CN210474319U

CN210474319U - Flotation cell and flotation line

Info

Publication number: CN210474319U
Application number: CN201921237264.3U
Authority: CN
Inventors: P·伯克; S·施密特; A·林内; J·托米嫩; V·瓦尔纳; A·佩尔托拉
Original assignee: Outotec Finland Oy
Current assignee: Metso Minerals Ltd; Metso Finland Oy
Priority date: 2018-08-01
Filing date: 2019-08-01
Publication date: 2020-05-08
Anticipated expiration: 2029-08-01
Also published as: EP3829774A1; CL2019002142U1; MX2021001130A; PE20191275Z; ZA202101403B; CN110787912A; AU2019100826A4; WO2020025850A1; PE20210792A1; EP3829774A4; AU2018435420A1

Abstract

The utility model discloses a flotation cell and flotation line. The flotation cell includes: a flotation cell having a center, a perimeter, a generally horizontal flat bottom, and a sidewall flotation cell; and a launder and launder rim around the periphery of the flotation cell; the flotation cell has a height measured as the distance from the bottom to the launder rim. The flotation cell also includes an injection pipe for introducing a slurry feed into the flotation cell, the injection pipe including: an inlet nozzle for feeding a slurry feed into the injection pipe; an inlet for pressurized gas; an elongated chamber; and an outlet nozzle configured to restrict flow of the slurry feed from the outlet nozzle and maintain the slurry feed in the elongated chamber under pressure; and the outlet nozzle is arranged inside the flotation cell at a vertical distance from the edge of the cell, the vertical distance being at least 1.5m according to the utility model discloses a flotation cell has improved the recovery of the fine particles that contain valuable material, can be used to improve the overall efficiency and the grade of recovery on wide particle size distribution.

Description

Flotation cell and flotation line

Technical Field

The present disclosure relates to a flotation cell and a flotation line for separating particles containing valuable material from particles suspended in a slurry.

Background

The flotation cell according to the present invention improves the recovery of fine particles containing valuable material compared to prior art flotation cells which normally do not provide good recovery of very small particles. The particles containing valuable material end up as tailings in the flotation cells of the prior art, thereby reducing the efficiency of the material recovery.

In prior art solutions that have improved fine particle recovery, the recovery of coarse particles may deteriorate. In contrast, the flotation cell according to the present invention can be used to improve the overall efficiency and grade of recovery over a wide particle size distribution.

SUMMERY OF THE UTILITY MODEL

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 an aspect of the present 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 according to the invention.

With the utility model described herein, the recovery of fine particles in the 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 a 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 proposed herein, introduction into the injection pipe is reducedCan improve flotation of fine and ultrafine particles containing, for example, mineral ore or coal, by increasing the flotation gas supply 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 jet 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 small enough 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, reducing the average 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 a flotation cell according to the invention, a bubble surface area 2.5 to 3 times higher can be achieved than in a flotation cell 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.

Through setting up a plurality of injection pipes in the flotation cell according to the utility model discloses a can increase the possibility of collision between the flotation bubble and the collision between bubble and the granule. 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.

According to the utility model discloses a flotation cell and flotation line and usage have such technological effect: 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 present 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 an overflow flotation cell, by introducing flotation bubbles into the slurry and by the vertical along the first flotation cellThe direction produces a continuous upward flow of slurry to treat the slurry. 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. As a result of this, more ore particles containing valuable minerals can be carried into the concentrate stream and the overall recovery of valuable material can be improved.

According to the utility model discloses an all flotation cells of flotation line can be single type, and the flotation cell is cleaned in the flotation cell of roughing in the roughing part, the scavenging flotation cell in the scavenging part and the scavenging of scavenging cleaning flotation line promptly can have single flotation cell type for flotation device only includes the flotation cell listed as above of a type. 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. Utilize the utility model discloses, can crowd the stopper and guide the foam towards foam overflow edge to reduce the foam and carry the distance (thereby reduce the risk that falls back), maintain or even reduce overflow edge length simultaneously. 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 utility model described herein, the area of froth on the pulp surface 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: the 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 an 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 an 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 center 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 lower.

In an embodiment of the flotation cell according to the invention, the ratio of the distance of the outlet nozzle from the bottom of the flotation tank to the height of the flotation tank 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 a flotation cell according to the invention, with a pressurized injection pipe, it is possible to introduce significantly more flotation gas into the process without increasing the bubble size or reducing the S_bBecause 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 in order to be processed 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 processing to a subsequent flotation cell and still improve the recovery of valuable material by the present invention.

In an embodiment of the flotation line according to the invention, the flotation tank according to the invention is preceded by a flotation tank. The former flotation cell may be of any suitable type.

