlet nozzle (43) is at a distance (h) from the bottom (13) of the flotation cell (10)1) Ratio (H) to the height (H) of the flotation cell1H) from 0.1 to 0.75.
7. A flotation cell according to any one of claims 1 to 6, characterized in that the height (H) of the flotation cell (10) and the height (H) from the bottom (13) at the outlet nozzle (43) are such that1) The ratio (H/D) of the diameters (D) of the flotation cells measured there is 0.5 to 1.5.
8. The float of any one of claims 1 to 7Cell, characterized in that the volume of the flotation cell (10) is at least 20m3Preferably 20m3To 1000m3。
9. A flotation cell according to any one of claims 1 to 8, characterized in that the flotation cell comprises 2-40 jet pipes (4), preferably 4-24 jet pipes.
10. The flotation cell according to any one of claims 1 to 9, characterized in that the jet pipe (4) is arranged concentrically to the periphery (12) of the flotation cell (10) at a distance from the centre (11) of the flotation cell.
11. Flotation cell according to claim 10, characterized in that the outlet nozzle (43) is at a distance (L) from the center (11)1) Is the distance (h) between the outlet nozzle (43) and the bottom (13) of the flotation cell1) From 10% to 40% of the diameter (D) of the flotation cell measured; preferably 25% of said diameter of the flotation cell.
12. The flotation cell according to any of the claims 1 to 9, characterized in that the injection pipe (4) is arranged parallel to the side wall (14) of the flotation cell (10) at a distance from the side wall.
13. A flotation cell according to claim 12, characterized in that the outlet nozzle (43) is at a distance (L) from the side wall (14) of the flotation cell (10)2) Is the distance (h) between the outlet nozzle (43) and the bottom (13) of the flotation cell1) From 10% to 40% of the diameter (D) of the flotation cell measured; preferably 25% of said diameter.
14. The flotation cell according to any of claims 1 to 13, characterized in that the spray pipes (4) are arranged equidistant from each other such that the distance between any two adjacent outlet nozzles (43) is the same.
15. Flotation cell according to any of claims 1 to 14, characterized in that the diameter of the outlet nozzle (43) is 10 to 30% of the diameter of the elongated chamber (40) of the injection pipe (4).
16. A flotation cell according to claim 15, characterized in that the diameter of the outlet nozzle (43) is 40mm to 100 mm.
17. The flotation cell according to any one of claims 1 to 16, wherein the injection pipe further comprises an impactor (44) configured to contact the slurry feed flow from the outlet nozzle (43) and direct the flow of slurry feed (100) radially outwards and upwards from the impactor.
18. Flotation cell according to claim 17, characterized in that the distance (L) from the bottom (440) of the impactor (44) to the outlet nozzle (43)3) From 2 to 20 times the diameter of the outlet nozzle.
19. Flotation cell according to claim 17 or 18, characterized in that the bottom (440) of the impactor (44) is at a distance (h) from the bottom (13) of the flotation cell (10)3) Is at least 0.3 m.
20. The flotation cell according to any one of claims 1 to 19, characterized in that the outlet nozzle (43) comprises a throttle valve for restricting the flow of the slurry feed (100) from the outlet nozzle.
21. A flotation cell according to any one of claims 1 to 20, characterized in that the flotation cell further comprises a conditioning circuit (3).
22. A flotation cell according to claim 21, characterized in that the conditioning circuit comprises a pump tank (30) in fluid communication with the flotation tank (10), in which pump tank the slurry portion (300) withdrawn from the flotation tank (10) via the outlet (31) and the feed of new slurry (200) are arranged to be combined into a slurry feed (100).
23. A flotation cell according to claim 22, characterized in that the outlet (31) is at a distance (L) from the bottom (13) of the flotation cell (10)4) Is arranged at the side wall (14) of the flotation cell (10).
24. Flotation cell according to claim 23, characterized in that the distance (L) of the outlet from the bottom of the flotation cell4) Is 0% to 50% of the height (H) of the flotation cell (10).
25. A flotation cell according to any of claims 21 to 24, characterized in that the conditioning circuit (3) further comprises a pump (32) arranged to suck in a pulp fraction (300) from the flotation cell (10) and to convey the pulp feed (100) onwards from the pump cell (30).
26. The flotation cell according to any of the claims 21 to 25, characterized in that the conditioning circuit (3) further comprises a distribution unit arranged to distribute the pulp feed (100) to the injection pipes (4).
27. A flotation line (8) comprising a plurality of fluidly connected flotation cells (1a), characterized in that at least one of the flotation cells is a flotation cell (1) according to any one of claims 1 to 26.
28. A flotation line according to claim 27, characterized in that the flotation cell (1) is preceded by a flotation cell (1 a).
29. A flotation line according to claim 27 or 28, characterized in that the flotation cell (1) is preceded by a mechanical flotation cell (1 b).
30. The flotation wire according to claim 28, characterized in that the flotation wire comprises:
a rougher section (81) with a flotation cell (1 a);
a scavenger section (82) with a flotation tank (1a) arranged to receive an underflow (400) from the rougher section; and
a scavenger cleaning section (820) with a flotation basin (1a) arranged to receive an overflow (500) from the scavenging section, wherein the scavenging section and/or the last flotation basin of the scavenging section is a flotation basin (1) according to any one of claims 1-23.
31. A flotation line according to claim 30, characterized in that the flotation cell (1) is preceded by a mechanical flotation cell (1 b).
32. Use of a flotation line (8) according to any one of claims 27 to 31 for recovering valuable material-containing particles suspended in a slurry.
33. Use according to claim 32 for the recovery of particles containing non-polar minerals such as graphite, sulphur, molybdenite, coal and talc.
34. Use according to claim 32 for recovering particles containing polar minerals.
35. Use according to claim 34 for recovering particles from minerals having a mohs hardness of 2 to 3, such as galena, sulphide minerals, PGM, and/or REO minerals.
36. Use according to claim 35 for recovering particles containing Pt.
37. Use according to claim 34 for recovering Cu-containing particles from minerals having a mohs hardness of 3 to 4.
38. Use according to claim 37 for recovering Cu-containing particles from low grade ore.
Technical Field
The present disclosure relates to a flotation cell for separating particles containing valuable material from particles suspended in a slurry, as well as a flotation line and its use.
Disclosure of Invention
The flotation cell according to the present disclosure is characterized by the flotation cell set forth in claim 1.
A flotation wire according to the present disclosure is characterized by the flotation wire set forth in claim 27.
The use of the flotation wire according to the present disclosure is characterized by the use set forth in
A flotation cell for treating particles suspended in a slurry and separating the slurry into an underflow and an overflow is provided. The flotation cell includes: a flotation cell including a center, a perimeter, a generally horizontal flat bottom, and a sidewall; and a launder rim around the periphery of the flotation cell. The flotation cell has a height measured as the distance from the bottom to the edge of the launder. The underflow is arranged to be removed from the flotation tank via a tailings outlet provided at the side wall of the flotation tank. The flotation cell is characterized in that the flotation cell further comprises an injection pipe for introducing the slurry feed into the flotation cell. The injection pipe comprises an inlet nozzle for feeding a slurry feed into the injection pipe; an inlet for a pressurized gas to which the slurry feed is subjected as it exits the inlet nozzle; an elongate chamber arranged to receive a slurry feed under pressure; and an outlet nozzle configured to restrict flow of the slurry feed from the outlet nozzle, maintain the slurry feed in the elongate chamber under pressure, and induce a supersonic shockwave in the slurry feed as it exits the injection tube; the outlet nozzle is arranged inside the flotation cell at a vertical distance from the launder rim, said distance being at least 1.5 m.
