FI20235822A1 - Slurry feeding arrangement, flotation unit, flotation plant, and method - Google Patents

Abstract

This publication relates to a slurry feed arrangement, a flotation unit, a flotation plant and a method for installing a slurry feed arrangement. The slurry feed arrangement (1000) comprises a plurality of downcomers (1100) for mixing flotation gas (1101) with slurry from a feed slurry stream (1010) to form a slurry-flushing gas mixture (1001) and for feeding the slurry-flushing gas mixture (1001) to a tank of the flotation unit, and a slurry feed piping (1200) for feeding slurry from the feed slurry stream (1010) to the plurality of downcomers (1100). The slurry feed piping (1200) comprises a first splitter (1210) for splitting a feed slurry stream (1010) to form a plurality of second slurry streams (1020) and a second splitter (1220) for splitting a second slurry stream (1021) from the plurality of second slurry streams (1020) to form a plurality of third slurry streams (1030).

Description

SLURRY FEEDING ARRANGEMENT, FLOTATION UNIT, FLOTATION

PLANT, AND METHOD

FIELD OF TECHNOLOGY

This disclosure concerns flotation and mineral pro- cessing. In particular, this disclosure concerns sepa- ration of minerals from their ores by flotation.

BACKGROUND

During the past two decades, the use of high-intensity flotation units commonly referred to as “Jameson cells” has become increasingly common in mineral processing.

In these flotation units, a combined stream of slurry and air is introduced into a tank of a flotation unit via one or more cylindrical columns referred to as "downcomers”.

A typical Jameson cell comprising a tank having a diam- eter of 6 meters can house up to 20 standard downcomers and sustain a feed rate of unrecycled slurry of up to 1000 m*/hr. This rate may be increased by increasing the diameter of the tank such that the number of downcomers to be housed in the tank may be increased. However, such an increase in tank volume may typically result in re- & duced feed rate of unrecycled slurry per unit volume. e Additionally, utilization of a larger tank may disturb = 20 the efficient collection of overflow and complicate typ- = ical maintenance functions related to operating the flo- & tation unit.

N

D In light of the above, it may be desirable to develop

N new solutions related to flotation units provided with

N 25 multiple downcomers.

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 slurry feeding arrange- ment is provided. The slurry feeding arrangement com- prises a plurality of downcomers for mixing flotation gas with slurry from an input slurry stream to form a slurry-flotation gas mixture and for feeding the slurry- flotation gas mixture into a tank of a flotation unit, and slurry feed piping for feeding slurry from the input slurry stream to the plurality of downcomers. The slurry feed piping comprises a primary splitter for splitting the input slurry stream to form a plurality of secondary slurry streams and a secondary splitter for splitting a secondary slurry stream of the plurality of secondary slurry streams to form a plurality of tertiary slurry

Streams.

According to a second aspect, a flotation unit is pro- e vided. The flotation unit comprises a tank and a slurry

S feeding arrangement in accordance with the first aspect

N for feeding slurry-flotation gas mixture into the tank. 2 25 According to a third aspect, a flotation plant compris-

E ing a flotation unit in accordance with the second as-

N pect is provided. 3 According to a fourth aspect, a method for installing a x slurry feeding arrangement is provided. The method com-

prises providing a tank, providing a plurality of down- comers for feeding slurry-flotation gas mixture into the tank, and coupling slurry feed piping with the plurality of downcomers for feeding slurry from an input slurry stream to the plurality of downcomers. The slurry feed piping comprises a primary splitter for splitting the input slurry stream to form a plurality of secondary slurry streams and a secondary splitter for splitting a secondary slurry stream of the plurality of secondary slurry streams to form a plurality of tertiary slurry streams.

In an embodiment of the fourth aspect, the slurry feed- ing arrangement is a slurry feeding arrangement in ac- cordance with the first aspect.

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 top view of a slurry feeding arrangement,

FIG. 2 depicts a schematic side view of the n slurry feeding arrangement of FIG. 1,

N

N FIG. 3 illustrates a schematic side view of a

S flotation unit, 0

T FIG. 4 shows a partial schematic view of a flo-

I

= 25 tation plant, and

N

S FIG. 5 illustrates a method for installing a

O

O slurry feeding arrangement.

O

N

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

Concerning slurry feeding arrangements, flotation units, and flotation plants discussed in this detailed description, the following shall be noted.

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.

S Further, “froth flotation” may refer to flotation,

N wherein froth is utilized for separation. Herein,

O “froth” may refer to a dispersion, comprising a greater

I 25 portion by volume of flotation gas dispersed as bubbles a 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

N have an average diameter greater than or equal to

0.2 mm, or to 0.5 mm, or to 1 mm. Additionally or al- ternatively, an average distance between neighboring flotation gas bubbles in froth not stabilized by solid particles may generally be less than or equal to some 5 tens of micrometers, for example, less than or equal to 50 um or 30 pm. Naturally, in froth stabilized by solid particles, average distance between neighboring flota- tion gas bubbles is increased in proportion to the av- erage size and quantity of said solid particles.

