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Title:
FEEDWELL APPARATUS, TROUGH, PLANT AND USE
Document Type and Number:
WIPO Patent Application WO/2021/064274
Kind Code:
A1
Abstract:
A feedwell apparatus trough, plant and use. The apparatus is adapted to materials comprising liquids carrying suspended particles, such as slurry containing minerals. The feedwell apparatus (100) comprises - a supply channel (1) for receiving the material, - a trough (2), a first end (2a) of which being connected in fluid communication with the supply channel (1), the trough (2) comprising a curved shape that turns in one direction, and - plurality of through-openings (3) in the wall(s) (4) of the trough (2).The through- openings (3) are arranged in the trough (2) in unequal pattern such that area of the through-openings (3) in proportion to the corresponding area of the walls (4) has its minimum value in portion of the trough (2) close to the first end (2a) thereof, and said relation being arranged to grow with the distance from the first end (2a).

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Inventors:
TRIGLAVCANIN RICHARD (AU)
VIDUKA STEPHEN (AU)
Application Number:
PCT/FI2019/050698
Publication Date:
April 08, 2021
Filing Date:
September 30, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
OUTOTEC FINLAND OY (FI)
International Classes:
B01D21/24; B03D1/14; C22B3/00
Domestic Patent References:
WO2008053065A12008-05-08
WO2016149650A12016-09-22
WO2012051536A12012-04-19
Foreign References:
EP2716342A12014-04-09
US4431531A1984-02-14
Attorney, Agent or Firm:
PAPULA OY (FI)
Download PDF:
Claims:
CLAIMS

1. A feedwell apparatus adapted to materials comprising liquids carrying suspended particles, such as slurry con- taining minerals, the feedwell apparatus comprising

- a supply channel for receiving the material,

- a trough, a first end of which being connected in fluid communication with the supply channel, the trough compris ing a curved shape that turns in one direction, and plurality of through-openings in the wall(s) of the trough, wherein

- the through-openings are arranged in the trough in une qual pattern such that area of the through-openings in proportion to the corresponding area of the walls has its minimum value in portion of the trough close to the first end thereof, and said relation being arranged to grow with the distance from the first end, the feedwell apparatus further comprising

- a reacting chamber arranged under the trough for receiv ing the material from the through-openings, and

- an outlet arranged in the reacting chamber for distrib uting the material out from the feedwell apparatus.

2. The apparatus as claimed in claim 1, wherein the width of the trough is arranged to decrease from the first end towards a second end of the trough.

3. The apparatus as claimed in claim 1, wherein the width of the trough is constant from the first end to a second end of the trough.

4. The apparatus as claimed in any of claims 1 - 3, where in the cross-section of the trough has an open top.

5. The apparatus as claimed in claim 4, wherein the trough has a U-shaped cross-section, with rectangular or rounded corners.

6. The apparatus as claimed in claim 4, wherein the trough has a V-shaped cross-section.

7. The apparatus as claimed in any of claims 1 - 3, where in the trough has a tubular cross-section.

8. The apparatus as claimed in any of the preceding claims, wherein the trough is arranged to make at least a 180° turn in the apparatus.

9. The apparatus as claimed in any of the preceding claims, wherein the trough is arranged to make at least a 360° turn in the apparatus.

10. The apparatus as claimed in any of the preceding claims, wherein the trough is arranged apart from the out er circumference wall of the reacting chamber.

11. The apparatus as claimed in any of claims 1 - 9, wherein the trough is arranged to constitute a part of the outer circumference wall of the reacting chamber. 12. The apparatus as claimed in any of the preceding claims, wherein turning radius of the trough is decreasing as the distance from the first end thereof is increasing.

13. The apparatus as claimed in any of the preceding claims, wherein the first end and the second end of the trough are arranged on a same horizontal level. 14. The apparatus as claimed in any of claims 1 - 12, wherein the first end of the trough is arranged higher than the second end.

15. The apparatus as claimed in any of claims 1 - 12, wherein the first end of the trough is arranged lower than the second end.

