Feed dilution unit for concentrators / clarifiers

Abstract

A feedwell assembly (1) having a feedwell (3) and a feed dilution device (27), characterized in that the feed dilution device (27) comprises a centrifugal impeller (16) arranged in a pump housing (9). The pump housing is arranged below a weir box (12) having an upper opening and an overflow lip (12b). The overflow lip (12b) is arranged at the upper periphery of the weir box (12). The overflow lip (12b) is configured to be arranged below an air-liquid interface (20) during operation so that an immersion depth (26) exists between the overflow lip (12b) and the air-liquid interface (20).

Description

Technical Field

[0001] The present invention relates to a feed dilution device for use in a concentrator / clarifier system in the sedimentation field. More specifically, the present invention relates to a centrifugal pumping device located upstream of a feed inlet that draws clarified liquid and solids entrained in foam near the water-air interface and mixes them with the feed slurry delivered to the feed inlet. Background Art

[0002] References to background art herein should not be construed as an admission that such art constitutes common general knowledge in the field.

[0003] Feedwells have been known for decades for use in sedimentation units such as concentrators / clarifiers. The purpose of a feedwell is generally to reduce the momentum, energy, and velocity associated with the incoming feed slurry so that a quiescent settling zone can be maintained within the primary settling tank area of ​​the concentrator / clarifier.

[0004] The feed slurry can be diluted in or upstream of the feedwell by using a conventional feed dilution system. Some examples of such prior art equipment and methods can be found in WO2010097762A1, WO2012071256A1, WO2012082530A1, WO2013096967A1, WO2014089433A1, US20140175020A1, US5389250A, US7988865B2, WO2003095062A1, AU2007100006 and AU2008100050.

[0005] FLSmidth The P-DUC feed dilution system is designed to maximize flocculation efficiency and settling rates, but it does not adequately address foam accumulation. Current P-DUC units utilize an axial flow pump and a submerged hood with an open lower floor. The axial flow pump draws clarified liquor from the upper layer within the concentrator and in a vertically upward direction. The clarified liquor received by the axial flow pump is brought to a point well below the air-liquid interface, potentially compromising the quiescent zone within the concentrator. The clarified liquor naturally mixes with the incoming slurry through the discharge before being introduced into the typically horizontally arranged mixing duct at the feed inlet. Due to its low opening configuration, the P-DUC design can disrupt the quiescent zone within the concentrator tank and may not adequately address foam entrained in the concentrator tank, which can form near the air-liquid interface and overflow the clarified liquor weir as product overflow. Foam accumulation within sedimentation units remains an industry-wide problem. Therefore, there has been a long-standing need to address foam accumulation in concentrator / clarifiers and ensure that all solids exit the circuit as underflow and that the clarified liquid product remains solids-free.

[0006] Similarly, Outotec's AutodilTM 、Directional Autodil TM and Turbodil TM Forced feed dilution systems have been used to dilute the feed slurry, but these systems also do not adequately address the issues of foam buildup and spillage product contamination.

[0007] During settling operations, solids may be entrained by swirling foam at the upper air-liquid interface of the concentrator / clarifier. Consequently, the solids intended to settle may short-circuit the process by flowing over the clarified phase weir, leading to contamination of the clarified product stream and / or a reduction in overall settler efficiency. It would be desirable to provide a more robust feed dilution system configured to reintroduce these floating solids with the feed slurry, giving them an additional opportunity to settle to the lower tank outlet without contaminating the upper clarified product phase.

[0008] Related devices have been proposed, the purpose of which is to break up foam (eg US20110067568A1) or to degas the feed (eg US20140352529A1). However, such devices cannot contribute to or assist the dilution of the feed slurry to a great extent.

[0009] Embodiments of the present invention are intended to improve upon existing forced dilution systems by incorporating a centrifugal impeller fed from above by a shallow immersion vessel. At this point, the feed slurry can be diluted and entrained foam solids can simultaneously be removed from the clarified phase and reintroduced into the feedwell for settling. Summary of the Invention

[0010] An object of the embodiments is to provide an improved feed dilution device for a precipitation apparatus (e.g., a concentrator / clarifier or settling tank) that overcomes or ameliorates one or more of the above-mentioned disadvantages or problems; or at least provides a useful alternative to conventional feed dilution systems.

[0011] It is another object of an embodiment to provide a feed dilution device that exhibits an improved ability to remove foam from the upper clear phase and / or reintroduce foam-entrained solids into the feedwell and settling process to promote their settling.

[0012] It is another object of an embodiment to provide a feed dilution device that reduces or at least prevents the formation of foam on the liquid surface of the concentrator during operation.

[0013] It is another object of an embodiment to provide a feed dilution device configured to utilize shear (eg, shear rate of liquid flowing along a weir box sidewall or into a pump casing including a rotating centrifugal impeller) to help break up foam received from an air-liquid interface.

[0014] It is another object of an embodiment to provide a feed dilution device configured to adjust the flow rate into the feed inlet to achieve optimal flocculation.

[0015] Another object of an embodiment is to provide a feed dilution device configured to adjust the proper mixing of the diluent with the feed slurry before entering the feedwell.

[0016] It is another object of an embodiment to provide a feed dilution device that can be configured to use a shorter mixing channel than conventionally required while maintaining the same dilution flow rate as the longer mixing channels found in the prior art.

[0017] Another object of an embodiment is to provide a feed dilution device designed to prevent, mitigate or completely avoid the presence of sand particles in the feedwell, feedwell inlet and / or mixing chamber / duct despite low flow rates (e.g., in the range of 1-1.5 m / s), but not limited thereto.

[0018] Other preferred objects of the present invention will become apparent from the following description. These and other objects of the present invention will become apparent from the accompanying drawings and description herein. Although each object of the present invention is considered to be achieved by at least one embodiment of the present invention, any one embodiment of the present invention does not necessarily achieve all objects of the present invention.

[0019] A feed port assembly (1) is disclosed. The feed port assembly (1) may include a feed port (3) and a feed dilution device (27), the feed dilution device (27) being configured to dilute the feed slurry with a diluent before the feed slurry enters the feed port (3). The feed dilution device (27) may include a mixing chamber (5) operably connected to a feed port inlet (4). The mixing chamber (5) may be configured to receive slurry from a slurry feed conduit (7) and combine the slurry with a diluent received from a diluent inlet (10). The mixing chamber (5) may be enclosed or configured as a conduit or channel with an open top (e.g., U-shaped), but is not limited thereto.

[0020] The feed dilution device (27) may include a pump (36) having a centrifugal impeller (16) arranged within a pump housing (9). The centrifugal impeller (16) may be arranged substantially horizontally so that its axis of rotation is substantially vertical and thus aligned substantially parallel to a central axis (not shown) of the feed inlet (3). As shown, the pump housing (9) may be arranged below the weir box (12). The weir box (12) may have an overflow lip (12b). The overflow lip (12b) may be arranged at an upper periphery of the weir box (12) (e.g., so as to form an upper weir boundary surface). The overflow lip (12b) may be configured to be arranged below the air-liquid interface (20) during operation, e.g., so that there is an immersion depth (26) between the overflow lip (12b) and the air-liquid interface (20). During operation, the weir box (12) may have its own air-liquid interface (not shown) that is lower in height than the air-liquid interface (20).