In this disclosure, a “unit” may refer to a device suit- able 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 flotation. A unit may generally comprise one or more parts, and each of the one or more parts may be classi- fied 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), e 25 necessary and/or beneficial for performing its specific = subprocess. = FIG. 1 depicts a schematic top view of a slurry feeding > arrangement 1000 according to an embodiment, and FIG. 2

N shows a schematic side view of the slurry feeding ar- 3 30 rangement 1000. In FIG. 2, some elements have been omit-

N ted in order to improve clarity and intelligibility of sald drawing. In FIG. 1, corresponding elements have been indicated with similar hatching, and the paths of characteristic slurry streams are indicated by dotted arrows in FIGs. 1 and 2.

Throughout this disclosure, “slurry” may refer to a dis- persion, comprising solid particles suspended in a con- tinuous phase of flotation liquid. The solid particles may have many different geometries, and are actually hardly ever perfectly spherical, but may have any pointy shapes and forms. Herein, “flotation liquid” may refer to any liquid substance or mixture suitable for use in flotation. Although in practical applications water or aqueous solutions are often used as flotation liquids, other types of liquid substances may also be utilized, as known to the skilled person. Consequently, a “slurry feeding arrangement” may refer to an arrangement of parts for or of a flotation unit suitable for or con- figured to feed slurry into a tank of said flotation unit.

In the embodiment of FIGs. 1 and 2, the slurry feeding arrangement 1000 comprises a plurality of downcom- ers 1100 suitable for mixing flotation gas 1101 with slurry from an input slurry stream 1010 to form a & slurry-flotation gas mixture 1001 and for feeding the e 25 slurry-flotation gas mixture 1001 into a tank of a flo- = tation unit. = In this specification, “flotation gas” may refer to any - gaseous substance suitable for use in flotation. Alt-

N hough in practical applications air is often used a 3 30 flotation gas, other types of gaseous substances may

N also be utilized, such as argon, nitrogen, hydrogen, or mixtures thereof, as known to the skilled person. Fur- ther, a "tank” may refer to a receptacle suitable for or configured to hold a fluid, for example, a liquid, and/or slurry.

In the embodiment of FIGs. 1 and 2, the slurry feeding arrangement 1000 comprises slurry feed piping 1200 for feeding slurry from the input slurry stream 1010 to the plurality of downcomers 1100.

Herein, “piping” may refer to a system of pipes and, optionally, one or more accompanying in-line components, such as fittings and valves, suitable for or configured to convey a fluid. Consequently, “slurry feed piping” may refer to piping suitable for or configured to feed slurry into a plurality of downcomers.

The slurry feed piping 1200 of the embodiment of FIGs. 1 and 2 comprises a primary splitter 1210 for splitting the input slurry stream 1010 to form a plurality of secondary slurry streams 1020 and a secondary split- ter 1220 for splitting a secondary slurry stream 1021 of the plurality of secondary slurry streams 1020 to form a plurality of tertiary slurry streams 1030.

Generally, slurry feed piping of a slurry feeding ar- @ rangement comprising a primary splitter for splitting

S the input slurry stream to form a plurality of secondary 5 25 slurry streams and a secondary splitter for splitting a © secondary slurry stream of the plurality of secondary

E slurry streams to form a plurality of tertiary slurry

AN streams may facilitate providing said slurry feeding & arrangement with a higher number of downcomers, which & 30 may, in turn, increase total slurry-flotation gas mix-

N ture output flow rate of said slurry feeding arrangement and/or enable maintaining higher mass throughput by re- ducing slurry recycle rate for said slurry feeding ar- rangement. Additionally or alternatively, a slurry feed piping of a slurry feeding arrangement comprising such primary splitter and such secondary splitter may facil- itate distributing a plurality of downcomers of said slurry feeding arrangement along at least two differ- ently sized concentric closed paths of mutually similar shapes, e.g., along at least two concentric circular paths, which may, in turn, enable housing said plurality of downcomers in a tank with less volume per unit total slurry-flotation gas mixture output flow rate.

Although not explicitly shown in FIGs. 1 and 2, each downcomer of a plurality of downcomers of a slurry feed- ing arrangement, e.g., each downcomer 1110 of the plu- rality of downcomers 1100 of the embodiment of FIGs. 1 and 2, may generally be provided with any suitable means, for example, one or more flotation gas inlets, for receiving flotation gas to be mixed with slurry from an input slurry stream.