According to one aspect of the invention, a flotation wire is provided. The flotation line comprises a plurality of fluidly connected flotation cells and is characterized in that at least one of the flotation cells is a flotation cell according to the invention.
According to another aspect of the invention, the use of a flotation wire according to the invention is intended for the recovery of particles comprising valuable material suspended in a slurry.
With the invention described herein, the recovery of fine particles in a flotation process can be improved. The particles may for example comprise mineral ore particles, such as metal-containing particles.
In froth flotation of mineral ores, upgrading the concentrate grade involves an intermediate particle size range between 40 μm and 150 μm. Thus, the fine particles are particles having a diameter of 0 μm to 40 μm, and the ultrafine particles may be considered to fall in the lower limit of the fine particle size range. The coarse particles have a diameter of more than 150 μm. In froth flotation of coal, upgrading the concentrate grade involves an intermediate particle size range between 40 μm and 300 μm. The fine particles in the coal treatment are particles having a diameter of 0 μm to 40 μm, and those ultra-fine particles falling within the lower limit of the fine particle size range. The coarse coal particles have a diameter of more than 300 μm.
Recovery of very coarse or very fine particles is challenging because in conventional mechanical flotation cells, fine particles are not easily captured by flotation bubbles and thus may be lost in the tailings. In froth flotation, flotation gas is typically introduced into a flotation cell or cell via a mechanical agitator. The flotation bubbles so generated have a relatively large size range (typically 0.8mm to 2.0mm or even larger) and are not particularly suitable for collecting particles having finer particle sizes.
Fine particle recovery can be improved by increasing the number of flotation cells within the flotation line, or by recycling the once floated material (overflow) or tailings stream (underflow) back to the beginning of the flotation line or to a preceding flotation cell. Also for fine particles, cleaning flotation lines can be used, in order to improve the grade in particular. In addition, many flotation devices have been designed which employ fine flotation bubbles or even so-called microbubbles. The introduction of these smaller bubbles or microbubbles may be done before the slurry is fed into the flotation cell, i.e. the ore particles are subjected to small bubbles at the feed connection or the like to promote the formation of ore particle-small bubble agglomerates, which may then be floated in a flotation cell, such as a flash flotation cell or a cylindrical cell. Alternatively, small bubbles or microbubbles may be introduced directly into the flotation cell, for example by jets using cavitation. With mechanical flotation cells, these types of solutions are not necessarily feasible, since the turbulence caused by mechanical agitation may cause the ore particles-small bubble agglomerates to break down before they can rise into the froth layer to be collected into the overflow and thus recovered.
The cylindrical flotation cell acts as a three-phase settler in which particles move downward in countercurrent flow in a hindered settling environment relative to an ascending flotation bubble flow generated by an eductor located near the bottom of the flotation cell. Although cylindrical flotation cells can improve the recovery of finer particles, the particle residence time depends on the settling velocity, which can affect the flotation of large particles. In other words, while the above flotation solutions may have a beneficial effect on the recovery of fine particles, the overall flotation performance (recovery of all valuable material, grade of the recovered material) may be impaired by a negative impact on the recovery of larger particles.
To overcome the above problems, so-called pneumatic flotation cells are used, in which flotation gas is introduced into a high shear device (e.g. a downcomer) with the slurry feed, thereby creating smaller flotation bubbles that are able to capture finer particles also already during the formation of bubbles in the downcomer. However, such high throughput flotation cells may require the creation of a vacuum in the downcomer to effectively achieve the required bubble formation rate to capture the desired particles within the short time that the slurry feed stays in the downcomer.
Once having left the downcomer, the flotation bubble-particle agglomerates immediately rise towards the froth layer located on the top part of the flotation cell and no further capture of particles takes place in the part of the flotation cell down from the downcomer outlet. This may result in a considerable part of the particles containing the desired material (minerals) falling only to the bottom of the flotation cell and eventually becoming tailings, which reduces the recovery of the flotation cell.
However, the so-called high throughput flotation cells or Jameson cell type pneumatic flotation cells in general do not comprise any flow restrictions for controlling the pressure in the downcomer after the formation of flotation bubble-particle agglomerates has taken place. Such control of the pressure is also advantageous in view of the pressure at which the flotation bubbles are formed (influence on the size of the bubbles), and also in view of the regulation of the relative pressure at which the flotation bubbles are to be used in the flotation cell. In this way, the polymerization of the bubbles after their formation can be minimized. This is particularly advantageous because the rate of particle capture by flotation bubbles decreases as the bubble size increases (assuming the air to liquid ratio remains the same).
In addition, so-called high-throughput flotation cells may be used for the dissociation operation of coal, in which there is usually a flotation line comprising one or two such flotation cells at the end of the dissociation loop for recovering particularly fine coal particles. In the dissociation loop, a process water recirculation system circulates water from the end portions of the loop (i.e. from the flotation line and the dewatering loop) back to the previous loop (the start of the dissociation loop). Flotation chemicals (especially frothers) often cause problems in the processing downstream of the flotation circuit. The problem can be alleviated to some extent by minimizing the use of frother in the flotation line, but if not enough frother is added to the flotation process, the foam formation in the downcomer according to the prior art may deteriorate, which leads to unstable process conditions in the flotation cell and particularly unstable downcomer operation and foam layer, which in turn negatively affects the recovery of desired particles, especially coarse particles. As the bubble size increases with lower blowing agent doses, the recovery of particles, particularly coarse particles, within the overall particle size distribution of the slurry is affected.
In the downcomers of the prior art, the flotation gas is introduced in a self-priming manner due to the creation of a vacuum in the downcomer. The residence time of the flotation air to be carried into the slurry is very short (3 to 5 seconds), so the system is very sensitive to process variations. The foaming agent needs to be added constantly to overcome the limiting effect on the air flow needed to maintain or even increase the vacuum inside the downcomer in order to keep the conditions as constant as possible for bubble-particle coalescence, as the foaming agent prevents the bubbles from polymerizing and rising back into the air space inside the downcomer not filled by the slurry. However, adding the amount of foaming agent required to stably use the prior art downcomer creates problems in other parts of the process, particularly in coal operations, as described above. The solution is therefore to reduce the dosage of frother, which negatively affects downcomer vacuum, bubble formation, and bubble size and surface area, and significantly reduces recovery of the desired particles, making the high throughput flotation cells known in the prior art inefficient in such applications.
By using the flotation cell according to the invention, the amount of frothing agent required to optimize the flotation process can be significantly reduced without significantly impairing bubble formation, bubble to particle bonding, stable froth formation, or recovery of desired material. At the same time, the problems associated with recirculating treated water from the downstream circuit to the preceding circuit can be alleviated. The sparge pipe, operating under pressure, is completely independent of the flotation cell. Better flotation gas flow can be obtained and smaller bubbles are produced and the use of frother is optimized because the operation of the jet tube is independent of frother dosage.
In the solutions known from the prior art, the problem is particularly related to the limitation of the amount of flotation gas that can be supplied relative to the amount of liquid flowing through the downcomer, and the need for relatively high concentrations of frother or other expensive surfactants for the generation of small bubbles. With the invention presented herein, flotation containing fine and ultrafine particles such as mineral ore or coal can be improved by reducing the size of flotation bubbles in the slurry feed introduced into the sparge pipe, by increasing the flotation gas feed rate relative to the flow rate of particles suspended in the slurry, and by increasing the shear strength or energy dissipation rate within or near the sparge pipe. The likelihood of finer particles attaching to or being trapped by smaller flotation bubbles increases and improved recovery of the material (e.g. mineral or coal) is desired. In the flotation cell according to the invention, flotation bubbles (so-called ultra fine bubbles) can be generated that are sufficiently small to ensure efficient capture of fine ore particles. Typically, the ultra-fine bubbles may have a bubble size distribution of 0.05mm to 0.7 mm. For example, will averageThe reduction of the flotation bubble size to a diameter of 0.3mm to 0.4mm means 1m3May be up to 3 to 7 million and the total average surface area of the bubbles may be up to 15m2To 20m2. In contrast, if the average bubble size is about 1mm, 1m2Has a total average surface area of 6m and a number of bubbles of about 2 million2. Thus, in the flotation cell according to the invention, a bubble surface area 2.5 to 3 times higher can be achieved than in flotation cells according to prior art solutions. It goes without saying that this increase in the surface area of the gas bubbles is significant in the recovery of the particles containing valuable material.
