FIELD OF TECHNOLOGY

This disclosure concerns mineral processing. In partic ular, this disclosure concerns separation of minerals from their ores by flotation.

BACKGROUND

The energy consumption of comminution processes, espe- d aily grinding, typically constitutes a significant part of overall energy consumption in mineral pro cessing. As such, significant effort has been invested in reducing energy consumption of grinding. This may generally be achieved by lowering the degree of liber- ation of ore, i.e., by increasing the average size of ore particles prior to concentration. Standard mechan ical flotation units are best suited for separation of particles within a size range of approximately 20 ym to 150 ym. Consequently, alternative solutions are required to increase the average particle size of ore beyond 150 ym.

One approach for increasing the recovery of coarser par ticles is commonly known as separation-in-froth flota tion or SIF flotation. However, a conventional separa- tion-in-froth flotation unit may be limited in its throughput in relation to its size. In light of this, it may be desirable to develop new solutions related to separation of coarser particles. SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

According to a first aspect, a froth-interaction flota tion unit for separation of input slurry is provided. The froth-interaction flotation unit comprises a tank for holding a volume of slurry and a froth layer over the volume of slurry, a coarse slurry feeding arrange ment for feeding coarse slurry to the froth layer, and a flotation gas supply arrangement for supplying flota tion gas into the volume of slurry. The froth-interac- tion flotation unit comprises a fine slurry feeding ar rangement for feeding fine slurry into the volume of slurry and a classification arrangement configured to classify the input slurry to form a coarser slurry frac tion and a finer slurry fraction, to feed the coarser slurry fraction to the coarse slurry feeding arrange ment, and to feed the finer slurry fraction to the fine slurry feeding arrangement.

Throughout this specification, "flotation" may refer to separation of a mixture by adhering a substance in said mixture at an interface. In flotation, separation of a mixture may be based on differences in the hydrophobi- city of substances in said mixture. Herein, "separation" may refer to the extraction or removal of a substance from a mixture for use or rejection. Further, "froth flotation" may refer to flotation, wherein froth is utilized for separation. Herein, "froth" may refer to a dispersion, comprising a greater portion by volume of flotation gas dispersed as bubbles in lesser portion by volume of a flotation liquid. Gen erally, froth may or may not be stabilized by solid particles. In froth, flotation gas bubbles may generally have an average diameter greater than or equal to 1 mm. Additionally or alternatively, an average distance be- tween neighboring flotation gas bubbles in froth not stabilized by solid particles may generally be less than or equal to some tens of micrometers, for example, less than or equal to 50 ym or 30 ym. Naturally, in froth stabilized by solid particles, average distance between neighboring flotation gas bubbles is increased in pro portion to the average size and quantity of said solid particles.

In this disclosure, a "layer" may refer to a generally sheet-formed element arranged on a surface. A layer may or may not be path-connected. Some layers may be locally path-connected and disconnected. Although a layer may generally comprise a plurality of sublayers of different material compositions, a "froth layer" may refer to a layer comprising, or comprising substantially, or con- sisting essentially of, or consisting of froth.

The term "flotation gas" may refer to any gaseous sub stance suitable for use in flotation. Although in prac tical applications air is often used a flotation gas, other types of gaseous substances may also be utilized, as known to the skilled person. On the other hand, "flotation liquid" may refer to any liquid substance or mixture suitable for use in flota tion. Although in practical applications water or aque ous solutions are often used as flotation liquids, other types of liquid substances may also be utilized, as known to the skilled person.

Throughout this specification, "froth-interaction flo tation" may refer to froth flotation, wherein slurry is fed to a froth layer. Herein, slurry being "fed to a froth layer" may refer to feeding said slurry onto, and/or into, and/or immediately below, e.g., at most 50 cm, or at most 40 cm, or at most 30 cm, or at most 20 cm, or at most 10 cm below, said froth layer. Additionally or alternatively, in embodiments, wherein a height of a launder lip defines a height of an upper surface of a froth layer, slurry being fed to said froth layer may refer to feeding said slurry into a tank at said launder lip height and/or at a position at most 60 cm, or at most 50 cm, or at most 40 cm, or at most 30 cm, or at most 20 cm below said launder lip height.

Herein, a "unit" may refer to a device suitable for or configured to perform at least one specific process. Naturally, a "flotation unit" may then refer to a unit suitable for or configured to subject material to flo tation. Naturally, a "froth-interaction flotation unit" may then refer to a unit configured to or suitable for separation of material by froth-interaction flotation. A unit may generally comprise one or more parts, and each of the one or more parts may be classified as belonging to an arrangement of said unit. An "arrangement" of a unit configured to perform a pro cess may refer to a set of parts of said unit suitable for or configured to perform at least one specific sub process of said process. As such, a "unit comprising an arrangement" may refer to said unit comprising parts belonging to said arrangement. Generally, an arrangement may comprise any component(s), for example, mechanical, electrical, pneumatic, and/or hydraulic component(s), necessary and/or beneficial for performing its specific subprocess.

In this disclosure, a "flotation gas supply arrangement" may refer to an arrangement of parts of a flotation unit suitable for or configured to supply flotation gas into a tank of said flotation unit. Generally, a flotation gas supply arrangement may comprise any part(s) suitable or necessary for supplying flotation gas into a tank, for example, one or more spargers, e.g., jetting and/or cavitation sparger(s), and/or one or more static mixers.

In this specification, a "tank" may refer to a recepta cle suitable for or configured to hold a fluid, for example, a liquid.

Further, "slurry" may refer to a dispersion, comprising solid particles suspended in a continuous phase of flo tation liquid. As such, a "volume of slurry" may refer to a certain amount of slurry. In flotation, slurry may be commonly referred to as coarse slurry or as fine slurry depending on its properties.

Throughout this specification, "coarse slurry" may refer to slurry, comprising solid particles of larger diame ters. As known to the skilled person, the definition of coarse slurry may be application-specific and/or ore- specific. For example, in some embodiments, coarse slurry may refer to slurry, having a particle-size dis tribution with a percent passing less than 80 % at a sieve size of 425 ym, or at a sieve size of 355 ym, or at a sieve size of 250 ym, or at a sieve size of 180 ym, or at a sieve size of 150 ym, or at a sieve size of 125 ym, or at a sieve size of 105 ym.

Consequently, a "coarse slurry feeding arrangement" may refer to an arrangement of parts of a flotation unit suitable for or configured to feed coarse slurry into a tank of said flotation unit. Generally, a coarse slurry feeding arrangement may or may not be also suitable for feeding fine slurry into a tank of said flotation unit.

On the other hand, "fine slurry" may refer to slurry, comprising solid particles of smaller diameters. As known to the skilled person, the definition of fine slurry may be application-specific and/or ore-specific. For example, in some embodiments, fine slurry may refer to slurry, having a particle-size distribution with a percent passing greater than or equal to 80 % at a sieve size of 425 ym, or at a sieve size of 355 ym, or at a sieve size of 250 ym, or at a sieve size of 180 ym, or at a sieve size of 150 ym, or at a sieve size of 125 ym, or at a sieve size of 105 ym.

Consequently, a "fine slurry feeding arrangement" may refer to an arrangement of parts of a flotation unit suitable for or configured to feed fine slurry into a tank of said flotation unit. Generally, a fine slurry feeding arrangement may or may not be also suitable for feeding coarse slurry into a tank of said flotation unit. A fine slurry feeding arrangement may or may not be configured to feed fine slurry into a tank of a flotation unit below a fine slurry outlet and/or at a lower section of said tank.

Throughout this specification, "classification" may re fer to sizing of solid particles in slurry to form at least two, i.e., two, three, or more, slurry fractions based on differences in the settling velocities of solid particles in said slurry. In practice, classification of slurry results in coarser particles in said slurry being preferentially directed to one or more coarser slurry fractions and finer particles in said slurry be ing preferentially directed to one or more finer slurry fractions. Naturally, a "classification arrangement" may then refer to an arrangement of parts of a flotation unit configured to or suitable for classification of slurry.

Further, a "fraction" may refer to a part of a mixture resulting from separation of said mixture. As such, a "slurry fraction" may refer to a fraction, comprising slurry and resulting from separation of slurry; a "coarser slurry fraction" may refer to a slurry frac tion, comprising solid particles of a larger median size by mass; and a "finer slurry fraction" may refer to a slurry fraction, comprising solid particles of a median size by mass smaller than the larger median size by mass of a coarser slurry fraction.

Generally, a classification arrangement of a froth-in teraction flotation unit being configured to feed a coarser slurry fraction to a coarse slurry feeding ar rangement and to feed a finer slurry fraction to a fine slurry feeding arrangement may increase a throughput and/or overall collection efficiency of said froth-in teraction flotation unit. In particular, by configuring a classification arrangement of a froth-interaction flo tation unit in such manner, the capacity of said froth- interaction flotation unit to feed slurry to a froth layer may be allocated more towards separation of coarse slurry. Additionally or alternatively, recovery of fine slurry may be increased, since probability of attachment of finer particles with flotation gas bubbles may be higher in slurry than in froth.

