WO2015175862A1

WO2015175862A1 - Valve apparatus for flotation cells

Info

Publication number: WO2015175862A1
Application number: PCT/US2015/030942
Authority: WO
Inventors: Alan Camomile; Mathew WALKER; Brad GERKE
Original assignee: FLSmidth AS
Current assignee: FLSmidth AS
Priority date: 2014-05-15
Filing date: 2015-05-15
Publication date: 2015-11-19
Anticipated expiration: 2016-11-15
Also published as: FI20165848A; FI20165848A7; CN106457262B; CN106457262A; CL2016002884A1; PE20161504A1

Abstract

Disclosed, is a retro-fittable valve apparatus for a flotation cell comprising: a valve assembly having a dart attached to a distal end of a linear-actuated valve rod; the valve assembly being provided on an upstream side of the flotation cell, wherein the valve assembly comprises a box which fluidly communicates with an upstream flotation cell. Also disclosed, is a method of flotation comprising: providing a valve assembly having a dart attached to a distal end of a linear-actuated valve rod; the valve assembly being provided on an upstream side of the flotation cell, wherein the valve assembly comprises a box which fluidly communicates with an upstream flotation cell; and linearly adjusting the linear-actuated valve rod to increase or decrease a flow rate of slurry or pulp between said flotation cell and said upstream flotation cell.

Description

VALVE APPARATUS FOR FLOTATION CELLS

Inventors: Alan Camomile

Mathew Walker

Brad Gerke

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority document U.S. Provisional Patent Application Serial No. 61/992,491 filed on 13 May 2014, and titled "VALVE APPARATUS FOR FLOTATION CELLS". This document is hereby incorporated by reference in its entirety for any and/or all purposes set forth herein.

FIELD OF THE INVENTION

This invention relates to flotation cells, and more particularly to valve apparatus used to transfer slurry or pulp from one flotation cell tank to another flotation cell tank in a controlled fashion.

BACKGROUND OF THE INVENTION

FIG. 1 describes performance characteristics of various conventional valve arrangements which have, to date, been used in conjunction with flotation apparatus. As can be seen in FIGS. 2-14, existing valve apparatus designs for flotation apparatus utilize dart valves, but they exhibit certain limitations and disadvantages because of their physical configuration/arrangement. One problem with existing downstream dart valve designs and/or configurations is that, as shown in FIG. 12, a flotation tank foundation needs to be shifted upstream or otherwise removed and/or elevated with concrete pilings and steel framework in order to allow clearance for downstream piping to connect to a subsequent downstream flotation tank. This poses engineering hurdles and possibly safety issues due to the significant weight of flotation cells filled with large amounts of slurry or pulp.

Another problem with existing upstream dart valve designs and/or configurations is that, as shown in FIG. 13, slurry or pulp flow cannot be easily controlled between flotation tanks with a hinged design. A hinged design provided to an upstream side of a flotation cell tank (also seen in FIGS. 6 and 7), does not allow a dart to be re-sized for different applications or process changes. Moreover, the fluid dynamics change, because opening of the dart valve involves an arcuate path, rather than a linear path. Accordingly, flow rate is more difficult to control precisely, since bottom portions of a hinged dart valve open at a different rate than upper portions. Such hinged designs advantageously facilitate installation, because no cutouts or foundation "shifting" or "pillaring" is necessary as with the design shown in FIG. 12. Such hinged designs are also advantageous due to their low pressure drop between tanks. However, such hinged designs may experience "misalignments" or "impingements" between the dart and the orifice. Moreover, such hinged designs may experience longevity issues such as intermittent hinge failures due to large forces over extended time periods. Additionally, it is extremely difficult to change dart valve sizes (i.e., one cannot replace a dart with a larger or smaller dart without changing the ability to close or open correctly or seal completely against the orifice grommet without interference). Yet another problem with existing external valve apparatus is that, as shown in FIGS. 8, and 9, 11, and 14, since the valve assembly piping and actuators are significantly pressurized (due to the head pressure of the adjacent tall flotation cells which are filled with heavy slurry or pulp), leaks may occur around seals, rings, and gaskets - particularly seals, gaskets, or rings which are positioned between two moving parts (e.g., actuator valve rod and sleeve). FIG. 8 shows a leaking external dart valve design, and FIG. 9 shows a failed stuffing box. While such apparatus do advantageously allow the valve apparatus to be maintained outside of a flotation cell, and afford linear (rather than arcuate) actuation of dart valve mechanisms, they are usually located underneath walkways and platforms making crane removal difficult. Moreover, they make use of a pressurized stuffing box which is notorious for wear issues. Additionally, there are significant challenges with correctly sizing a dart valve due to pressurized box geometries. Each box and dart valve combination needs to be sized for driving head and slurry flow. There are also significant pressure drops between flotation tanks when utilizing such apparatus. Higher costs of such external valve apparatus pose another disadvantage.

