Mobile pumping system

Abstract

A pumping system for pumping solids from near a bed of a salt pond is described. The pumping system comprises: (i) a first and second floating platform mutually coupled; (ii) at least one hydraulic directional jet coupled to the first floating platform for moving the floating platform over the surface of the pond; (iii) a winch mounted on the first floating platform and having a cable extending through a central aperture; and (iv) a submersible dewatering pump coupled to the winch cable. The submersible pump includes a downwards directed sparger device for breaking up salt solids on the pond bed to suspend the salt solids in liquid and thereby enable pumping thereof by the submersible pump.

Description

MOBILE PUMPING SYSTEM Technical Field

[001] The present invention generally relates to a mobile pumping system for recovering solids or viscous liquids from a waterbody. In particular, but not exclusively, the invention relates to a mobile pumping system for recovering a salt solution from near a bed of a salt pond. Background

[002] To recover minerals from a salt brine, the liquid brine is typically first extracted from deep wells normally located around a salt flat. This liquid brine is pumped into ponds for salt recovery in a subsequent drying process. During this drying process other chemicals and salts are obtained from the liquid brine through precipitation, crystallisation, or some other chemical process. Some of these salts are deposited as solids at the bottom of the pond, thereby reducing its depth. After a few months, the pond needs to be drained and then machinery is used for mechanical removal of all the salts that have accumulated at the bottom of the pond due to the drying process. Normally, this takes approximately 3 months, and it is inefficient and expensive.

[003] Salt ponds differ radically from tailings ponds. Tailings ponds are typically enclosed by walls that contain the liquid tailings therein. Storing tailings does not typically involve any treatment of the stored liquid, or of the solids suspended in, or settling out of, the liquid. In contrast, salt ponds are used as part of a processing operation for the purpose of harvesting salts. A salt pond is typically much shallower than a tailings pond because the salt pond requires evaporation of water and crystallisation of salts dissolved in the water. Typical salt ponds are shallower than approximately 3 metres; whereas, tailings ponds may be over 10 metres deep.

[004] A similar problem occurs in ponds in mining processing plants where solids settle to the bottom of the pond. The pond is periodically drained and the solids on the bottom of the pond are mechanically removed.

[005] In both cases, the processing is discontinuous because intervention is required to remove the solids build-up.

[006] There is a need for new or improved system and / or method for preventing solids build- up on the bed of a pond, and / or continuously processing the salts in the salt pond in a more efficient manner.

[007] US 2020 / 0270845 to Goodwin et al discloses a method of dewatering a tailings lagoon retained by a dam to prevent drainage pipes in the dam from blocking and the dam failing. The solution proposed by Goodwin involves a relatively large and heavy barge having submersible pumps lowered therefrom. Such a solution would not be suitable for a salt pond because of its size. Furthermore, salt ponds do not experience the failure mode contemplated by Goodwin et al. Summary

[008] According to a first aspect there is provided a pumping system for pumping a salt slurry from near a bed of a salt pond, the pumping system comprising:(i) a first floating platform configured to float on a surface of the pond, the first floating platform having an opening; (ii) at least one hydraulic directional jet coupled to the first floating platform for moving the first floating platform over the surface of the pond; (iii) a lifting mechanism on the first floating platform; and (iv) a submersible pump positioned within the opening and coupled to the lifting mechanism, the submersible pump being operable to extract salt-rich liquid from near a bottom of the pond, the submersible pump including a downwards directed sparger device for breaking up crystallised salts which have accumulated on a bed of the pond and suspending the salt solids in liquid to form a brine and thereby enable pumping thereof by the submersible pump; and a second floating platform tethered to the first floating platform to allow some independent movement of each platform, and configured to float on a surface of the pond, and including an auxiliary pump for providing hydraulic power to the first floating platform.

[009] Optionally, the lifting mechanism may comprise a winch with the submersible pump coupled to the winch via a winch cable extending through the opening to control vertical displacement of the submersible pump.

[010] Optionally, the lifting mechanism may comprise at least one motor (such as a linear motor) coupled to the submersible pump to control vertical displacement thereof. It is to be appreciated that the lifting mechanism may have other configurations and may comprise other known lifting systems to control the vertical displacement of the submersible pump.