In an embodiment of the first aspect, the finer slurry fraction has a solids fraction, f ^£X , lower than a solids fraction, f ^OX , of the coarser slurry fraction.

Herein, a "solids fraction" may refer to a ratio between a mass (m _s ) of solids in a slurry sample and a mass (m _sl ) of said slurry sample.

Generally, a maintaining higher f ^OX is advantageous for froth-interaction flotation. On the other hand, a lower f ^£X may facilitate introduction of fine slurry into a volume of slurry.

In an embodiment of the first aspect, the coarser slurry fraction has a solids fraction, f ^OX , in a range from 0.5 to 0.8, or in a range from 0.55 to 0.75 or in a range from 0.6 to 0.7.

Generally, a coarser slurry fraction having a solids fraction, f ^OX , in a range from 0.5 to 0.8, or in a range from 0.55 to 0.75 or in a range from 0.6 to 0.7 may facilitate feeding slurry from said coarser slurry frac tion to a froth layer. In an embodiment of the first aspect, the finer slurry fraction has a solids fraction, f ^£X , in a range from 0.05 to 0.35, or in a range from 0.1 to 0.25 or in a range from 0.15 to 0.2.

Generally, a finer slurry fraction having a solids frac tion, f ^£X , in a range from 0.05 to 0.35, or in a range from 0.1 to 0.25 or in a range from 0.15 to 0.2 may facilitate feeding slurry from said finer slurry frac tion into a volume of slurry. Additionally or alterna tively, a finer slurry fraction having such solids frac tion, f ^£X , may facilitate maintaining a viscosity of a volume of slurry within a specified viscosity range. Additionally or alternatively, a finer slurry fraction having such solids fraction may facilitate maintaining a suitable level of stabilization of a froth layer by solid particles.

In an embodiment of the first aspect, the classification arrangement comprises a classification hydrocyclone.

Throughout this specification, a "hydrocyclone" or a "cyclone" may refer to a device suitable for separation of suspended solid particles in slurry. Typically a hy drocyclone comprises a generally cylindrical feed sec tion; an overflow pipe, extending upwardly from the feed section; and a generally conical base section, extending from the feed section and ending at an apex opening. During operation of a hydrocyclone, slurry is fed tan gentially into the feed section in order to create a vortex inside said hydrocyclone. In a hydrocyclone, slurry fed into said hydrocyclone is parceled out as underflow and overflow. Herein, "underflow" and "overflow" from a hydrocyclone may refer to a product streams discharged via an apex opening and an overflow pipe of said hydrocyclone, re spectively.

In this disclosure, a "classification hydrocyclone" may refer to hydrocyclone configured to or suitable for classification of solid particles in a slurry. In min eral processing, classification hydrocyclones are typ ically used to separate coarser particles from finer particles in order to limit resource consumption of grinding circuits. Generally, a classification hydrocy clone may have a cut-off particle size greater than 10 ym, as measured under typical hydrocyclone operating conditions. Additionally or alternatively, a classifi cation hydrocyclone may have an internal diameter, meas ured across its feed section, greater than or equal to 8 cm.

Herein, "typical hydrocyclone operating conditions" may refer, at least, to holding a hydrocyclone upright; us age of feed slurry, consisting substantially of water and spherical particles with a density of 2650 kg/m ³ at a feed slurry solids fraction of 0.02; and maintaining a pressure drop of 70 kPa. Although a cut-off particle size of a hydrocyclone may be measured under typical hydrocyclone operating conditions, any hydrocyclone may or may not be operated under typical hydrocyclone oper ating conditions in a flotation unit.

Herein, a "cut-off particle size" of a hydrocyclone may refer to a particle size such that a first half and a second half of solid particles in feed slurry of said particle size report to underflow and overflow of said hydrocyclone, respectively. Generally, solid particles smaller than the cut-off particle size are preferen tially directed to overflow, whereas solid particles larger than the cut-off particle size are preferentially directed to underflow.

Generally, a classification arrangement comprising a classification hydrocyclone may simplify said classifi cation arrangement and/or provide a higher throughput with a reduced footprint.

In an embodiment of the first aspect, the classification hydrocyclone has a cut-off particle size, d^o, in a range from 15 ym to 200 ym, or from 40 ym to 175 ym, or from 60 ym to 150 ym, or from 75 ym to 125 ym, as meas ured under typical hydrocyclone operating conditions.

Generally, a cut-off particle size, d^o, in a range from 15 ym to 200 ym, or from 40 ym to 175 ym, or from 60 ym to 150 ym, or from 75 ym to 125 ym, as measured under typical hydrocyclone operating conditions may provide an advantageous division of input slurry to from a coarser slurry fraction and a finer slurry fraction for a froth-interaction flotation unit, even with a single classification stage.

In an embodiment of the first aspect, the tank comprises a launder with a launder lip for collecting froth from the froth layer, a fine slurry outlet below the launder lip for collecting output slurry from the volume of slurry, and a coarse slurry outlet below the fine slurry outlet for discharging coarse output slurry from the volume of slurry.

Throughout this specification, a "launder" may refer to a trough arranged at an upper section of a tank for collecting a flotation product from said tank. Typi cally, a launder comprises a launder lip. Herein, a "launder lip" may refer to a part of a launder over which a flotation product is arranged to flow into said launder for collection.

In this specification, an "outlet" may refer to a means of discharge, e.g., an opening or a through-hole, for a fluid. Generally, an outlet may be arranged in a tank in any suitable manner, for example, at a side wall or at a bottom of a tank, or at an end of a pipe or other suitable conduit for passing fluid through a side wall or a bottom of a tank, or at an end of a pipe or other suitable conduit for passing fluid over a side wall of a tank.

As such, a "fine slurry outlet" may refer to an outlet configured to or suitable for passing fine slurry out of a tank. A fine slurry outlet may additionally be configured to or suitable for passing any other suitable type(s) of slurry, for example, coarse slurry, and/or pristine slurry, out of a tank. Typically, a fine slurry outlet is arranged at an upper section of a tank. In embodiments, wherein a tank comprises a launder with a launder lip, a fine slurry outlet may be arranged below said launder lip. Additionally or alternatively, in em bodiments, wherein a tank comprises a coarse slurry out let, a fine slurry outlet may be arranged above said coarse slurry outlet.

On the other hand, a "coarse slurry outlet" may refer to an outlet configured to or suitable for passing coarse slurry out of a tank. A coarse slurry outlet may additionally be configured to or suitable for passing any other suitable type(s) of slurry, for example, fine slurry, and/or pristine slurry, out of a tank. Typi cally, a coarse slurry outlet is arranged at a lower section of a tank for collecting a flotation product from said tank.

Generally, arranging a fine slurry outlet below a laun der lip of a launder of a tank and above a coarse slurry outlet of said tank may enable collecting from a volume of slurry mainly coarser particles of a first type, e.g., mineral particles, and finer particles of a second type, e.g., gangue particles, which may be further sep arated with relative ease. Additionally or alterna tively, arranging a fine slurry outlet below a launder lip of a launder of a tank and above a coarse slurry outlet of said tank may enable utilization of said fine slurry outlet to provide a discharge path from said tank such that a fluidized bed may extend below said fine slurry outlet.

In an embodiment of the first aspect, the froth-inter- action flotation unit comprises a solid-liquid separa tion arrangement configured to collect output slurry from the volume of slurry via the fine slurry outlet and to separate suspended solids and flotation liquid from the output slurry to form a solids portion and a liquid portion.

Throughout this specification, "solid-liquid separa tion" may refer to separation of suspended solid parti cles and flotation liquid from slurry. Consequently, a "solid-liquid separation arrangement" may refer to an arrangement of parts of a flotation unit configured to or suitable for solid-liquid separation of slurry. Further, a "solids portion" formed by separation of sus pended solid particles and flotation liquid from slurry may refer to a fraction of said slurry, resulting from solid-liquid separation of said slurry, wherein at least 90 % by mass, or at least 95 % by mass, or at least 98 % by mass of suspended solid particles in said slurry have been collected into said fraction.

On the other hand, a "liquid portion" formed by separa tion of suspended solid particles and flotation liquid from slurry may refer to a fraction of said slurry, resulting from solid-liquid separation of said slurry and comprising at least 90 % by mass, or at least at least 95 % by mass, or at least 98 % by mass, or at least 99 % by mass of flotation liquid.

Generally, a froth-interaction flotation unit compris ing a solid-liquid separation arrangement configured to collect output slurry from a volume of slurry via a fine slurry outlet and to separate suspended solids and flo tation liquid from the output slurry to form a solids portion and a liquid portion may facilitate further flo tation of said solids portion. Additionally or alterna tively, a froth-interaction flotation unit comprising such solid-liquid separation arrangement may enable channeling flotation liquid from output slurry within a mineral processing apparatus in order to maintain a de vice or unit with a higher flotation liquid consumption operational.