16. The apparatus as claimed in any of the preceding claims, comprising more than one trough.

17. The apparatus as claimed in any of the preceding claims, wherein the through-openings are arranged in a bottom section of the trough. 18. The apparatus as claimed in any of the preceding claims, wherein the trough comprises through-openings in an innermost wall of said trough.

19. The apparatus as claimed in any of the preceding claims, wherein the trough comprises through-openings in an outermost wall of said trough.

20. The apparatus as claimed in any of the preceding claims, wherein, wherein

- the through-openings arranged in the bottom section of the trough are arranged in the unequal pattern, and - the trough comprises through-openings at least in one of the innermost and outermost wall of said trough, wherein the through-openings in the innermost wall and/or the outermost wall(s) are arranged in a constant pattern from the first end to the second end of the trough.

21. The apparatus as claimed in in any of claims 1 - 19, wherein

- the through-openings arranged in at least in one of the innermost and outermost wall are arranged in the unequal pattern, and wherein

- the through-openings in the bottom section of the trough are arranged in a constant pattern from the first end to the second end of the trough.

22. The apparatus as claimed in in any of claims 1 - 19, wherein

- the through-openings arranged in at least in one of the innermost and outermost wall are arranged in the unequal pattern, and wherein

- the through-openings in the bottom section of the trough are arranged in a unequal pattern from the first end to the second end of the trough.

23. The apparatus as claimed in any of the preceding claims, wherein

- the through-openings have a same size, and wherein

- the change of proportion of the through-openings and the corresponding area of the walls is realized by varying distances between the through-openings.

24. The apparatus as claimed in any of the preceding claims, wherein

- the through-openings vary in their size, and wherein

- the change of proportion of the through-openings and the corresponding area of the walls is realized by arranging the smallest through-openings near the first end and the largest through-openings near the second end of the trough.

25. The apparatus as claimed in any of the preceding claims, wherein the cross-section of at least some of the through-openings is round.

26. The apparatus as claimed in any of the preceding claims, wherein the cross-section of at least some of the through-openings is elongated.

27. The apparatus as claimed in any of the preceding claims, wherein the cross-section of at least some of the through-openings is polygon.

28. The apparatus as claimed in any of the preceding claims, wherein the proportion of the area of the through- openings to the area of the wall is arranged to grow grad ually.

29. The apparatus as claimed in any of the preceding claims, wherein the proportion of the area of the through- openings to the area of the wall is arranged to grow step- by-step.

30. The apparatus as claimed in any of the preceding claims, wherein the proportion of the area of the through- openings to the area of the wall is selected as follows:

- 0% - 15% in a first quarter of length of the trough,

- 5% - 15% in a second quarter,

- 5% - 20% in a third quarter, and

- 8% - 30% in a fourth quarter of said length.

31. The apparatus as claimed in claim 30, wherein the pro portion of the area of the through-openings to the area of the wall is selected as follows:

- 3% - 7% in a first quarter of length of the trough,

- 5% - 9% in a second quarter,

- 7% - 11% in a third quarter, and

- 10% - 14% in a fourth quarter of said length.

32. The apparatus as claimed in any of the preceding claims, wherein at least some of the through-openings are provided with a nozzle that extends from the wall at a first distance in a direction away from an inside of the trough.

33. The apparatus as claimed in any of the preceding claims, wherein the length of the nozzle is in range of 0.15 x D - 0.6 x D, wherein D is the diameter of the re spective through-opening.

34. The apparatus as claimed in any of claims 31 - 33, wherein the cross-section of the nozzle is round, and the inner diameter of said nozzle is 0.05 x Ws - 0.15 x Ws, wherein Ws is the starting width of the first end of the trough.

35. The apparatus as claimed in any of the preceding claims, comprising dilution openings arranged to an outer circumference wall of the reacting chamber for feeding di lution substance in the reacting chamber.

36. The apparatus as claimed in claim 35, wherein the di lution openings are arranged all around the outer circum ference wall of the reacting chamber.

37. The apparatus as claimed in any of the preceding claims, wherein the wall of the trough comprises a polymer lined metallic structure.

38. The apparatus as claimed in any of the preceding claims, wherein the wall of the trough comprises polymer composite structure.