In an embodiment of the flotation line, the flotation tank according to the invention is preceded by a mechanical flotation tank.

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 last flotation cell of the scavenging section and/or the scavenging cleaning section is according to the utility model.

In a further embodiment of the flotation line, the flotation tank according to the invention is preceded by a mechanical flotation tank.

The flotation wire according to the invention can be used 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 utility model 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.

According to the utility model discloses a flotation line can be used for retrieving the granule that contains polarity mineral.

The flotation wire may be used to recover particles from minerals having a mohs hardness of 2 to 3 (e.g. galena, sulphide, PGM, and/or REO minerals).

A flotation wire may be used to recover the Pt-containing particles.

The flotation wire can be used to recover particles containing Cu from minerals having a mohs hardness of 3 to 4.

The flotation line can be used to recover 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 present 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. Through according to the utility model discloses a flotation cell can further improve and retrieve.

By using the flotation device according to the invention, the recovery of such small amounts of valuable minerals (e.g. 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 underflow 400 and an overflow 500, the overflow 500 comprising a concentrate of the desired mineral.

With particular reference to fig. 1-5, the flotation cell 1 includes a flotation cell 10, the flotation cell 10 having a center 11, a perimeter 12, a bottom 13, and a sidewall 14. The flotation cell 1 also comprises a launder 2 and a launder rim 21 around the perimeter 12 of the flotation cell 10.

In the figures, the launder 2 is a peripheral launder. It is to be understood that the launder 2 may alternatively or additionally comprise a central launder arranged at the centre 11 of the flotation cell 10, as known in the art. The cell edge of the central cell may face towards the periphery 12 of the flotation cell 10, or towards the center 11 of the flotation cell 10, or towards both the periphery 12 and the center 11 of the flotation cell 10. Overflow 500 passes through the launder as it passesThe lip 21 is collected from the froth layer formed in the upper part of the flotation cell 10 into the launder 2 or launders. The froth layer comprises an open froth surface a at the top of the flotation cell 10_f。

The underflow 400 is removed or drawn from the flotation cell via the tailings outlet 140. According to one embodiment, the tailings outlet 140 may be arranged at the side wall 14 of the flotation cell 10 (see fig. 4). The tailings outlet 140 may be arranged at the side wall 14 of the flotation cell 10 at a distance from the bottom 13 of the flotation cell 10. The distance should be understood as the distance of the lowest point of the tailings outlet 140 or outlet opening in the side wall 14 of the flotation cell 10 from the cell bottom 13. Distance L₆May be 1% to 15% of the height H of the flotation cell 10. E.g. distance L₆May be 2% or 5% or 7.5% or 12% of the height H. Alternatively, the tailings outlet 140 may be arranged at the bottom 13 of the flotation cell 10 (see fig. 1). The tailings outlet 140 can be controlled by a dart valve or by any other suitable means known in the art to control the flow of underflow from the flotation cell 10. Even if the tailings outlet 140 is controlled by an internal or external structure, such as an up-flow or down-flow dart box, respectively, the tailings outlet 140 is ideally located at the lower portion of the flotation cell 10, i.e. close to or adjacent to the bottom 13 of the flotation cell, or even at the bottom 13 of the flotation cell 10. More specifically, the underflow 400 or tailings is removed from the lower portion of the flotation tank 10, as well as at or near the sidewall 14 of the flotation tank 10.

The flotation cell 10 may also include a froth plug 6 shaped to direct the open froth surface a towards the cell rim 21_fThe foam of (1). The froth plug 6 may be a central froth plug (as shown in figure 2) or an internal peripheral froth plug that is disposed within the flotation cell 10 at a desired depth at the sidewall of the flotation cell 10.

The central froth plug 61 is arranged concentrically with the centre 11 of the flotation cell 10. The central foam plug 61 may have a conical or frustoconical shape. The central foam plunger 61 may have a pyramidal or frusto-pyramidal shape. In other words, the vertical cross-section of the central foam plunger 61 may be an inverted triangleForm in which the apex points towards the bottom 13 of the flotation cell in the case of a central foam plug 61 having a truncated structure or shape, the apex is only functional, i.e. the apex will be considered to be the lowest point of the truncated structure or shape when continuing to the full non-truncated form, whereby the included angle α can be determined irrespective of the actual shape or form of the central foam plug, the included angle α can be 20 ° to 80 °, for example, the included angle α can be 22 °, or 37.5 °, or 45 °, or 55 °, or 63.75 °, or 74 °_f25% to 40%.

