AU2007201772A1 - System for reducing water evaporation - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicants: TECHNOLOGICAL RESOURCES PTY. LIMITED Invention Title: SYSTEM FOR REDUCING WATER EVAPORATION The following statement is a full description of this invention, including the best method for performing it known to us: 2 EVAPORATION REDUCTION APPARATUS AND A SYSTEM AND APPARATUS FOR REDUCING WATER EVAPORATION Field of the Invention The present invention relates to the reduction of evaporation from water and tailings storage facilities.

Specifically, the invention relates to a system and an apparatus for reducing evaporative loss from a body of liquid such as a body of water or tailings storage facilities.

Background of the Invention The need to conserve water in many parts of the world to support increasing demands placed on water resources by growing populations competing with environmental requirements is becoming more evident with time. This has fuelled interest in ways to reduce evaporative losses from open storages.

Numerous suggestions to reduce evaporation involving the use of floating objects have been made in the past with different degrees of success and associated problems. While evaporative loss is known to be reduced by covering the surface of the water with a cover of plastic or like sheeting, and while such techniques are used with success in swimming pools, such arrangements have limited success with water storage facilities having large surface areas which are exposed to extreme weather conditions, and particularly high winds.

Other suggestions include the use of floating balls and other floating covers made from plastic sheeting.

N.\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 3 In a study conducted by one of the present inventors, floating water surface modules which cover most of the surface of the water have been determined to provide a practical solution for large water surface areas, as they are relatively stable in high winds. Such modules are the subject of International patent publication WO 05/090696. The content of the International application is incorporated herein by this reference.

While such modules are relatively stable in high winds, they can be susceptible to the combined effect of wave and wind action. This susceptibility is critical in some locations where dams are subject to strong prevailing winds. In larger dams, the wind travels across a fetch of water that is large enough to generate waves that have a trough level below the level of a lower edge of the module. In such circumstances, the wind can get underneath the module. Ultimately, the combined effect of wave and wind action can destabilize the modules and even flip them over.

One solution proposed in British patent GB1008495 (Doxiadis Ionides Associates Limited) involves filling a ring-like tube with water or sand as ballast and placing a membrane over the top of the ring to cover the water surface. In such a construction the ring is flexible and is inflated by air for buoyancy or by water or sand for ballast.

The ballast advantage provided by the water or sand is off-set by the time consuming and uneconomical process of inflating each ring. This represents a significant disadvantage in terms of deployment of the ring, especially where a body of water can only be adequately covered by thousands of rings.

Ni\Melbourne\Caees\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 4 Doxiadis also teaches that rigid or semi-rigid units can be used in place of flexible rings. The stability of a rigid or semi-rigid unit is provided in part by connection of each of the units together to provide a screen or raft that floats on the surface of the water. That is, the movement of a given unit is restricted by its connection to adjacent units. In other words, the adjacent connected units provide resistance to destabilization through their connection to the unit that is subject to the wave and wind action. So as long as the adjacent units remain stable, the given unit is stabilized.

The stability of the units is also partly provided by forming the units to receive ballast and filling the units with ballast.

These units suffer the same ballast-related problems described above in reference to the flexible units.

While interconnecting the units to provide a screen is suitable for relatively small bodies of liquid, this technique is not appropriate for large ponds and bodies of water because connecting thousands of modules to each other is labour intensive and is not cost effective.

Additionally, the position of the modules must be controlled to prevent the modules travelling under wind and wave action from a designated location. In some cases, modules will become beached on an inclined side wall of a pond or caught in soft mud at the edge of a pond when the level of liquid in the pond decreases.

Summary of the Invention It is an object of the first aspect of the N:\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 O present invention to alleviate, at least in part, one or Smore of the above problems.

The invention provides in a first aspect an apparatus for reducing evaporative loss from a body of liquid, such as a tailings dam or body of water, the apparatus comprising: a plurality of loose buoyant modules for together covering at least a substantial part of the surface of the body of liquid; and a plurality of linked buoyant modules positioned near at least part of the perimeter of a group of the loose buoyant modules, for containing said loose modules in a group formation covering at least a predetermined part of the surface of the body of liquid.

It will be appreciated that the linked buoyant modules constrain the movement of the loose modules to a desired location or area when the modules are subjected to wave and wind action. Constraining the movement of the modules to a predetermined location provides improved control over evaporative loss from the body of liquid.

For example, beaching of modules can be avoided by placing linked buoyant modules in a position to form a barrier that catches modules before they move onto an inclined side wall of a dam under wave and wind action. In the event that movement of the modules is unconstrained, the modules would beach on the dam side wall and would not contribute to reducing evaporative loss. The barrier formed by the linked modules thereby improves control over evaporative loss, at least, in windy conditions.

Preferably, the linked buoyant modules confines movement of the loose modules in at least one direction.

N,\Melbourne\Cases\Patent\59000-59999\P59230.AU.\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 6 Preferably, the linked buoyant modules includes anchor means for restricting the movement of the linked buoyant modules relative to a body of liquid such that the contained group of modules are contained to cover at least a predetermined part of the surface of a body of liquid.