39. The apparatus as claimed in any of the preceding claims, wherein the supply channel is arranged to the first end of the trough such that a horizontal alignment angle of the supply channel with relation to said first end is in range of ±20°.

40. A trough of a feedwell apparatus, the trough compris ing a curved shape that turns in one direction, the trough comprising

- a first end for receiving material comprising liquids carrying suspended particles, such as slurry containing minerals,

- a second end opposite to the first end, plurality of through-openings in the wall(s) of the trough, wherein the through-openings are arranged in unequal pattern such that area of the through-openings in proportion to the corresponding area of the wall(s) has its minimum val ue in portion of the trough close to the first end there of, and said relation being arranged to grow with the distance from the first end.

41. A thickener plant, comprising at least one thickener tank, wherein at least one of said thickener tank(s) is arranged to receive the material from the feedwell appa ratus as claimed in any of the preceding claims.

42. Use of the feedwell apparatus as claimed in any of claims 1 - 39 for handling tailings from a mineral process of a mining plant. 43. Use of the feedwell apparatus as claimed in any of claims 1 - 39 for handling flow from a flotation process of a mining plant.

44. Use of the feedwell apparatus as claimed in any of claims 1 - 39 for handling tailings from a flotation pro cess of a mining plant.

Description:
FEEDWELL APPARATUS, TROUGH, PLANT AND USE

BACKGROUND

The invention relates to a feedwell apparatus adapted to materials comprising liquids carrying suspended particles, such as slurry containing minerals.

The invention further relates to a trough of a feedwell apparatus.

The invention further relates to thickener plant, compris ing at least one thickener tank.

The invention still further relates to use of the feedwell apparatus.

Thickener/clarifier tanks are used in a wide variety of industries to separate feed slurry, "material", comprising a solids or particulate-containing fluid to produce a "clarified" liquid phase having a lower concentration of solids than the feed slurry and an underflow stream having a higher concentration of solids than the feed slurry.

Many thickener/clarifier tanks are constructed with a feedwell apparatus, usually centrally located within the tank, into which the influent material stream is deliv ered. The feedwell apparatus generally serves the purpose of reducing the fluid velocity of the incoming influent material stream so that the energy in the stream may be dissipated to some degree before entering the tank.

However, the potential for performance improvement of thickener/clarifier feedwell apparatuses exist.

BRIEF DESCRIPTION

Viewed from a first aspect, there can be provided a feed- well apparatus adapted to materials comprising liquids carrying suspended particles, such as slurry containing minerals, the feedwell apparatus comprising a supply chan nel for receiving the material, a trough, a first end of which being connected in fluid communication with the sup ply channel, the trough comprising a curved shape that turns in one direction, and plurality of through-openings in the wall(s) of the trough), wherein the through- openings are arranged in the trough in unequal pattern such that area of the through-openings in proportion to the corresponding area of the walls has its minimum value in portion of the trough close to the first end thereof, and said relation being arranged to grow with the distance from the first end, the feedwell apparatus further com prising a reacting chamber arranged under the trough for receiving the material from the through-openings, and an outlet arranged in the reacting chamber for distributing the material out from the feedwell apparatus.

Thereby an increase in performance of a feedwell apparatus may be achieved by providing at least one of the following advantages: a higher feed energy dissipation, a higher solids hold-up, a more homogeneous mixing of sol- ids/liquor/flocculant, a higher solids exit symmetry, a lower solids exit energy, and lower solids exit shear rate.

Viewed from a further aspect, there can be provided a trough of a feedwell apparatus, the trough comprising a curved shape that turns in one direction, the trough com prising a first end for receiving material comprising liq uids carrying suspended particles, such as slurry contain ing minerals, a second end opposite to the first end, plu rality of through-openings in the wall(s) of the trough, wherein the through-openings are arranged in unequal pat tern such that area of the through-openings in proportion to the corresponding area of the wall(s) has its minimum value in portion of the trough close to the first end thereof, and said relation being arranged to grow with the distance from the first end.

Thereby a trough providing a higher feed energy dissipa tion, a higher solids hold-up, a more homogeneous mixing of solids/liquor/flocculant, a higher solids exit sym metry, a lower solids exit energy, and/or a lower solids exit shear rate may be achieved.