At the same time, by obtaining a high flotation gas fraction in the slurry and by having no highly turbulent zone in the zone below the froth layer, the recovery of coarser particles can be kept at an acceptable level. That is, even though there may not necessarily be any mechanical agitation in the flotation cell, the known advantages of mechanical flotation cells can be exploited. Furthermore, the upward movement of the slurry or pulp within the flotation cell also increases the likelihood that coarser particles rise towards the froth layer as the slurry flows.
One of the effects that can be obtained by the present invention is to increase the depth or thickness of the foam layer. A thicker foam layer contributes to a higher grade and also to an improved recovery of smaller particles and may eliminate the separate foam washing step normally used in cylindrical flotation cells.
By arranging a plurality of injection pipes in the flotation cell according to the invention, the probability of collisions between flotation bubbles and between bubbles and particles can be increased. Having a plurality of injection pipes ensures an improved distribution of the flotation bubbles within the flotation cell and that the bubbles leaving the injection pipes are evenly distributed throughout the flotation cell, the distribution areas of the individual injection pipes having the possibility of intersecting and converging with each other, thereby promoting a widely even distribution of the flotation bubbles within the flotation cell, which in turn may beneficially affect the recovery of particularly smaller particles and also contribute to the above mentioned even and thick froth layer. When there are multiple injection pipes, collisions between flotation bubbles and/or particles in the slurry feed from different injection pipes are promoted, because different flows mix and create local mixing sub-areas. As the collisions increase, more bubble-particle aggregates are generated and captured into the foam layer, thus improving the recovery of valuable materials.
By generating fine flotation bubbles or ultra-fine bubbles, by contacting the bubbles with particles, and by controlling the flotation bubble-particle aggregate-liquid mixture of the slurry, the recovery of hydrophobic particles into the froth layer and into the flotation cell overflow or concentrate can be maximized, thereby increasing the recovery of the desired material regardless of the particle size distribution of the desired material within the slurry. High grade can be obtained for a part of the pulp flow, while high recovery can be obtained for the whole pulp flow through the flotation line.
By arranging the outlet nozzle of the jet pipe at a suitable depth, i.e. at a certain vertical distance from the edge of the launder, the distribution of flotation bubbles can be optimized in a uniform and constant manner. Since the residence time of the gas bubbles in the mixing zone can be kept sufficiently high by the appropriate depth of the jet pipe outlet nozzle, the gas bubbles can effectively contact and attach to the fine particles in the slurry, thereby improving recovery of smaller particles and also promoting froth depth, stability and uniformity at the top of the flotation cell.
By mixing zone is meant herein the vertical part or section of the flotation cell where effective mixing of particles suspended in the slurry with the flotation bubbles takes place. In addition to such mixing zones formed throughout the vertical section of the flotation cell, separate and locally independent mixing sub-zones may also be formed at the areas where the flows of slurry directed radially outwardly by the individual impactors meet and become mixed. This may further promote contact between flotation bubbles and particles, thereby increasing recovery of valuable particles. Moreover, this additional mixing may eliminate the need for a mechanical mixer for suspending the solids in the slurry.
By sedimentation zone is meant a vertical section or section of the flotation tank in which particles that are not associated with the flotation bubbles or that otherwise cannot rise towards the froth zone on the top portion of the flotation tank fall and settle towards the bottom of the flotation tank to be removed as underflow in the tailings. The settling zone is below the mixing zone.
By arranging the tailings outlet at the side wall of the flotation tank, the underflow can be removed at a region where the majority of the slurry comprises particles that descend or settle towards the bottom of the flotation tank. In the flotation cell according to the invention, the sedimentation zone is deeper near the side wall of the flotation cell. At such regions, the mixing action and turbulence created by the ejector tube do not affect the settled particles, while most of the settled particles do not contain any valuable material, or only contain very small amounts of valuable material. At this section, the settling effect is also most pronounced since there is no turbulence interfering with the descent of the particles under gravity. In addition, the friction created by the flotation cell side walls further reduces turbulence and/or flow. Thus, taking the underflow from the flotation tank at a location arranged on such a relatively calm settling zone, it can be ensured that as few particles containing valuable material as possible are removed from the flotation tank-instead these particles should be floated or, if for some reason end up in the settling zone, should be recirculated back into the flotation tank as slurry feed through the injection pipe. Furthermore, by removing the underflow from the settling zone near the side wall of the flotation cell, the entire volume of the flotation cell can be effectively utilized-without the need to construct a separate lower settling zone below the sparge pipe, as is the case in Jameson cells, for example. In certain embodiments, it is even foreseeable that the volume of the flotation cell may be reduced at the center of the flotation cell, thereby reducing the volume of the settling zone where turbulence caused by the slurry feed from the jet pipe may affect the likelihood of particles settling toward the bottom of the flotation cell, and allowing the volume of the flotation cell to be fully utilized. The volume of the flotation cell can be reduced at the centre of the flotation cell, for example by arranging a bottom structure at the bottom of the flotation cell at the centre of the flotation cell. In addition, it is possible to arrange the jet pipe (outlet nozzle) relatively deep in the flotation cell, but still ensure a sufficiently calm settling zone at the side wall of the flotation cell. This further promotes efficient use of the entire volume of the flotation cell.
The flotation cell, and the flotation line and its use according to the invention have the technical effect that: allows for flexible recovery of various particle sizes and efficient recovery of ore particles containing value minerals from lean ore feed materials initially having relatively low amounts of value minerals. The advantage provided by the structure of the flotation wire allows to precisely adjust the structural parameters of the flotation wire according to the targeted valuable material at each device.
By treating the slurry according to the invention as defined in the present disclosure, the recovery of particles containing valuable material can be increased. The initial grade of the recovered material may be lower, but the material (i.e. slurry) is therefore also ready for further processing (which may include, for example, regrinding and/or cleaning).
In the present disclosure, the following definitions are used with respect to flotation.
Basically, flotation aims at recovering a concentrate of ore particles containing valuable minerals. By concentrate is meant herein the fraction of the slurry recovered in the overflow or underflow that is drawn from the flotation cell. By valuable minerals, it is meant any mineral, metal or other material of commercial value.
Flotation involves phenomena related to the relative buoyancy of the objects. The term flotation includes all flotation techniques. Flotation may be, for example, froth flotation, Dissolved Air Flotation (DAF) or induced gas flotation. Froth flotation is a process for separating hydrophobic materials from hydrophilic materials by adding a gas (e.g. air or nitrogen or any other suitable medium) to the process. Froth flotation can be performed based on natural hydrophilic/hydrophobic differences or on hydrophilic/hydrophobic differences obtained by adding surfactants or collector chemicals. The gas can be added to the flotated raw material object (slurry or pulp) in a number of different ways.