As an alternative or in addition to the central froth plug 61, the flotation cell may comprise an inner peripheral plug 62 arranged in the side wall 14 of the flotation cell 10 such that the lowest point 620 of the inner peripheral plug is located at a distance h from the bottom 13 of the flotation cell 10₂To (3). Distance h₂May be 1/2 to 2/3 of the height H of the flotation cell 10. The inner peripheral constriction 62 may be formed to include a diagonal inlet port that starts at the nadir 620, angles towards the center 11 of the flotation cell 10, and extends between a first portion of the side wall 14 and a second portion of the side wall 14 of the flotation cell 10 such that the diagonal inlet port is inclined at an angle of 20 ° to 80 ° relative to the first portion of the side wall 14. The tilt angle may be, for example, 22 °, or 37.5 °, or 45 °, or 55 °, or 63.75 °, or 74 °. The inner peripheral plug 62 may be arranged to plug the slurry area a at the mixing zone a_p1/5 to 1/4, at a distance h of the outlet nozzle 43 of the spray pipe 4 from the bottom 13 of the flotation cell 10₁Measure the pulp area A_p. A mixing zone a (i.e. the portion or zone in the vertical direction of the flotation cell in which the slurry is agitated or otherwise induced to mix the ore particles suspended in the slurry with the flotation bubbles) is formed in the vertical cross-section of the flotation cell 10 substantially around the lower portion of the sparging tube 4 and the impactor 44 (see figure 5).

Additionally or alternatively, the flotation cell 10 may also comprise a bottom structure 7 (see fig. 5 and 9), the bottom structure 7 being arranged on the bottom 13 and having such a shape: this shape allows particles suspended in the slurry to mix in a mixing zone a formed above the bottom structure 7 and settle in a settling zone surrounding the bottom structure 7.

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 functional triangle 700, the functional triangle 700 comprising a first (top) apex 71 pointing away from the bottom 13 of the flotation cell 10; a second vertex 71 a; and a third apex 71b, the latter two apexes being arranged at the bottom 13 of the flotation cell 10. The first side a is formed between the first vertex 71 and the second vertex 71 a. The second side b is formed between the first vertex 71 and the third vertex 71 b. A base c is formed between the second apex 71a and the third apex 71b, which base c is thus parallel to the bottom 13 of the flotation tank 10 and is located on the bottom 13 of the flotation tank 10. The central axis 70 of the functional triangle 700 is substantially concentric with the center 11 of the flotation cell 10. In this context, "substantially" should be understood as meaning that, during the manufacture and/or installation of the bottom structure 7, it is possible that slight deviations from the center 11 of the flotation cell 10 may naturally occur. However, it is intended that the two axes, i.e. the central axis 70 of the functional triangle (which is also the central axis of the bottom structure 7) and the central axis of the flotation cell 10, are coaxial.

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 flotation cell 10 is 20 ° to 60 °, for example, the angle α may be 22 °, or 27.5 °, or 35 °, or 45 °, or 53.75 °, and the angle β between the first side a and the second side b is 20 ° to 100 °, preferably the angle β is 20 ° to 80 °, for example, the angle β may be 22 °, or 33.5 °, or 45 °, or 57.75 °, or 64 °, or 85.5 °.

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 flotation cell 10. The conical or frusto-conical shape may be of a form suitable for flotation cells having a circular cross-section. The pyramidal or truncated pyramidal shape may be in a form suitable for flotation cells having a rectangular cross-section.

The bottom structure 7 comprises a base 73, the base 73 corresponding to the base c of the functional triangle 700 (i.e. the base c of the functional triangle 700 defines the base 73 of the bottom structure 7) and being arranged on the bottom 13 of the flotation cell 10. Furthermore, the bottom structure includes a hood 72. The hood 72 is defined by at least a first vertex 71, a second vertex 71a, and a third vertex 71b of the functional triangle 700. Thus, regardless of the actual form of the substructure 7, the functional triangles 700 define the extreme physical dimensions of the substructure 7. For example, in case the bottom structure 7 has an irregular form but is still rotationally symmetric, the bottom structure 7 will fit entirely into the functional triangle 700 (see last panel of fig. 9). In one embodiment, the cover 72 is at least partially defined by a first side a and a second side b of the functional triangle. An example of such an embodiment is a bottom structure 7 having a frustoconical form (see the middle view of fig. 9). In one embodiment, the cover 72 is substantially completely defined by the first side a and the second side b of the functional triangle 700, i.e. the bottom structure 7 has a conical form (see the first drawing of fig. 9).