Viewed from a further aspect, there can be provided a thickener plant, comprising at least one thickener tank, wherein at least one of said thickener tank(s) is arranged to receive the material from the feedwell apparatus as de fined above.

Thereby a plant providing increased unit area throughput and high efficiency may be achieved.

Viewed from a still further aspect, there can be provided use of the feedwell apparatus as defined above for han dling tailings from a mineral process of a mining plant, for handling flow from a flotation process of a mining plant, or for handling tailings from a flotation process of a mining plant.

Thereby more efficient processes may be achieved.

The arrangement, the trough, the plant and the use are characterised by what is stated in the independent claims. Some other embodiments are characterised by what is stated in the other claims. Inventive embodiments are also dis closed in the specification and drawings of this patent application. The inventive content of the patent applica tion may also be defined in other ways than defined in the following claims. The inventive content may also be formed of several separate inventions, especially if the inven tion is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups. Some of the definitions contained in the following claims may then be unnecessary in view of the separate in ventive ideas. Features of the different embodiments of the invention may, within the scope of the basic inventive idea, be applied to other embodiments.

In one embodiment, the width of the trough is arranged to decrease from the first end towards a second end of the trough. An advantage is that high initial feed or material speed may be maintained in the trough, and thus an effi cient transport of the material through the whole trough is achieved.

In one embodiment, the width of the trough is constant from the first end to a second end of the trough. An ad vantage is that the capacity of the trough to receive ma terial may be high.

In one embodiment, the cross-section of the trough has an open top. An advantage is that the structure of the trough is simple, and that entrained air in the influent material may escape, and that the slurry stream potentially may be observed.

In one embodiment, the trough has a U-shaped cross- section, with rectangular or rounded corners. An advantage is that the structure of the trough is simple.

In one embodiment, the trough has a V-shaped cross- section. An advantage is that the structure of the trough is simple, and reduces a build-up of settled material which may be required. In one embodiment, the trough has a tubular cross-section. An advantage is that the structure of the trough isolates the material from surroundings.

In one embodiment, the trough is arranged to make at least a 180° turn in the apparatus. An advantage is that a long trough may be provided without extending the dimensions of the feedwell apparatus, and thus the efficiency of the ap paratus may be raised.

In one embodiment, the trough is arranged to make at least a 360° turn in the apparatus. An advantage is that even more efficient feedwell apparatus may be achieved with better material distribution.

In one embodiment, the trough is arranged apart from the outer circumference wall of the reacting chamber. An ad vantage is that the trough may be construed as an element that is easy to remove from the feedwell apparatus, or to retrofit in a feewdell apparatuses, and that the trough maybe be more centrally located in the reacting chamber optimising material distribution.

In one embodiment, the trough is arranged to constitute a part of the outer circumference wall of the reacting cham ber. An advantage is that the structure of the feedwell apparatus may be simplified.

In one embodiment, the turning radius of the trough is de creasing as the distance from the first end thereof is in creasing. An advantage is that high initial feed or mate rial speed may be maintained largely throughout the trough.

In one embodiment, the first end and the second end of the trough are arranged on a same horizontal level. An ad- vantage is that the height of the feedwell apparatus may be reduced and thus a more compact apparatus achieved.

In one embodiment, the first end of the trough is arranged higher than the second end. An advantage is that material velocity may be maintained high in the trough.

In one embodiment, the first end of the trough is arranged lower than the second end. An advantage is that material velocity in the trough may be lowered in a controlled way.

In one embodiment, the apparatus comprises more than one trough. An advantage is that the efficiency of the appa ratus may be raised, and operation of the apparatus can be maintained in the event one of the multiple feed systems is inoperable.

In one embodiment, the through-openings are arranged in a bottom section of the trough. An advantage is that gravity is exploited in changing horizontal kinetic energy of ma terial into vertical energy.

In one embodiment, the trough comprises through-openings in an innermost wall of said trough. An advantage is that sanding of the through at the innermost wall may be less ened or eliminated, and it improves material distribution within the reacting chamber.