[011] Optionally, the first floating platform comprises a barge having a diameter (or maximum lateral width) below 3 metres.

[012] Optionally, the first floating platform is operable to float in less than one metre depth of water.

[013] Optionally, the first floating platform opening is located generally centrally to maintain balance of the platform as the submersible pump is lowered.

[014] Optionally, the second floating platform comprises a barge having a diameter (or maximum lateral width) below 3 metres.

[015] Optionally, each directional hydraulic jet is fed with high pressure fluid by the auxiliary pump. The high pressure fluid may be sourced from the pond (for example, liquid near the surface of the pond) or from a location adjacent the pond.

[016] Optionally, each directional hydraulic jet may be oriented, or capable of being oriented, in a different direction, to facilitate movement of the first floating platform in any direction on the surface of the pond. This enables the first floating platform to be moved above an area of the pond bed that needs to have salt solids removed therefrom. Separating the auxiliary pump from the submersible pump enables smaller floating platforms to be used, which enables the first floating platform to access the entire pond.

[017] Optionally, the auxiliary pump is operable to provide high pressure fluid to the sparger device of the submersible pump.

[018] Optionally, the submersible pump comprises a slurry pump that is able to pump a relatively high concentration of solids entrained in liquid. In some embodiments, solids having a mass concentration (Cw) of over 70% may be pumped by the submersible slurry pump. The mass concentration is the ratio of the weight of the solids in a given volume of salt slurry to the total mixture weight (the weight of the solids plus the liquid). In some embodiments, the d50 of solids in the salt slurry may be greater than 150 microns.

[019] Optionally, the sparger device comprises a sparger ring having apertures directed downwards.

[020] Optionally, the ring surrounds a pump chamber of the submersible pump.

[021] Optionally, the first or second floating platform further comprises a global positioning system.

[022] Optionally, the first or second floating platform further comprises a depth measurement device (such as a transducer) to enable the floating platform to detect a depth of the pond. The transducer may use sonar, lidar, or the like.

[023] Optionally, the depth measurement device is arranged to determine the thickness of salt solids accumulated at the bed of the pond at various locations.

[024] Optionally, a depth survey may be prepared before liquid is transferred to the salt pond and after salt solids have crystallised so that a salt accumulation profile (indicating the depth of salt accumulation) is created for the pond bed.

[025] Optionally, the first or second floating platform further comprises a pressure sensor mounted on or near the submersible pump for detecting a pressure at the depth of the pump. This may be used to measure and control the depth of the submersible pump.

[026] Optionally, the controller is mounted on the first or second floating platform and controls operation of the first and second floating platform. The controller may monitor various sensors associated with the first or second floating platform to control the operation of the submersible pump and / or auxiliary pump, the lifting mechanism and directional jets.

[027] Optionally, the auxiliary pump comprises a vertical pump having a volute that may be immersed in the pond to pump fluid therefrom. Optionally, the second floating platform 4 includes a central opening through which the auxiliary pump extends such that the volute is immersed in the pond to pump liquid brine close to the pool surface with a low salt concentration therefrom.

[028] Optionally, a winch is mounted on the second floating platform with the auxiliary pump coupled to the winch via a winch cable extending through the opening.

[029] According to a second aspect there is provided a method of harvesting salt from a salt pond or extracting solids from a pond, the method comprising: using a second floating platform to move a first floating platform, which is tethered thereto by a flexible coupling to allow some independent movement of each platform, over the surface of the pond using hydraulic directional jets mounted on the first platform and energised by a pump on the second platform; locating an area of the pond where salt solids or other solids have accumulated on the bed; using fluid in the pond to hydraulically break up the accumulated solids on the pond bed at the located area to suspend the solids in liquid to form a salt slurry; and extracting the salt slurry from the area near a bottom of the pond using a pump extending downwards from the first floating platform.

[030] The method may comprise the further steps of: measuring a depth of the pond bed, and lowering a submersible pump to within 1 metre of the measured depth.

[031] The flexible coupling may comprise a pipe through which high pressure fluid (such as the pond liquid) is pumped.

[032] The method may comprise ceasing pumping of the salt solids when the pond depth is restored to its original depth (i.e. before the salt accumulation thereon). This has the advantage of preventing removal of that part of the pond bed that does not contain salt.