The bottom structure 7 has a height h measured from the highest part of the bottom structure 7 to the bottom 13 of the flotation cell 10₄. If the base structure is in the form of a cone or pyramid, the highest portion is also the first vertex 71 of the functional triangle 700. If the bottom structure 7 has some truncated form, the height h is measured from the horizontal top of the truncated form (see middle diagram of fig. 8) to the bottom 13 of the flotation cell 10₄. Height h₄Greater than 1/5 and less than 3/4 of the height H of the flotation cell 10. Further, the diameter d of the base 73 of the bottom structure 7₃May be the diameter d of the bottom 13 of the flotation cell 10₁1/4 to 3/4. If the flotation cell 10 and/or the bottom structure 7 has a non-circular cross-section, the diameter is measured as the largest diagonal of the respective section (base 73 and bottom 13). In one embodiment, the surface area of the base 73 of the bottom structure 7 is less than 80% of the surface area of the bottom 13 of the flotation cell 10. The surface area of the substrate 73 may be a flotation cell10 of 25% to 80% of the surface area of the bottom 13.

Furthermore, the volume of the flotation cell 10 occupied by the bottom structure 7 may be 30% to 70% of the volume of the flotation cell 10 occupied by the mixing zone a.

The bottom structure 7 may additionally comprise any suitable support structure and/or connection structure on the bottom 13 of the flotation tank 10 for mounting the bottom structure 7 into the flotation tank 10. The bottom structure 7 may be made of any suitable material, such as metal (e.g. stainless steel).

The flotation cell 10 has a height H measured as the distance from the bottom 13 of the flotation cell 10 to the cell rim 21. At the periphery 12 of the flotation cell 10, the height H is at most 20% lower than the height H at the centre 11 of the flotation cell 10. In other words, the flotation tank 10 may have a different vertical profile (see fig. 8), for example the side wall 14 of the flotation tank 10 may comprise a portion at its lower portion that is inclined towards the centre 11 of the flotation tank 10.

Furthermore, the flotation cell 10 has a distance h at the outlet nozzle 43 from the bottom 13 of the flotation cell 10₁The measured diameter D. In one embodiment, the ratio H/D of the height H to the diameter D of the flotation cell 10 is between 0.5 and 1.5.

The flotation cell 10 may have at least 20m³The volume of (a). The flotation cell 10 may have a width of between 20m³To 1000m³The volume in between. For example, the flotation cell 10 may have a volume of 100m³Or 200m³Or 450m³Or 630m³。

The flotation cell 10 comprises a spray pipe 4 for introducing a slurry feed 100 into the flotation cell 10. The injection pipe 4 comprises an inlet nozzle 41 for feeding a slurry feed 100 into the injection pipe 4; an inlet 42 for pressurized air or other gas, such that the slurry feed 100 may be subjected to pressurized air or other gas as it is discharged from the inlet nozzle 41; an elongated chamber 40 arranged to receive a slurry feed 100 under pressure; an outlet nozzle 43 configured to restrict the flow of the slurry feed 100 from the outlet nozzle 43 and to maintain the slurry feed in the elongated chamber 40 under pressure.

According to one embodiment, the outlet nozzle 43 may also be configured to generate a supersonic shock wave in the slurry feed that causes the formation of flotation bubble-particle agglomerates. For example, the outlet nozzle 43 may induce a supersonic shockwave in the slurry feed 100 as the slurry feed 100 exits the injection tube 40. In addition, the supersonic shock wave may extend to the slurry adjacent to or around the outlet nozzle, so that the generation of small size flotation bubble-particle aggregates is thus possible even outside the jet pipe.

The flotation gas is entrained by the turbulent mixing action induced by the jet and is dispersed into small bubbles in the slurry feed 100 as it travels down the elongated chamber 40 to the outlet nozzle 43, the outlet nozzle 43 being configured to restrict the flow of the slurry feed 100 from the outlet nozzle 43 and also configured to maintain the slurry feed under pressure in the elongated chamber 40.

To restrict the flow, the outlet nozzle 43 may comprise a throttle, such as a throat restriction. The slurry feed 100 flows under pressure out of the outlet nozzle 43, more specifically from the throttling valve, into the flotation cell 10.

As the slurry feed 100 passes through the outlet nozzle 43 or through the throttling valve of the outlet nozzle 43, the size of the flotation bubbles decreases due to pressure variations and due to the high shear environment downstream of the outlet nozzle 43. As the flow of slurry feed 100 becomes choked, the velocity of the gas-liquid mixture in outlet nozzle 43 or the throttle valve may exceed sonic velocity, and the flow downstream of the throttle valve becomes supersonic and forms a shockwave in the diverging portion of outlet nozzle 43. In other words, the outlet nozzle 43 is configured to induce a supersonic shockwave in the slurry feed 100.