In the embodiment of FIGs. 1 and 2, the primary split- ter 1210 comprises at least three slurry outlets. In particular, the at least three slurry outlets of the & primary splitter 1210 comprise a first slurry out- e 25 let 1211, a second slurry outlet 1212, a third slurry = outlet 1213, and a fourth slurry outlet 1214. Generally, = a primary splitter comprising at least three slurry out-

T lets may facilitate providing a slurry feeding arrange-

N ment with a higher number of downcomers. In other em- 2 30 bodiments, a primary splitter may comprise any suitable

N number of, for example, at least two, at least three, at least four, etc., slurry outlets.

In the embodiment of FIGs. 1 and 2, the slurry feed piping 1200 comprises a separate secondary split- ter 1220 for each secondary slurry stream 1021 of the plurality of secondary slurry streams 1020. In other embodiments, slurry feed piping may or may not comprise a separate secondary splitter for each secondary slurry stream of a plurality of secondary slurry streams. For example, in some embodiments, slurry feed piping may comprise only a single secondary splitter.

The slurry feeding arrangement 1000 of the embodiment of FIGs. 1 and 2 further comprises a tertiary split- ter 1230 for splitting a tertiary slurry stream 1031 of the plurality of tertiary slurry streams 1030 to form a plurality of quaternary slurry streams 1040. Generally, a slurry feeding arrangement of a slurry feeding ar- rangement further comprising a tertiary splitter for splitting a tertiary slurry stream of a plurality of tertiary slurry streams to form a plurality of auater- nary slurry streams may further facilitate providing sald slurry feeding arrangement with a higher number of downcomers. Additionally or alternatively, a slurry feeding arrangement of a slurry feeding arrangement fur- ther comprising such tertiary splitter may further fa-

Q cilitate distributing a plurality of downcomers of said

N 25 slurry feeding arrangement along at least two differ-

S ently sized concentric closed paths of mutually similar 2 shapes. In other embodiments, a slurry feeding arrange-

E ment may or may not comprise a tertiary splitter for

N splitting a tertiary slurry stream of a plurality of 3 30 tertiary slurry streams to form a plurality of auater-

O nary slurry streams. In other embodiments, wherein a slurry feeding arrangement comprises such tertiary splitter, said slurry feeding arrangement may or may not further comprise any suitable number of further splitter stages downstream of said tertiary splitter.

In the embodiment of FIGs. 1 and 2, the slurry feed piping 1200 comprises a separate tertiary splitter 1230 for splitting each tertiary slurry stream 1031 formed by the secondary splitters 1220. In other embodiments, slurry feed piping may or may not comprise a separate tertiary splitter for splitting each tertiary slurry stream formed by a plurality of secondary splitters.

For example, in some embodiments, slurry feed piping may comprise only a single tertiary splitter.

The slurry feed piping 1200 of the embodiment of FIGs. 1 and 2 1s configured to balance head losses between the primary splitter 1210 and each of the plurality of down- comers 1100. Generally, slurry feed piping of a slurry feeding arrangement being configured to balance head losses between a primary splitter and each of a plural- ity of downcomers may facilitate maintaining similar slurry-flotation gas mixture output flow rates for each of said plurality of downcomers.

In other embodiments, slurry feed piping of a slurry n feeding arrangement may or may not be configured to

S balance head losses between a primary splitter and each

N 25 of a plurality of downcomers. For example, in some em- n bodiments, a first portion of a plurality of downcomers = of a slurry feeding arrangement may be configured to > operate at a first slurry-flotation gas mixture output

N flow rate and a second portion of said plurality of 3 30 downcomers may be configured to operate at a second

N slurry-flotation gas mixture output flow rate different to the first slurry-flotation gas mixture output flow rate, and slurry feed piping of said slurry feeding arrangement may be configured to provide a first head loss between a primary splitter and each downcomer of said first portion and a second head loss different to said first head loss between said primary splitter and each downcomer of said second portion in order to main- tain said first slurry-flotation gas mixture output flow rate and said second slurry-flotation gas mixture output flow rate.

Throughout this specification, "head loss” may refer to a reduction in total head of a fluid or slurry. Further, slurry feed piping being "configured to balance head losses between a primary splitter and each of a plural- ity of downcomers” may refer to said slurry feed piping exhibiting an arithmetic mean head loss between said primary splitter and each of said plurality of downcom- ers and a head loss standard deviation less than or equal to 0.25, or to 0.2, or to 0.15, or to 0.1, or to 0.05 times said arithmetic mean head loss, for a fluid, e.g., water, or slurry, e.g., slurry consisting sub- stantially of water and spherical particles with a den- sity of 2650 kg/m? at solids fraction of 0.02, as it

Q moves through said slurry feed piping. Herein, a “solids

N 25 fraction” may refer to a ratio between a mass of solids

S in a slurry sample and a mass of said slurry sample. - In the embodiment of FIGs. 1 and 2, each downcomer 1110

T of the plurality of downcomers 1100 is configured to

S receive a quaternary slurry stream 1041 formed by a 2 30 tertiary splitter 1230. In other embodiments, a down-

N comer of a plurality of downcomers may be configured to receive any suitable type of slurry stream originating from an input slurry stream, for example, a secondary slurry stream, a tertiary slurry stream, or a quaternary slurry stream, etc. Typically, at least two downcomers of a plurality of downcomers are configured to receive slurry streams of tertiary stage or higher.