In an embodiment of the first aspect, the solid-liquid separation arrangement is configured to guide the solids portion out of the froth-interaction flotation unit. Generally, a solid-liquid separation arrangement of a froth-interaction flotation unit being configured to guide a solids portion out of said froth-interaction flotation unit may enable further processing, e.g., flo tation, of solid particles in said solids portion at a distance from said froth-interaction flotation unit.

In an embodiment of the first aspect, wherein the froth- interaction flotation unit comprises a circulation ar rangement for circulating flotation liquid collected from the tank via the fine slurry outlet back into the tank.

Throughout this specification, "circulation" may refer to passage of a fluid along a generally loop-shaped path. Generally, circulation may be intermittent, re peated (e.g., periodic), or continuous. As such, a "cir culation arrangement" may refer to an arrangement of a flotation unit configured to suitable for circulation of flotation liquid collected from a tank of said flo tation unit back into said tank. Generally, flotation liquid may be fed back into a tank by a circulation arrangement in any suitable form(s), for example, in liquid form and/or as a part of slurry or a slurry- flotation gas mixture.

Generally, a flotation unit comprising a circulation arrangement may enable forming an internal slurry feed back loop for a tank, which may increase recovery of solid particles from slurry. Additionally or alterna tively, a flotation unit comprising a circulation ar rangement may reduce consumption of flotation liquid of a froth-interaction flotation unit. In an embodiment of the first aspect, the circulation arrangement is configured to circulate flotation liquid collected from the tank via the fine slurry outlet by adding such flotation liquid to fine slurry, which the fine slurry feeding arrangement is configured to feed into the volume of slurry.

Generally, circulating flotation liquid by adding it to fine slurry to be fed into a tank by a fine slurry feeding arrangement may simplify the structure of a flo tation unit.

In an embodiment of the first aspect, the tank comprises a circulation inlet and the circulation arrangement is configured to feed flotation liquid collected from the tank via the fine slurry outlet back into the tank via the circulation inlet.

Throughout this specification, an "inlet" may refer to a means of entry, e.g., an opening or a through-hole, for a fluid. Generally, an inlet may be arranged in a tank in any suitable manner, for example, at a side wall or at a bottom of a tank, or at an end of a pipe or other suitable conduit for passing fluid through a side wall or a bottom of a tank, or at an end of a pipe or other suitable conduit for passing fluid over a side wall of a tank.

Consequently, a "circulation inlet" may refer to an in let configured to or suitable for introducing fluid propagating along a generally loop-shaped path into a tank. Additionally or alternatively, a circulation inlet of a tank may be configured to or suitable for feeding flotation liquid collected from said tank back into said tank. Generally, flotation liquid may be fed through a circulation inlet of a tank as a fluid, comprising flo tation liquid and, optionally, one or more of flotation gas and solid particles collected from said tank.

Generally, circulating flotation liquid by feeding it into a tank via circulation inlet separate from any inlet through which fine slurry is fed into said tank may enable operating a circulation arrangement inde pendently of a fine slurry feeding arrangement, which may, in turn, increase a reliability of a flotation unit.

In an embodiment of the first aspect, the flotation gas supply arrangement is configured to supply flotation gas into the volume of slurry by injecting flotation gas to flotation liquid, which the circulation arrangement is configured to feed back into the tank via the circula tion inlet.

In an embodiment of the first aspect, the tank comprises a fine slurry inlet and a flotation gas inlet below the fine slurry inlet, the fine slurry feeding arrangement is configured to feed fine slurry into the volume of slurry via the fine slurry inlet, and the flotation gas supply arrangement is configured to supply flotation gas into the volume of slurry via the flotation gas inlet.

In this specification, a "fine slurry inlet" may refer to an inlet configured to or suitable for passing fine slurry into a tank, and/or a "flotation gas inlet" may refer to an inlet configured to or suitable for passing flotation gas into a tank.

Generally, arranging a flotation gas inlet below a fine slurry inlet may increase recovery of solid particles passed into a tank via said fine slurry inlet. In an embodiment of the first aspect, the tank comprises a fine slurry-flotation gas mixture inlet, and the flo tation gas supply arrangement is configured to supply flotation gas into the volume of slurry by injecting flotation gas into fine slurry, which the fine slurry feeding arrangement is configured to feed into the vol ume of slurry via the fine slurry-flotation gas mixture inlet.

In this disclosure, a "fine slurry-flotation gas mixture inlet" may refer to an inlet configured to or suitable for passing a mixture of fine slurry and flotation gas into a tank.

Generally, supplying flotation gas into a volume of slurry by injecting flotation gas into fine slurry, which a fine slurry feeding arrangement is configured to feed into the volume of slurry may promote attachment of flotation gas bubbles to solid particles in said fine slurry.

In an embodiment of the first aspect, the fine slurry feeding arrangement comprises a slurry sump with a sump slurry outlet at a lower section of the slurry sump, the classification arrangement is configured to channel the finer slurry fraction to the slurry sump, and the fine slurry feeding arrangement is configured to feed fine slurry into the volume of slurry via the sump slurry outlet.

In this disclosure, a "sump" may refer to a reservoir, e.g., a pit or a container, suitable for or configured to collecting and/or holding a liquid. As such, a "slurry sump" may refer to a sump for collecting and/or holding slurry. Generally, collecting fine slurry to be fed into a vol ume of slurry from a slurry sump may increase a solids fraction of fine slurry to be fed into said volume of slurry, which may, in turn, increase a solids fraction of coarse slurry collected via a coarse slurry outlet. This may contribute towards reducing consumption of flo tation liquid in a flotation unit. Additionally or al ternatively, when a froth-interaction flotation unit comprises a classification arrangement for separating input slurry into a coarser slurry fraction to be fed to a froth layer and to a finer slurry fraction to be fed into a volume of slurry below said froth layer, said finer slurry fraction may have a relatively low solids fraction, and increasing said solids fraction may in crease recovery of solid particles from both said coarser slurry fraction and from said finer slurry frac tion.

In an embodiment of the first aspect, the froth-inter- action flotation unit comprises a flotation liquid sup ply arrangement for supplying flotation liquid into the volume of slurry.

In this disclosure, a "flotation liquid supply arrange ment" may refer to an arrangement of parts of a flotation unit configured to or suitable for supplying flotation liquid into a tank of a flotation unit from a source external to the flotation unit, e.g., a process water unit of a mineral processing apparatus or a body of water.

Generally, a flotation unit comprising a flotation liq uid supply arrangement may facilitate maintaining a top surface of a volume of slurry at a set distance from a launder lip of a launder of a tank. Additionally of alternatively, a flotation unit comprising a flotation liquid supply arrangement may facilitate controlling viscosity of slurry in a tank.

In an embodiment of the first aspect, the tank comprises a flotation liquid inlet, and the flotation liquid sup ply arrangement is configured to feed flotation liq uid into the volume of slurry via the flotation liquid inlet.

Herein, a "flotation liquid inlet" may refer to a an inlet configured to or suitable for passing flotation liquid into a tank.

In an embodiment of the first aspect, the flotation liquid supply arrangement is configured to supply flo tation liquid into the volume of slurry by adding flo tation liquid to fine slurry, which the fine slurry feeding arrangement is configured to feed into the vol ume of slurry.

In an embodiment of the first aspect, the tank comprises a downwardly tapering bottom cone.

Throughout this specification, a "bottom cone" of a tank may refer to a generally funnel-shaped and downwardly tapering bottom structure of said tank suitable for or configured to guide settled solid particles towards an outlet or an inlet.

Generally, a tank comprising a bottom cone may reduce sanding in said tank.

In an embodiment of the first aspect, the froth-inter- action flotation unit comprises a slurry agitation ar rangement for agitating the volume of slurry. Throughout this specification, a "agitation" may refer stirring, mixing and/or disturbing a fluid, e.g., a liq uid.

Consequently, a "slurry agitation arrangement" may refer to an arrangement of parts of a flotation unit config ured to or suitable for agitation of slurry.

Generally, a slurry agitation arrangement may increase a homogeneity of a volume of slurry in a tank. Addi tionally or alternatively, a froth-interaction flota tion unit comprising a slurry agitation arrangement may facilitate maintaining a fluidized bed in a volume of slurry in a tank.

In an embodiment of the first aspect, the froth-inter- action flotation unit is implemented as a fluidized-bed flotation unit.

Throughout this disclosure, a "fluidized bed" may refer to a solid-fluid mixture, which exhibits fluid-like properties. As known to the skilled person, a fluidized bed may be maintained by passing pressurized fluid (s), i.e., liquid(s) and/or gas(es), through a particulate medium.