[0021] An adjustable connection (11) may be provided between the weir box (12) and the pump housing (9). The adjustable connection (11) may include, for example, a telescopic connection as shown in the figure. The telescopic connection (11) may be located between or comprised of a lower nested pipe portion (12a) of the weir box (12) and an upper nested pipe portion (9a) of the pump housing (9). The upper nested pipe portion (9a) of the pump housing (9) may extend from and be located above the upper surface (9b) of the pump housing (9), but is not limited thereto.

[0022] The feed dilution device (27) may further include at least one actuator (18) or actuating device. The at least one actuator (18) may be configured to move the lower nested tube portion (12a) relative to the upper nested tube portion (9a) in any conceivable mechanical manner known in the art. The at least one actuator (18) may be configured to move at least one support structure (14) that is connected to a portion of the weir box (12). For example, the at least one actuator (18) may move the at least one support structure (14) and the weir box (12) up and down relative to one or more other parts of the feed port assembly (1), such as the feed port (3) and / or the bridge (8) structure, but is not limited thereto. The overflow lip (12b) (and / or the weir box 12) may be configured to move relative to the pump housing (9) to change the immersion depth (26), but is not limited thereto.

[0023] The pump housing (9) may include a pump outlet (9e). The pump outlet (9e) may extend (e.g., substantially horizontally) from a volute sidewall (9c) of the pump housing (9). A portion of the pump outlet (9e) may define a radially outermost fluid-bounding surface portion of the pump housing (9). As shown, the pump outlet (9e) may be operatively connected to the mixing chamber (5), e.g., via a diluent inlet (10).

[0024] The feed dilution device (27) is further characterized in that the pump outlet (9e) can be positioned at a lower level than the mixing chamber (5), the feed port inlet (4) and / or the slurry feed conduit (7), but is not limited thereto.

[0025] The pump outlet (9e) can be operably connected to the inlet portion (10a) of the diluent inlet (10). The mixing chamber (5) can be operably connected to the outlet portion (10c) of the diluent inlet (10). The main channel (10b) of the diluent inlet (10) can extend between the inlet portion (10a) and the outlet portion (10c), for example at a certain angle relative to the air-liquid interface (20) shown. The lower surface of the inlet portion (10a) can be located below (or lower than) the lower surface of the outlet portion (10c), but is not limited to this. It is also conceivable that, although not shown, the main channel (10b) can be arranged to extend in a generally horizontal direction, or to extend at a very small angle relative to the air-liquid interface (20).

[0026] The feed inlet (6) of the mixing chamber (5) may extend vertically between the mixing chamber (5) and the slurry feed conduit (7). The diluent inlet (10) may be located below the slurry feed conduit (7). It is further contemplated, although not shown, that the feed inlet (6) of the mixing chamber (5) may extend horizontally from the mixing chamber (5); or at an angle relative to the air-liquid interface (20) between the mixing chamber (5) and the slurry feed conduit (7).

[0027] A drive shaft (5) can connect a drive device (17) (e.g., comprising a direct drive motor or a motor with an optional transmission / reducer) to the centrifugal impeller (16). As shown, the drive shaft (5) can extend through the weir box (12) and the open center portion of the pump housing (9). The pump housing (9) can have a closed bottom surface (9d) to prevent damage to the static area below the pump housing (9). The closed bottom surface (9d) can be provided below the centrifugal impeller (16).

[0028] The feed inlet assembly (1) may further comprise a valve (19). The valve (19) may form part of the feed dilution assembly (27). The valve (19) may be located between the pump housing (9) and the mixing chamber (5) to restrict the flow of liquid between the pump housing (9) and the mixing chamber (5). For example, the valve (19) may be provided on a portion of the pump outlet (9e) or on a portion (10a, 10b, 10c) of the diluent inlet (10), but is not limited thereto. Although not shown, multiple valves (19) may be used in series, but are not limited thereto. The valve (19) may be of any type, including but not limited to a gate valve, a ball valve, a check valve, a butterfly valve, a throttle valve, a knife valve, a diaphragm valve, a stop valve, a plug valve, a solenoid valve or a slide valve, but is not limited thereto.

[0029] According to some embodiments, the weir box (12) may include one or more baffles (30). The one or more baffles (30) may extend radially along a sidewall (12c) of the weir box (12). The one or more baffles (30) may extend from a central portion of the weir box (12) at an angle (34) relative to a radial line (35).

[0030] In some embodiments, the blades (16b) of the centrifugal impeller (16) may include a flared outer profile (16h) to help propel or bias the flow radially outward.

[0031] A method for diluting slurry entering the feed port (3) of a concentrator / clarifier is also disclosed. Slurry may enter the feed port assembly (1) from a slurry feed conduit (7).

[0032] The method may include the step of providing a feedwell assembly (1) having a feed dilution device (27) as described above. The method may include the step of rotating a centrifugal impeller (16). The method may include the step of drawing clarified liquid and / or foam (from near the air-liquid interface (20)) over an overflow lip (12b) and through an immersion depth (26) into a weir box (12). The method may include the step of shearing the clarified liquid and / or foam within the weir box (12) and / or within the pump housing (9).

[0033] The method may comprise the step of conveying the sheared clarified liquor and / or foam to a mixing chamber (5). The method may comprise the step of combining the sheared clarified liquor and / or foam with the slurry in the mixing chamber (5). The method may comprise the step of supplying a mixture of the slurry (i.e. from the feed conduit 7) and the sheared clarified liquor and / or foam (i.e. from the pump housing 9) to the feed inlet (3).

[0034] Further details, features and advantages of the present invention will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Preferred embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, by way of example only.

[0036] To supplement the ongoing description and to aid in a better understanding of the features of the present invention, a set of drawings illustrating various systems and methods according to certain embodiments have been added to this specification as an integral part thereof, wherein the following description has been given in an illustrative and non-limiting manner. It should be understood that like reference numerals used in the figures, if used, may identify like components. In the drawings:

[0037] Figure 1 and Figure 2 is an alternative isometric view showing a feedwell assembly 1 including a novel feed dilution device 27 according to a non-limiting embodiment of the present invention.

[0038] Figure 3 yes Figure 1 and 2 A side view of the feed port assembly 1 is shown.

[0039] Figure 4 is a cross-sectional side view of a portion of the feedwell assembly 1 , particularly showing the feed dilution device 27 comprising the centrifugal impeller 16 and the submersible weir box 12 .

[0040] Figure 5 yes Figure 1-3 1 isometric view of the feedwell assembly 1 with the pump housing 9 and skimmer baffle 13 (not shown) removed for clarity.

[0041] Figure 6 yes Figure 1-3 1 isometric view of the feedwell assembly 1 with the weir box 12 (not shown) removed for clarity.

[0042] Figure 7 yes Figure 1-3 An isometric view of the feed port assembly 1 with a portion of the pump housing 9 removed (ie not shown) for clarity.

[0043] Figure 8 Six non-limiting alternative profiles for the sidewall 12c of the weir box 12 according to embodiments of the present invention are presented.

[0044] Figure 9 Four non-limiting alternative profiles for the overflow lip 12b of the weir box 12 according to embodiments of the present invention are presented.