The plurality of downcomers 1100 of the embodiment of

FIGs. 1 and 2 comprises 18 downcomers 1110. In other embodiments, a plurality of downcomers of a slurry feed- ing arrangement may comprise any suitable number of downcomers, for example, at least three downcomers, at least four downcomers, at least five downcomers, etc.

In the embodiment of FIGs. 1 and 2, each downcomer 1110 of the plurality of downcomers 1100 extends parallel to an imaginary primary line 1002, and the plurality of downcomers 1100 are arranged rotationally symmetrically with respect to the primary line 1002. Generally, a plu- rality of downcomers of a slurry feeding arrangement being arranged rotationally symmetrically with respect to a primary line may facilitate utilization of said slurry feeding arrangement in a flotation unit compris- ing a rotationally symmetric tank. In other embodiments, each downcomer of a plurality of downcomers may or may not extend parallel or substantially parallel to an im- & aginary primary line, and said plurality of downcom- e 25 ers may or may not be arranged rotationally symmetri- = cally or substantially rotationally symmetrically with = respect to such primary line. For example, in some em- & bodiments, downcomer of a plurality of downcomers may

S be arranged rotationally asymmetrically and, option- 2 30 ally, randomly. &

Herein, a "primary line” may refer to an imaginary line extending parallel to one or more downcomers, for exam- ple, each downcomer of a plurality of downcomers. Ad- ditionally or alternatively, a primary line may refer to an imaginary axis of rotational symmetry of posi- tioning of a plurality of downcomers. Generally, a pri- mary line may or may not extend via a center, e.g., a centroid, of a primary splitter.

Further, a plurality of downcomers being arranged "ro- tationally symmetrically with respect to a primary line” may refer to each downcomer of said plurality of down- comers comprising a slurry-flotation gas mixture outlet for feeding slurry-flotation gas mixture into a tank of a flotation unit, such slurry-flotation gas mixture out- lets of said plurality of downcomers being arranged in a first arrangement such that a rotation of said plu- rality of downcomers about said primary line would re- sult in a second arrangement of said slurry-flotation gas mixture outlets corresponding to said first arrange- ment.

In the embodiment of FIGs. 1 and 2, the plurality of downcomers 1100 are arranged at varying distances from the primary line 1002. Generally, a plurality of down- & comers being arranged at varying distances from a pri- e 25 mary line may further facilitate providing said slurry = feeding arrangement with a higher number of downcomers = and/or facilitate housing said plurality of downcomers

T in a tank with less volume per unit total slurry-flota-

N tion gas mixture output flow rate. In other embodiments, 2 30 wherein each downcomer of a plurality of downcomers ex-

R tend parallel or substantially parallel to an imaginary primary line and said plurality of downcomers is ar- ranged rotationally symmetrically or substantially ro- tationally symmetrically with respect to such primary line, said plurality of downcomers may or may not be arranged at varying distances from said primary line.

For example, in some embodiments, each downcomer of a plurality of downcomers may be arranged along a single circular path surrounding a primary line.

Throughout this specification, a “distance” of a down- comer from a primary line may refer to a length measured between said primary line and a slurry-flotation gas mixture outlet of said downcomer.

Further, a plurality of downcomers being arranged "at varying distances from a primary line” may refer to said plurality of downcomers being divisible to at least two groups such that each of said at least two groups has a different average distance from said primary line.

In particular, the plurality of downcomers 1100 of the embodiment of FIGs. 1 and 2 are distributed along an imaginary first circular path 1003 and an imaginary sec- ond circular path 1004 extending parallel to the primary line 1002. The first circular path 1003 and the second n circular path 1004 extend at a first distance (dy) and

S at a second distance (d,) higher than d; from the primary

N 25 line 1002. In other embodiments, wherein a plurality of o downcomers are arranged at varying distances from the

T primary line, said plurality of downcomers may be ar- a ranged in any suitable manner, for example, randomly; & or along a polygonal path, e.g., regular polygonal path, & 30 surrounding said primary line; or at least two circular

N paths extending at different distances from said primary line, or combinations thereof.