[033] By virtue of these aspects, a pumping system and method are provided that can continuously remove salts and other solids in solution and provide them to a processing facility. Removing solids from the pond bed avoids the need to dredge the bed or drain the pond and mechanically remove the solids build-up. By providing positioning and depth information, the pumping system is able to map the pond bed and identify areas with the greatest solids build-up. The mobile pumping system may prioritise pumping at those areas.

[034] According to a third aspect there is provided a method of harvesting salt (or other chemicals) from a liquid brine stored in evaporation ponds, the method comprising: allowing salt and / or chemicals in the brine to precipitate / crystalize at a bottom of the pond, providing a first floating platform and a second floating platform which are movable over the surface of the pond using hydraulic directional jets to locate an area in the pond where solids have been accumulated on the bed; using fluid to hydraulically break up the accumulated solids on the pond bed at the located area to suspend the solids in liquid to form a salt slurry to be extracted 5 by a pump; pumping the suspended salt solids to a classification plant for removal of the solids therefrom.

[035] Optionally, the method comprises using the second floating platform having an auxiliary pump to move the first floating platform, which is tethered thereto by a flexible coupling to allow some independent movement of each platform, by providing pressurised fluid to the directional jets.

[036] Optionally, the fluid from which the solids have been removed by the classification plant is returned to an evaporation pond for further processing.

[037] Optionally, the method includes using a depth measurement device to determine the thickness of salt and / or chemical which have accumulated at the bed of the pond to ascertain when sufficient salt and / or chemicals in the brine have precipitated / crystalized.

[038] Optionally, the method includes measuring the concentration of predetermined salt and / or chemicals in the brine to ascertain if salt and / or chemicals in the brine have precipitated / crystalized.

[039] Optionally, the method includes pumping liquid brine into the pond to allow salt and / or chemicals in the brine to precipitate / crystalize at the bottom of the pond as the salt slurry is extracted from the pond.

[040] According to a fourth aspect there is provided a method of harvesting salt from a liquid brine stored in evaporation ponds, the method comprising: allowing salt and / or chemicals in the brine to precipitate / crystalize at a bottom of the pond; providing a first floating platform which is movable over the surface of the pond using hydraulic directional jets to locate an area in the pond where solids have been accumulated on the bed; using fluid to hydraulically break up the accumulated solids on the pond bed at the located area to suspend the solids in liquid to form a salt slurry to be extracted by a pump; and pumping the suspended salt solids to a classification plant for removal of the solids therefrom.

[041] These and other aspects will be apparent from the following specific description, given by way of example only, with reference to the accompanying drawings, in which:

[042] Fig. 1 is a schematic view of a mobile pumping system according to a first embodiment of the present invention, where the mobile pumping system is floating on a pond and providing fluid to a salt processing system;

[043] Fig. 2 is a schematic view showing the mobile pumping system of Fig. 1 in more detail;

[044] Fig. 3 is a schematic sectional view of a primary barge of the mobile pumping system of Fig. 1;

[045] Fig. 4 is a schematic view of the auxiliary barge of the mobile pumping system of Fig. 2; and 6

[046] Fig. 5 is a schematic view showing part of the mobile pumping system of Fig. 1 (the submersible pump) in more detail. Detailed Description

[047] Reference is now made to the drawings, and particularly to Fig. 1, which is a schematic view of a mobile pumping system 10 according to an embodiment of the present invention, where the mobile pumping system is floating on a pond 12 and providing fluid to a salt processing system 14. In this embodiment the pond 12 is a brine pond from which salts are recovered using the salt processing system 14, which located on or near a bank of the pond.

[048] The pond 12 is formed in a dip in the surrounding land 16 and includes water (containing brine) 18. An original bed 20 of the land in the dip has received salt deposits 22, which reduce the depth of the pond 12. An upper surface of the salt deposits 22 forms a deposited pond bed 24. The pumping system 10 floats on a surface 26 of the pond 12. The brine is more dense than clean water so it tends to sink to near the bottom of the pond 12; whereas clean water tends to be located near the surface 26. The pond 12 is typically below 4 metres deep at its deepest, and is less than 3 metres deep across most of its expanse.