[0045] Figure 10 An alternative embodiment of the feed dilution device 27 is proposed.

[0046] Figure 11-16 An alternative embodiment of the weir box 12 is presented, showing a baffle 30 disposed within the weir box 12. As shown, in some embodiments, a pump 36 may include an impeller 16 including an upper impeller 16c and a lower impeller 16d connectable to a drive shaft 15 via a hub 16a.

[0047] Figure 11 An isometric view of a non-limiting alternative embodiment of a feed dilution device 27 according to the present invention is shown.

[0048] Figure 12 yes Figure 11 A cross-sectional view of the feed dilution device 27 is shown.

[0049] Figure 13 Depicts Figure 11 and 12The baffle 30 component of the feed dilution device 27 is shown in FIG.

[0050] Figure 14 Shown Figure 11 and 12 The weir box 12 component of the feed dilution device 27 is shown.

[0051] Figure 15 Shown Figure 11 and 12 The upper impeller 16c portion of the rotor 16 is shown in the feed dilution device 27.

[0052] Figure 16 Shown Figure 11 and 12 The lower impeller 16d component of the rotor 16 is shown in the feed dilution device 27. As shown, the two impeller portions 16c, 16d can be independently fixed to the drive shaft 15 by their respective hubs; however, the lower impeller 16d can be connected to or directly fixed to the upper impeller 16c (for example, by fastening or welding the hub 16a together), but is not limited thereto.

[0053] Figure 17-19 Different baffle 30 arrangements are depicted that may help counteract eddy currents from the impeller 16 and / or shaft 15 rotation. DETAILED DESCRIPTION

[0054] As will be appreciated from this description and the accompanying drawings, a novel feed dilution device design is disclosed. The feed dilution device comprises a centrifugal pumping device 36 that draws diluent from the surface of the contents within the concentrator / clarifier into the pump housing, utilizing a closed housing bottom and an upper open end. This unique design configuration encourages clarified liquid (and any foam present thereon) to overflow the confines of the upper opening and enter the upper portion of the pump housing 9. Upon entering the pump housing, the centrifugal pumping device 36 can, by shearing and rotating the impeller 16, break up the air and entrained solids within the foam, and by pumping, combine the resulting mixture of solids and diluent with the feed slurry upstream of the feed inlet.

[0055] A shrouded agitator (e.g., a rotating centrifugal impeller comprising blades) can be positioned below the upper fluid surface boundary of the liquid / slurry contents within the concentrator / clarifier tank. The agitator can preferably be configured as a pumping device capable of pulling fluid downward from the surface portion of the liquid contents within the concentrator / clarifier and moving it into the mixing chamber. The shear rate of the fluid approaching the shrouded agitator can aid in breaking up any foam that may be present therein.

[0056] A slurry feed pipe or launder arranged near the hooded agitator can be arranged to extend through a portion of the tank wall of the concentrator / clarifier. It can be configured to be suspended under and / or supported by a bridge structure and can extend at a 1% slope to a kill box just outside the feed inlet. The slurry can be redirected from the kill box and enter a mixing chamber (e.g., a "mixing channel," "mixing conduit," or "launder") leading to the feed inlet, with dilution water from a centrifugal pumping unit flowing below the heavier slurry feed flow. By directing the incoming diluent below the denser incoming feed slurry, improved mixing can be exhibited.

[0057] The unique embodiments described herein provide the unique ability to discharge dilution water substantially horizontally relative to the agitator, thereby avoiding potential problems associated with existing feed dilution systems, which typically require vertically upward pumping (via axial impellers). Thus, using the provided embodiments, the more complex task of converting pressure head into a steady horizontal diluent flow can be avoided.

[0058] Turning now to the figures, according to some embodiments, a feed port assembly 1 includes a feed port 3 supported by a bridge structure 8. The feed port 3 can be supported, for example, by a plurality of support structures 2—each extending between a portion of the bridge structure 8 and a corresponding portion of the feed port 3, but is not limited thereto. As shown, the feed port 3 can include an open bottom 29 and can have a lower shelf 28 and sidewalls leading to the feed port inlet 4. It is contemplated that a large number of feed port 3 configurations, shapes, sizes, and designs can be used with the embodiments described herein. A mixing chamber 5 can be provided upstream of the feed port inlet 4, which is configured to receive a feed slurry and a diluent. For example, emanating from the mixing chamber 5 can be a feed inlet 6 and a diluent inlet 10. The feed inlet 6 can extend from, be operably connected to, and / or be in fluid communication with, a slurry feed conduit 7. As shown, the feed inlet 6 can be configured to slow down or change the direction of the slurry, or otherwise configured as a "kill box," but is not limited thereto. For example, the feed inlet 6 may extend vertically between the mixing chamber 5 and the slurry feed conduit 7, or extend at a certain angle relative to a horizontal plane, but is not limited thereto.

[0059] The slurry feed conduit 7 can be configured to deliver feed slurry from upstream process equipment to the feedwell assembly 1. The slurry entering the mixing chamber 5 can be diluted with a diluent that flows into the mixing chamber 5 through the diluent inlet 10. The diluent can be supplied to the mixing chamber 5 by a feed dilution device 27 comprising a centrifugal pump device. As previously described, mixing can be improved by positioning the diluent inlet 10 below the feed inlet 6.

[0060] As shown in the drawings, the feed dilution device 27 comprises a weir box 12, which may be supported by the pump housing 9 or the bridge structure 8 via a support structure 14. Other methods of supporting the weir box 12 are contemplated.

[0061] The support structure 14 may be operably connected to the interior or exterior of the weir box 12, including but not limited to the upper or inner surface of the side wall 12c of the weir box 12, the lower or outer surface of the side wall 12c of the weir box 12, or the upper overflow lip 12b portion of the weir box 12. Figure 1 7 and 10, the support structure 14 can extend upwardly so as to be operably connected to a portion of the bridge structure 8 that spans a portion of the concentrator / clarifier tank (not shown). However, although not shown, the support structure 14 may alternatively be placed between a portion of the weir box 12 and a portion of at least one of the pump housing 9, the diluent inlet 10, or another component of the feedwell assembly 1 (e.g., the skimmer baffle 13), but is not limited thereto.

[0062] The pump housing 9 may include a top surface 9b, a volute sidewall 9c, and a preferably closed bottom surface 9d, which together house the centrifugal impeller 16 therein. The bottom surface 9d may be substantially or completely closed to prevent further disruption of the underlying static zone. Extending from the top surface 9b, an upper nested tube portion 9a may be provided, configured to receive or be received within the lower nested tube portion 12a of the weir box 12. Openings may be present in the center portions of the lower nested tube portion 12a and the upper nested tube portion 9a. Although the pump housing 9 may be provided as a single, unitary piece, it is preferably constructed as a multi-part component. For example, the pump housing 9 may have a clamshell or two-piece design. The pump housing 9 may employ one or more connecting flanges 9f provided on each part of the clamshell or two-piece design. The connecting flanges 9f may be secured together using fasteners (e.g., rivets or bolts and nuts). The components of the pump housing 9 may be fully or partially disassembled to facilitate lateral (i.e., horizontal) removal and / or insertion of the centrifugal impeller 16. The pump housing sections may be hinged together, but are not limited thereto. It is contemplated that in other alternative embodiments (not shown), the pump housing 9 may be configured so that the bottom surface 9d is removable from the rest of the pump housing 9, thereby allowing the centrifugal impeller 16 to be removed downwardly from the pump housing 9. Still alternatively, the upper surface 9b may be made removable from the pump housing 9 to allow the drive shaft 15 and centrifugal impeller 16 to be withdrawn upwardly and inserted downwardly into the pump housing 9 from above.