When the ratio of the absolute pressure upstream of the outlet nozzle 43 to the absolute pressure downstream of the throttle or other restriction of the outlet nozzle 43 exceeds a critical value, the flow of the slurry feed 100 becomes impeded. When the pressure ratio is above the critical value, the flow of the slurry feed 100 downstream of the throttle of the outlet nozzle 43 becomes supersonic and forms a shock wave. The small flotation bubbles in the slurry feed 100 mixture are broken up into even smaller bubbles as a result of being forced by the shock wave and are forced into contact with the hydrophobic ore particles in the slurry feed 100, thereby creating flotation bubble-ore particle agglomerates.

To restrict the flow, the outlet nozzle 43 may comprise a throttle, such as a throat restriction. The slurry feed 100 flows under pressure out of the outlet nozzle 43, more specifically from the throttling valve, into the flotation cell 10. As the slurry feed 100 passes through the outlet nozzle 43 or through the throttling valve of the outlet nozzle 43, the size of the flotation bubbles decreases due to pressure variations and due to the high shear environment downstream of the outlet nozzle 43. As the flow of slurry feed 100 becomes choked, the velocity of the gas-liquid mixture in outlet nozzle 43 or the throttle valve may exceed sonic velocity, and the flow downstream of the throttle valve becomes supersonic and forms a shockwave in the diverging portion of outlet nozzle 43. In other words, the outlet nozzle 43 is configured to induce a supersonic shockwave in the slurry feed 100. When the ratio of the absolute pressure upstream of the outlet nozzle 43 to the absolute pressure downstream of the restriction of the outlet nozzle 43 exceeds a critical value, the flow of the slurry feed 100 becomes impeded. When the pressure ratio is above the critical value, the flow of the slurry feed 100 downstream of the restriction of the outlet nozzle 43 becomes supersonic and forms a shock wave. The small flotation bubbles in the slurry feed 100 mixture are broken up into even smaller bubbles as a result of being forced by the shock wave and are forced into contact with the hydrophobic ore particles in the slurry feed 100, thereby creating flotation bubble-ore particle agglomerates.

The outlet nozzle 43 may be positioned within the flotation cell 10 at a desired depth. The outlet nozzle 43 may be positioned at a vertical distance L from the runner rim 21₅A distance L₅Is at least 1.5 m. In other words, the length of the part of the injection pipe 4 which is arranged inside the flotation cell 10 below the level of the launder edge 21 is at least 1.5 m. In one embodiment, the distance L₅Is at least 1.7m and the outlet nozzle 43 is at a distance h from the bottom 13 of the flotation cell 10₁Is at least 0.4 m. E.g. distance L₅May be 1.55m, or 1.75m, or 1.8m, or 2.2m, or 2.45m, or 5.25 m; and regardless of the distance L₅How, distance h₁May be 0.45m, 0.55m, 0.68m, 0.9m or 1.2 m. And, a distance L₅With flotation cells 10The ratio of the height H may be 0.9 or less. In fig. 6, a flotation cell 10 is shown by way of example, wherein the jet pipes 4 are arranged at different depths in the flotation cell 10. The depth at which the injection pipe 4 is arranged in the flotation cell 10 may depend on many factors, for example on the properties of the pulp and/or valuable minerals to be treated in the flotation cell 1, or on the construction of the flotation line in which the flotation cell 1 is arranged.

The distance h of the outlet nozzle 43 from the bottom 13 of the flotation cell 10₁The ratio H to the height H of the flotation cell 10₁the/H may be from 0.1 to 0.75.

The diameter of the outlet nozzle 43 may be 10% to 30% of the diameter of the elongated chamber 40 of the ejector tube 4. The diameter of the outlet nozzle 43 may be 40mm to 100 mm. For example, the diameter of the outlet nozzle 43 may be 55mm, or 62mm, or 70 mm.

The injection pipe 4 may further include an impactor 44, the impactor 44 being configured to contact the flow of the slurry feed 100 from the outlet nozzle 43 and direct the flow of the slurry feed 100 radially outward and upward from the impactor 44. The slurry feed 100 exiting from the outlet nozzle 43 is thus directed to contact the impactor 44. Distance L from bottom 440 of impactor 44 to outlet nozzle 43₃May be 5 to 20 times the diameter of the outlet nozzle 43. E.g. distance L₃May be 7 times, or 12 times, or 15 times the diameter of the outlet nozzle 43.

Distance L₃Distance h from the outlet nozzle 43 to the bottom 13 of the flotation cell 10₁Ratio L of₃/h₁May be lower than 1.0. Furthermore, the distance h of the bottom 440 of the impactor 44 from the bottom 13 of the flotation cell 10₃May be at least 0.3 m. E.g. distance h₃May be 0.4m, or 0.55m, or 0.75m, or 1.0 m.