Consequently, "fluidized-bed flotation" may refer to flotation, wherein a fluidized bed is maintained in a volume of slurry by suitably passing flotation liquid and/or flotation gas through said volume of slurry, and a "fluidized-bed flotation unit" may refer to a unit suitable for or configured to subject material to flu- idized-bed flotation.

Generally, maintaining a fluidized bed in a tank of a flotation unit may increase recovery of coarser parti cles. Additionally or alternatively, when coarse slurry is fed to a froth layer for froth-interaction flotation and a fluidized bed is maintained in a volume of slurry below said froth layer, coarser particles of said coarse slurry that have inadvertently dropped into said volume of slurry may settle through said fluidized bed and may be recollected more efficiently to the froth layer.

According to a second aspect, this disclosure relates to use of a froth-interaction flotation unit according to the first aspect or any embodiment thereof for sep aration of a valuable material suspended in slurry.

In an embodiment of the second aspect, this disclosure relates to use of a froth-interaction flotation unit according to the first aspect or any embodiment thereof for separation of particles, comprising copper (Cu), from low-grade ore.

According to a third aspect, a mineral processing appa ratus, comprising a froth-interaction flotation unit according to the first aspect or any embodiment thereof, is provided.

Throughout this specification, an "apparatus" may refer to equipment suitable for or configured to perform a systematic series of processes. An apparatus may com prise any suitable number, for example, one or more, units. Consequently, a mineral processing apparatus" may refer to an apparatus suitable for or configured to separation of mineral(s) from ore. A mineral processing apparatus may generally comprise any unit(s) suitable or necessary for flotation and, optionally, any unit(s) suitable or necessary for pre-treating material prior to flotation and/or post-treating material following flotation. In an embodiment of the third aspect, the mineral pro cessing apparatus comprises a comminution unit config ured to grind ore to form ground ore, to mix the ground ore with flotation liquid to form pristine slurry, and to feed the pristine slurry to the froth-interaction flotation unit.

Throughout this specification, "comminution" may refer to any action (s) taken in order to reduce an average particle size of solid material. As such, comminution may comprise, for example, crushing and/or grinding. In mineral processing, comminution is commonly used for liberation of valuable mineral(s) from gangue.

Consequently, a "comminution unit" may refer to a device suitable for or configured to reduce an average particle size of a solid material.

Generally, a comminution unit being configured to feed pristine slurry to a froth-interaction flotation unit may allow removal of a larger amount of gangue at an earlier stage, which may, in turn simplify the structure of a mineral processing apparatus downstream from said froth-interaction flotation unit and/or reduce overall energy and/or flotation liquid consumption of said min eral processing apparatus. A froth-interaction flota tion unit in accordance with this specification may be particularly suited for flotation of slurry with a broader particle size distribution. As such, a comminu tion unit may feed such froth-interaction flotation unit with pristine slurry, which may have a particle size distribution dictated mainly by characteristics of com minution processes performed by said comminution unit. As known to the skilled person, such particle size dis tribution may (substantially) follow, for example, a so- called Weibull distribution, also referred to as a Rosin-Rammler distribution in relation to mineral pro cessing.

In an embodiment of the third aspect, the mineral pro cessing apparatus comprises a comminution unit, a pre classification unit, and a primary flotation unit. The comminution unit is configured to grind ore to form ground ore, to mix the ground ore with flotation liquid to form pristine slurry, and to feed the pristine slurry to the pre-classification unit. The pre-classification unit is configured to classify the pristine slurry to form a coarser pristine slurry fraction and a finer pristine slurry fraction and to feed the finer pristine slurry fraction to the primary flotation unit. The pri mary flotation unit is configured to separate the finer pristine slurry fraction to form an overflow and an underflow and to feed the underflow to the froth-inter- action flotation unit.

Generally, in standard flotation, underflow from a pri mary flotation unit may comprise a considerable amount of coarser particles of valuable mineral(s) mixed with finer gangue particles. Since a froth-interaction flo tation unit in accordance with this specification may be particularly suited for flotation of slurry with a broader particle size distribution, a primary flotation unit being configured to feed its underflow to a froth- interaction flotation unit in accordance with this spec ification may facilitate further flotation of said un derflow. Naturally, similar considerations apply, muta- tis mutandis, in case of reverse flotation. According to a fourth aspect, a method for separation of input slurry using froth-interaction flotation is provided. The method comprises providing a tank for holding a volume of slurry and a froth layer over the volume of slurry, supplying flotation gas into the vol ume of slurry, classifying the input slurry to form a coarser slurry fraction and a finer slurry fraction, feeding the coarser slurry fraction to the froth layer, and feeding the finer slurry fraction into the volume of slurry.

In an embodiment of the fourth aspect, the method com prises maintaining a fluidized bed in the volume of slurry.

In an embodiment of the fourth aspect, the finer slurry fraction has a solids fraction, f ^£X , lower than a solids fraction, f ^OX , of the coarser slurry fraction.

In an embodiment of the fourth aspect, the coarser slurry fraction has a solids fraction, f ^OX , in a range from 0.5 to 0.8, or in a range from 0.55 to 0.75 or in a range from 0.6 to 0.7.

In an embodiment of the fourth aspect, the finer slurry fraction has a solids fraction, f ^£X , in a range from 0.05 to 0.35, or in a range from 0.1 to 0.25 or in a range from 0.15 to 0.2.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood from the following detailed description read in light of the accompanying drawings, wherein: FIG. 1 shows a schematic view of a froth-in teraction flotation unit,

FIG. 2 depicts a schematic view of another froth-interaction flotation unit, and

FIG. 3 shows a schematic view of a mineral pro cessing apparatus,

FIG. 4 depicts a schematic view of another min eral processing apparatus, and

FIG. 5 illustrates a method for separation of input slurry using froth-interaction flotation.

Unless specifically stated to the contrary, any drawing of the aforementioned drawings may be not drawn to scale such that any element in said drawing may be drawn with inaccurate proportions with respect to other elements in said drawing in order to emphasize certain structural aspects of the embodiment of said drawing.

Moreover, corresponding elements in the embodiments of any two drawings of the aforementioned drawings may be disproportionate to each other in said two drawings in order to emphasize certain structural aspects of the embodiments of said two drawings.

DETAILED DESCRIPTION

FIG. 1 depicts a froth-interaction flotation unit 1000 according to an embodiment.

The froth-interaction flotation unit 1000 of the embod iment of FIG. 1 may be used in so-called "standard flo tation", wherein valuable mineral (s) in input slurry 1601 is collected as overflow and gangue is di rected to underflow. In other embodiments, a froth-interaction flotation unit may be used in any suitable manner, for example, in standard flotation and/or in so-called "reverse flota tion", wherein valuable mineral(s) in input slurry is directed to underflow and gangue is collected as over flow.

The froth-interaction flotation unit 1000 of the embod iment of FIG. 1 may specifically be used in so-called "coarse flotation", wherein slurry comprising a consid erable amount of coarser solid particles is used as feed material for flotation.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a tank 1100.

The tank 1100 of the embodiment of FIG. 1 is configured to hold a volume of slurry 1001 and a froth layer 1002 over the volume of slurry 1001. In other embodiments, a tank may be configured to or suitable for holding a volume of slurry and a froth layer over said volume of slurry.

Although a single tank is depicted in FIG. 1, a froth- interaction flotation unit may generally comprise one or more, e.g., one, two, three, four, etc., tanks.

The tank 1100 of the embodiment of FIG. 1 comprises a launder 1101, which comprises a launder lip 1102. The launder 1101 is configured to collect froth 1003 from the froth layer 1002. Generally, a tank comprising a launder may facilitate collection of a flotation product from said tank. In other embodiments, a tank may com prise any suitable means, for example, a launder with a launder lip, for collecting a flotation product from an upper section of said tank. The froth-interaction flotation unit 1000 may be con figured to maintain a froth depth, d ^f , of approximately 10 cm for the froth layer 1002.

Herein, a "froth depth" may refer to a thickness of a froth layer in a tank, measured as a vertical distance between a launder lip and a surface of a volume of slurry in said tank, when said tank is in use.

In other embodiments, any suitable substantially non zero d ^f , for example, a d ^f in a range from 1 cm to 20 cm, may be used.

The tank 1100 of the embodiment of FIG. 1 comprises a fine slurry inlet 1103. In other embodiments, a tank may or may not comprise such fine slurry inlet.

The tank 1100 of the embodiment of FIG. 1 comprises a fine slurry-flotation gas mixture inlet 1104. In other embodiments, a tank may or may not comprise such fine slurry-flotation gas mixture inlet.

The tank 1100 of the embodiment of FIG. 1 comprises a coarse slurry outlet 1106 for discharging coarse output slurry 1107 from the volume of slurry 1001.