[0063] The pump outlet 9e may extend from the volute sidewall 9c of the pump housing 9. As shown, the pump outlet 9e may be operatively connected to and / or in fluid communication with the inlet portion 10a of the diluent inlet 10. The pump outlet 9e may be located near the radially outermost sidewall 9c portion of the pump housing 9, but is not limited thereto. Figure 10As shown, a valve 19 can be provided at a portion of the pump outlet 9e, for example, between the pump outlet 9e and the diluent inlet 10, and / or on any portion of the diluent inlet 10, to regulate or restrict the flow of diluent to the mixing chamber 5 downstream of the centrifugal pumping device. By adjusting the valve 19, an optimal amount of mixing can be produced between the diluent and the feed slurry arriving from the conduit 7 via the slurry inlet 6. In addition, by varying the orifice geometry of the valve 19 over time, pump performance can be improved and idling of the centrifugal impeller 16 can be avoided.

[0064] The pump housing 9 can be arranged substantially horizontally (as shown), such that the centrifugal impeller 16 rotates in a plane generally parallel to the air-liquid interface 20 within the concentrator / clarifier, but is not limited thereto. However, it is contemplated that other horizontal orientations are also possible. As shown, the weir box 12 can be arranged above the pump housing 9 such that its overflow lip 12b is arranged slightly below the air-liquid interface 20. In operation, a depth of submerged distance 26 exists between the overflow lip 12b and the air-liquid interface 20, allowing the centrifugal pump apparatus to be continuously supplied with diluent and / or foam.

[0065] The weir box 12 can be operably connected to the pump housing 9 using a rigid connector (not shown), but as shown, it can also be operably connected to the pump housing 9 via an adjustable connector 11 between the weir box 12 and the pump housing 9. The adjustable connector 11 can be, but is not limited to, a sliding telescopic connector between the upper nested tube portion 9a of the pump housing 9 and the lower nested tube portion 12a of the weir box 12. A seal such as an O-ring or piston ring (not shown) can be placed between the upper nested tube portion 9a and the lower nested tube portion 12a, or around the connector 11, but is not limited to such. Alternatively, a flexible sleeve or tubing (e.g., a bellows or accordion type) can connect the weir box 12 to the pump housing 9 and serve as a telescopic connector, eliminating the need for nested telescopic components 9a, 12a.

[0066] To deliver the diluent to the mixing chamber 5, the weir box 12 is supported so that it remains positioned so that its overflow lip 12b is below the air-liquid interface 20 (referenced as the immersion depth 26). The foam, containing entrained solids and clarified liquid, is able to overflow the overflow lip 12b and enter the weir box 12, which in turn feeds the centrifugal pumping device 36 below. The centrifugal impeller 16 within the pump housing 9 rotates, thereby drawing the foam, containing entrained solids and clarified liquid, into the pump housing 9 and then out of the pump outlet 9e. The flow of the foam, containing entrained solids and clarified liquid, can be regulated by an optional valve 19 before being discharged into the mixing chamber 5.

[0067] The fluid and entrained solids leaving the pump outlet 9e can enter the inlet portion 10a of the diluent inlet 10 and then pass through the main channel 10b and outlet portion 10c of the diluent inlet 10 before entering the mixing chamber 5. As shown, an embodiment can have an immersed centrifugal pump 36 so as to be arranged below the mixing chamber 5 (i.e., in a side view). Therefore, the inlet portion 10a and outlet portion 10c of the diluent inlet 10 can each be arranged at different respective heights relative to each other, with a varying vertical distance or pressure differential between the two. Any difference in height can be compensated by the pumping characteristics input by the impeller 16 and / or the drive 17.

[0068] An optional skimmer baffle 13 may be arranged to extend across a portion of the concentrator / clarifier air-liquid interface 20 to encourage the clarified liquid containing entrained solids and froth to flow into the weir box 12. The skimmer baffle 13 may be attached to one or more portions of the bridge structure 8, the weir box 12, or other components of the feedwell assembly 1 in any manner that encourages or biases the froth and / or clarified phase over the overflow lip 12b and into the weir box 12.

[0069] Although not shown, the feed dilution device 27 can be configured to minimize the overall height of the weir box 12 and to provide a relatively shallow angle of the sidewall 12c relative to the horizontal plane. In such an embodiment, the inlet portion 10a and the outlet portion 10b can be disposed at the same or very similar height (or depth relative to the air-liquid interface 20), but are not limited thereto.

[0070] Now go to Figure 8 , depicting a number of alternative profile shapes for the sidewall 12c of the weir box 12. This figure shows Figure 1-7 A side cross-sectional view of a portion of the weir box 12 is shown. 12c' represents an alternative sidewall shape / profile in which the sidewall 12c may extend substantially vertically upward to the overflow lip 12b (i.e., without an inclination angle). 12c'"'" represents an alternative profile for the sidewall 12c of the weir box 12 in which the lower annular shelf may be configured to extend radially outward from 12a, and a substantially vertical sidewall portion may extend upward from the outer edge of the lower annular shelf. The sidewall 12c" suggests that a smooth raised (e.g., annular or donut-shaped) surface may be provided between the overflow lip 12b and the lower nested tube portion 12a, but is not limited to such. Such an embodiment may help to reduce turbulence and improve flow over the overflow lip 12b toward the inlet of the pump housing 9. The sidewall alternatives 12c'" and 12c"" indicate that various compound curves or complex serpentine profiles may be used for the sidewall 12c of the weir box 12, but are not limited to such. Other envisioned geometries of the weir box sidewall 12c are envisioned, and Figure 8This is provided by way of example only to illustrate that the inventors have considered various cross-sectional shapes of the weir box 12. It is envisaged that computational fluid dynamics (CFD) principles or empirical experimental information may be used to optimise the geometry of the feed diluter 27 components to improve the flow pattern and overall performance of the feedwell arrangement 1.

[0071] It should also be understood and appreciated that while the weir box 12 is shown in the figures as a frustoconical member with the overflow lip 12b comprising a circular or elliptical annular shape (i.e., in top view), it may take on many other top view profile shapes, including but not limited to a trapezoidal overflow lip 12b, a rectangular overflow lip 12b, a square overflow lip 12b, a chevron overflow lip 12b, a triangular overflow lip 12b, etc. Thus, the top plan view peripheral geometry of the weir box 12 may take on any regular or irregular annular shape (e.g., a polygon) without departing from the spirit and scope of the inventive concepts described herein.