In one embodiment, the trough comprises through-openings in an outermost wall of said trough. An advantage is that sanding of the through at the outermost wall may be less ened or eliminated.

In one embodiment, the through-openings arranged in the bottom section of the trough are arranged in the unequal pattern, and the trough comprises through-openings at least in one of the innermost and outermost wall of said trough, and the through-openings in the innermost wall and/or the outermost wall(s) are arranged in an unequal pattern from the first end to the second end of the trough. An advantage is even massflow distribution inside the feedwell reacting chamber and minimum material build up from particle settling.

In one embodiment, the through-openings arranged in the bottom section of the trough are arranged in the unequal pattern, and the trough comprises through-openings at least in one of the innermost and outermost wall of said trough, and the through-openings in the innermost wall and/or the outermost wall(s) are arranged in a constant pattern from the first end to the second end of the trough. An advantage is that the manufacturing of the in nermost wall and/or the outermost wall(s) may be simpli fied.

In one embodiment, the through-openings arranged in at least in one of the innermost and outermost wall are ar ranged in the unequal pattern, and wherein the through- openings in the bottom section of the trough are arranged in a constant pattern from the first end to the second end of the trough. An advantage is that the manufacturing of the bottom section may be simplified.

In one embodiment, the through-openings have a same size, and the change of proportion of the through-openings and the corresponding area of the walls is realized by varying distances between the through-openings. An advantage is that the unequal pattern is easy to manufacture.

In one embodiment, the through-openings vary in their size, and the change of proportion of the through-openings and the corresponding area of the walls is realized by ar- ranging the smallest through-openings near the first end and the largest through-openings near the second end of the trough. An advantage is that the geometry of the une qual pattern may be tailored very precisely and thus an efficient transport of material may be achieved.

In one embodiment, the cross-section of at least some of the through-openings is round. An advantage is that round shapes are easy to manufacture.

In one embodiment, the cross-section of at least some of the through-openings is elongated. An advantage is that the shape of the through-openings may be optimized for changing horizontal kinetic energy of material flow in vertical energy.

In one embodiment, the cross-section of at least some of the through-openings is polygon. An advantage is that the shape of the through-openings may be optimized for chang ing horizontal kinetic energy of material flow in vertical energy.

In one embodiment, the proportion of the area of the through-openings to the area of the wall is arranged to grow gradually. An advantage is that a trough providing even massflow distribution inside the feedwell reacting chamber and minimum material build-up from particle set tling may be achieved.

In one embodiment, the proportion of the area of the through-openings to the area of the wall is arranged to grow step-by-step. An advantage is that the manufacturing step of the through-openings may be simplified. In one embodiment, the proportion of the area of the through-openings to the area of the wall is selected as follows:

- 0% - 15% in a first quarter of length of the trough,

- 5% - 15% in a second quarter,

- 5% - 20% in a third quarter, and

- 8% - 30% in a fourth quarter of said length.

An advantage is that the efficiency of the feedwell appa ratus may be improved.

In one embodiment, the proportion of the area of the through-openings to the area of the wall is selected as follows:

- 3% - 7% in a first quarter of length of the trough,

- 5% - 9% in a second quarter,

- 7% - 11% in a third quarter, and

- 10% - 14% in a fourth quarter of said length.

An advantage is that the efficiency of the feedwell appa ratus may further be improved.

In one embodiment, at least some of the through-openings are provided with a nozzle having a length in a direction away from an inside of the trough. An advantage is that it is possible to boost conversion of the initial forward and rotational kinetic energy of the material flow into a ver tical downwards directing flow.

In one embodiment, the length of the nozzle is in range of 0.15 x D - 0.6 x D, wherein D is the diameter of the re spective through-opening. An advantage is that an effec tive conversion of the forward and rotational kinetic en ergy into the vertical downwards directing flow may be achieved.

In one embodiment, the cross-section of the nozzle is round, and the inner diameter of said nozzle is 0.05 x W - 0.15 x W, wherein W is width of a transition box. An ad vantage is that a better material distribution into the feedwell reacting chamber may be provided, and that the holes are large enough to not block but numerous enough to provide a multitude of material streams.