In the embodiment of FIGs. 1 and 2, each downcomer 1110 of the plurality of downcomers 1100 comprises a slurry- flotation gas mixture outlet 1111 and a throttle 1112 for restricting flow of the slurry-flotation gas mix- ture 1001 via the slurry-flotation gas mixture out- let 1111. Generally, a downcomer of a slurry feeding arrangement comprising a throttle for restricting flow of slurry-flotation gas mixture via a slurry-flotation gas mixture outlet of said downcomer may enable operat- ing said slurry feeding arrangement such that slurry- flotation gas mixture exits said downcomer at supersonic flow speeds, which may, in turn, promote the formation of agglomerates of solid particles and flotation gas by splitting flotation gas into smaller bubbles. Generally, downcomers operated such that slurry-flotation gas mix- ture exits said downcomer at a supersonic speed may be referred to as a "blast tube”.

In other embodiments, one or more downcomers, e.g. each downcomer, of a plurality of downcomers may or may not comprise a slurry-flotation gas mixture outlet and a throttle for restricting flow of slurry-flotation gas & mixture via said slurry-flotation gas mixture outlet. e 25 For example, in some embodiments, each downcomer of a = plurality of downcomers may be implemented as a so- = called "Jameson downcomer” configured to operate at sub-

T sonic slurry-flotation gas mixture flow speeds.

N It is to be understood that the embodiments of the first 3 30 aspect described above may be used in combination with

N each other. Several of the embodiments may be combined together to form a further embodiment.

Above, mainly features of slurry feeding arrangements are discussed. In the following, more emphasis will lie on features related to flotation units and flotation plants. What is said above about the ways of implemen- tation, definitions, details, and advantages related to the first aspect applies, mutatis mutandis, to the as- pects discussed below. The same applies vice versa.

FIG. 3 depicts a schematic side view of a flotation unit 3000 according to an embodiment. The embodiment of

FIG. 3 may be in accordance with any of the embodiments disclosed with reference to and/or in conjunction with

FIGs. 1 and 2. Additionally or alternatively, although not explicitly shown in FIG. 3, the embodiment of FIG. 3 or any part thereof may generally comprise any features and/or elements of the embodiment of FIGs. 1 and 2 which are omitted from FIG. 3.

In the embodiment of FIG. 3, the flotation unit 3000 comprises a tank 3100 and a slurry feeding arrange- ment 3200 in accordance with the first aspect for feed- ing slurry-flotation gas mixture 3201 into the tank 3100.

O

O The tank 3100 of the embodiment of FIG. 3 comprises a 5 25 launder 3110 comprising a launder lip 3111, and the pri- © mary splitter 3221 of the slurry feeding arrange-

E ment 3200 is configured to be arranged below the launder

N lip 3111 during operation of the flotation unit 3000. & Generally, a primary splitter of a slurry feeding ar- & 30 rangement of a flotation unit being configured to be = arranged below a launder lip of a launder of a tank of said flotation unit may provide improved access to upper parts of said tank during operation of said flotation unit. Additionally or alternatively, a primary splitter of a slurry feeding arrangement of a flotation unit being configured to be arranged below a launder lip of a launder of a tank of said flotation unit may facilitate providing said tank with a central froth crowder and/or a central launder and/or facilitate adjusting the posi- tions of froth crowders and/or a launders of said tank.

In other embodiments, wherein a tank comprises a laun- der comprising a launder lip, a primary splitter of a slurry feeding arrangement of a flotation unit may or may not be configured to be arranged below said launder lip during operation of said flotation unit. For exam- ple, in some such embodiments, a primary splitter may be arranged above a launder lip.

In the embodiment of FIG. 3, the secondary splitter 3222 of the slurry feeding arrangement 3200 is configured to be arranged below and/or above the launder lip 3111 dur- ing operation of the flotation unit 3000. Generally, a secondary splitter of a slurry feeding arrangement of a flotation unit being configured to be arranged below a launder lip of a launder of a tank of said flotation & unit may provide improved access to upper parts of said e 25 tank during operation of said flotation unit. Addition- = ally or alternatively, a secondary splitter of a slurry = feeding arrangement of a flotation unit being configured

T to be arranged below a launder lip of a launder of a

N tank of said flotation unit may facilitate providing 2 30 said tank with a radial froth crowder and/or a radial

R launder and/or facilitate adjusting the positions of froth crowders and/or a launders of said tank. In other embodiments, wherein a tank of a flotation unit com- prises a launder comprising a launder lip and a primary splitter of a slurry feeding arrangement of said flota- tion unit is configured to be arranged below a launder lip during operation of said flotation unit, a secondary splitter of said slurry feeding arrangement may or may not be configured to be arranged below said launder lip during operation of said flotation unit.

The launder 3110 of the embodiment of FIG. 3 is imple- mented as a radial launder, and the tank 3100 further comprises a central launder 3120. During operation of the flotation unit 3000, overflow collected over the launder lip 3111 is first conveyed by the launder 3110 to the central launder 3120 wherefrom it is conveyed further out of the flotation unit 3000. In other embod- iments, a tank of a flotation unit may be provided with any suitable means for collection of overflow, for ex- ample, one or more launders, e.g., a central launder; one or more radial launders; and/or a perimeter launder, such as an external perimeter launder or an internal perimeter launder.