[0072] Now go to Figure 9 , a partial side cross-sectional view of the weir box 12 illustrates various alternative embodiments of the overflow lip 12b. The overflow lip 12b may simply comprise a sharp upper edge portion of the sidewall 12c, or it may comprise a smooth surface profile or geometry including a gradually arcuate (e.g., annular) surface 12b"" extending from the edge of the sidewall 12c to improve flow, optimize fluid mechanics / fluid dynamics, and / or reduce turbulence within the concentrator / clarifier tank in the surrounding portion of the weir box 12. The overflow lip 12b' may comprise a sharp, depending annular protrusion as shown, or the overflow lip 12b" may alternatively comprise a flat portion between the upper edge of the sidewall 12c and the depending annular protrusion or flange. In some embodiments, the overflow lip 12b'" may comprise a smooth surface profile or geometry including a gradually arcuate (e.g., annular or donut-shaped) surface 12b'"' extending from the flat portion, but is not limited thereto.

[0073] The plurality of support structures 14 supporting the weir box 12 can optionally be configured to directly or indirectly adjust the submergence depth 26 of the overflow lip 12b. For example, the support structure 14 can form part of an actuator 18, such as, but not limited to, a linear actuator. The actuator 18 can be manually actuated or automatically actuated by the control system 24, but not limited to such. In some embodiments, the support structure 14 can include, for example, a portion of the actuator 18, such as, but not limited to, an extendable / retractable piston rod of a hydraulic or pneumatic cylinder; an extendable plunger of a solenoid; a screw driven by a worm; a screw driven by a nut; a rack that can be driven by a pinion; a belt that can be part of a ratchet mechanism; a cable equipped with an adjustable turnbuckle mechanism; or other means for adjustably supporting the weir box 12 from, but not limited to, the bridge structure 8, the pump housing 9, the diluent inlet 10, the concentrator / clarifier tank, or other components forming part of the feedwell assembly 1. The support structure 14 may be positioned between, but is not limited to, a portion of the pump housing 9 and a portion of the sidewall 12c of the weir box 12. One or more actuators 18 and one or more support structures 14 may be used as a means for raising and lowering the weir box 12 to affect and vary the submergence depth 26.

[0074] like Figure 1-7 As shown, the support structure 14 may extend from a portion of the inner surface of the weir box 12. Figure 10 As shown, support structure 14 can extend from a portion of the outer surface of weir box 12. Although not shown, support structure 14 can extend between a portion of the surface of weir box 12 and a portion of a component of feedwell assembly 1 or a surface of a concentrator / clarifier, but is not limited thereto. In any of the above configurations, support structure 14 can be rigid, flexible, or adjustable, such as by using one or more actuators 18, but is not limited thereto. Drive shaft 15 can be used to drive and rotate centrifugal impeller 16 within pump housing 9. Drive shaft 15 can have a driven end 15a connected to a portion of centrifugal impeller 16, such as a hub 16a portion of centrifugal impeller 16. Hub 16a can include a plurality of straight or curved blades 16b oriented in any direction, which can help draw fluid onto overflow lip 12b and / or pump fluid into mixing chamber 5. As shown, in some embodiments, hub 16a of centrifugal impeller 16 can simply include a bottom wall to which blades 16b are secured, with distal drive end 15a of the shaft being secured.

[0075] The driving end 15b of the drive shaft 15 can be mounted on a drive device 17. The drive device 17 can include a motor, such as a variable frequency drive (VFD) motor with an optional speed reducer, but is not limited thereto. The driven end 15b of the drive shaft 15 can be coupled to the drive device 17 in any manner known in the art.

[0076] like Figure 10As shown, one or more actuators 18 can be used to raise and lower the weir box 12 to change the immersion depth 26 of the overflow lip 12b and / or to vary the amount of clarified phase / foam entering the weir box 12. The actuator 18 can be as simple as a nut that can be manually rotated to raise and lower the support structure 14, which can be configured as a vertically extending screw. However, the actuator 18 can include more complex linear actuators, cylinders, hydraulic arms, mechanized linkages, rotatable reels for raising and lowering the support structure 14 configured as cables, and the like. It should be understood that the combination of numerals 14 and 18 can include any known equivalent device that can be used to adjust the relative positioning between the overflow lip 12b and the air-liquid interface 20. If the device 26 for adjusting the immersion depth of the overflow lip 12 is automated, the control system 24 can transmit periodic control signals 25c, 25e to the one or more actuators 18 to raise and / or lower the weir box 12, but is not limited thereto.

[0077] In some embodiments, the feed dilution device 27 of the feedwell assembly 1 may include an ultrasonic level sensor 21 to periodically determine the real-time level of the air-liquid interface 20 or the relative position of a portion of the weir box 12 (e.g., the overflow lip 12b) relative to the air-liquid interface 20. The ultrasonic level sensor 21 may periodically measure to determine the submergence depth 26 and periodically send a control signal 25b to the control system 24. The period used may be infrequent or frequent to provide continuous online monitoring and control. The control system 24 may include a graphical user interface (GUI) (not shown) that may be configured to display the current submergence depth 26 on a screen. In this regard, the operator of the concentrator / clarifier may be notified, alerted, or otherwise made aware of the current operating conditions of the feed dilution device 27, including, but not limited to, the real-time submergence depth 26 or adjustments required to correct the submergence depth 26. Other operating conditions that may be displayed include, but are not limited to, the RPM of the drive unit 17 and / or the centrifugal impeller 16, the flow rate of the valve 19, and the liquid level within the weir box 12.

[0078] In addition to or in lieu of the ultrasonic level sensor 21, a mechanical level sensor 22 can be used to measure the submerged depth 26 of the overflow lip 12b relative to the air-liquid interface 20. The mechanical level sensor 22 can incorporate a float 23, such as a ball filled with gas or a low-density solid material (e.g., closed-cell foam). The float 23 can find a neutrally buoyant position near the air-liquid interface 20, and the mechanical level sensor 22 can transmit one or more control signals 25a to a control system 24, as previously described for the ultrasonic level sensor 21. The level sensors 21, 22 can be used individually or in conjunction with one another for redundancy and / or to avoid errors caused by foam accumulation at the upper fluid surface boundary of the concentrator / clarifier contents.

[0079] Drive 17 may include a variable frequency drive (VFD) motor that receives one or more control signals 25d from control system 24. Signals 25d may also be transmitted from drive 17 back to control system 24, and these signals may include information regarding operating parameters of drive 17 (e.g., temperature, RPM, vibration, voltage, torque, current draw, etc.), but are not limited thereto. Furthermore, one or more control signals 25f may be transmitted between control system 24 and valve 19. For example, signal 25f may be transmitted from control system 24 to valve 19 to regulate (e.g., by opening or closing valve 19) the back-end discharge flow of material exiting centrifugal pumping apparatus 36. If the RPM of drive 17 causes centrifugal impeller 16 to enter a "dry run" condition, or if the liquid level within weir box 12 is too low or empty, valve 19 may be adjusted (e.g., closed more partially or completely) to reduce the flow therethrough, the current drawn by drive 17 may be reduced, and / or the submersion depth 26 may be increased to allow more diluent to reside within pump housing 9 while maintaining proper dilution of the feed slurry within mixing chamber 5. The aforementioned changes may be temporary (ie, until the dry-run condition is no longer detected, or the operating conditions have improved or stabilized).