The coarse slurry outlet 1106 of the embodiment may have an opening diameter, d _o ^S , of approximately 10 cm. Gen erally, a coarse slurry outlet with a higher d _o ^S may facilitate passage of coarser solid particles via said coarse slurry outlet, which may, in turn, facilitate flotation of (extremely) coarse slurry. In other embod iments, a coarse slurry outlet may have any suitable d _o ^S , for example, an d _o ^S in a range from 2 cm to 20 cm. Herein, an "opening diameter" may refer to a shortest transverse measurement of an opening, measured perpen dicular to an intended fluid flow direction through said opening.

In the embodiment of FIG. 1, the tank 1100 comprises a downwardly tapering bottom cone 1105. In other embodi ments, a tank may or may not comprise such bottom cone.

In the embodiment of FIG. 1, the coarse slurry out let 1106 is arranged at the bottom of the bottom cone 1105. Generally, a tank comprising a bottom cone and a coarse slurry outlet at the bottom of said bottom cone may facilitate discharge of extremely coarse slurry out of said tank and/or reduce sanding in said tank. In other embodiments, a coarse slurry outlet may be ar ranged in any suitable manner, for example, at the bot tom of a bottom cone. For example, in some embodiments, a tank may comprise a flat bottom; a side wall, extending from said bottom; and a coarse slurry outlet arranged at said side wall, and in some embodiments, a tank may comprise a bottom cone and a fine slurry inlet at the bottom of said bottom cone.

The tank 1100 of the embodiment of FIG. 1 comprises a flotation gas inlet 1108. In other embodiments, a tank may or may not comprise such flotation gas inlet.

The flotation gas inlet 1108 of the embodiment is ar ranged below the fine slurry inlet 1103. In other em bodiments, a flotation gas inlet and a fine slurry inlet may be arranged in any suitable manner, for example, such that said flotation gas inlet is arranged below said fine slurry inlet. The tank 1100 of the embodiment of FIG. 1 comprises a fine slurry outlet 1110 for collecting output slurry 1701 from the volume of slurry 1001. In other embodiments, a tank may or may not comprise such fine slurry outlet.

In the embodiment of FIG. 1, the fine slurry outlet 1110 is arranged below the launder lip 1102 and above the coarse slurry outlet 1106. In other embodiments, a fine slurry outlet may be arranged in any suitable manner, for example, below a launder lip of a launder and above a coarse slurry outlet.

In the embodiment of FIG. 1, the output slurry 1701 col lected from the volume of slurry 1001 via the fine slurry outlet 1110 may comprise fine gangue particles and coarse particles of valuable mineral(s). In other embodiments, output slurry collected from a volume of slurry via a fine slurry outlet may comprise any suit able type(s) of particles, for example, fine gangue par ticles and coarse particles of valuable mineral(s) or fine particles of valuable mineral(s) and coarse gangue particles.

The tank 1100 of the embodiment of FIG. 1 comprises a flotation liquid inlet 1109. In other embodiments, a tank may or may not comprise such flotation liquid in let.

The flotation liquid inlet 1109 of the embodiment is arranged below the fine slurry outlet 1110. Generally, when a fluidized bed is to be maintained in a volume of slurry, arranging a flotation liquid inlet below a fine slurry outlet may enable utilization of flotation liquid fed into a tank via said flotation liquid inlet in main taining said fluidized bed. In other embodiments, a flo tation liquid inlet may be arranged in any suitable manner, for example, below a fine slurry outlet.

The tank 1100 of the embodiment of FIG. 1 comprises a circulation inlet 1111. In other embodiments, a tank may or may not comprise such circulation inlet.

The circulation inlet 1111 of the embodiment of FIG. 1 is arranged below the fine slurry outlet 1110. Gener ally, when a fluidized bed is to be maintained in a volume of slurry, arranging a circulation inlet below a fine slurry outlet may enable utilization of flotation liquid fed into a tank via said circulation inlet in maintaining said fluidized bed. In other embodiments, a circulation inlet may be arranged in any suitable man ner, for example, below a fine slurry outlet.

The froth-interaction flotation unit 1000 is imple mented as a fluidized-bed flotation unit. As such, when the froth-interaction flotation unit 1000 is in use, a fluidized bed 1004 is maintained in a volume of slurry 1001. In other embodiments, a froth-interaction flotation unit may or may not be implemented as a flu- idized-bed flotation unit.

Although in FIG. 1 the fluidized bed 1004 extends from above the circulation inlet 1111 to above the fine slurry outlet 1110, a fluidized bed may generally be arranged in a tank of a froth-interaction flotation unit in any suitable manner, for example, to extend between any suitable horizontal levels of a tank. In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a coarse slurry feeding ar rangement 1200. The coarse slurry feeding arrange ment 1200 of the embodiment of FIG. 1 is configured to feed coarse slurry 1201 to the froth layer 1002. Gener ally, feeding coarse slurry to a froth layer may in crease a recovery of mineral particles in said coarse slurry. In other embodiments, a coarse slurry feeding arrangement may be suitable for or configured to feed coarse slurry to a froth layer.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a fine slurry feeding ar rangement 1400. As indicated by dashed arrows in FIG. 1, the fine slurry feeding arrangement 1400 may be config ured to feed fine slurry 1401 into the volume of slurry 1001 via the fine slurry inlet 1103 and/or via the fine slurry-flotation gas mixture inlet 1104. In other embodiments, a fine slurry feeding arrangement may be suitable for or configured to feed fine slurry into a tank in any suitable manner, for example, by feeding fine slurry into a volume of slurry via a fine slurry inlet and/or a fine slurry-flotation gas mixture inlet.

The fine slurry feeding arrangement 1400 of the embod iment of FIG. 1 comprises a slurry sump 1402, comprising a sump slurry outlet 1403 at a lower section of the slurry sump 1402. In other embodiments, a fine slurry feeding arrangement may or may not comprise such slurry sump.

The fine slurry feeding arrangement 1400 of the embod iment of FIG. 1 is configured to collect fine slurry 1401 to be fed into the volume of slurry 1001 from the slurry sump 1402 via the sump slurry out let 1403. In other embodiments, a fine slurry feeding arrangement may or may not be arranged in such manner.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a classification arrange ment 1600 configured to classify input slurry 1601 to form a coarser slurry fraction 1602 and a finer slurry fraction 1603. The classification arrangement 1600 of the embodiment of FIG. 1 is configured to feed the coarser slurry fraction 1602 to the coarse slurry feed ing arrangement 1200 and to feed the finer slurry frac tion 1603 to the fine slurry feeding arrangement 1400.

Although not depicted in FIG. 1, a classification ar rangement may generally be configured to classify input slurry so that product(s) other than a coarser slurry fraction and a finer slurry fraction are also formed. In such case, a classification arrangement may be con figured to channel such other product(s) to any suitable location (s), arrangement(s), or unit(s).

The classification arrangement 1600 of the embodiment of FIG. 1 is configured to feed the finer slurry frac tion 1603 into the slurry sump 1402. In other embodi ments, a classification arrangement may be configured to feed a finer slurry fraction to a fine slurry feeding arrangement in any suitable manner, for example, by feeding said finer slurry fraction to a slurry sump of said fine slurry feeding arrangement.

In the embodiment of FIG. 1, the finer slurry frac tion 1603 may have a solids fraction, f ^£X , which is lower than the solids fraction, f ^OX , of the coarser slurry fraction 1602. In other embodiments, a finer slurry fraction fed by a classification arrangement to a fine slurry feeding arrangement may or may not have a f ^£X lower than a f ^OX of a coarser slurry fraction fed by said classification arrangement to a coarse slurry feed ing arrangement.

In the embodiment of FIG. 1, the coarser slurry frac tion 1602 may have a solids fraction, f ^OX , of approxi mately 0.6. In other embodiments, a coarser slurry frac tion may have any suitable solids fraction, f ^OX , for example, a f ^OX in a range from 0.5 to 0.8, or in a range from 0.55 to 0.75 or in a range from 0.6 to 0.7.

In the embodiment of FIG. 1, the finer slurry frac tion 1603 may have a solids fraction, f ^£X , of approxi mately 0.2. In other embodiments, a finer slurry frac tion may have any suitable solids fraction, f ^£X , for example, a f ^£X in a range from 0.05 to 0.35, or in a range from 0.1 to 0.25 or in a range from 0.15 to 0.2.

The classification arrangement 1600 of the embodiment of FIG. 1 comprises a classification hydrocyclone 1604. In other embodiments, a classification arrangement may or may not comprise a classification hydrocyclone.

Although a single classification hydrocyclone 1604 is depicted in FIG. 1, a classification arrangement may generally comprise one or more classification hydrocy clones.

In some embodiments, in addition to or as an alternative to a classification hydrocyclone, a classification ar rangement may comprise one or more of a non-mechanical sedimentation classifier, e.g., a settling cone; a me- chanical sedimentation classifier, e.g., a rake classi fier or a spiral classifier; a free-settling classifier; and a hindered-settling classifier, e.g., a hydrosizer.