In the embodiment of FIG. 3, the flotation unit 3000 further comprises a flotation gas supply arrange- & ment 3300 for supplying flotation gas 3301 to the plu- e 25 rality of downcomers 3210 of the slurry feeding arrange- = ment 3200. The flotation gas supply arrangement 3300 is = configured to supply the flotation gas 3301 at an ele-

T vated pressure relative to the ambient atmospheric pres-

N sure at the location of the flotation unit 3000. Gener- 2 30 ally, a flotation unit comprising a flotation gas supply x arrangement for supplying flotation gas to a plurality of downcomers of a slurry feeding arrangement of said flotation unit at an elevated pressure relative to the ambient atmospheric pressure at the location of the flo- tation unit may enable utilization higher flotation gas flow rates, and/or producing flotation gas bubbles at a smaller Sauter mean diameter, and/or reducing the usage of surface-active agents, such as frothers.

In other embodiments, a flotation unit may or may not comprise a flotation gas supply arrangement for supply- ing flotation gas to a plurality of downcomers of a slurry feeding arrangement of said flotation unit. For example, in some embodiments, downcomers of a plurality of downcomers may be provided with flotation gas inlets in fluid communication with the ambient such that flo- tation gas may be introduced in a self-aspirating manner into said downcomers due to the formation of negative pressure conditions in said downcomers. In such embod- iments, said downcomers may be implemented as Jameson downcomers. In other embodiments, wherein a flotation unit comprises a flotation gas supply arrangement for supplying flotation gas to a plurality of downcomers of a slurry feeding arrangement of said flotation unit, said flotation gas supply arrangement may or may not be configured to supply flotation gas at an elevated pres-

Q sure relative to the ambient atmospheric pressure at the

N 25 location of said flotation unit. Generally, a flotation

S gas supply arrangement may be implemented in any suit- 2 able manner, for example, as a compressed air flotation

E gas supply arrangement, as a forced air flotation gas

N supply arrangement, or as a self-aspiration flotation 3 30 gas supply arrangement.

S Although not explicitly shown in FIG. 3, a tank of a flotation unit, such as the tank 3100 of the flotation unit 3000 of the embodiment of FIG. 3, may generally be provided with any suitable means for collection of un- derflow, for example, one or more slurry outlets, which may be arranged at a bottom portion, e.g., bottom half, of said tank.

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

Above, mainly features of slurry feeding arrangements and flotation units are discussed. In the following, more emphasis will lie on features related to flotation plants. What is said above about the ways of implemen- tation, definitions, details, and advantages related to the first aspect and the second aspect applies, mutatis mutandis, to the third aspect discussed below. The same applies vice versa.

FIG. 4 depicts a partial schematic view of a flotation plant 4000 according to an embodiment, the flotation plant 4000 comprising a flotation unit 4400 in accord- ance with the second aspect. The embodiment of FIG. 4 may be in accordance with any of the embodiments dis- n closed with reference to and/or in conjunction with any

S of FIGs. 1 to 3. Additionally or alternatively, although

N 25 not explicitly shown in FIG. 4, the embodiment of FIG. 4 n or any part thereof may generally comprise any features = and/or elements of the embodiments of FIGs. 1 to 3 which a are omitted from FIG. 4. & Herein, a “plant” may refer to machinery suitable for & 30 or configured to run an industrial process. Conse- = quently, a “flotation plant” may refer to plant suitable for or configured to run a flotation process. Generally, a flotation plant may generally comprise any unit(s) suitable or necessary for flotation and, optionally, any unit(s) suitable or necessary for pre-treatment of ma- terial prior to flotation and/or post-treatment of ma- terial following flotation.

In the embodiment of FIG. 4, the flotation plant 4000 comprises a comminution unit 4100, a pre-classification unit 4200, and a primary flotation unit 4300; the com- minution unit 4100 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 4200; the pre-classification unit 4200 is configured to classify the pristine slurry 4101 to form a coarser pristine slurry fraction 4201 and a finer pristine slurry frac- tion 4202 and to feed the finer pristine slurry frac- tion 4202 to the primary flotation unit 4300; and the primary flotation unit 4300 is configured to separate the finer pristine slurry fraction 4202 to form an over- flow 4301 and an underflow 4302 and to feed the under- flow 4302 to the flotation unit 4400. In other embodi- ments, a flotation plant may or may not comprise such a

Q comminution unit, and/or such a pre-classification unit,

N 25 and/or such a primary flotation unit. 2 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

S may comprise, for example, crushing and/or grinding. In 2 30 mineral processing, comminution is commonly used for

R liberation of valuable mineral(s) from gangue. Conse-

quently, a “comminution unit” may refer to a unit suit- able for or configured to reduce an average particle size of a solid material. Generally, a comminution unit may be configured for dry grinding and/or wet grinding.