[049] Reference is now also made to Fig. 2, which is a schematic view showing the mobile pumping system 10 in more detail. The mobile pumping system 10 comprises a primary barge 30 shown in more detail in Fig. 3 and an auxiliary barge 32 shown in more detail in Fig. 4.

[050] The primary barge 30 is used to extract fluid (liquid and solids suspended in liquid) from near the deposited pond bed 24. The primary barge 30 comprises a floating platform 40 defining a generally central aperture 41 therethrough (in other embodiments, the aperture may be offset from the centre of the primary barge 30). A lifting mechanism 42 in the form of a winch is mounted on the floating platform 40 for winding and unwinding a cable 44 attached thereto. The cable 44 passes through the aperture 41. A submersible pump 46 is coupled to the free end of the cable 44 and depends from the winch 42. The cable 44 is sufficiently long to allow the submersible pump 46 to be lowered to the original bed 20, if required. It is to be appreciated that other lifting mechanisms such as linear motors could be use in addition or alternatively to the winch.

[051] The primary barge 30 is relatively small. In this embodiment, the primary barge 30 is less than 3 metres in diameter, and is highly buoyant so that it floats with a small draught (approximately 0.5 metres). This is important because the pond 12 is shallow.

[052] The primary barge 30 also includes a support frame 48 located above the generally central aperture 41, and mounted on opposing sides thereof. The support frame 48 provides a guiding eyelet 49 through which the cable 44 is routed so that the support frame 48 takes 7 the load of the submersible pump 46. In the illustrated example, the support frame is substantially inverted U-shape.

[053] A controller 50 is mounted on the floating platform 40 and controls the operation of the primary barge 30. In particular, the controller 50 monitors various sensors on the barge 30. These sensors include a depth sensor 52, an underwater pressure sensor 54, and a GPS sensor 56. The depth sensor 52 comprises a commercially available transducer, such as a GT20 sensor, available from Garmin (trade mark). The underwater pressure sensor 54 comprises a commercially available sensor, such as a PS3417 Hydrostatic submersible pressure transmitter, available from IFM (ifm electronic ltd). Based on the readings from the sensors 52, 54, the controller 50 can raise or lower the submersible pump 46 so that it is close to the deposited pond bed 24. In this embodiment, the submersible pump 46 is lowered to between 1m and 0.5m from the deposited pond bed 24.

[054] The primary barge 30 includes a plurality of each directional jets 60 mounted beneath the floating platform 40. The jets 60 are oriented in different directions so that they can be selectively activated to facilitate movement of the floating platform 40 in any direction on the pond surface 26. The controller 50 selectively activates the jets 60 based on a desired location on the pond 26 surface to which the primary barge 30 is to move, or at which the primary barge 30 is to remain.

[055] The primary barge 30 also includes an output pipeline 62 that connects the submersible pump 46 to the salt processing system 14 so that fluids are pumped from the water 24 near the deposited pond bed 24 thereto. In some embodiments, where the output pipeline 62 is particularly long, one or more repeater pumps (not shown) may be provided in the output pipeline 62 to boost the pumping distance.

[056] The primary barge 30 also includes a pipe manifold 64 having a plurality of outputs. Each directional jet 60 is coupled to one of the pipe manifold outputs. Each pipe manifold output includes an isolation valve (not shown) selectively actuatable by the controller 50. One of the pipe manifold outputs is also coupled to the submersible pump 46, as described in more detail below, via a sparger fluid pipe 66. An input to the pipe manifold 64 is coupled to an auxiliary pipe 68. The auxiliary pipe 68 is used as a conduit for high pressure water and also acts as a tether so that the auxiliary barge 32 is towed (or sometimes pushed) by the primary barge 30 wherever the primary barge 30 moves. In other embodiments, a separate tether, or other type of mutual coupling, may be used. The tether may allow the auxiliary barge 32 to push or pull the primary barge 30.

[057] The auxiliary barge 32 includes a floating (or second) platform 70 on which is mounted an auxiliary pump (which is a vertical pump in this embodiment) 72. The auxiliary pump 72 includes a volute 74 at a lower end which, in use, is submerged into the water 18 to provide a source of fluid and the pump output is coupled to the auxiliary pipe 66 to provide high pressure water thereto. In this embodiment, the high pressure water will depend on the characteristics of the pond bed 24 and solids being pumped, but may be between 100 and 300 kPa. In this embodiment, the auxiliary pump 72 is not used for dewatering, instead it is used to provide hydraulic power to the primary barge 30. The primary barge 30 uses this hydraulic power for two main purposes. The first purpose is to move the floating platform 40 to (or to maintain the floating platform 40 in) a desired position using the directional hydraulic jets 60. The second purpose is to provide the submersible pump 46 with high pressure fluid to break up the solids on the deposited pond bed 24, as described below in more detail.