In the embodiment of FIG. 1, the classification hydro cyclone 1604 may have a cut-off particle size, d§ _0/ of approximately 100 ym, as measured under typical hydro cyclone operating conditions. In other embodiments, a classification hydrocyclone may have any suitable d§ _0/ for example, a dj ₀ in a range from 15 ym to 200 ym, or from 40 ym to 175 ym, or from 60 ym to 150 ym, or from 75 ym to 125 ym, as measured under typical hydrocyclone operating conditions.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a solid-liquid separation arrangement 1700 configured to collect output slurry 1701 from the volume of slurry 1001 via the fine slurry outlet 1110 and to separate suspended solids and flotation liquid from the output slurry 1701 to form a solids portion 1702 and a liquid portion 1703. In other embodiments, a froth-interaction flotation unit may or may not comprise such solid-liquid separation arrange ment. For example, in some embodiments, output slurry collected via a fine slurry outlet may be subjected to classification to form slurry of generally finer parti cle size and slurry of generally coarser particle size. In said embodiments, such slurry of generally finer par ticle size may be circulated back into a tank and/or such slurry of generally coarser particle size may be guided out of a solid-liquid separation arrangement.

The solid-liquid separation arrangement 1700 of the em bodiment of FIG. 1 is configured to guide the solids portion 1702 out of the froth-interaction flotation unit 1000, for example, to a further flotation unit. In other embodiments, a solid-liquid separation arrange ment may or may not be configured to guide a solids portion out of said froth-interaction flotation unit. For example, in some embodiments, solid particles in output slurry collected via a fine slurry outlet may be channeled from a solid-liquid separation arrangement to a classification arrangement.

The solid-liquid separation arrangement 1700 of the em bodiment of FIG. 1 is configured to feed the liquid portion 1703 to a circulation arrangement 1800 of the froth-interaction flotation unit 1000 (see below). In other embodiments, a solid-liquid separation arrange ment may or may not be configured to feed a liquid portion to a circulation arrangement.

Although not depicted in FIG. 1, a solid-liquid separa tion arrangement may generally be configured to separate suspended solids and flotation liquid from output slurry so that product(s) other than a solids portion and a liquid portion are also formed. In such case, a solid- liquid separation arrangement may be configured to chan nel such other product(s) to any suitable location (s), arrangement (s), or unit(s).

In the embodiment of FIG. 1, the solids portion 1702 may have a solids fraction, f ^Xr , of approximately 0.3. Gen erally, a solids portion having a sufficiently high solids fraction may facilitate further flotation of said solids portion. In other embodiments, a solids portion may have any suitable solids fraction, for example, a solids fraction greater than or equal to 0.2, or greater than or equal to 0.3 or greater than or equal to 0.4.

In the embodiment of FIG. 1, the liquid portion 1703 may have a solids fraction, f ^1r , of approximately 0.05. Gen erally, a liquid portion having a lower solids fraction may facilitate usage of said liquid portion in main taining device (s) and/or unit(s) with a higher flotation liquid consumption (s) operational. In other embodi ments, a liquid portion may have any suitable solids fraction, for example, a solids fraction less than or equal to 0.1, or less than or equal to 0.05, or less than or equal to 0.02, or less than or equal to 0.01.

The solid-liquid separation arrangement 1700 of the em bodiment of FIG. 1 comprises a solid-liquid separation hydrocyclone 1704. In other embodiments, a solid-liquid separation arrangement may or may not comprise a solid- liquid separation hydrocyclone.

In some embodiments, in addition to or as an alternative to a solid-liquid separation hydrocyclone, a solid-liq uid separation arrangement may comprise one or more of a gravitational sedimentation device, e.g., a thickener or a inclined plate settler; a centrifuge; and a fil tration device, e.g., a pressure filter, a tube press, a vacuum filter, or a rotary-drum filter.

Throughout this specification, a "solid-liquid separa tion hydrocyclone" or a "dewatering hydrocyclone" may refer to a hydrocyclone configured to or suitable for solid-liquid separation of slurry. Generally, a solid- liquid separation hydrocyclone may have a cut-off par ticle size less than or equal to 10 ym, as measured under typical hydrocyclone operating conditions. Addi tionally or alternatively, a solid-liquid separation hydrocyclone may have an internal diameter, measured across its feed section, less than 8 cm.

The solid-liquid separation hydrocyclone 1704 of the embodiment of FIG. 1 may have a cut-off particle size, dso, of approximately 10 ym, as measured under typical hydrocyclone operating conditions. In other em bodiments, a solid-liquid separation hydrocyclone may have any suitable d^o, for example, a d|o less than or equal to 10 ym, or less than or equal to 8 ym, or less than or equal to 6 ym.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a circulation arrange ment 1800 for circulating flotation liquid 1801, 1802 collected from the tank 1100 via the fine slurry out let 1110 back into the tank 1100.

The circulation arrangement 1800 of the embodiment of FIG. 1 is configured to supply flotation liquid 1801, 1802 collected from the tank 1100 via the fine slurry outlet 1110 back into the tank 1100 such that said flo tation liquid 1801, 1802 is reintroduced into the tank 1100 below the fine slurry outlet 1110. Generally, configuring a circulation arrangement to supply flota tion liquid collected from a tank via a fine slurry outlet back into said tank such that said flotation liquid is introduced into said tank below a fine slurry outlet may enable utilizing circulation of flotation liquid for maintaining a fluidized bed in said tank. In other embodiments, a circulation arrangement may be con figured to supply flotation liquid collected from a tank via a fine slurry outlet back into said tank in any suitable manner, for example, such that said flotation liquid is introduced into said tank below a fine slurry outlet.

As indicated in FIG. 1 using dashed arrows, the circu lation arrangement 1800 of the embodiment of FIG. 1 may be configured to feed flotation liquid 1801 collected from the tank 1100 via the fine slurry outlet 1110 back into the tank 1100 via the circulation inlet 1111 and/or to add such flotation liquid 1802 to fine slurry 1401, which the fine slurry feeding arrangement 1400 is con figured to feed into the volume of slurry 1001. In other embodiments, a circulation arrangement may or may not be configured in such manner.

The circulation arrangement 1800 of the embodiment of FIG. 1 may be specifically configured to add flotation liquid 1802 collected from the tank 1100 via the fine slurry outlet 1110 to fine slurry 1401, which the fine slurry feeding arrangement 1400 is configured to feed into the volume of slurry 1001, by feeding said flota tion liquid 1802 into the slurry sump 1402. In other embodiments, a circulation arrangement may be configured to add flotation liquid to fine slurry to be fed into a tank by a fine slurry feeding arrangement in any suit able manner, for example, by feeding said flotation liq uid into a slurry sump.

The circulation arrangement 1800 of the embodiment of FIG. 1 is configured to receive the liquid portion 1703, which the solid-liquid separation arrangement 1700 is configured to channel to the circulation arrange- ment 1800. In other embodiments, a circulation arrange ment may or may not be configured to receive a liquid portion formed by a solid-liquid separation arrangement through separation of suspended solids and flotation liquid from output slurry collected via a fine slurry outlet. For example, in some embodiments, a froth-in teraction flotation unit may be configured to operate in the absence of a solid-liquid separation arrangement. In such embodiments, a circulation arrangement may be configured to collect output slurry via a fine slurry outlet.

In the embodiment of FIG. 1, flotation liquid 1801, which the circulation arrangement 1800 may be configured to feed back into the tank 1100 via the circulation inlet 1111, and/or flotation liquid 1802, which the cir culation arrangement 1800 may be configured to add to fine slurry 1401, which the fine slurry feeding arrange ment 1400 is configured to feed into the volume of slurry 1001, may be taken from the liquid portion 1703 channeled to the circulation arrangement 1800 by the solid-liquid separation arrangement 1700. In other em bodiments, a circulation arrangement may or may not be configured to feed flotation liquid from a liquid por tion back into a tank via a circulation inlet and/or to add flotation liquid from a liquid portion to fine slurry, which a fine slurry feeding arrangement is con figured to feed into a volume of slurry.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a flotation gas supply ar rangement 1300. The flotation gas supply arrange ment 1300 is configured to supply flotation gas 1301, 1302, 1303 into the volume of slurry 1001. In other embodiments, a flotation gas supply arrangement may be suitable for or configured to supply flotation gas into a volume of slurry held in a tank.

In the embodiment of FIG. 1, air may be used as the flotation gas 1301, 1302, 1303. In other embodiments, any suitable flotation gas(es), e.g., air, argon, ni trogen, hydrogen, or mixtures thereof, may be used.

The flotation gas supply arrangement 1300 of the embod iment of FIG. 1 is configured to supply flotation gas 1301, 1302, 1303 into the volume of slurry 1001 such that the froth layer 1002 is maintained over the volume of slurry 1001. In other embodiments, a flotation gas supply arrangement may be suitable for or configured to supply flotation gas into a volume of slurry such than a froth layer is maintained over said volume of slurry.