FIG. 10 shows an external atmospheric design that has been used to remedy the problems associated with the external pressurized design shown in FIG. 11. The external valve apparatus shown in FIG. 10 comprises a long pipe that extends upwards to allow pressure equalization to ambient conditions and to provide the ability to maintain and operate the mechanicals of the valve apparatus at ambient pressure above the fill level of the surrounding filtration tanks. This elevated design is normally located underneath walkways and platforms making crane removal difficult. Moreover, it is still difficult to size dart valve components due to box geometries. Therefore, while external atmospheric valve apparatus designs/configurations may reduce stress on seals, gaskets, or rings and reducing potential for leaks, they add tremendous cost, complexity, weight (due to the buffer fill of slurry or pulp), and significantly increase space requirements and still do not overcome certain drawbacks (e.g., removal and sizing challenges). As with the aforementioned external pressurized valve apparatus, external atmospheric systems such as the one shown in FIGS. 10 and 14 may cost substantially more than the proposed solutions disclosed herein.

It is desired to provide a robust valve apparatus for flotation cells which overcomes the problems of the prior art.

OBJECTS OF THE INVENTION

It is, therefore, an object of some embodiments of the invention to provide a robust valve apparatus for flotation cells which overcomes problems seen with conventional valve apparatus.

It is also an object of some embodiments of the invention to reduce or eliminate the need to cut away, shift, add pilings/pillars, supports, or otherwise modify a concrete foundation on which one or more flotation cells or banks of cells are supported.

It is further an object of some embodiments of the invention to provide a valve apparatus which advantageously incorporates a valve rod that travels linearly, rather than arcuately, in order to more accurately predict and manage flow rate.

Moreover, it is an object of some embodiments of the invention to facilitate dart valve and orifice grommet changes due to flow rate changes.

Yet other objects of some embodiments of the invention include providing a valve apparatus which exhibits a significantly improved ease of dart valve box replacement, refurbishment, operation, and/or maintenance. It is yet another object of some embodiments of the invention to more accurately calculate flow rate as a function of dart valve/valve rod lift.

These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the objects of the invention.

SUMMARY OF THE INVENTION

A retro-fittable valve apparatus for a flotation cell is disclosed. The retro-fittable valve apparatus may comprise a valve assembly having a dart attached to a distal end of a linear- actuated valve rod. The valve assembly may be provided on an upstream side of the flotation cell. The valve assembly may comprise a box which fluidly communicates with an upstream flotation cell. In some embodiments, the valve apparatus may further comprise a box outlet duct provided to the lower end of the box. In some embodiments, the valve apparatus may further comprise an inlet flange connected to an upstream portion of the box. In some embodiments, the inlet flange may be configured to seal the box from slurry or pulp within the flotation cell. In some embodiments, the inlet flange may be configured to connect to an outlet flange of said upstream flotation cell.

A method of flotation is also disclosed. In some embodiments, the method may comprise providing a valve assembly having a dart attached to a distal end of a linear- actuated valve rod. The valve assembly may be provided on an upstream side of the flotation cell. The valve assembly may comprise a box which fluidly communicates with an upstream flotation cell. The valve rod may be linearly adjusted in order to increase or decrease a flow rate of slurry or pulp, for example, a flow rate of slurry or pulp between said flotation cell and said upstream flotation cell.