In one embodiment, the apparatus comprises dilution open ings arranged to an outer circumference wall of the react ing chamber for feeding dilution substance into the react ing chamber. An advantage is that the material may be di luted with the dilution substance and the flow of material in the apparatus optimized.

In one embodiment, the dilution openings are arranged all around the outer circumference wall of the reacting cham ber. An advantage is that the material may be evenly di luted with the dilution substance.

In one embodiment, the wall of the trough comprises of a polymer lined metallic structure. An advantage is that wear caused by high velocity of material may be reduced.

In one embodiment, the wall of the trough comprises of a polymer composite structure. An advantage is that a light structure of the trough may be achieved.

In one embodiment, the supply channel is arranged to the first end of the trough such that a horizontal alignment angle of the supply channel with relation to said first end is in range of ±20°. An advantage is that an effective transport of material through the trough may be assured.

BRIEF DESCRIPTION OF FIGURES

Some embodiments illustrating the present disclosure are described in more detail in the attached drawings, in which Figure 1 is a schematic perspective view of a feedwell ap paratus, Figure 2 is a schematic top view of the feedwell apparatus shown in Figure 1,

Figure 3 is a schematic partial cross-section-view along line A-A in Figure 2,

Figure 4 is a schematic partial cross-section-view along line B-B in Figure 2,

Figure 5 is a schematic perspective view of another feed- well apparatus,

Figure 6 is a schematic side-view of a feedwell apparatus arranged inside a thickener tank, Figure 7 is schematic top view of some embodiments of the through-opening,

Figure 8 is a schematic side view of a nozzle in partial cross-section,

Figure 9 is schematic top view of cross-sections of some embodiments of the trough,

Figure 10 is a schematic top view of another trough, and

Figure 11 is a schematic view of still another feedwell apparatus.

In the figures, some embodiments are shown simplified for the sake of clarity. Similar parts are marked with the same reference numbers in the figures. DETAILED DESCRIPTION

Figure 1 is a schematic perspective view of a feedwell ap paratus, Figure 2 is a schematic top view of the feedwell apparatus shown in Figure 1, Figure 3 is a schematic par- tial cross-section-view along line A-A in Figure 2, and Figure 4 is a schematic partial cross-section-view along line B-B in Figure 2.

The feedwell apparatus 100 is adapted to be used for mate- rials comprising liquids carrying suspended particles, such as slurry containing minerals. Typically, the feed- well apparatus 100 is arranged inside a thickener tank 13, for instance as shown in Figure 6. The thickener tank 13 is arranged to receive the material from the feedwell ap- paratus 100.

The feedwell apparatus 100 comprises a supply channel 1 arranged to receive the material to be handled. The supply channel 1 is connected in fluid communication with a first end 2a of a trough 2 by a transition box 14.

The trough 2 has a curved shape that turns in one direc tion. In an embodiment, the width W of the trough decreas es from the first end 2a towards a second end 2b of the trough. However, in another embodiment, the trough 3 has a constant width W from the first end 2a to the second end 2b.

The trough 2 or its wall 4 may be manufactured from vari- ous materials, such as metals or alloys. In an embodiment, the trough 2 comprises a metallic structure that is lined or coated by a polymer layer. In another embodiment, the wall 4 of the trough comprises polymer composite struc ture, that may be lined or coated by a polymer layer. In an embodiment, the cross-section of the trough 2 has an open top. In the embodiment shown in Figures, the cross- section of the trough 2 is open at the top and has a rec tangular U-shape. In another embodiment, corners of the cross-section have a rounded shape. Figure 9 is showing cross-sections of some embodiments of the trough. In an embodiment, the trough 2 has a V-shaped cross-section. In another embodiment, the trough 2 has a tubular cross- section, for instance a circular cross-section.

According to an aspect, the trough 2 is arranged to make at least a 180° turn in the apparatus 100. In other embod iments, such as shown in Figures, the trough 2 is arranged to make about a 360° turn in the apparatus 100. In some embodiments, the turn may even be more than 360°.

In an embodiment, the trough 2 is arranged apart from the outer circumference wall 7 of the reacting chamber. Ac cording to an aspect, the trough 2 as such is a component or structural element (being made up of one or plurality of sub-elements) that can be used as a retrofitting ele ment in thickener plants.