As indicated in FIG. 1 by dashed arrows, the flotation gas supply arrangement 1300 of the embodiment of FIG. 1 may be configured to feed flotation gas 1301 into the volume of slurry 1001 via the flotation gas inlet 1108. In other embodiments, a flotation gas supply arrangement may be configured to supply flotation gas into a tank in any suitable manner(s), for example, by feeding flo tation gas into a volume of slurry via a flotation gas inlet.

As indicated in FIG. 1 by dashed arrows, the flotation gas supply arrangement 1300 of the embodiment of FIG. 1 may be configured to supply flotation gas into the vol ume of slurry 1001 by injecting flotation gas 1302 into fine slurry 1401, which the fine slurry feeding arrange ment 1400 is configured to feed into the volume of slurry 1001 via the fine slurry-flotation gas mixture inlet 1104 and/or by injecting flotation gas 1303 to flotation liquid 1801 collected via the fine slurry out let 1110, which the circulation arrangement 1800 is con figured to feed back into the tank 1100 via the circu lation inlet 1111. In other embodiments, a flotation gas supply arrangement may or may not be configured in such manner.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a flotation liquid supply arrangement 1500 for supplying flotation liquid 1501, 1502 into the volume of slurry 1001. In other embodi ments, a flotation unit may or may not comprise such flotation liquid supply arrangement. For example, in some embodiments, maintaining a top surface of a volume of slurry at a set distance from a launder lip of a launder of a tank may be achieved by controlling the operation of slurry feeding arrangements and slurry out let (s) of said tank.

As indicated in FIG. 1 by dashed arrows, the flotation liquid supply arrangement 1500 of the embodiment of FIG. 1 may be configured to feed flotation liquid 1501 into the volume of slurry 1001 via the flotation liquid inlet 1109 and/or to supply flotation liquid 1502 into the volume of slurry 1001 by adding flotation liq uid 1502 to fine slurry 1401, which the fine slurry feeding arrangement 1400 is configured to feed into the volume of slurry 1001. In other embodiments, a flotation liquid supply arrangement may be configured to supply flotation liquid into a tank in any suitable manner(s), for example, by feeding flotation liquid into a volume of slurry via a flotation liquid inlet and/or by adding flotation liquid to fine slurry, which a fine slurry feeding arrangement is configured to feed into said tank.

The flotation liquid supply arrangement 1500 of the em bodiment of FIG. 1 may be specifically configured to supply flotation liquid 1502 into the volume of slurry 1001 by feeding flotation liquid 1502 into the slurry sump 1402. In other embodiments, a flotation liq uid supply arrangement may be configured to add flota tion liquid to fine slurry, which a fine slurry feeding arrangement is configured to feed into a tank, in any suitable manner, for example, by feeding flotation liq uid to a slurry sump of said fine slurry feeding ar rangement.

In the embodiment of FIG. 1, the froth-interaction flo tation unit 1000 comprises a slurry agitation arrange ment 1900 for agitating the volume of slurry 1001. In other embodiments, a froth-interaction flotation unit may or may not comprise such slurry agitation arrange ment. In embodiments, wherein a froth-interaction flo tation unit comprises a slurry agitation arrangement, said slurry agitation arrangement may be implemented in any suitable manner.

The slurry agitation arrangement 1900 of the embodiment of FIG. 1 comprises a rotor 1901 fixed to a drive shaft 1902. In other embodiments, a slurry agitation arrangement of a froth-interaction flotation unit may or may not comprise such rotor and such drive shaft.

The rotor 1901 of the embodiment of FIG. 1 is arranged at a lower section of the tank 1100. Generally, arrang ing a rotor of a slurry agitation arrangement at a lower section of a tank may facilitate subjecting settled par ticles of sediment formed in a tank to further flotation in said tank. In other embodiments, a rotor of a slurry agitation arrangement may be arranged in a tank in any suitable manner, for example, at a lower section of said tank.

In embodiments, wherein a slurry agitation arrangement comprises a rotor and a drive shaft, said slurry agita tion arrangement may further comprise a stator such that said rotor and said stator form a rotor-stator mechanism and/or a standpipe surrounding said drive shaft such that a flotation gas supply arrangement may be config ured to supply flotation gas into a volume of slurry held in a tank through said standpipe.

FIG. 2 depicts a froth-interaction flotation unit 2000 for separation of input slurry 2601 according to an em bodiment. Although not explicitly shown in FIG. 2, the froth-interaction flotation unit 2000, any part thereof, and/or any arrangement of the froth-interaction flotation unit 2000 may generally comprise any fea ture (s) and/or element(s) of the embodiment of FIG. 1 or any other embodiments disclosed with reference to, in conjunction with, and/or concomitantly with FIG. 1.

The froth-interaction flotation unit 2000 of the embod iment of FIG. 2 comprises a tank 2100 for holding a volume of slurry 2001 and a froth layer 2002 over the volume of slurry 2001.

The tank 2100 of the embodiment of FIG. 2 comprises a launder 2101 with a launder lip 2102 for collecting froth 2003 from the froth layer 2002, a fine slurry in let 2103, a coarse slurry outlet 2106 below the fine slurry inlet 2103 at a lower section of the tank 2100 for collecting coarse output slurry 2107, and a flota tion gas inlet 2108 at the bottom of the tank 2100.

The froth-interaction flotation unit 2000 of the embod iment of FIG. 2 comprises a coarse slurry feeding ar rangement 2200 for feeding coarse slurry 2201 to the froth layer 2002, a fine slurry feeding arrangement 2400 for feeding fine slurry 2401 into the volume of slurry 2001 via the fine slurry inlet 2103, and a flo tation gas supply arrangement 2300 configured to feed flotation gas 2301 into the volume of slurry 2001 via the flotation gas inlet 2108.

The froth-interaction flotation unit 2000 of the embod iment of FIG. 2 further comprises a classification ar rangement 2600 configured to classify the input slurry 2601 to form a coarser slurry fraction 2602 and a finer slurry fraction 2603, to feed the coarser slurry fraction 2602 to the coarse slurry feeding arrange ment 2200, and to feed the finer slurry fraction 2603 to the fine slurry feeding arrangement 2400.

As indicated by dashed arrows in FIG. 2, the tank 2100 may further comprise a flotation liquid inlet 2109, and the froth-interaction flotation unit 2000 may further comprise a flotation liquid supply arrangement 2500 for supplying flotation liquid 2501 into the volume of slurry 2001.

As shown in FIG. 2, the froth-interaction flotation unit 2000 differs from the froth-interaction flotation unit 1000 of the embodiment of FIG. 1, at least, in that the froth-interaction flotation unit 2000 is configured to operate in the absence of a bottom cone in the tank 2100 and in the absence of a fluidized bed in the volume of slurry 2001.

It is to be understood that the embodiments of the first aspect described above may be used in any combination with each other. Several of the embodiments may be com bined together to form a further embodiment.

Above, mainly structural aspects of froth-interaction flotation units are discussed. In the following, more emphasis will lie on aspects related to mineral pro cessing apparatus. What is said above about the ways of implementation, definitions, details, and advantages related to froth-interaction flotation units apply, mu- tatis mutandis, to the mineral processing apparatus dis cussed below. The same applies vice versa.

FIG. 3 depicts a mineral processing apparatus 3000 ac cording to an embodiment. The mineral processing appa ratus 3000 of the embodiment of FIG. 3 comprises a froth-interaction flotation unit 3200 with a classifi cation arrangement 3201.

Although not explicitly shown in FIG. 3, the froth-in teraction flotation unit 3200, any part thereof, and/or any arrangement of the froth-interaction flotation unit 3200 may generally comprise any feature (s) and/or element (s) of the embodiments of any of FIGs. 1-2 or any other embodiments disclosed with reference to, in con junction with, and/or concomitantly with any of FIGs. 1-2.

The mineral processing apparatus 3000 of the embodiment of FIG. 3 further comprises a comminution unit 3100. In other embodiments, a mineral processing apparatus may or may not comprise a comminution unit. The comminution unit 3100 of the embodiment of FIG. 1 is configured to grind ore to form ground ore, to mix the ground ore with flotation liquid to form pristine slurry 3101, and to feed the pristine slurry 3101 to the froth-interaction flotation unit 3200. In embodiments, wherein a mineral processing apparatus comprises a com minution unit, said comminution unit may be configured to operate in any suitable manner.

As indicated in FIG. 3 using dashed arrows, a classifi cation arrangement may generally be configured to clas sify input slurry so that product(s) other than a coarser slurry fraction and a finer slurry fraction are also formed. In such case, a classification arrangement may be configured to channel such other product(s) to any suitable location (s), arrangement(s), or unit(s).