It will be appreciated from this disclosure, and the drawings, that various

features/components and method steps described herein may be altered without significantly departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

To complement the description which is being made, and for the purpose of aiding to better understand the features of the invention, a set of drawings illustrating preferred valve apparatus and methods of using the same is attached to the present specification as an integral part thereof, in which the following has been depicted with an illustrative and non-limiting character. It should be understood that like reference numbers used in the drawings may identify like components. In the figures:

FIGS. 1-14 describe or illustrate various aspects of the prior art;

FIG. 15 is a side cutaway view of a valve assembly according to some embodiments; FIG. 16 is an upper isometric view of a valve assembly according to some embodiments; FIG. 17 is a side cutaway view of a tank showing a placement of a valve assembly according to some embodiments;

FIG. 18 is a close-up isometric view of a valve assembly according to some

embodiments; FIG. 19 is a first close-up cutaway view of a valve assembly according to some embodiments;

FIG. 20 is a second close-up cutaway view of a valve assembly according to some embodiments;

FIG. 21 is cutaway view of a valve assembly within a flotation circuit/cell bank according to some embodiments;

FIG. 22 is a close-up cutaway view of actuator mechanisms of a valve assembly according to some embodiments;

FIG. 23 is an isometric view showing a supporting structure of a valve assembly according to some embodiments;

FIG. 24 is a close-up cutaway view of actuator mechanisms of a valve assembly according to some embodiments;

FIG. 25 is a second close-up cutaway view of the actuator mechanisms of FIG. 24;

FIG. 26 is a cutaway view of a valve assembly according to some embodiments;

FIGS. 27 and 28 are partial cutaway view of a valve assembly showing the mechanicals of actuator mechanisms according to some embodiments;

FIG. 29 shows a cutaway view of a valve assembly according to some embodiments; and,

FIGS. 30 and 31 show different isometric cross-sectional views of a valve assembly arrangement according to some embodiments.

In the following, the invention will be described in more detail with reference to drawings in conjunction with exemplary embodiments. DETAILED DESCRIPTION OF THE INVENTION

Shown in the figures are a first flotation cell tank 10 (e.g., an "upstream" flotation cell tank) having a floor 11 and an optional angled lower baffle 12. The first flotation cell tank 10 spills into a second flotation cell tank 20 (e.g., an "upstream" flotation cell tank) via a connection 40 between an outlet flange 49 of the first flotation cell tank 10, and an inlet flange 41 of the second flotation cell tank 20. The second flotation cell tank 20 may have a floor 21 and/or an angled lower baffle 22 as shown. While not expressly shown, third, fourth, and/or fifth flotation cell tanks 20 may be provided downstream of the second flotation cell tank 20, in series, to form a cell bank/flotation circuit (e.g., a rougher/scavenger circuit).

The second flotation cell tank 20 comprises a valve assembly 30 at an upstream portion thereof, adjacent the outlet flange 49 of the first flotation cell tank 10 and most adjacent to an inlet flange 41 of the second flotation cell tank 20, which may extend radially inwardly into the second flotation cell tank 20 and radially outwardly of the second flotation cell tank 20 as shown. The valve assembly 30 may extend vertically upward to an enclosure having an enclosure top panel 37, enclosure side panels 32, and an enclosure access panel 33. A support structure 31, such as steel framework, may be used to support the valve assembly 30 adjacent the upstream side of the second flotation cell tank 20. Additional frame 35 members may be used as necessary to distribute weight and/or load, and/or to support other flotation cell components which are not shown for clarity (e.g., motor, gearbox, rotor, stator, shaft, walking platforms, railings, housings, drives, air intakes, baffles, etc.).

The valve assembly 30 may comprise a first actuator 34 and/or a second actuator 36 - each of which may be disposed within the supported enclosure. While not shown, a single valve assembly 30 may be used, or multiple valve assemblies 30 may be used, wherein each valve assembly 30 may have at least one dart 60, orifice 66, and/or grommet 63 combination. In the instant case, the single valve assembly 30 comprises two dart 60/orifice 66/grommet 63 combinations.

One or more linkages 38 and/or valve rod couplings 38 A may be used between the actuator rods 34A, 36A and valve rods 39 in order to compensate for distance, spacing, tolerances, angles, run out, and the like. A submersion box 48 comprising one or more box side panels 42, a box top panel 43, a box front panel 44, a lower mounting flange 45 configured to interface with a lower box outlet duct 46 may be provided. The box 48 may take many shapes, forms, and/or sizes, and may comprise one or more curved box side panels 42, box top panel 43, box front panel 44, lower mounting flange 45, and/or inlet flange 41, without limitation. For example, a round box 48 (not shown) may be employed, without limitation; wherein a flat false bottom may be employed to the round box to facilitate mounting of grommet 63 and/or to facilitate the provision of orifice 66. In some non-limiting embodiments, box 48 may comprise a tube or pipe-shaped chamber, rather than the rectangular chamber shown.