[058] A lifting mechanism (not shown) in the form of a winch is mounted on the floating platform 70 for winding and unwinding a cable 73 attached thereto. A free end of the cable 75 is coupled to the auxiliary pump 72 and depends on the winch (not shown).

[059] The auxiliary barge 32 also includes a support frame 75 located above the floating (or second) platform 70, and mounted on opposing sides thereof. The support frame 76 provides a guiding eyelet 78 through which the cable 73 is routed so that the support frame 76 takes the load of the auxiliary pump 72. In the illustrated example, the support frame is substantially inverted U-shape.

[060] Reference is now also made to Fig. 5, which is a schematic view showing the submersible pump 46 in more detail. The submersible pump 46 comprises a waterproof drive housing 80 which houses a motor (not shown) that powers the rotation of a drive shaft (not shown) that is attached to an impeller (not shown). A lower end of the submersible pump 46 includes a perforated strainer basket 82 (having a large number of relatively small apertures therein) that prevents large items of debris (e.g. sticks, twigs, or the like) from reaching (and potentially blocking) the impeller. These features are conventional for certain submersible pumps, such as the WARMAN SHW (trade marks) submersible pump, available from The Weir Group PLC (www.global.weir).

[061] The submersible pump 46 also includes a sparger device 84 that defines apertures (not clearly visible in Fig. 3) that are directed downwards towards the deposited pond bed 24. The sparger fluid pipe 66 is coupled to a sparger device inlet 86 of the sparger device 84 and provides high pressure water thereto, via the pipe manifold 64, in the direction shown by arrow 87.

[062] As shown by broken lines 88 in Fig. 3, directional jets of water (sparger jets) are forced through the sparger device apertures towards the deposited pond bed 24 such that, in use, solid particles are dislodged therefrom forming a slurry in the area indicated by broken cylinder 90. This enables the slurry to be pumped out by the submersible pump 46 and delivered to the salt processing system 14. 9

[063] The controller 50 may be programmed with algorithms so that it can operate autonomously, directing itself to areas above the pond bed that require salt removal, measuring the depth, lowering the submersible pump to the required depth, actuating the pump 72, and detecting when the salt deposits 22 have been removed. If desired, the primary barge 30 (and the auxiliary barge 32) may be controlled remotely, from a panel, computer, tablet or any controller device.

[064] It will now be appreciated that these embodiments have the advantage of providing a mobile pumping system 10 that can map the deposited pond bed 24 to identify areas of large solids build up that need to be broken down. The mobile pumping system 10 can then move, or be moved, to the areas having the largest build up of solids, and the solids can be broken up and pumped out by the submersible pump 46. If all of the solids build up has been removed, the brine liquid near the original bed 20 can be pumped out for processing by the salt processing system 14 or any slurry processing system plant for mining applications or solids processing.

[065] At least some of these embodiments provide an autonomous pumping system for dredging solid materials from brines or any other type of ore, slurry or liquid with solids, from tanks, ponds, pools or any other damp or natural river or liquid reservoir. As an example, it is used for removing salt solution from a pond to allow continuous processing and improve its efficiency

[066] Various modifications may be made to the above described embodiments. For example the solids may not be salts, the pond may be seawater or a natural pond, lake, or river, and other types of sensors may be used than those described.

[067] In some embodiments, the submersible pump 46 may be replaced with a pump mounted on the floating platform and having an elongate snout that can be lowered to the vicinity of the pond bed. The snout may have a sparger device located beside or around it, and the auxiliary pump 72 may be coupled to an inlet of the sparger device.