Flotation cells are used to treat mineral ore particles suspended in a slurry by flotation. Thus, ore particles containing valuable metals are recovered from ore particles suspended in the slurry. By flotation line is herein meant a flotation device in which a plurality of flotation cells are arranged in fluid connection with each other such that the underflow of each preceding flotation cell is introduced as feed to the following or subsequent flotation cell up to the last flotation cell of the flotation line, from where it is led away from the flotation line as tailings or reject stream. The slurry is fed through a feed inlet to a first flotation cell of the flotation line to start the flotation process. The flotation lines may be part of a larger flotation plant or apparatus comprising one or more flotation lines. Thus, as known to those skilled in the art, many different pre-and post-treatment devices or stages may be operatively connected with the components of the flotation device.
The flotation cells in the flotation line are fluidly connected to each other. The fluid connection may be achieved by conduits of different lengths (e.g. pipes or tubes) which may also include a pump or regrinding unit, the length of the conduit depending on the overall physical configuration of the flotation device. Alternatively, the flotation cells may be arranged in direct cell connection with each other. By direct tank connection is herein meant an arrangement where the outer walls of any two consecutive flotation tanks are connected to each other to allow the outlet of a first flotation tank to be connected to the inlet of a subsequent flotation tank without the aid of any separate conduit. Direct contact reduces the need for piping between two adjacent flotation cells. It therefore reduces the need for components during construction of the flotation line, speeding up the process. Furthermore, it may reduce sanding and simplify maintenance of the flotation line. The fluid connection between the flotation cells may comprise various adjustment mechanisms.
By "adjacent", "adjacent" or "adjoining" flotation cells is meant herein the relation between the flotation cells in the rougher flotation line or in the scavenger flotation line immediately after or before (downstream or upstream) any flotation cell, or the flotation cell of the rougher flotation line and the flotation cell of the scavenger flotation line to which the underflow from the flotation cell of the rougher flotation line is directed.
By flotation cell is herein meant a tank or container in which the steps of the flotation process are performed. The flotation cell is generally cylindrical in shape, the shape being defined by one or more outer walls. The flotation cell usually has a circular cross-section. The flotation cell may also have a polygonal (e.g. rectangular, square, triangular, hexagonal or pentagonal) or other radially symmetrical cross-section. As known to those skilled in the art, the number of flotation cells may vary depending on the particular flotation line and/or operation used to process a particular type and/or grade of ore.
The flotation cell may be a froth flotation cell, for example a mechanically agitated cell such as a TankCell, a cylindrical flotation cell, a Jameson cell, or a double flotation cell. In a double flotation cell, the flotation cell comprises at least two separate vessels, a first mechanically agitated pressure vessel with a mixer and flotation gas input, and a second vessel with tailings output and overflow froth discharge, the second vessel being arranged to receive the agitated slurry from the first vessel. The flotation tank may also be a fluidized bed flotation tank (e.g. HydroFloat)TMA cell) in which air bubbles or other flotation bubbles dispersed by the fluidization system permeate through the hindered settling area and attach to the hydrophobic component, changing the density of the hydrophobic component and making it buoyant enough to be floated and recovered. In a fluidized bed flotation cell, no axial mixing is required. The flotation cell may also be an overflow flotation cell operating with a constant slurry overflow. In the overflow flotation cell, the slurry is treated by introducing flotation bubbles into the slurry and by generating a continuous upward flow of slurry in the vertical direction of the first flotation cell. At least a portion of the ore particles containing the valuable metal attach to the gas bubbles and rise by buoyancy, at least a portion of the ore particles containing the valuable metal attach to the gas bubbles and rise with the continuous upward slurry stream, and at least a portion of the ore particles containing the valuable metal rise with the continuous upward slurry stream. Ore particles containing valuable metals are recovered by leading a continuous upward flow of slurry as a slurry overflow from at least one overflow flotation cell. Since the overflow launder operates with almost no froth depth or froth layer, practically no froth zone is formed on the surface of the slurry at the top part of the flotation cell. The foam may be discontinuous over the entire flotation cell. This is oneAs a result, more ore particles containing valuable minerals can be carried into the concentrate stream and the overall recovery of valuable material can be improved.
All flotation cells of the flotation line according to the invention may be of a single type, i.e. the rougher flotation cells in the rougher section, the scavenger flotation cells in the scavenger section and the scavenger cleaning flotation cells of the scavenger cleaning flotation line may be of a single flotation cell type, so that the flotation device comprises only one type of flotation cell as listed above. Alternatively, a plurality of flotation cells may be of one type, while the other flotation cells are of one or more types, so that the flotation line comprises two or more types of flotation cells as listed above.
Depending on the type of flotation cell, the flotation cell may include a mixer for agitating the slurry to keep it suspended. By mixer is meant herein any suitable device for agitating the slurry in the flotation cell. The mixer may be a mechanical agitator. The mechanical agitator may comprise a rotor-stator having a motor and a drive shaft, the rotor-stator structure being arranged at a bottom portion of the flotation cell. The flotation cell may have auxiliary agitators arranged higher in the vertical direction of the flotation cell to ensure a sufficiently strong and continuous upward flow of pulp.
The flotation cell may include one or more foam packing elements (crowder). By froth plug is herein meant a froth plug, a froth baffle, or a plug plate arrangement, or any other such structure or side structure (e.g. an inclined or vertical side wall with a plug effect, i.e. a plug side wall), which may also be a plug side wall inside the flotation cell, i.e. an inner peripheral plug.
By using a froth plug, it is possible to more effectively and reliably direct a so-called "breakable froth", i.e. a loosely textured froth layer comprising generally larger flotation bubbles gathered with the mineral ore particles for recovery, towards the froth overflow edge and the froth collecting launder. Breakable foams can easily break down because the bubble-ore particle aggregates are less stable and have reduced toughness. Such froth or froth layer cannot easily sustain the transport of ore particles, especially coarser particles, towards the froth overflow edge to be captured into the launder, thus resulting in particles falling back into the pulp or slurry within the flotation cell or cell and reducing the recovery of the desired material. Breakable froth is generally associated with low mineralization, i.e. a limited amount of bubble-ore particle aggregates in which ore particles of the desired mineral are contained, which have been able to attach to bubbles in the flotation process in a flotation cell or cell. This problem is particularly pronounced in large flotation cells or cells having large volumes and/or large diameters. With the present invention, it is possible to plug and guide the foam towards the foam overflow edge to reduce the foam transport distance (and thus the risk of falling back) while maintaining or even reducing the overflow edge length. In other words, the treatment and guidance of the froth layer in the froth flotation cell or flotation cell can become more efficient and direct.
Froth recovery may also be improved, thus improving the recovery of valuable mineral particles from breakable froth in large flotation cells or cells, particularly in later stages of the flotation line, e.g. in the rougher and/or scavenger stages of the flotation process.
Furthermore, with the invention described herein, the area of froth on the surface of the slurry inside the flotation cell can be reduced in a robust and simple mechanical way. At the same time, the total overflow edge length in the froth flotation unit can be reduced. In this case, the robustness is considered to mean structural simplicity and durability. By reducing the froth surface area of the flotation cell by froth plugs rather than adding additional froth collecting launders, the froth flotation cell as a whole can be of simpler construction, for example because there is no need to direct the collected froth and/or overflow off of the added plugs. In contrast, the overflow of the collector would have to be drawn from the additional launder, which would increase the constructional components of the flotation unit.