The lower box outlet duct 46 may be configured with an outlet duct opening 47 which may force flow of slurry or pulp from the first flotation cell tank 10 towards the floor 21 of the second flotation cell tank 20. First 53 and second 57 valve rod housings may extend between the box 48 and the actuators as shown. Valve rod housings 53, 57 may comprise one or more upper bushing boxes 52, 56 and/or one or more lower bushing boxes 54, 58, without limitation. The bushing boxes 52, 54, 56, 58 (if utilized) may comprise annular bushings 55, such as HDPE bushings, UHMWPE bushings, bronze bushings, or the like, without limitation. The bushings 55 may keep the valve rods 39 aligned within the valve rod housings 53, 57 and enable smooth linear travel of the valve rods 39 to actuate valve components.

A dart 60 portion of the valve assembly may be provided at the end of each valve rod 39. The dart 60 may take many shapes, profiles, forms, and sizes - and may be constructed of many types of material (e.g., HDPE, UHMWPE, natural or synthetic rubber, or other polymer or combination thereof). Each dart 60 may comprise an upper frustoconical surface 61 and a lower frustoconical surface 62 as shown. The lower frustoconical surface 62 may be configured to mate with or operatively engage an orifice grommet 63 having a shape or profile which is complementary to the dart (e.g., circular as shown). In this regard, when a dart 60 is forced against an orifice grommet 63, the valve may be closed off and restrict flow between the first and second flotation cell tanks 10, 20. It should be understood that various profiles and cross- sectional shapes of darts 60 and complimentary profiles and cross-sectional shapes of orifice grommets 63 are anticipated. The orifice grommet 63 may take many shapes, profiles, forms, and sizes - and may be constructed of many types of material (e.g., HDPE, UHMWPE, natural or synthetic rubber, or other polymer or combination thereof). The orifice grommet 63 preferably matches a profile of the corresponding dart 60. One or more mounting fasteners 64 or features such as snap fits, quick connects, threaded interfaces, welds, adhesives, clamps, or the like may be utilized to connect the orifice grommet 63 to a mounting ring/flange 65. In some

embodiments, an orifice grommet 63 surrounds a pre-sized orifice 66 which allows the flow of slurry to enter into the second flotation cell tank 20 from the first flotation cell tank 10.

While not expressly shown, it should be understood that the valve apparatus, valve assemblies, and/or components thereof may be provided in duplicates. For example, multiple flotation cells 20 may be provided in series and/or in parallel - and each of said multiple flotation cells 20 may incorporate the valve apparatus, valve assemblies, and/or components thereof. It should also be appreciated that in order to improve flow and prevent sanding on/around floors 11, 21, and areas extending between floors 11, 21 and angled lower baffles 12, 22 upstream of the valve assembly 30 (see left side of FIG. 31 and representative dotted lines in center or FIG. 21), one or more chamfers, curves, baffles, venturi, and/or other devices which may optimize the fluid dynamics between cell tanks 10 may be employed (though these are not shown for clarity). In some embodiments, such devices may be employed within the preceding flotation cell tank 10, for example, upstream of a box 48 of a flotation cell tank 20, without limitation. In some embodiments, such devices may be employed within a box 48 of a flotation cell tank 20, without limitation. In some embodiments, such devices may be employed upstream of an inlet flange 41 of a flotation cell tank 20, for example, upstream of an outlet flange 49 in a flotation cell tank 10.

In short, the proposed design comprises a channel extending from a first flotation cell tank 10 and into a second flotation cell tank 20. The channel extends far enough into the second flotation cell tank 20 that a linear dart valve may be provided therein. The end of the channel is closed so as to prevent ingress of slurry into the second flotation cell tank 20 prior to escaping through the linear dart valve. Preferably, the linear dart valve comprises a dart valve assembly which may be actuated up and down in a generally vertical direction. Flow exiting the linear dart valve may pass between a dart 60 and grommet 63, through an orifice 66, into a lower outlet duct 46, and then into the second flotation cell tank 20. By placing the linear dart valve in the upstream portion of a flotation cell tank 20, via box 48, problems associated with prior art designs may be avoided.