[068] In some embodiments, the auxiliary pump 72 may be used to provide a dewatering function to empty water from the pond (not liquid brine, just normal water near the top of the pond). In some embodiments, a different processing system may be used than the salt processing system 14. Reference Numerals Mobile pumping system 10 Pond 12 Salt processing system 14 Surrounding land 16 Water (containing brine) 18 Original bed 20 Salt deposits 22 Deposited pond bed 24 Pond surface 26 Primary barge 30 Auxiliary barge 32. Floating platform 40 Central aperture 41 Winch 42 Cable 44 Submersible pump 46 Support frame 48 Guiding eyelet 49 Controller 50 Depth sensor 52 Underwater pressure sensor 54 GPS sensor 56 Directional jets 60 Output pipeline 62 Pipe manifold 64 Sparger fluid pipe 66 Auxiliary pipe 68 Floating platform 70 Auxiliary pump 72 Cable 73 Volute 74 Support frame 76 Guiding eyelet 78 Waterproof drive housing 80 Strainer basket 82 Sparger device 84 Sparger device inlet 86 Arrow showing high pressure fluid direction 87 Sparger water jets 88 Slurry area 90

Claims

1. A pumping system for pumping a salt slurry from near a bed of a salt pond, the pumping system comprising: (i) a first floating platform configured to float on a surface of the pond, the first floating platform having an opening therein; (ii) at least one hydraulic directional jet coupled to the first floating platform for moving the first floating platform over the surface of the pond; (iii) a lifting mechanism mounted on the first floating platform; and (iv) a submersible pump positioned within the opening and coupled to the lifting mechanism, the submersible pump being operable to extract salt-rich liquid from near a bottom of the pond, the submersible pump including a downwards directed sparger device for breaking up crystallised salts solids which have accumulated on a bed of the pond and suspending the broken up salt solids in liquid to form a brine and thereby enable pumping thereof by a dewatering pump; and (v) a second floating platform tethered to the first floating platform to allow independent movement of each platform, and configured to float on a surface of the pond, and including an auxiliary pump for providing hydraulic power to the first floating platform.

2. The pumping system of claim 1, wherein the lifting mechanism comprises a winch with the submersible pump coupled to the winch via a winch cable extending through the opening to control vertical displacement of the submersible pump.

3. The pumping system of claim 1, wherein the lifting mechanism comprises a motor coupled to submersible pump to control vertical displacement of the submersible pump.

4. The pumping system of any one of claims 1 to 3, wherein the first floating platform comprises a plurality of hydraulic directional jets, each hydraulic directional jet being oriented, or capable of being oriented, in a different direction, to facilitate movement of the first floating platform in any direction on the surface of the waterbody.

5. The pumping system of any one of claims 1 to 4, wherein the sparger device comprises a sparger ring having apertures therein directed downwards.

6. The pumping system of claim 5, wherein the sparger ring surrounds a pump chamber of the dewatering pump.

7. The pumping system of any one of claims 1 to 6, wherein the first floating platform further comprises a global positioning system.

8. The pumping system of any one of claims 1 to 7, wherein the first floating platform further comprises a depth measurement device.

9. The pumping system of any one of claims 1 to 8, wherein the first floating platform further comprises a pressure sensor mounted on or near the submersible pump for detecting a pressure at the depth of the pump.

10. The pumping system of any one of claims 1 to 9, which includes a controller arranged to control the operation of the first floating platform based on various sensors and to operate the submersible, the auxiliary pump, the lifting mechanism or hydraulic directional jets.

11. A method of harvesting salt from a salt pond or extracting solids from a pond, the method comprising: (i) using a second floating platform to move a first floating platform, which is tethered thereto by a flexible coupling to allow independent movement of each platform, over the surface of the pond using hydraulic directional jets mounted on the first platform and energised by a pump on the second platform; (ii) locating an area of the pond where solids have accumulated on the bed; (iii) using fluid in the pond to hydraulically break up the accumulated solids on the pond bed at the located area to suspend the solids in liquid to form a slurry; and (iv) extracting the slurry from the area near a bottom of the pond using a pump extending downwards from the first floating platform.

12. The method of claim 11, further comprising using an auxiliary pump to provide high pressure fluid to move the floating platform and to break up solids on the waterbody bed.

13. The method of claim 11 or 12, wherein the step of hydraulically breaking up solids is preceded by the steps of: (i+1) measuring a depth of the waterbody bed, and (i+2) lowering a submersible pump to within one metre of the measured depth.