[0080] In some cases, to avoid surge conditions in the weir box 12, it may be beneficial to elect to run the pump assembly 36 dry, for example to the extent that a portion of the centrifugal impeller 16 is exposed to immersion. The decision to run dry (i.e., in a "full flush mode") may be unique to a particular process and may depend on the specific flow requirements and the shape / size of the feed dilution device 27 that can be accommodated in a particular concentrator. The control system 24 can therefore make dry determinations as needed.

[0081] The control system 24 may include a processor (e.g., a CPU, a PLC), hardware, memory, an operating system (OS), and executable files containing software or code containing algorithms. Signals 25a-25f may be transmitted from one or more components 17, 18, 19, 21, 22 of the feed dilution device 27 to the control system 24 via known wired or wireless protocols. The signals 25a-25f received by the control system 24 may be interpreted by the processor, for example, using an algorithm, to determine one or more optimal setting requirements for one or more of the various components 17, 18, 19, 21, 22 of the feed dilution device 27. The algorithm may determine whether the current settings, input variable parameters, or configuration or orientation of a particular component 17, 18, 19, 21, 22 need to be adjusted to achieve optimal performance of the feed dilution device 27.

[0082] Based on the received inputs (i.e., inputs collected from the input control signals 25a-25f), the algorithm may determine an appropriate corresponding corrective action plan and / or may identify one or more corrective measures (if any) to be taken in relation to the recommended operating configuration of the feed diluter 27. To improve or maintain continued operation of the feed diluter 27, the processor may compare the outputs recommended by the algorithm with the received inputs. If the operation of the feed diluter 27 can be improved by one or more configuration modifications, the processor may transmit appropriate output control signals 25a-25f to one or more of the corresponding components 17, 18, 19, 21, 22 to change the configuration of the feed diluter 27 and improve the performance of the feedwell assembly 1.

[0083] The feed inlet assembly 1 and feed dilution device 27 (including the configuration of the pump housing 9, centrifugal impeller 16, weir box 12, pump outlet 9e, diluent inlet 10, and other components thereof) described and illustrated herein are provided merely as examples to which the claimed invention may be applied. This description does not imply that the claimed invention is limited to or applicable only to the specific apparatus or configuration shown and described herein.

[0084] The velocity at which the mixed feed slurry and diluent enter the feed port can be adjusted to achieve optimal flocculation. For example, the flow velocity within the feed port inlet 4 and / or mixing chamber 5 can be in the range of about 0.5 m / s to 5 m / s, more preferably in the range of about 1.5 m / s to 2.2 m / s, but not limited thereto. Computational fluid dynamics (CFD) model data indicates that under such flow conditions, shear of the flocs exiting the feed port bottom opening 29 may be increased, and velocities lower than the above velocity range may result in larger aggregates. However, by maintaining a velocity range of about 1.5 m / s to 2.2 m / s, sanding in the mixing chamber 5 can be reduced or avoided entirely, but not limited thereto.

[0085] It should be understood that at lower feed port inlet velocities, the loading rate may be relatively low, thus requiring a larger feed port 3 for proper operation. However, the inventors contemplate that the feed port 3 used in conjunction with the feed dilution device 27 described and illustrated herein may be configured with a larger inlet and / or a larger shelf to maintain the same downward flow rate and feed port 3 size, but are not limited thereto. In such an embodiment, it is preferred to tilt the lower shelf 28 of the feed port 3 to minimize the possibility of sand accumulation.

[0086] Now go to Figure 11-16 In some embodiments, a plurality of fixed weir box baffles 30 may be disposed within the weir box 12, for example, above the sidewall 12b. The baffles 30 may extend generally radially relative to the center of the weir box 12 and may be constrained to not extend radially beyond the overflow lip, but are not limited thereto.

[0087] Baffle 30 may extend at an angle 34 relative to a radial line 35 extending from the center of weir box 12, as shown. This angle 34 may be zero degrees, or greater or less than zero degrees. Thus, the baffle may not extend perpendicular to a tangent to overflow lip 12b, or may be angled in any one or more of the three axial dimensions, without limitation. Angle 34 may be optimized and / or configured to initiate the rotational direction of the fluid entering the passage defined by tube portion 12a. Thus, baffle 30 may be configured to direct water flow into the housing in a tangential direction to prevent water crowding at the inlet and / or to counteract vortex effects caused by the rotation of shaft 15 and / or impeller 16, without limitation. Figure 17-19 Some non-limiting examples of how baffles may be arranged at an angle to counteract vortex effects caused by the rotation of the shaft 15 and / or impeller 16 are depicted.

[0088] In some embodiments, one or more baffles 30 may include one or more bends 31. These bends 31 may be used to prevent splashing (e.g., by defining an overall "shroud" in each baffle 30). These bends 31 may also provide work hardening in each baffle 30 to provide a stiffening or strengthening effect.

[0089] like Figure 13 As best shown in FIG, all baffles 30 may include at least one bend 31, but are not limited thereto. As shown, each bend 31 may be oriented along the length of the respective baffle 30, but one or more bends 31 may also be oriented along its width (not shown) to more effectively wrap the incoming flow. Baffles 30 may be substantially straight, as shown, or may include a curved profile (not shown) similar to baffles 16b of impeller 16, but are not limited thereto.

[0090] The weir box baffles 30 can be fastened (e.g., by bolting or welding) to a portion of the sidewall 12c of the weir box 12, preferably within the circumference / peripheral confines of the overflow lip 12b. In some contemplated embodiments, the baffles 30 can be supported or interconnected, for example, by one or more rings, such as an inner support ring 32 and an outer support ring 33, as shown. The baffles 30 can be fully submerged (i.e., positioned below the overflow lip 12b), or they can be configured to protrude above the hydraulic head line over which the clarified liquid moves. For example, the bend 31 shown can be above the liquid-air interface 20. The support structure 14 can be connected to one or more of the rings 32, 33. Alternatively, the rings 32, 33 themselves can serve as the support structure 14, but are not limited thereto.

[0091] Now go to Figure 14A plurality of support gussets 12d may optionally be provided on the weir box 12 to support the sidewalls 12c and / or provide rigidity to the assembly and / or device 27, but is not limited thereto. These gussets 12d may be used in conjunction with the support structure 14 described above, and in some embodiments, may form one or more portions of the support structure 14, but is not limited thereto. For embodiments where the support gussets 12d extend from the diluent inlet 10, as in Figure 1-5 The support structure 14 shown extending upwardly from the weir box side wall 12c may be optional.

[0092] Now go to Figure 15 and 16 In some embodiments, the centrifugal impeller 16 may include an upper impeller 16c and a lower impeller 16d. The two may be separable and defined as separate components as described, or they may be manufactured and / or provided together as a single, homogeneous, integral component. The upper portion 16c of the impeller 16 may have a hub 16a and a lower portion 16d. As shown, the blades 16b on the upper impeller 16c may have different features (e.g., profile, shape, and / or size) than the blades 16b on the lower impeller 16d. The blades 16b of each impeller portion 16c, 16d may be flush with each other to form a modular (i.e., "two-piece") blade structure of the impeller 16.