Especially in the downstream end of the flotation line, the amount of desired material that can be trapped in the froth within the slurry can be very low. To collect this material from the froth layer into the froth collector launder, the froth surface area should be reduced. By arranging the froth plug in the flotation cell, the open froth surface between the froth overflow edges can be controlled. A packing element may be utilised to direct or guide the upwardly flowing slurry within the flotation cell closer to the froth overflow edge of the froth collection launder, thereby enabling or facilitating froth formation very close to the froth overflow edge, which may increase the collection of valuable ore particles. The froth plugs may also affect the overall coalescence of flotation bubbles and/or bubble-ore particle agglomerates in the froth layer. For example, if a stream of bubbles and/or bubble-ore particle agglomerates is directed to the center of the flotation cell, froth plugs may be utilized to increase the froth zone at the periphery of the flotation cell and/or closer to any desired froth overflow edge. In addition, the open froth surface can be reduced with respect to the overflow edge length, thereby improving the recovery efficiency in the froth flotation cell.
The flotation cell may comprise a bottom structure arranged on the bottom of the flotation tank and having a shape that allows particles suspended in the slurry to mix in a mixing zone above the bottom structure and settle in a settling zone surrounding the bottom structure, the mixing zone being created by the slurry feed stream from the outlet nozzle of the injection pipe.
By arranging a bottom structure at the bottom of the flotation cell, which bottom structure extends upwards in the flotation cell, a better distribution of fine and/or small particles suspended in the slurry can be obtained. At the centre of the flotation cell, the particles cannot descend and settle, because the slurry feed stream from the spray pipe will reach the raised central part of the flotation cell, which ensures good mixing at said raised central part. Particles that may have detached from the flotation bubbles and started to descend may be recaptured by the bubbles due to turbulent conditions in the mixing zone. On the other hand, the bottom of the flotation tank, which is closer to the periphery of the flotation tank, has a sufficiently deep area that allows the non-floating, most likely worthless particles to settle and fall down to be efficiently removed from the flotation tank. This settling zone is unaffected by the slurry feed stream from the spray pipe. Moreover, such relatively calm zones can inhibit the formation of short flows of slurry streams within the flotation cell (where the same slurry material remains recirculated within the flotation cell without undue separation or settling). The above features may facilitate improved recovery of fine particles.
By arranging the bottom structure to have a certain size, in particular with respect to the mixing zone, the mixing zone and the settling zone can be designed to have the desired characteristics (size, depth, turbulence, residence time of the particles in the mixing zone, settling velocity and probability of the non-valuable part in the settling zone, etc.). In a conventional flotation cell, a large portion of this area (without any mechanical mixing at the bottom of the flotation cell) will be subjected to sanding, as there is little or no mixing. If the zone is filled with solids, there is a risk that such solid matter collapses and simultaneously plugs the tailings outlet and/or the recycle outlet located at the settling zone.
By jet tube is meant a dual high shear device in which flotation gas is introduced into the slurry feed, thereby producing finer flotation bubbles that are capable of capturing also finer particles already during bubble formation in the jet tube. In particular, the injection pipes in the flotation cell according to the invention operate under pressure and do not require vacuum.
By overflow is herein meant the part of the pulp that is caught in the launders of the flotation cell and thus leaves the flotation cell. The overflow may include foam, foam and slurry, or in some cases only slurry or the largest portion is slurry. In some embodiments, the overflow can be an accepted flow containing particles of the valuable material collected from the slurry. In other embodiments, the overflow may be a reject stream. This is the case when the flotation device, apparatus and/or method is used for reverse flotation.
By underflow is meant herein the portion or fraction of the slurry that does not float into the surface of the slurry in the flotation process. In some embodiments, the underflow may be a reject stream leaving the flotation tank via an outlet typically arranged in the lower portion of the flotation tank. Finally, the underflow from the flotation line or the last flotation cell of the flotation plant can leave the whole plant as tailings stream or final residue of the flotation plant. In some embodiments, the underflow may be an accept stream containing valuable mineral particles. This is the case when the flotation device, apparatus and/or method is used for reverse flotation.
By reverse flotation is meant herein a reverse flotation process that is normally utilized in the recovery of iron. In this case, the flotation process is used to collect the non-valuable portion of the slurry stream into the overflow. The overflow used in the reverse flotation process of iron usually contains silicates, while the mineral particles containing valuable iron are collected in the underflow. Reverse flotation can also be used for industrial minerals, i.e. geological minerals (which are not fuel nor metal sources) mined for their commercial value, such as bentonite, silica, gypsum and talc.
By downstream is herein meant the direction in line with the flow of slurry towards the tailings (forward flow, indicated by arrows in the figure), while by upstream is herein meant the direction opposite or opposite to the flow of slurry towards the tailings.
By concentrate is meant herein the floated fraction or portion of the slurry containing ore particles of the valuable mineral. In normal flotation, the concentrate is the portion of the slurry that floats into the froth layer and is therefore collected as overflow into the launder. The first concentration concentrate may comprise ore particles containing one mineral value and the second concentration concentrate may comprise ore particles containing another mineral value. Alternatively, the differential definition "first", "second" may refer to two concentrates of ore particles comprising the same value mineral but having two distinct particle size distributions.
By rougher flotation, the rougher section of the flotation line, the rougher stage and/or the rougher cell is meant herein the first flotation stage that produces a concentrate. The aim is to remove the maximum amount of valuable minerals with the particle size as coarse as possible. The main objective of the roughing stage is to recover as much valuable minerals as possible without much regard to the quality of the concentrate produced.
The rougher concentrate is typically subjected to further cleaning flotation stages in a rougher cleaning flotation line to discard more undesired minerals that have been entrained to froth in a process known as cleaning. The cleaned product is called cleaned concentrate or final concentrate. There may be a regrinding step prior to the cleaning process.
Rougher flotation is typically followed by scavenger flotation applied to the rougher tailings. By scavenger flotation, scavenging section of the flotation line, scavenger stage and/or scavenger tank is meant a flotation stage in which the purpose is to recover any valuable mineral material that has not been recovered during the initial rougher stage. This can be achieved by: flotation conditions are changed to be more stringent than the initial rougher flotation, or microbubbles are introduced into the slurry in some embodiments of the invention. Concentrate from the scavenger cell or stage may be returned to the rougher feed for refloating or directed to a regrinding step and thereafter directed to a scavenger cleaning flotation line.
By cleaning flotation, rougher/scavenger cleaning line, cleaner/cleaning stage and/or cleaning basin is meant a flotation stage in which the purpose of cleaning is to produce as high a concentrate grade as possible.
By pre-and/or post-treatment and/or further processing is meant, for example, comminution, grinding, separation, screening, classification, fractionation, conditioning or cleaning, all of which are conventional processes known to those skilled in the art. The further processing step may further comprise at least one of: can be another flotation tank, a recovery tank, a roughing tank or a scavenging tank of the conventional cleaning flotation tank.
By pulp surface level is meant herein the height of the pulp surface in the flotation cell measured from the bottom of the flotation cell to the launder edge of the flotation cell. In practice the height of the pulp is equal to the height of the trough edge of the flotation tank measured from the bottom of the flotation tank to the trough edge of the flotation tank. For example, any two consecutive flotation cells may be arranged in a stepwise manner in the flotation line such that the pulp surface level of such flotation cells is different (i.e. the pulp surface level of a first one of such flotation cells is higher than the pulp surface level of a second one of such flotation cells). This difference in the level of the pulp surface is defined herein as the "step" between any two consecutive flotation cells. The step or difference in the level of the pulp surface is a height difference that allows the pulp flow to be driven by gravity or gravity by creating a hydraulic head between two successive flotation cells.
By flotation line is herein meant an assembly or device comprising a plurality of flotation cells or flotation cells in which flotation stages are performed to form a flotation line, and which are arranged in fluid connection with each other to allow gravity driven or pumped slurry to flow between the flotation cells. In the flotation line a number of flotation cells are arranged in fluid connection with each other so that the underflow of each preceding flotation cell is led as feed to the following or subsequent flotation cell up to the last flotation cell of the flotation line, from where it is led away from the flotation line as tailings or reject flow. It is also conceivable that the flotation line may comprise only one flotation stage performed in one flotation cell or, for example, in two or more parallel flotation cells.