A contractor or other entity may provide a flotation valve apparatus or operate a flotation valve apparatus in whole, or in part, as shown and described. For instance, the contractor may receive a bid request for a project related to designing or operating a flotation valve apparatus, or the contractor may offer to design any number of valve apparatuses or components thereof, or a process for a client involving one or more of the features shown and described herein. The contractor may then provide, for example, any one or more of the devices or features thereof shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer. The contractor may subcontract the fabrication, delivery, sale, or installation of a component of the devices disclosed, or of other devices used to provide said devices. The contractor may also survey a site and design or designate one or more storage areas for storing the material used to manufacture the devices, or for storing the devices and/or components thereof. The contractor may also maintain, modify, or upgrade the provided devices. The contractor may provide such maintenance or modifications by subcontracting such services or by directly providing those services or components needed for said maintenance or modifications, and in some cases, the contractor may modify a preexisting flotation apparatus or valve apparatus of a flotation circuit, subassemblies thereof, components thereof, and/or parts thereof with one or more "retrofit kits" to arrive at a modified valve apparatus or method of operating a valve apparatus comprising one or more method steps, devices, components, or features of the systems and processes discussed herein.

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

REFERENCE NUMERAL IDENTIFIERS

10 flotation cell tank

11 floor

12 angled lower baffle

20 flotation cell tank

21 floor

22 angled lower baffle

30 valve assembly

31 support structure

32 enclosure side panels

33 enclosure access panel

34 first actuator

35 frame

36 second actuator

36A actuator rod

37 enclosure top panel

38 linkage

38A valve rod coupling

39 valve rod

40 connection

41 inlet flange

42 box side panels

43 box top panel

44 box front panel

45 box lower mounting flange/box-duct interface

46 box outlet duct

47 outlet duct opening

48 box

49 outlet flange

52 upper bushing box

53 valve rod housing

54 lower bushing box

55 bushings

56 upper bushing box

57 valve rod housing

58 lower bushing box

60 dart

61 upper frustoconical surface

62 lower frustoconical surface

63 orifice grommet

64 mounting fasteners

65 mounting ring/flange

66 orifice

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A retro-fittable valve apparatus for a flotation cell [20] comprising:

a valve assembly[30] having a dart [60] attached to a distal end of a linear-actuated valve rod [39]; the valve assembly [30] being provided on an upstream side of the flotation cell [20], wherein the valve assembly [30] comprises a box [48] which fluidly communicates with an upstream flotation cell [10].

2. The valve apparatus according to claim 1, further comprising a box outlet duct [46] provided to the lower end of the box [48] .

3. The valve apparatus according to claim 1, further comprising an inlet flange [41] connected to an upstream portion of the box [48].

4. The valve apparatus according to claim 3, wherein the inlet flange [41] is configured to seal the box [48] from slurry or pulp within the flotation cell [20].

5. The valve apparatus according to claim 3, wherein the inlet flange [41] is configured to connect to an outlet flange [49] of said upstream flotation cell [10].

6. A method of flotation comprising:

providing a valve assembly[30] having a dart [60] attached to a distal end of a linear- actuated valve rod [39]; the valve assembly [30] being provided on an upstream side of the flotation cell [20], wherein the valve assembly [30] comprises a box [48] which fluidly communicates with an upstream flotation cell [10]; and

linearly adjusting the linear-actuated valve rod to increase or decrease a flow rate of slurry or pulp between said flotation cell [20] and said upstream flotation cell [10].

7. The method of claim 6, wherein the valve assembly [30] further comprises a box outlet duct [46] provided to the lower end of the box [48] .

8. The method of claim 6, wherein the valve assembly [30] further comprises an inlet flange [41] connected to an upstream portion of the box [48].

9. The method of claim 8, wherein the inlet flange [41] is configured to seal the box [48] from slurry or pulp within the flotation cell [20] .

10. The method of claim 9, wherein the inlet flange [41] is configured to connect to an outlet flange [49] of said upstream flotation cell [10].