[0093] A hole 16e can extend through the impeller 16 (e.g., through each hub 16a), and any number of drive shaft anti-rotation features 16f (e.g., splines, keyways) can be disposed within the hole 16e. When the drive shaft 15 is received by the rotor 16, the features 16f can prevent relative rotational movement between the drive shaft 15 and the rotor 16. These anti-rotation features 16f can also prevent the upper and lower impeller portions 16c, 16d from rotating relative to each other. One or more drive shaft connection features 16g (e.g., setscrews having threaded openings) can also be provided to secure (e.g., semi-permanently) to the drive shaft 15 while still allowing removal for replacement or maintenance of the pump 36.

[0094] As shown, upper portion 16c of impeller 16 may include blades 16b having a flared outer profile 16h. For example, the radially outer edge portions of blades 16b may be curved, flared, outwardly tapered, rounded, and / or bell-shaped, but are not limited thereto. This profile 16h may be used to bias or urge downwardly flowing fluid (entering through 12a) in a radially outward direction toward sidewall 9c of pump housing 9.

[0095] In some embodiments, upper impeller 16c may include a radially inner upper end 16i where the presence of hub 16a is reduced, thereby maximizing the hydrodynamic effect of the upper portions of blades 16b. For example, as shown, upwardly projecting finger-like portions 16j of blades 16b may provide a close transition between the flared outer profile 16h and the outer surface of drive shaft 15. However, it should be understood that in alternative embodiments, hub 16a may rise and extend completely to or closely adjacent radially inner upper end 16i. It is contemplated that in such embodiments, hub 16a may gradually taper to the outer diameter of drive shaft 15 as it extends upward to radially inner upper end 16i, but is not limited thereto.

[0096] The depicted radially outer tip 16k may define the outermost portion of the upper impeller 16c and may serve to transition the flared profile 16h to the blades 16b of the lower portion 16d. A cutout 161, defining a lower, downwardly depending protrusion 16m, may be provided below the radially outer tip 16k. As shown, a lower radial inner cavity 16n may accommodate the hub 16a of the lower impeller 16d. The base plate 16o of the lower impeller portion 16d may be rotated adjacent to the bottom surface 9d of the pump housing 9 and form the lower portion of the impeller 16, but is not limited thereto.

[0097] The exact height to which the blades 16b may extend upwardly toward the drive shaft 15 (e.g., the vertical position of the radially inner ends 16i) may depend on the flow rate through 12c. At higher flow rates, it is contemplated that the fingers 16j, the upper portions of the blades 16b, and / or the radially inward upper ends 16i may extend higher up the drive shaft 15.

[0098] As shown, the blades 16b of the upper impeller 16c and the lower impeller 16d can overlap with each other to jointly define a smooth blade surface. In this regard, the two-piece manufacturing of the impeller 16 can be more easily performed while reducing its hydrodynamic pumping effect. It should be understood that Figure 15 and 16 The upper and lower impeller components 16c, 16d shown in the figure can be made into a homogeneous, single integral piece together, but is not limited to this. In this case, the blades 16b can extend upwards from the base plate 16o along the drive shaft 15 towards the radially inner upper end 16i.

[0099] In this specification, adjectives such as first and second may be used solely to distinguish between various elements or actions without necessarily requiring or implying any actual such relationship or order. Where the context permits, references to integers, components, or steps (etc.) should not be interpreted as being limited to only one of the integers, components, or steps, but may be one or more of the integers, components, or steps, etc.

[0100] The above description of the present invention is provided for the purpose of describing it to those skilled in the relevant art. It is not intended to be exhaustive or to limit the present invention to a single disclosed embodiment. As described above, many alternatives and variations of the present invention will be apparent to those skilled in the art of the above teachings. Therefore, although some alternative embodiments have been discussed in detail, other embodiments will be apparent, or those skilled in the art can develop other embodiments relatively easily. The present invention is intended to encompass all alternatives, modifications, and variations of the present invention discussed herein, as well as other embodiments that fall within the spirit and scope of the foregoing invention.

[0101] In this specification, the terms "comprises," "includes," "contains," "has," "shows," or similar terms are intended to represent non-exclusive inclusion, such that a method, system, or apparatus that includes a list of elements includes not only those elements but may also include other elements that are not listed.

[0102] Reference Signs List

[0103] 1 Feed inlet assembly

[0104] 2 Support structure

[0105] 3 Feed inlet

[0106] 4 Feed inlet

[0107] 5. Mixing chamber (i.e. mixing duct)

[0108] 6 Feed inlet (to mixing chamber 5)

[0109] 7 Slurry feed conduit

[0110] 8 Bridge structure

[0111] 9 Pump housing (such as protective cover)

[0112] 9a Upper nested tube section

[0113] 9b Top surface

[0114] 9c volute side wall

[0115] 9d bottom

[0116] 9e Pump outlet

[0117] 9f Connecting flange

[0118] 10 diluent inlet (to mixing chamber 5)

[0119] 10a Entrance

[0120] 10b Main channel

[0121] 10c Exit section

[0122] 11 Adjustable connection (between weir box 12 and pump housing 9)

[0123] 12 Weir Box

[0124] 12a Lower nested tube section

[0125] 12b Overflow lip

[0126] 12b' Overflow lip (alternative)

[0127] 12b" overflow lip (alternative)

[0128] 12b" overflow lip (alternative)

[0129] 12b"" overflow lip (alternative)

[0130] 12c sidewall

[0131] 12c' sidewall (alternative)

[0132] 12c" sidewall (alternative)

[0133] 12c'" sidewall (alternative)

[0134] 12c"" sidewall (alternative)

[0135] 12c"'" sidewall (alternative)

[0136] 12c""" sidewall (alternative)

[0137] 12d support angle brace

[0138] 13 Skimmer baffle

[0139] 14 Support structure (weir box 12)

[0140] 15 drive shaft

[0141] 15a Driven end

[0142] 15b drive end

[0143] 16 centrifugal impellers / rotors

[0144] 16a wheel hub

[0145] 16b blade

[0146] 16c upper impeller

[0147] 16d lower impeller

[0148] 16e hole

[0149] 16f Drive shaft anti-rotation features (e.g., splines, keyways)

[0150] 16g drive shaft connection features (e.g. setscrew with threaded opening)

[0151] 16h flared outer profile (e.g. curved, flared, tapering outwards, bell-shaped)

[0152] 16i radial inner upper end

[0153] 16j upward-projecting finger

[0154] 16k radial outer tip

[0155] 16l cutout

[0156] 16m downward hanging protrusion

[0157] 16n lower radial cavity

[0158] 16o base plate

[0159] 17 Drive unit (e.g. VFD motor with optional speed reducer)

[0160] 18 actuators

[0161] 19 valve

[0162] 20 Air-Liquid Interface

[0163] 21 Ultrasonic liquid level sensor (air-liquid interface 20)

[0164] 22 Mechanical liquid level sensor (air-liquid interface 20)

[0165] 23 Float

[0166] 24 Control System

[0167] 25a control signal (mechanical liquid level sensor 22)

[0168] 25b control signal (ultrasonic liquid level sensor)

[0169] 25c control signal (actuator 18)

[0170] 25d control signal (drive device 17)

[0171] 25e control signal (actuator 18)

[0172] 25f control signal (valve 19)

[0173] 26 Immersion depth (distance between the air-liquid interface 20 and the overflow lip 12b)