The impactor 44 may include an impaction surface for contacting the stream of slurry feed 100 exiting the outlet nozzle 43. The impact surface may be made of a wear resistant material to reduce the need for replacement or maintenance.

The slurry rising from the impactor 44, which is essentially a gas-liquid-solid three phase mixture, enters the upper portion of the flotation cell 10 and the flotation bubbles rise and separate from the liquid to form a froth layer. The froth rises and is discharged as an overflow 500 over the trough edge 21 into the launder 2 and out of the flotation cell 1. The tailings or underflow 400 from which the desired material has been substantially removed exits the flotation cell 10 through an outlet disposed at or near the bottom 13 of the flotation cell 10.

Some of the coarse hydrophobic particles carried into the froth may then separate from the flotation bubbles and fall back into the flotation cell 10 as the bubbles in the froth coalesce. However, most of such particles fall back into the flotation cell 10 in such a way and location that they can be caught by bubbles newly entering the flotation cell 10 from the injection pipe 4 and carried into the froth layer again.

2-40 injection pipes 4, or 4-24 injection pipes 4 may be arranged in the flotation cell 1. In one embodiment, there are 16 injection tubes 4. In another embodiment, there are 24 ejector tubes 4. In another embodiment, there are 8 injection tubes 4. The exact number of injection pipes 4 may be chosen according to the specific operation, such as the type of slurry being processed in the flotation cell 1, the volumetric feed rate to the flotation cell 1, the mass throughput to the flotation cell 1, or the volume or size of the flotation cell 10. In order to properly disperse the flotation gas into the

flotation cell

10, 4 to 6 injection pipes 4 may be used.

The injection pipe 4 may be arranged concentrically to the periphery 12 of the flotation cell 10 at a distance from the centre 11 of the flotation cell 10. This may be the case when the flotation cell 10 is circular in cross-section. The injection pipes 4 may also be arranged such that each injection pipe 4 is located at a distance L of the outlet nozzle 43 from the centre 11 of the flotation cell 10₁Said distance is preferably equal for each injection pipe 4. E.g. distance L₁May be 10% to 40% of the diameter D of the flotation cell 10. According to different embodiments of the flotation cell 1, the distance L₁May be 12.5%, or 15%, or 25%, or 32.5% of the diameter D of the flotation cell 10.

The ejector tube 4 may be at a distance L from the side wall 14₂Is arranged parallel to the side wall 14 of the flotation cell 10. This may be the case when the flotation cell 10 is rectangular in cross-section. Said distance L of the outlet nozzle 43 of the injection pipe 4 from the side wall 14 of the flotation cell 10₂May be straight in the flotation cell 1010% to 40% of diameter D. In one embodiment, the distance L₂25% of the diameter D of the flotation cell 10. According to different embodiments of the flotation cell 10, the distance L₂May be 12.5%, or 15%, or 27%, or 32.5% of the diameter D of the flotation cell 10. In addition, the parallel arranged injection pipes 4 can also be arranged in a straight line within the flotation cell 10.

Moreover, in all the above embodiments, the injection pipes 4 may be arranged equidistantly from each other such that the distance between any two adjacent outlet nozzles 43 is the same.

The slurry fraction 300 can be withdrawn from the flotation cell 10 via an outlet 31 arranged at the side wall 14 of the flotation cell 10. This slurry fraction 300 is recycled as feed slurry to the injection pipe 4. In one embodiment, the slurry feed 100 includes 50% or less of the slurry portion 300. In one embodiment, the slurry feed 100 includes 30% of the slurry portion 300. For example, the slurry feed may include 5%, or 12.5%, or 20%, or 30%, or 37.5%, or 45% of the slurry portion 300. Alternatively, the slurry feed 100 may comprise a 0% slurry fraction 300, i.e. the slurry withdrawn from the flotation tank 10 is not recirculated back into the flotation cell, but the slurry feed 100 comprises 100% new slurry 200, e.g. from a previous flotation cell (i.e. the underflow 400 from a previous flotation cell) or from a previous treatment step.