Further, “classification” may refer 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 being preferentially di- rected to one or more finer slurry fractions. Naturally, a “classification arrangement” may then refer to an ar- rangement of parts of a flotation unit configured to or suitable for classification of slurry.

Herein, 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.

Above, mainly structural features of slurry feeding ar- rangements, flotation units, and flotation plants are n discussed. In the following, more emphasis will lie on

S features of methods for installing slurry feeding ar-

N 25 rangements. What is said above about the ways of imple-

O mentation, definitions, details, and advantages related = to the first, second, and third aspects apply, mutatis - mutandis, to the method aspect discussed below. The same

S applies vice versa.

N 30 FIG. 5 illustrates a method 5000 for installing a slurry = feeding arrangement according to an embodiment. In other embodiments, a method for installing a slurry feeding arrangement may be identical, similar, or different to the method 5000 of the embodiment of FIG. 25.

In the embodiment of FIG. 5, the method 5000 comprises providing a tank 5100, providing a plurality of down- comers 5200 for feeding slurry-flotation gas mix- ture 1001 into the tank, and coupling slurry feed pip- ing 5400 with the plurality of downcomers for feeding slurry from an input slurry stream to the plurality of downcomers. The slurry feed piping comprises a primary splitter for splitting the input slurry stream to form a plurality of secondary slurry streams and a secondary splitter for splitting a secondary slurry stream of the plurality of secondary slurry streams to form a plural- ity of tertiary slurry streams.

The method 5000 of the embodiment of FIG. 5 may be im- plemented as a retrofitting method, whereby a tank of an existing flotation unit is equipped with a new slurry feeding arrangement. In other embodiments, a method for installing a slurry feeding arrangement may or may not be implemented as such a retrofitting method.

As shown in FIG. 5 using dashed lines, the method 5000 n may further comprise dismantling at least part of a pre-

S installed slurry feeding arrangement 5300 configured to

N 25 feed slurry into the tank. In other embodiments, a n method for installing a slurry feeding arrangement may = or may not comprise dismantling at least part of a pre- a installed slurry feeding arrangement. & In particular, the process of dismantling at least part & 30 of a pre-installed slurry feeding arrangement 5300 of = the method 5000 of the embodiment of FIG. 5 may comprise a step of disconnecting previously used slurry feed pip- ing 5310. In other embodiments, wherein a method for installing a slurry feeding arrangement comprises dis- mantling at least part of a pre-installed slurry feeding arrangement, said process of dismantling at least part of a pre-installed slurry feeding arrangement may or may nor comprise disconnecting previously used slurry feed piping.

In this specification, a “process” may refer to a series of one or more steps, leading to an outcome. As such, a process may be a single-step or a multi-step process.

Additionally, a process may be divisible to a plurality of sub-processes, wherein individual sub-processes of such plurality of sub-processes may or may not share common steps. Herein, a “step” may refer to a measure taken in order to achieve a pre-defined result.

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. n It will be understood that any benefits and advantages

S described above may relate to one embodiment or may

N 25 relate to several embodiments. The embodiments are not n limited to those that solve any or all of the stated = problems or those that have any or all of the stated a benefits and advantages. & The term “comprising” is used in this specification to & 30 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. 0

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REFERENCE SIGNS ds first distance d, second distance 1000 slurry feeding ar- 1200 slurry feed piping rangement 1210 primary splitter 1001 slurry-flotation gas 1211 first slurry outlet mixture 1212 second slurry outlet 1002 primary line 1213 third slurry outlet 1003 first circular path 1214 fourth slurry outlet 1004 second circular path 1220 secondary splitter 1010 input slurry stream 1230 tertiary splitter 1020 plurality of secondary 3000 flotation unit slurry streams 3100 tank 1021 secondary slurry 3110 launder stream 3111 launder lip 1030 plurality of tertiary 3120 central launder slurry streams 3200 slurry feeding ar- 1031 tertiary slurry stream rangement 1040 plurality of quater- 3201 slurry-flotation gas nary slurry streams mixture

JN 1041 quaternary slurry 3210plurality of downcom-

S stream ers

N 1100 plurality of downcom- 3220 slurry feed piping 0 ers 3221 primary splitter = 1101 flotation gas 3222 secondary splitter - 1110 downcomer 3223 tertiary splitter

S 1111 slurry-flotation gas 3300 flotation gas supply & mixture outlet arrangement