In an embodiment, turning radius of the trough 2 is de creasing as the distance from the first end 2a thereof is increasing. In another embodiment, said radius is increas ing as the distance from the first end 2a is increasing. In still another embodiment, said radius is constant all the length of the turning section of the trough 2.

In an embodiment, the first end 2a and the second end 2b of the trough are arranged on a same horizontal level. In another embodiment, the ends are on different level. Thus, the first end 2a may be on a higher or a lower level than the second end 2b. The trough 2 comprises plurality of through-openings 3 in the walls 4 of the trough 2. The through-openings 3 are arranged in the trough 2 in unequal pattern such that area of the through-openings 3 in proportion to the correspond ing area of the walls 4 has its minimum value in portion of the trough 2 close to the first end 2a, and said rela tion being arranged to grow as the distance from the first end 2a is growing.

In an embodiment, such as in one shown in Figure 1, the through-openings 3 have a same size and shape (e.g. round), and the change of proportion of the through- openings 3 and the corresponding area of the walls 4 is realized by varying distances between the through-openings 3.

Figure 7 shows some embodiments of through-openings. The shape or cross-section of the through-openings 3 may be selected rather freely: it may have a shape of closed curve, such as round or ellipse; or polygon, such as square, quadrilateral or pentagon. The shape may be elon gated. In an embodiment, all the through-openings 3 have a similar shape. In another embodiment, there are different ly shaped through-openings 3 in the trough 2.

In the embodiments shown in Figures, the through-openings 3 are arranged in a bottom section 8 and in an innermost wall 9 of the trough 2. In another embodiment, there are also through-openings 3 in an outermost wall 10 of the trough 2. In some other embodiments, there are through- openings 3 only either in the bottom section 8, in the in nermost wall 9 or in the outermost wall 10, or any combi nations of the bottom section and the walls.

The through-openings 3 and their unequal pattern may be realized in various ways. In an embodiment, the through- openings 3 are arranged in the bottom section 8 in the un equal pattern, whereas through-openings 3 arranged at least in one of the innermost and outermost wall 9, 10 are arranged in a constant pattern from the first end 2a to the second end 2b of the trough. In another embodiment, the through-openings 2 arranged in the innermost or outer most wall 9, 10, or both, are arranged in the unequal pat tern, and the through-openings 3 in the bottom section 8 are arranged in a constant pattern from the first end 2a to the second end 2b of the trough. In still another em bodiment, in the wall 4, i.e. the bottom section 8, the innermost wall 9 and the outermost wall 10, all the through-openings 3 are in the unequal pattern.

The proportion of the area of the through-openings 3 to the area of the wall 4 may be arranged to grow gradually or step-by-step.

In an embodiment, the trough is divided lengthwise in four sections SI - S4, and the proportion of the area of the through-openings 3 to the area of the wall 4 is selected as follows:

- 0% - 15% in a first quarter SI of length of the trough

2,

- 5% - 15% in a second quarter S2,

- 5% - 20% in a third quarter S3, and

- 8% - 30% in a fourth quarter S4 of said length.

In another embodiment, the selection is made as follows:

- 3% - 7% in the first quarter SI,

- 5% - 9% in the second quarter S2,

- 7% - 11% in the third quarter S3, and

- 10% - 14% in the fourth quarter S4 of said length.

The feedwell apparatus 100 comprises further a reacting chamber 5 that is arranged under the trough 2. The react- ing chamber 5 receives the material dropping from the through-openings 3. An outlet 6 is arranged in the react ing chamber 5 for distributing the material out from the feedwell apparatus 100. In the shown embodiment, the out let 6 comprises a gap that circumferences the reacting chamber in a continuous way.

The feedwell apparatus 100 may comprise dilution openings 12 arranged to an outer circumference wall 7 of the react ing chamber for feeding dilution substance in the reacting chamber 5. The dilution substance may be a supernatant di lution liquor which may be mixed with flocculant. In an embodiment, such as shown in Figures, the dilution open ings 12 are arranged all around and evenly spaced in the outer circumference wall 7 of the reacting chamber. In other embodiments, the dilution openings 12 are arranged in only some limited section or sections of the outer cir cumference wall 7, and/or the dilution openings 12 are spaced not evenly in the outer circumference wall 7. All the dilution openings 12 may have a same size, as in Fig ures, or thy may comprise various sizes.