[0174] 27 Feed dilution device

[0175] 28 Feed port rack

[0176] 29 Feed inlet bottom opening

[0177] 30 Weir box baffle

[0178] 31 Bend

[0179] 32 Inner support ring

[0180] 33 External support ring

[0181] 34 Angle

[0182] 35 radial lines

[0183] 36 Centrifugal Pump

Claims

1. A feedwell assembly (1) comprising a feedwell (3) and a feed dilution device (27), the feed dilution device (27) being configured to dilute a feed slurry with a diluent before the feed slurry enters the feedwell (3), the feed dilution device (27) comprising a mixing chamber (5) operatively connected to a feedwell inlet (4), the mixing chamber (5) being configured to receive slurry from a slurry feed conduit (7) and to combine the slurry with a diluent received from a diluent inlet (10), the feed dilution device (27) being characterized in that The invention relates to a centrifugal pump device (36) having a centrifugal impeller (16) arranged in a pump housing (9), the pump housing (9) being arranged below a weir box (12), the weir box (12) having an overflow lip (12b) arranged at an upper periphery of the weir box (12), wherein the overflow lip (12b) is configured to be arranged below an air-liquid interface (20) during operation such that an immersion depth (26) exists between the overflow lip (12b) and the air-liquid interface (20), The pump housing (9) comprises a pump outlet (9e), the pump outlet (9e) extending from a volute side wall (9c) of the pump housing (9) and operatively connected to and / or in fluid communication with an inlet portion (10a) of the diluent inlet (10), the pump outlet (9e) being operatively connected to the mixing chamber (5) via the diluent inlet (10); The pump outlet (9e) is located near the radially outermost side wall (9c) of the pump housing (9); The feed dilution device (27) is further configured to suck the foam containing entrained solids and clarified liquid into the pump housing (9) when the centrifugal impeller (16) rotates in the pump housing (9), and then discharge it from the pump outlet (9e), and allow the foam containing entrained solids and clarified liquid to overflow the overflow lip (12b) and enter the weir box (12), and the weir box (12) further supplies the centrifugal pump device (36) below.

2. The feed port assembly (1) according to claim 1, wherein: An adjustable connection (11) is provided between the weir box (12) and the pump housing (9).

3. The feed port assembly (1) according to claim 2, wherein: The adjustable connection (11) comprises a telescopic connection between a lower nested pipe portion (12a) of the weir box (12) and an upper nested pipe portion (9a) extending from and located above an upper surface (9b) of the pump housing (9).

4. The feed port assembly (1) according to claim 3, wherein: The feed dilution device (27) further comprises at least one actuator (18) configured to move the lower nested tube section (12a) relative to the upper nested tube section (9a).

5. The feed port assembly (1) according to claim 4, wherein: The at least one actuator (18) is configured to move at least one support structure (14) connected to a portion of the weir box (12).

6. A feedwell assembly (1) according to any one of the preceding claims, wherein: The overflow lip (12b) is configured to move relative to the pump housing (9) to vary the immersion depth (26).

7. The feed port assembly (1) according to claim 6, wherein: The feed dilution device (27) is further characterized in that the pump outlet (9e) is at a lower height than the mixing chamber (5), the feed inlet (4) and / or the slurry feed conduit (7).

8. The feed port assembly (1) according to claim 7, wherein: The pump outlet (9e) is operably connected to the inlet portion (10a) of the diluent inlet (10), and the mixing chamber (5) is operably connected to the outlet portion (10c) of the diluent inlet (10), and the main channel (10b) extends between the inlet portion (10a) and the outlet portion (10c) at an angle relative to the air-liquid interface (20); the lower surface of the inlet portion (10a) is located below the lower surface of the outlet portion (10c).

9. A feedwell assembly (1) according to any one of the preceding claims, wherein: The diluent inlet (10) is located below the slurry feed conduit (7).

10. A feedwell assembly (1) according to any one of the preceding claims, wherein A drive shaft (15) connects a drive device (17) to the centrifugal impeller (16), the drive shaft (15) extending through the weir box (12) and the central portion of the pump housing (9).

11. A feedwell assembly (1) according to any one of the preceding claims, wherein: The pump housing (9) has a closed bottom surface (9d) below the centrifugal impeller (16).

12. The feedwell assembly (1) according to any one of the preceding claims, further comprising a valve (19) located between the pump housing (9) and the mixing chamber (5) to restrict the flow of liquid between the pump housing (9) and the mixing chamber (5).

13. A feedwell assembly (1) according to any one of the preceding claims, wherein: The weir box (12) includes one or more baffles (30).

14. The feed port assembly (1) according to claim 13, wherein: The one or more baffles (30) extend radially along the sidewall (12c) of the weir box (12).

15. The feed port assembly (1) according to claim 14, wherein: The one or more baffles (30) extend from a central portion of the weir box (12) at an angle (34) relative to a radial line (35).

16. A feedwell assembly (1) according to any one of the preceding claims, wherein The blades (16b) of the centrifugal impeller (16) include a flared outer profile (16h).

17. A method of diluting slurry entering a feed port (3) of a concentrator / clarifier from a slurry feed conduit (7), comprising the steps of: Providing a feedwell assembly (1) according to any one of the preceding claims; Rotating centrifugal impeller (16); Suck the clarified liquid and / or foam near the air-liquid interface (20) through the immersion depth (26) over the overflow lip (12b) and into the weir box (12); shearing the clarified liquid and / or foam within the weir box (12) and / or within the pump housing (9); conveying the sheared clarified liquid and / or foam to a mixing chamber (5); mixing the sheared clarified liquid and / or foam with the slurry in a mixing chamber (5); as well as A mixture of slurry and sheared clarified liquid and / or foam is fed to the feed port (3).

18. A feed dilution device (27) for diluting a feed slurry with a diluent before the feed slurry enters a feed port (3), the feed dilution device (27) comprising a mixing chamber (5) operatively connected to a feed port inlet (4), the mixing chamber (5) being configured to receive slurry from a slurry feed conduit (7) and to combine the slurry with a diluent received from a diluent inlet (10), the feed dilution device (27) being characterized in that it comprises a centrifugal A pump device (36) comprising a centrifugal impeller (16) arranged in a pump housing (9), the pump housing (9) being arranged below a weir box (12), the weir box (12) having an overflow lip (12b) arranged at an upper periphery of the weir box (12), wherein the overflow lip (12b) is configured to be arranged below an air-liquid interface (20) during operation such that an immersion depth (26) exists between the overflow lip (12b) and the air-liquid interface (20), The pump housing (9) comprises a pump outlet (9e), the pump outlet (9e) extending from a volute side wall (9c) of the pump housing (9) and operatively connected to and / or in fluid communication with an inlet portion (10a) of the diluent inlet (10), the pump outlet (9e) being operatively connected to the mixing chamber (5) via the diluent inlet (10); The pump outlet (9e) is located near the radially outermost side wall (9c) of the pump housing (9); The feed dilution device (27) is further configured to suck the foam containing entrained solids and clarified liquid into the pump housing (9) when the centrifugal impeller (16) rotates in the pump housing (9), and then discharge it from the pump outlet (9e), and allow the foam containing entrained solids and clarified liquid to overflow the overflow lip (12b) and enter the weir box (12), and the weir box (12) further supplies the centrifugal pump device (36) below.

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