N 1112 throttle 3301 flotation gas

4000 flotation plant 5000 method 4100 comminution unit 5100 providing a tank 4101 pristine slurry 5200 providing a plurality 4200 pre-classification of downcomers unit 5300 dismantling at least 4201 coarser pristine part of a pre-installed slurry fraction slurry feeding arrange- 4202 finer pristine slurry ment fraction 5310 disconnecting previ- 4300 primary flotation unit ously used slurry feed 4301 overflow piping 4302 underflow 5400 coupling slurry feed 4400 flotation unit piping 0

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Claims (15)

1. A slurry feeding arrangement (1000) com- prising: - a plurality of downcomers (1100) for mixing flota- tion gas (1101) with slurry from an input slurry stream (1010) to form a slurry-flotation gas mix- ture (1001) and for feeding the slurry-flotation gas mixture (1001) into a tank of a flotation unit, and - slurry feed piping (1200) for feeding slurry from the input slurry stream (1010) to the plurality of downcomers (1100); and wherein the slurry feed piping (1200) com- prises a primary splitter (1210) for splitting the input slurry stream (1010) to form a plurality of secondary slurry streams (1020) and a secondary splitter (1220) for splitting a secondary slurry stream (1021) of the plurality of secondary slurry streams (1020) to form a plurality of tertiary slurry streams (1030).

2. A slurry feeding arrangement (1000) accord- ing to claim 1, wherein the primary splitter (1210) com- prises at least three slurry outlets.

3. A slurry feeding arrangement (1000) accord- = ing to claim 1 or 2, wherein the slurry feeding arrange- N ment (1000) comprises a tertiary splitter (1230) for S 25 splitting a tertiary slurry stream (1031) of the plu- = rality of tertiary slurry streams (1030) to form a plu- E rality of quaternary slurry streams (1040).

N 4. A slurry feeding arrangement (1000) accord- 3 ing to any of the preceding claims, wherein the slurry O 30 feed piping (1200) is configured to balance head losses between the primary splitter (1210) and each of the plu- rality of downcomers (1100).

5. A slurry feeding arrangement (1000) accord- ing to any of the preceding claims, wherein each down- comer (1110) of the plurality of downcomers (1100) ex- tends parallel to a primary line (1002), and the plu- rality of downcomers (1100) are arranged rotationally symmetrically with respect to the primary line (1002).

6. A slurry feeding arrangement (1000) accord- ing to claim 5, wherein the plurality of downcom- ers (1100) are arranged at varying distances from the primary line (1002).

7. A slurry feeding arrangement (1000) accord- ing to any of the preceding claims, wherein each down- comer (1110) of the plurality of downcomers (1100) com- prises a slurry-flotation gas mixture outlet (1111) and a throttle (1112) for restricting flow of the slurry- flotation gas mixture (1001) via the slurry-flotation gas mixture outlet (1111).

8. A flotation unit (3000) comprising a tank (3100) and a slurry feeding arrangement (3200) in accordance with any of the preceding claims for feeding slurry-flotation gas mixture (3201) into the e tank (3100). S 25

9. A flotation unit (3000) according to N claim 8, wherein the tank (3100) comprises a laun- o der (3110) comprising a launder lip (3111), and the pri- = mary splitter (3221) of the slurry feeding arrange- a ment (3200) is configured to be arranged below the laun- & 30 der lip (3111) during operation of the flotation S unit (3000).

10. A flotation unit (3000) according to claim 9, wherein the secondary splitter (3222) of the slurry feeding arrangement (3200) is configured to be arranged below and/or above the launder lip (3111) dur- ing operation of the flotation unit (3000).

11. A flotation unit (3000) according to any of claims 8 to 10, wherein the flotation unit (3000) comprises a flotation gas supply arrangement (3300) for supplying flotation gas (3301) to the plurality of down- comers (3210) of the slurry feeding arrangement (3200).

12. A flotation plant (4000) comprising a flo- tation unit (4400) in accordance with any of claims 8 or 11.

13. A method (5000) for installing a slurry feeding arrangement, the method (5000) comprising: - providing a tank (5100), - providing a plurality of downcomers (5200) for feeding slurry-flotation gas mixture (1001) into the tank, and - coupling slurry feed piping (5400) with the plu- rality of downcomers for feeding slurry from an input slurry stream to the plurality of downcomers; wherein the slurry feed piping comprises a pri- n mary splitter for splitting the input slurry stream to S 25 form a plurality of secondary slurry streams and a sec- N ondary splitter for splitting a secondary slurry stream o of the plurality of secondary slurry streams to form a = plurality of tertiary slurry streams. a

14. A method (5000) according to claim 13, & 30 wherein the method (5000) further comprises dismantling & at least part of a pre-installed slurry feeding arrange- N ment (5300) configured to feed slurry into the tank.

15. A method (5000) according to claim 13 or 14, wherein the slurry feeding arrangement is a slurry feeding arrangement (1000) in accordance with any of claims 1 to 7.

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