The pulp fraction 300 may be recirculated to all the injection pipes 4 of the flotation cell 10 or alternatively to some of the injection pipes 4, while other injection pipes 4 receive new pulp 200, said pulp 200 comprising the underflow 400 of a previous flotation cell or a pulp flow from a certain previous treatment step, depending on the position of the flotation cell 1 in the flotation line 8. The outlet 31 may be arranged at a distance L from the bottom 13 of the flotation cell 10₄To (3). The distance is to be understood as the distance of the lowest point of the outlet or outlet opening in the side wall 14 of the flotation cell 10 from the cell bottom 13. Distance L₄From 0% to 50% of the height H of the flotation cell 10. The outlet 31 may advantageously be positioned at a settling zone, where particles suspended in the slurry but not captured by the flotation bubbles and/or the upward flow of slurry are directed towards the bottom of the flotation cell 1013 is lowered. In one embodiment, the outlet 31 is arranged at a lower part of the flotation cell 10. E.g. distance L₄May be 2%, or 8%, or 12.5%, or 17%, or 25% of the height H of the flotation cell 10. Even if the outlet 31 is controlled by an internal or external structure, such as an up-flow or down-flow dart box, the outlet 31 is ideally located at the lower portion of the flotation cell 10, i.e. near or adjacent to the bottom 13 of the flotation cell. More specifically, the slurry portion 300 is removed from the lower portion of the flotation cell 10.

The flotation cell 1 may also comprise a conditioning circuit 3. The conditioning circuit 3 may comprise a pump tank 30 or other such further container in fluid communication with the flotation tank 10. In the pump tank 30, the slurry portion 300 taken out of 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, which slurry feed 100 is then introduced into the injection pipe 4 of the flotation tank 10. The new pulp 200 may be, for example, the underflow 400 from a previous flotation cell or, if the flotation cell 1 is the first flotation cell of a flotation line, the pulp feed from a grinding unit/step or a classification unit/step. It is also possible that the slurry portion 300 and the new slurry 200 are dispensed into the injection pipe 4 without first being combined in the pump tank 30.

The combined slurry may be recirculated to all the injection pipes 4 of the flotation cell 10 or alternatively to some of the injection pipes 4, while other injection pipes 4 receive new slurry 200, the new slurry 200 comprising the underflow 400 of a previous flotation cell or a flow of slurry from a certain previous treatment step, depending on the position of the flotation cell 1 within the flotation line 8.

The outlet 31 may be at a distance L from the bottom 13 of the flotation cell 10₄Is arranged at the side wall 14 of the flotation cell 10. Distance L₄May be between 0% and 50% of the height H of the flotation cell 10. E.g. distance L₄May be 2%, or 8%, or 12.5%, or 20%, or 33% of the height H of the flotation cell 10.

In addition, the conditioning circuit may comprise a pump 32, the pump 32 being arranged to suck the slurry portion 300 from the flotation tank 10 and to forward the slurry feed 100 from the pump tank 30 to the injection pipe 4. The slurry portion 300 may include particles having a low settling velocity, such as slow floating fine particles. The slurry fraction may be taken from the bottom of the flotation cell 10 or from near the bottom of the flotation cell 10. Additionally or alternatively, the conditioning circuit 3 may also comprise a distribution unit (not shown in the figures) arranged to distribute the slurry feed 100 into the injection pipes 4. The pump 32 may also be used to forward the slurry feed 100 into the injection pipe 4. In order to distribute the slurry feed 100 evenly into the injection pipes 4, a distribution unit may be utilized. The distribution unit may for example comprise a feed conduit inside the flotation cell 10 configured to distribute the slurry fraction 300 directly into the injection pipe 4. For example, the distribution unit may comprise a conduit arranged outside the flotation cell 10 leading to a separate feed distributor configured to distribute the slurry portion 300 or a combination of the slurry portion 300 and fresh slurry 200 into the injection pipe 4.

According to another aspect of the invention, a flotation line 8 is shown in fig. 7a and 7 b. The flotation line 8 comprises a plurality of fluidly connected flotation cells 1a, and at least one of the flotation cells is a flotation cell 1 according to the above-described embodiment of the flotation cell 1 of the present invention. In one embodiment of the flotation line 8, the flotation tank 1 according to the invention is preceded by a flotation tank 1 a. The flotation tank 1a may be of any type known in the art. Alternatively or additionally, the flotation tank 1 may be preceded by a mechanical flotation tank 1b (see fig. 7 a).

In one embodiment of the flotation line 8, the flotation line 8 comprises a rougher section 81 with a flotation cell 1 a; a scavenger section 82 with a flotation tank 1a arranged to receive underflow 400 from a rougher section 81; and a scavenger cleaning section 820 with a flotation basin 1a arranged to receive an overflow 500 from the scavenging section 82 (see figure 7 b). In the flotation line 8, the last flotation basin 1 of the scavenging section 82, and alternatively or additionally the last flotation basin 1 of the scavenging section 820, are flotation basins 1 with injection pipes 4 according to the invention. In addition, in the flotation line 8, as described above, the flotation tank 1 with the injection pipe 4 according to the invention may be preceded by a mechanical flotation tank 1 b.