The slurry is fed through a feed inlet to a first flotation cell of the flotation line to start the flotation process. The flotation lines may be part of a larger processing plant comprising one or more flotation lines, and a number of other processing stages for the dissociation, cleaning and other processing of the desired material. Thus, as known to the person skilled in the art, many different pre-and post-treatment devices or apparatuses may be operatively connected with the components of the flotation line.
By ultra fine bubbles is herein meant flotation bubbles falling within the size range of 0.05mm to 0.7mm, which bubbles are introduced into the slurry in the jet pipe. In contrast, "normal" flotation bubbles utilized in froth flotation exhibit a size range of about 0.8mm to 2 mm. Larger flotation bubbles may have a tendency to coalesce into even larger bubbles during their residence in the mixing zone where collisions between particles and flotation bubbles and collisions between only flotation bubbles occur. Since the ultra-fine bubbles are introduced into the slurry feed before it is fed into the flotation cell, such polymerization of the ultra-fine bubbles is less likely to occur, and the size of the ultra-fine bubbles can be kept small throughout their residence in the flotation cell so as not to affect the ability of the ultra-fine bubbles to capture fine particles.
In one embodiment of the flotation cell according to the invention, the outlet nozzle is configured to generate a supersonic shock wave in the slurry feed, the supersonic shock wave causing the formation of flotation bubble-particle agglomerates.
Supersonic shock waves are generated when the velocity of the slurry feed through the outlet nozzle exceeds sonic velocity, i.e. the flow of the slurry feed becomes choked when the pressure ratio of the absolute pressure upstream of the outlet nozzle to the absolute pressure downstream of the throttle of the outlet nozzle exceeds a critical value. When the pressure ratio is above the threshold value, the flow of the slurry feed downstream of the throttle portion of the outlet nozzle becomes supersonic and forms a shockwave. The small flotation bubbles in the slurry feed mixture are broken up into even smaller bubbles by being forced through the shock wave and are forced into contact with the hydrophobic ore particles in the slurry feed, thereby creating flotation bubble-ore particle agglomerates. The supersonic shock wave band generated in the slurry feed at the outlet nozzle discharge is directed into the slurry within the flotation tank immediately adjacent the outlet nozzle, thereby also promoting the formation of flotation bubbles in the slurry outside the outlet nozzle. After leaving the outlet nozzle, the fine ore particles may secondarily contact the fine flotation bubbles because there are several such jet pipes/outlet nozzles discharging into a common mixing zone where the probability of secondary contact between bubbles and particles is increased by the mixed flow of slurry leaving the jet pipes.
In one embodiment of the flotation cell, the outlet nozzle is at a distance of at least 1.7m from the edge of the launder and the outlet nozzle is at a distance of at least 0.4m from the bottom of the flotation cell.
In one embodiment of the flotation cell according to the invention the height of the flotation cell is at most 20% lower at the periphery of the flotation cell than at the centre of the flotation cell.
In an embodiment of the flotation cell according to the invention the ratio of the distance of the outlet nozzle from the edge of the launder to the height of the flotation cell is 0.9 or less.
In one embodiment of the flotation cell according to the invention the ratio of the distance of the outlet nozzle from the bottom of the flotation cell to the height of the flotation cell is 0.1 to 0.75.
In one embodiment of the flotation cell, the ratio of the height of the flotation cell to the diameter of the flotation cell measured at a certain height of the outlet nozzle from the bottom of the flotation cell is 0.5 to 1.5, i.e. the ratio of the cell height to the cell diameter is 0.5 to 1.5.
In one embodiment of the flotation cell, the volume of the flotation cell is at least 20m3Preferably 20m3To 1000m3。
By arranging the flotation cell with a sufficient volume, the flotation process can be better controlled. The rise distance to the froth layer on the top portion of the flotation cell does not become too great, which can help ensure that flotation bubble-ore particle agglomerates remain together up to the froth layer and can ensure that particle fall back is reduced. Moreover, a suitable bubble rise rate can be obtained to maintain good concentrate quality. The use of a flotation cell with a sufficient volume size increases the probability of collisions between gas bubbles, for example generated in the flotation cell by the rotor, and particles containing valuable minerals, thereby increasing the recovery of valuable minerals and the overall efficiency of the flotation device. Larger flotation cells have higher selectivity because more collisions between gas bubbles and ore particles can occur due to the longer time the slurry stays in the flotation cell. Thus, a large part of the ore particles including the valuable minerals can be floated. In addition, the fall back of buoyant ore particles may be high, which means that ore particles containing a very small amount of valuable minerals fall back into the bottom of the flotation tank. Thus, the overflow from the larger flotation cell and/or the grade of the concentrate can be higher. These kinds of flotation tanks ensure high grade and high recovery. Furthermore, the overall efficiency of the flotation cell and/or the entire flotation line can be improved. In addition, if the first flotation cell in the flotation line has a relatively large volume, a large subsequent flotation cell may not be needed, but instead the flotation cell downstream of one or more first flotation cells may be smaller and thus more efficient. In the flotation process of certain minerals, it may be easy to float a substantial part of the high grade ore particles containing valuable minerals. In this case it is possible to provide a flotation cell with a smaller volume downstream of the flotation line, but still obtain a high recovery.
In an embodiment of the flotation cell according to the invention, the flotation cell comprises 2 to 40 jet pipes, preferably 4 to 24 jet pipes.
The number of injection pipes directly affects the amount of flotation gas that can be dispersed in the slurry. In conventional froth flotation, dispersing an increased amount of flotation gas will result in an increase in flotation bubble size. For example, in Jameson cells, an air-to-bubble ratio of 0.50 to 0.60 is used. Increasing the average bubble size will adversely affect the bubble surface area flux (S)b) This means that recovery may be reduced. In the flotation cell according to the invention, with the pressurized jet pipe, it is possible to introduce significantly more flotation gas into the process without increasing the bubble size or reducing SbBecause the flotation bubbles generated in the slurry feed remain relatively small compared to conventional treatment. On the other hand, by keeping the number of jet pipes as small as possible, the costs of retrofitting an existing flotation cell or the capital expenditure for setting up such a flotation cell can be kept under control without causing any loss of flotation performance of the flotation cell.
In one embodiment of the flotation cell, the injection pipe is arranged concentrically to the periphery of the flotation cell at a distance from the centre of the flotation cell.
In another embodiment of the flotation cell, the outlet nozzle of the injection pipe is at a distance from the centre of the flotation cell of 10% to 40% of the diameter of the flotation cell measured at a distance of the outlet nozzle from the bottom of the flotation cell; preferably 25% of said diameter of the flotation cell.
In one embodiment of the flotation cell, the injection pipe is arranged parallel to the side wall of the flotation cell at a distance from the side wall.
In another embodiment of the flotation cell, the outlet nozzle of the injection pipe is at a distance from the side wall of the flotation cell of 10% to 40% of the diameter of the flotation cell measured at a distance of the outlet nozzle from the bottom of the flotation cell; preferably 25% of said diameter of the flotation cell.
In one embodiment of the flotation cell, the spray pipes are arranged equidistant from each other such that the distance between any two adjacent outlet nozzles is the same.