In an embodiment, all or at least some of the through- openings 3 are provided with a nozzle 11 that extends from the wall 4 at a first distance D in a direction away from an inside of the trough 2, as shown in Figure 8 . In an em bodiment, the length L of the nozzle 11 is selected in range of 0.15 x D - 0.6 x D, wherein D is the diameter of the respective through-opening 3. In another embodiment, the length L of the nozzle 11 is in range of 0.25 x D - 0.35 x D. All the nozzles 11 may have an equal length L, or there may be variations in said lengths.

In an embodiment, the cross-section of the nozzle 11 is round, and the inner diameter D of said nozzle is 0.05 x Ws - 0.15 x Ws, wherein Ws is width of the starting width of the first end of the trough.

In an embodiment, the supply channel 1 is arranged to the first end of the trough 2a such that a horizontal align ment angle K of the supply channel 1 with relation to said first end 2a is in range of ±20°. In the Figures, angle K is 0°.

Figure 5 is a schematic perspective view of another feed- well apparatus. This embodiment has many features common with the apparatus shown in Figures 1 - 4. However, now the trough 2 is arranged to constitute a part of the outer circumference wall 7 of the reacting chamber.

Figure 6 is a schematic side-view of a feedwell apparatus 100 arranged inside a thickener tank 13 (shown by dashed lines). The feedwell apparatus 100 and the thickener tank 13 are a part of a thickener plant 200 (shown by dot-and- dash lines). The thickener plant 200 may comprise just one thickener tank 13, or plurality of thickener tanks 13. At least one of the thickener tanks 13, but not necessary all, is arranged to receive the material from the feedwell apparatus 100 described in this description.

According to an aspect, the feedwell apparatus 100 is used for handling tailings from a mineral process of a mining plant.

According to an aspect, the feedwell apparatus 100 is used for handling flow from a flotation process of a mining plant.

According to an aspect, the feedwell apparatus 100 is used for handling tailings from a flotation process of a mining plant. Figure 10 is a schematic top view of another trough. In an embodiment, the change of proportion of the through- openings 3 and the corresponding area of the walls 4 is realized by varying the size of the through-openings 3 such that the smallest through-openings 3 are arranged near the first end 2a and the largest through-openings 3 near the second end 2b of the trough. As shown in Figure 10, all the through-openings 3 may have a similar shape. In another embodiment, the size of the through-openings 3 is arranged to decrease not only by scaling-down the size of the through-openings but also changing shape thereof. For instance, the largest through-openings 3 may have an elongated shape, such as an elliptical shape, whereas the smallest through-openings 3 are round.

Figure 11 is a schematic view of still another feedwell apparatus. In one embodiment, the apparatus comprises more than one trough 2. Figure 11 is showing a feedwell appa- ratus 100 that comprises two troughs. In the shown embodi ment, the two troughs 2 are at least essentially identical to each other. In another embodiment, there are some structural variations or differences in the troughs. The invention is not limited solely to the embodiments de scribed above, but instead many variations are possible within the scope of the inventive concept defined by the claims below. Within the scope of the inventive concept the attributes of different embodiments and applications can be used in conjunction with or replace the attributes of another embodiment or application.

The drawings and the related description are only intended to illustrate the idea of the invention. The invention may vary in detail within the scope of the inventive idea de fined in the following claims. REFERENCE SYMBOLS

1 supply channel

2 trough 2a first end of trough 2b second end of trough

3 through-opening

4 wall

5 reacting chamber 6 outlet

7 outer circumference wall

8 bottom section of trough

9 innermost wall of trough

10 outermost wall of trough 11 nozzle

12 dilution opening

13 thickener tank

14 transition box 100 feedwell apparatus 200 thickener plant

D diameter of through-opening

K angle L length of nozzle

S section of trough

W width of trough

Ws starting width of the trough