The flotation line 8 may be preceded by other treatments such as grinding, classification, screening, dense media treatment, coarse particle recovery treatment, spiraling, and other separation treatments; and other flotation processes. The flotation line 8 may be followed by various treatments such as regrinding, cleaning or other flotation processes, centrifugation, filtration, screening or dewatering.

The flotation line 8 can be used to recover particles containing valuable material suspended in the slurry. In one embodiment, the use may involve the recovery of particles containing non-polar minerals (e.g., graphite, sulfur, molybdenite, coal, talc).

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. Accordingly, the present invention and its embodiments are not limited to the above examples; rather, they may vary within the scope of the claims.

Claims

1. A flotation cell for treating particles suspended in a slurry and for separating the slurry 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 the slurry feed from the outlet nozzle and to maintain the slurry feed in the elongate chamber 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, 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 3, characterized in that the vertical distance (L)₅) Ratio (L) to the height (H) of the flotation cell₅H) is 0.9 or less.

6. A flotation cell according to any one of claims 1 to 3, 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 3, 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. A flotation cell according to any one of claims 1 to 3, characterized in that the volume of the flotation cell (10) is at least 20m³。

9. A flotation cell according to claim 8, characterized in that the flotation cell (10) has a volume of 20m³To 1000m³。

10. A flotation cell according to any one of claims 1 to 3, characterized in that the flotation cell comprises 2-40 injection pipes (4).

11. The flotation cell according to claim 10, characterized in that the flotation cell comprises 4-24 jet pipes.

12. A flotation cell according to any one of claims 1 to 3, 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.

13. Flotation cell according to claim 12, 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.

14. Flotation cell according to claim 13, characterized in that the outlet nozzle (43) is at a distance (L) from the center (11)₁) 25% of said diameter of the flotation cell.

15. A flotation cell according to any one of claims 1 to 3, characterized in that the injection pipe (4) is arranged parallel to the side wall (14) of the flotation cell (10) at a distance from said side wall.

16. A flotation cell according to claim 15, 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.

17. A flotation cell according to claim 16, characterized in that the outlet nozzle (43) is at a distance (L) from the side wall (14) of the flotation cell (10)₂) 25% of said diameter of the flotation cell.

18. A flotation cell according to any one of claims 1 to 3, characterized in that the spray pipes (4) are arranged equidistant from each other so that the distance between any two adjacent outlet nozzles (43) is the same.

19. A flotation cell according to any one of claims 1 to 3, 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).

20. A flotation cell according to claim 19, characterized in that the diameter of the outlet nozzle (43) is 40mm to 100 mm.

21. The flotation cell according to any of claims 1 to 3, wherein the injection pipe further comprises an impactor (44) configured to contact the slurry feed flow from the outlet nozzle (43) and to direct the flow of slurry feed (100) radially outwards and upwards from the impactor.

22. Flotation cell according to claim 21, 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.

23. Flotation cell according to claim 21, 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.

24. A flotation cell according to any one of claims 1 to 3, characterized in that the outlet nozzle (43) comprises a throttle valve for restricting the flow of the pulp feed (100) from the outlet nozzle.

25. A flotation cell according to any one of claims 1 to 3, characterized in that the flotation cell further comprises a conditioning circuit (3).

26. A flotation cell according to claim 25, 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).

27. A flotation cell according to claim 26, 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).

28. Flotation cell according to claim 27, 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).

29. A flotation cell according to any one of claims 26 to 28, 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).

30. The flotation cell according to any one of claims 26 to 28, characterized in that the conditioning circuit (3) further comprises a distribution unit arranged to distribute the pulp feed (100) to the injection pipes (4).

31. A flotation line comprising a plurality of flotation cells of any type fluidly connected, characterized in that at least one of the flotation cells is a new type of flotation cell, i.e. a flotation cell (1) according to any one of claims 1 to 30.

32. A flotation line according to claim 31, characterized in that the new flotation cell (1) is preceded by any type of flotation cell (1 a).

33. A flotation line according to claim 31 or 32, characterized in that the new flotation cell (1) is preceded by a mechanical flotation cell (1 b).

34. The flotation wire according to claim 32, characterized in that the flotation wire comprises:

a rougher section (81) with any type of flotation cell;

a scavenger section (82) with any type of flotation cell arranged to receive underflow (400) from the rougher section; and

a scavenger cleaning section (820) with any type of flotation basin arranged to receive an overflow (500) from the scavenger section, wherein the scavenger section and/or the last flotation basin of the scavenger cleaning section is a new type of flotation basin, i.e. a flotation basin (1) according to any of the claims 1-30.

35. A flotation line according to claim 34, characterized in that the new flotation cell (1) as the last flotation cell is preceded by a mechanical flotation cell (1 b).