The exact number of sparge tubes within a flotation cell may depend on the size or volume of the cell, the type of material to be collected, and other processing parameters. By arranging a sufficient number of injection pipes in the flotation cell and by arranging the injection pipes in a specific manner with respect to the centre, periphery and/or side walls of the flotation cell, an even distribution of small bubbles can be ensured, while at the same time a high probability of collisions between bubbles and ore particles is ensured. A homogeneous mixing effect caused by shear forces in the flotation cell can be ensured.
In one embodiment of the flotation cell, the diameter of the outlet nozzle is 10% to 30% of the diameter of the elongated chamber of the injection pipe.
In another embodiment of the flotation cell the diameter of the outlet nozzle is 40mm to 100 mm.
By arranging the outlet nozzle to have a certain diameter, the velocity of the slurry feed can be maintained at a level that favours the generation of small size flotation bubbles and the possibility of these bubbles coming into contact with the ore particles in the slurry. In particular, in order to maintain the shock wave after the outlet nozzle, it is necessary to maintain a slurry velocity of 10m/s or more. By designing the outlet nozzle in relation to the dimensions of the injection pipe, the influence of the pulp feed flow in different types of flotation cells can be solved.
In an embodiment of the flotation cell according to the invention, the injection pipe further comprises an impactor configured to contact the slurry feed stream from the outlet nozzle and to direct the slurry feed stream radially outwards and upwards from the impactor.
In a further embodiment of the flotation cell, the distance from the bottom of the impactor to the outlet nozzle is 2 to 20 times the diameter of the outlet nozzle.
In another embodiment of the flotation cell, the bottom of the impactor is at least 0.3m from the bottom of the flotation cell.
The impactor deflects the slurry feed stream radially outward to the flotation cell side walls and upward toward the flotation cell upper surface (i.e., froth layer) so that small flotation bubble-ore particle agglomerates do not short stream (short circuit) into the tailings. All slurry feed from the jet pipe is forced to rise towards the froth layer located at the top region of the flotation cell before gravity has the opportunity to influence the particles that are not attached to the flotation bubbles, forcing them down and eventually entrained to the tailings stream or underflow. Thus, the possibility of short streams of particles containing valuable material may be reduced. The slurry is highly agitated by the energy of the deflected flow and forms a mixing vortex in which the size of the bubbles can be further reduced due to shear forces acting on the bubbles. The high shear conditions advantageously also cause substantial contact between flotation bubbles and particles in the slurry in the flotation cell. As the slurry flow is forced upward toward the froth layer, turbulence is reduced and the flow becomes relatively uniform, which can contribute to the stability of the bubbles that have formed, as well as the stability of the flotation bubble-particle aggregates, particularly those including coarser particles.
By arranging the outlet nozzle and the impactor at an optimal distance from each other, the impactor may be configured to deflect and direct the slurry feed stream radially outward and upward from the impactor to create the previously mentioned mixing zone within the flotation cell and promote the rise of particles toward the froth layer. At the same time, it may be desirable to minimize the wear caused by the high velocity slurry flow on the impactor. By positioning the outlet nozzle and the impactor in a certain relationship with respect to each other, it is possible to optimize the flotation process in a flotation cell equipped with a jet pipe and to minimize wear on the components of the impactor.
In an embodiment of the flotation cell according to the invention, the outlet nozzle comprises a throttle valve for restricting the flow of the slurry feed from the outlet nozzle.
Supersonic shock waves are generated when the velocity of the slurry feed through the outlet nozzle exceeds sonic velocity, i.e. the flow of the slurry feed becomes choked when the pressure ratio of the absolute pressure upstream of the outlet nozzle to the absolute pressure downstream of the throttle of the outlet nozzle exceeds a critical value. When the pressure ratio is above the threshold value, the flow of the slurry feed downstream of the throttle portion of the outlet nozzle becomes supersonic and forms a shockwave. The small flotation bubbles in the slurry feed mixture are broken up into even smaller bubbles by being forced through the shock wave and are forced into contact with the hydrophobic ore particles in the slurry feed, thereby creating flotation bubble-ore particle agglomerates. After leaving the outlet nozzle, the fine ore particles may secondarily contact the fine flotation bubbles because there are several such jet pipes/outlet nozzles discharging into a common mixing zone where the probability of secondary contact between bubbles and particles is increased by the mixed flow of slurry leaving the jet pipes.
In an embodiment of the flotation cell, the flotation cell further comprises a conditioning circuit.
In another embodiment of the flotation cell, the conditioning circuit comprises a pump tank in fluid communication with the flotation tank, in which pump tank the slurry portion withdrawn from the flotation tank via the outlet is arranged to be combined with a feed of new slurry into a slurry feed.
In another embodiment of the flotation cell, the outlet is arranged at the side wall of the flotation cell at a distance from the bottom of the flotation cell.
In another embodiment of the flotation cell, the outlet is at a distance of 0% to 50% of the height of the flotation cell from the bottom of the flotation cell.
In another embodiment of the flotation cell, the conditioning circuit further comprises a pump arranged to suck in a pulp fraction from the flotation cell and to convey the pulp feed forward from the pump cell.
In another embodiment of the flotation cell, the conditioning circuit further comprises a distribution unit arranged to distribute the slurry feed into the injection pipe.
By taking the slurry from the bottom of the flotation cell it can be ensured that finer particles settling to the bottom of the flotation cell can be efficiently reintroduced into the part of the flotation cell where efficient flotation treatment takes place before said finer particles are entrained into the tailings. Thus, the recovery rate of valuable materials can be improved since particles containing even a minimum amount of valuable materials can be collected into the concentrate.
By recirculating the pulp fraction taken from the lower part of the flotation tank via an outlet arranged at the side wall of the flotation tank into the injection pipe, a recirculation fraction is thus obtained at the zone where the majority of the pulp comprises particles descending or settling towards the bottom of the tank. However, due to the probabilistic nature of the flotation process, the particles may still contain valuable material. Especially at the settling zone closest to the side wall of the flotation cell, the slurry may comprise particles containing valuable material that are not captured by the flotation bubbles and/or by the upwardly directed slurry flow near the impactor at the mixing zone. At this location, the slurry is also affected by the slurry feed flow from the single injector tube creating turbulence. Thus, there is a higher probability that particles containing valuable material are not captured by the flotation bubbles and/or the upwardly directed slurry flow. In order to recover valuable material from these particles as well, it may be advantageous to treat this slurry fraction again, for example in the same flotation cell as part of the slurry feed. Thus, the overall recovery can be further improved.
The flotation process can be made more efficient when only a part of the slurry in the flotation cell is recirculated back to the same flotation cell as slurry feed via the injection pipe. In particular, since the impactor (which is designed to direct the flow of slurry radially outwards and upwards to create turbulent conditions for the mixing zone and additional mixing sub-zones, as explained earlier) very efficiently creates favorable conditions for the formation of flotation bubble-particle agglomerates and thus ensures efficient recovery of particles containing valuable material, it may not be necessary to recirculate a large amount of slurry to be reprocessed in the same flotation cell. Treating tailings from one flotation cell in another flotation cell may be sufficient to ensure high recovery. Due to the possibility of short flows of particles containing valuable material into the tailings/underflow, it may not be necessary to recycle a portion of the slurry from the flotation cell, or it may only be necessary to recycle a small portion of the slurry in order to improve recovery in this way.
The injection pipe and especially the impactor may create advantageous conditions with respect to particle recovery, and the flotation cell may be arranged to only process fresh slurry, i.e. slurry feed from a previous flotation cell or a previous processing step. It may not be necessary to recirculate the slurry from the flotation cell for treatment again in the same flotation cell, but any particles comprising valuable material remaining in the portion of the slurry descending towards the bottom of the cell may be directed for further treatment to a subsequent flotation cell and still improve the recovery of valuable material by the invention.