FIG. 4 depicts a mineral processing apparatus 4000 ac cording to an embodiment. The mineral processing appa ratus 4000 of the embodiment of FIG. 4 comprises a froth-interaction flotation unit 4200 with a classifi cation arrangement 4201.

Although not explicitly shown in FIG. 4, the froth-in teraction flotation unit 4200, any part thereof, and/or any arrangement of the froth-interaction flotation unit 4200 may generally comprise any feature (s) and/or element (s) of the embodiments of any of FIGs. 1-2 or any other embodiments disclosed with reference to, in con junction with, and/or concomitantly with any of FIGs. 1-2.

The mineral processing apparatus 4000 of the embodiment of FIG. 4 further comprises a comminution unit 4100, a pre-classification unit 4300, and a primary flotation unit 4400. In other embodiments, a mineral processing apparatus may or may not comprise one or more of a comminution unit, a pre-classification unit 4300, and a primary flotation unit 4400.

The comminution unit 4100 of the embodiment of FIG. 4 is configured to grind ore to form ground ore, to mix the ground ore with flotation liquid to form pristine slurry 4101, and to feed the pristine slurry 4101 to the pre-classification unit 4300.

The pre-classification unit 4300 of the embodiment of FIG. 4 is configured to classify the pristine slurry 4101 to form a coarser pristine slurry frac tion 4301 and a finer pristine slurry fraction 4302 and to feed the finer pristine slurry fraction 4302 to the primary flotation unit 4400.

The primary flotation unit 4400 of the embodiment of FIG. 4 is configured to separate the finer pristine slurry fraction 4302 to form overflow 4401 and under flow 4402 and to feed the underflow 4402 to the froth- interaction flotation unit 4200.

As indicated in FIG. 4 using dashed lines, a primary flotation unit may generally comprise one or more tanks. In embodiments, wherein a primary flotation unit com prises a plurality of tanks, individual tanks of said plurality of tanks may be arranged in series.

Herein, individual tanks of a plurality of tanks being "arranged in series" may refer to underflow from one tank being fed to the next until a last individual tank of said plurality of tanks.

Above, mainly structural aspects of froth-interaction flotation units and mineral processing apparatus are discussed. In the following, more emphasis will lie on aspects related to methods for separation of slurry us ing froth-interaction flotation. What is said above about the ways of implementation, definitions, details, and advantages related to froth-interaction flotation units and mineral processing apparatus apply, mutatis mutandis, to the methods discussed below. The same ap plies vice versa.

It is specifically to be understood that any method ac cording to this specification may be used to operate a froth-interaction flotation unit according to this spec ification. Correspondingly, any froth-interaction flo tation unit according to this specification may be op erated in accordance with a method according to this specification .

FIG. 5 illustrates a method 5000 for separation of input slurry using froth-interaction flotation according to an embodiment.

In the embodiment of FIG. 5, the method 5000 comprises, in process 5100, providing a tank for holding a volume of slurry and a froth layer over the volume of slurry.

Herein, a "process" may refer to a set of operations, leading to an end result. A process may be divisible to a plurality of subprocesses, wherein individual sub processes of such plurality of sub-processes may or may not share common operations.

Herein, an "operation" may refer to a measure taken in order to achieve an effect. Individual operations of a process may generally be performed at least partly suc cessively or at least partly concurrently with one an other. Throughout this disclosure, "providing" may refer to arranging available the element or part at issue.

In the embodiment of FIG. 5, the method 5000 comprises, in subprocess 5200, supplying flotation gas into the volume of slurry.

In the embodiment of FIG. 5, the method 5000 comprises, in subprocess 5300, classifying the input slurry to form a coarser slurry fraction and a finer slurry fraction.

In the embodiment of FIG. 5, the method 5000 comprises, in subprocess 5400, feeding the coarser slurry frac tion to the froth layer.

In the embodiment of FIG. 5, the method 5000 comprises, in subprocess 5500, feeding the finer slurry frac tion into the volume of slurry.

As indicated in FIG. 5 using dashed lines, the method 5000 of the embodiment of FIG. 5 may further com prise, in subprocess 5600, maintaining a fluidized bed in the volume of slurry. In other embodiments, a method for separation of input slurry using froth-in teraction flotation may or may not comprise maintaining a fluidized bed in the volume of slurry.

Generally, a method for separation of input slurry using froth-interaction flotation may comprise any pro cess (es), operation (s), and/or feature (s) not disclosed herein in relation to the method 5000 of the embodiment of FIG. 5.

For example, in some embodiments, a finer slurry frac tion may have a solids fraction, f ^£X , lower than a solids fraction, f ^OX , of the coarser slurry fraction. In some embodiments, a coarser slurry fraction may have a solids fraction, f ^OX , in a range from 0.5 to 0.8, or in a range from 0.55 to 0.75 or in a range from 0.6 to

0.7.

In some embodiments, a finer slurry fraction may have a solids fraction, f ^£X , in a range from 0.05 to 0.35, or in a range from 0.1 to 0.25 or in a range from 0.15 to

0.2.

In some embodiments, a method for separation of input slurry using froth-interaction flotation may comprise collecting froth from a tank into a launder of said tank, for example, over a launder lip of said launder.

In some embodiments, a method for separation of input slurry using froth-interaction flotation may comprise collecting coarse output slurry from a volume of slurry at a first height, ly, which may be situated below a launder lip of a launder.

In some embodiments, a method for separation of input slurry using froth-interaction flotation may comprise collecting output slurry from a volume of slurry at a second height, h ₂ , which may be situated above a first height, ly, and/or below a launder lip.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The in vention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.

It will be understood that any benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. The term "comprising" is used in this specification to mean including the feature(s) or act(s) followed there after, without excluding the presence of one or more additional features or acts. It will further be under stood that reference to 'an' item refers to one or more of those items.

REFERENCE SIGNS dso cut-off particle size of classification hydro cyclone dso cut-off particle size of solid-liquid separa tion hydrocyclone f ^OX solids fraction of the coarser slurry fraction f ^RX solids fraction of the finer slurry fraction f ^Xr solids fraction of the solids portion f ^0X solids fraction of the output slurry f ^1r solids fraction of the liquid portion d ^f froth depth of the froth layer d _o ^S opening diameter of the coarse slurry outlet

1000 froth-interaction flo- 1110 fine slurry outlet tation unit 1111circulation inlet

1001 volume of slurry 1200coarse slurry feeding

1002 froth layer arrangement

1003 froth 35 1201coarse slurry

1004 fluidized bed 1300 flotation gas supply 1100 tank arrangement

1101 launder 1301 flotation gas

1102 launder lip 1302 flotation gas

1103 fine slurry inlet 40 1303 flotation gas

1104 fine slurry-flotation 1400 fine slurry feeding gas mixture inlet arrangement

1105 bottom cone 1401 fine slurry

1106 coarse slurry outlet 1402 slurry sump

1107 coarse output slurry 45 1403 sump slurry outlet

1108 flotation gas inlet 1500 flotation liquid sup 1109 flotation liquid inlet ply arrangement 1501 flotation liquid 2102 launder lip

1502 flotation liquid 2103 fine slurry inlet

1600 classification ar3-5 2106coarse slurry outlet rangement 2107 coarse output slurry 1601 input slurry 2108 flotation gas inlet

1602 coarser slurry frac 2109 flotation liquid inlet tion 2200 coarse slurry feeding

1603 finer slurry fractiordO arrangement

1604 classification hydro- 2201 coarse slurry cyclone 2300 flotation gas supply

1700 solid-liquid separa ^¬ arrangement tion arrangement 2301 flotation gas

1701 output slurry 45 2400 fine slurry feeding

1702 solids portion arrangement 1703 liquid portion 2401 fine slurry

1704 solid-liquid separa ^¬ 2500 flotation liquid sup ^¬ tion hydrocyclone ply arrangement

1800 circulation arrange-0 2501 flotation liquid ment 2600 classification ar 1801 flotation liquid rangement

1802 flotation liquid 2601 input slurry

1900 slurry agitation ar 2602 coarser slurry frac rangement 55 tion

1901 rotor 2603 finer slurry fraction 1902 drive shaft

3000mineral processing ap ^¬

2000 froth-interaction flo paratus tation unit

3100 comminution unit

2001volume of slurry

2002 froth layer 60 3101pristine slurry 2003 froth 3200 froth-interaction flo

2100 tank tation unit

2101 launder 3201 classification ar 4400primary flotation unit rangement 4401 overflow

4000mineral processing ap ^¬ 4402 underflow paratus 20 5000method 4100 comminution unit 5100providing a tank

4101pristine slurry 5200 supplying flotation

4200 froth-interaction flo gas tation unit 5300 classifying the input

4201 classification ar2-5 slurry rangement 5400 feeding the coarser

4300pre-classification slurry fraction unit 5500 feeding the finer

4301 coarser pristine slurry fraction slurry fraction 30 5600maintaining a fluid ^¬ 4302 finer pristine slurry ized bed fraction