In an embodiment of the flotation line according to the invention the flotation cell according to the invention is preceded by a flotation cell. The former flotation cell may be of any suitable type.
In one embodiment of the flotation line, the flotation cell according to the invention is preceded by a mechanical flotation cell.
In another embodiment of the floating line, the floating line comprises: a roughing section with a flotation cell; a scavenger section with a flotation tank arranged to receive underflow from the rougher section; and a scavenging cleaning section with flotation cells arranged to receive overflow from the scavenging section, wherein the scavenging section and/or the last flotation cell of the scavenging cleaning section is a flotation cell according to the invention.
In a further embodiment of the flotation line, the flotation cell according to the invention is preceded by a mechanical flotation cell.
One embodiment of the use of a flotation wire according to the invention is used in particular for the recovery of mineral ore particles containing non-polar minerals, such as graphite, sulphur, molybdenite, coal and talc.
The treatment of slurries for the recovery of industrial minerals such as bentonite, silica, gypsum or talc can be improved by using reverse flotation. In the recovery of industrial minerals, the target of flotation can be, for example, to remove dark particles into the reject overflow and to recover white (white) particles into the accept underflow. In such a process, some lighter and finer white particles may end up in the overflow. Those particles can be efficiently recovered by the invention according to the present disclosure. In anti-flotation, particles containing unwanted material are removed from the slurry by: the bubbles are arranged to attach to those particles and remove them from the flotation cell in the overflow, while particles containing valuable material are recovered in the underflow, thus reversing the accept stream of conventional flotation to the overflow and the reject stream to the underflow. In reverse flotation generally, the large mass pull of worthless material can cause significant problems in controlling the flotation process.
One embodiment of the use of a flotation wire according to the invention is used in particular for the recovery of particles containing polar minerals.
One embodiment of the use of a flotation wire is used in particular for recovering particles from minerals having a mohs hardness of 2 to 3, such as galena, sulphide minerals, PGM minerals, and/or REO minerals.
Another example of the use of a flotation wire is particularly useful for recovering particles containing Pt.
One embodiment of the use of a flotation wire is used in particular for recovering particles containing Cu from minerals having a mohs hardness of 3 to 4.
Another embodiment of the use of a flotation line is used in particular for recovering particles containing Cu from low grade ore.
The valuable mineral may be, for example, Cu, or Zn, or Fe, or pyrite, or a metal sulfide such as gold sulfide. According to various aspects of the invention, mineral ore particles containing other valuable minerals, such as Pb, Pt, PGM (platinum group metals Ru, Rh, Pd, Os, Ir, Pt), oxide minerals, industrial minerals such as Li (i.e. spodumene), petalite, and rare earth minerals, may also be recovered.
For example, during the recovery of copper from low grade ores obtained from lean mineral deposits, the amount of copper may be as low as 0.1% by weight of the feed (i.e. the slurry feed fed into the flotation line). The flotation line according to the invention can be very practical for recovering copper, since copper is a so-called mineral that can be easily floated. During the dissociation of ore particles containing copper, a relatively high grade can be obtained from the first flotation cell of the flotation line. The recovery can be further improved by the flotation cell according to the invention.
By using the flotation device according to the invention, the recovery of such small amounts of valuable minerals, such as copper, can be effectively increased and even lean deposits can be used economically and effectively. As known rich deposits have been increasingly used, there is also a definite need to deal with less favorable deposits that may not have been previously mined due to the lack of suitable techniques and processes for recovering the very low amounts of valuable materials in the ore.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description help to explain the principles of the disclosure. In the drawings:
figure 1 is a 3D projection of a flotation cell according to an embodiment of the invention,
figure 2 shows the flotation cell as seen from above according to an embodiment of the invention,
figure 3 shows a flotation cell according to an embodiment of the invention in a side view,
figure 4 is a vertical section along section a-a of the flotation cell of figure 3,
fig. 5 is a schematic illustration of a flotation cell according to the invention, showing in detail the dimensions of the flotation cell,
fig. 6 schematically shows an embodiment of the flotation cell, where the jet pipes are arranged at different depths in the flotation cell,
fig. 7a and 7b are schematic views of a flotation line according to an embodiment of the invention, an
Figure 8 shows a schematic vertical section of an embodiment of a flotation cell according to the invention.
Fig. 9 is a schematic view of the form of a bottom structure according to an embodiment of the flotation cell.
Detailed Description
Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.
The following description discloses some embodiments in detail to enable a person skilled in the art to utilize the flotation cell, the flotation line and their use based on the present disclosure. Not all of the steps of the embodiments are specifically discussed, as many of the steps will be apparent to those of skill in the art based on this disclosure.
For reasons of simplicity, in the case of repeating members, component reference numerals will be maintained in the following exemplary embodiments.
Figures 1-6 and 8 show the flotation cell 1 in more detail. The figures are not drawn to scale and many components of the flotation cell 1 have been omitted for clarity. Fig. 7a-7b show an embodiment of the flotation line in a schematic way. The direction of the flow of slurry is shown in the figure by the arrows.
The flotation cell 1 according to the invention is intended for processing mineral ore particles suspended in a slurry and for separating the slurry into an
With particular reference to fig. 1-5, the flotation cell 1 includes a
In the figures, the
The
The
The
As an alternative or in addition to the
Additionally or alternatively, the
The shape of the bottom structure 7 may be defined as follows (see fig. 9): the vertical cross section of the bottom structure may be understood to take the form of a
The bottom angle α between the first side a and the base c (and/or between the second side b and the base c) with respect to the bottom 13 of the
The functional triangle is essentially a form which can be determined by the above-mentioned features irrespective of the actual form of the bottom structure 7, which can be, for example, conical, frustoconical, pyramidal or truncated pyramidal depending on the cross section and other constructional details of the
The bottom structure 7 comprises a
The bottom structure 7 has a height h measured from the highest part of the bottom structure 7 to the bottom 13 of the
Furthermore, the volume of the
The bottom structure 7 may additionally comprise any suitable support structure and/or connection structure on the bottom 13 of the
The
Furthermore, the
The
The
According to one embodiment, the
The flotation gas is entrained by the turbulent mixing action induced by the jet and is dispersed into small bubbles in the
To restrict the flow, the
As the slurry feed 100 passes through the
When the ratio of the absolute pressure upstream of the
To restrict the flow, the
The
The distance h of the
The diameter of the
The
Distance L3Distance h from the
The impactor 44 may include an impaction surface for contacting the stream of
The slurry rising from the impactor 44, which is essentially a gas-liquid-solid three phase mixture, enters the upper portion of the
Some of the coarse hydrophobic particles carried into the froth may then separate from the flotation bubbles and fall back into the
2-40
The
The
Moreover, in all the above embodiments, the
The
The
The flotation cell 1 may also comprise a
The combined slurry may be recirculated to all the
The
In addition, the conditioning circuit may comprise a
According to another aspect of the invention, a
In one embodiment of the
The
According to another aspect of the invention, the
According to another embodiment, the use may involve recovering particles containing polar minerals.
In another embodiment, the use relates to recovering particles from minerals having a mohs hardness of 2 to 3 (e.g. galena, sulphide, PGM, and/or REO minerals). In a further embodiment, the use is particularly directed to the recovery of platinum containing particles.
In another embodiment, the use relates to the recovery of copper-containing particles from mineral particles having a mohs hardness of 3 to 4. In a further embodiment, the use relates in particular to the recovery of copper-containing particles from low grade ore.
The embodiments described above may be used in any combination with each other. Several embodiments may be combined together to form further embodiments. The flotation cell to which the present disclosure relates may comprise at least one of the embodiments described above. It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; rather, they may vary within the scope of the claims.
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