Preferably, the linked buoyant modules are linked together by connection to a common tether or to at least one neighbouring module.

Preferably, the linked buoyant modules are anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located.

Alternatively, the linked buoyant modules may be anchored to another barrier that is anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located.

Preferably, at least one of the linked buoyant modules include means for improving the stability of the buoyant modules against the effect of wind and/or wave action.

Preferably, the linked buoyant modules include two or more rows of linked modules and adjacent rows are linked together.

Preferably, each buoyant module has a rim portion for extending into a body of liquid and a cover portion extending from the rim portion and covering the surface of the body of liquid encompassed by the rim portion and means for giving buoyancy to the module.

Preferably, the linked modules are linked to a tether and/or to a neighbouring module by a connection means.

NI\Melbourne\Casea\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.dOC 19/04/07 7 Preferably, the connection means enables restricted universal movement of a module relative to a linked tether or neighbouring module such that the module is able to ride over waves and such that the module is prevented from being lifted by wave action to the extent that the rim leaves the liquid.

Preferably, the connection means attaches to the rim of the linked buoyant modules and the rim of the linked buoyant modules is reinforced for linking neighboring modules and/or linking the buoyant module to a tether.

Preferably, the buoyant modules are nestable to facilitate transport and handling of the buoyant modules.

It is an object of a second aspect of the present invention to improve the stability of floating water storage cover modules and, advantageously, to alleviate the deployment problems outlined above.

The invention provides, in a second aspect, a stabilizer for an evaporation reduction module that has a rim, a cover and means for giving buoyancy to the module such that in use the rim is submerged in the water, said cover being configured to define an air space above the water, wherein the stabilizer extends from the module for location into a body of liquid, the stabilizer in use extending to a depth where the liquid is calm relative to the surface of the liquid such that the stabilizer located in the relatively calm liquid resists movement of the module caused by wave and wind action at the surface of the liquid.

It will be appreciated that by forming the wall to be located in the relatively calm water below the N:\Melbourne\Cases\Patent\59000-59999\P59230.AU.l\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 8 surface, the level of wave troughs does not extend below the lower extent of the wall and, therefore, wind is not able to get underneath the rim and lift the module.

Additionally, rocking movement of the module under the influence of wave action at the surface of the water is resisted by the wall which is located in relatively calm water. Hence, the wall diminishes the impact of wave and wind action on the rocking movement of the module and the travelling movement of the module across the surface of the water.

Preferably, the stabilizer is a wall that extends from the module.

The wall may be formed for extending beyond the level of the rim into the body of liquid by a distance in the range 5 50cm. Preferably, the wall is formed for extending beyond the level of the rim into the body of liquid by a distance in the range 8 The wall may be integrally formed with the module, but is preferably formed as a retro-fittable attachment.

In terms of the retro-fitting option, the wall includes attachment means that are co-operable with attachment means formed on a rim for fitting the wall to a rim. The attachment means on the wall and a rim are preferably simple and fast to operate in order to minimize the time and effort involved in fitting walls to modules.

Accordingly, the wall and rim preferably have snap-fit attachment means.

The wall preferably fits around the perimeter of a module. In other words, the wall preferably has a shape that complements the shape or a portion of the shape of a N,\Melbourne\Caeee\Patent\59000-59999\P59230.AU.\Speci\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 9 rim.

The applicant recognizes that a rim with a circular profile is preferable because it provides the most efficient coverage according to random stacking theory. While hexagonal, triangular and square profiles could be adopted, the randomness of the deployment of the modules onto the surface of the water means that accurate alignment is difficult to achieve. It has been found that a circular profile achieves a higher consistency of coverage of the surface of the water, and for this reason is preferred. In any event, it is believed to be preferable to leave at least a small part of the water surface exposed to maintain water quality.

Accordingly, the wall is preferably formed with a profile of a circle or with a profile of an arc of a circle with a radius closely corresponding to the radius of the rim to facilitate attachment of the wall to the rim. However, the wall may be formed with other profiles to match the profile of the rim.

In one particular embodiment, the wall is formed with a semi-circular profile and is fitted to a module on a windward side of the module. The wall, therefore, is useful to stabilize the windward side against the influence of wind and waves in the circumstances that there is a prevailing wind.

The wall preferably includes a formation for increasing resistance of the module to vertical movement.

The formation is preferably located at a lower extent of the wall such that the formation is in the calmest water reached by the wall. Such location maximizes the resistance provided by the formation.

N.\Melbourne\Caes\Patent\59000-59999\P59230.AU.l\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 10 In one embodiment, the formation is a return portion that extends from the wall and toward the module to define an open channel.

In another embodiment, the formation is a return portion that extends from the wall and toward the module to define a closed channel. The channel is closed by a panel that includes a plurality of apertures for allowing water to flow into and out of the channel. The apertures are sized to permit only a small flow of water from the channel so any ballast effect, if the channel is lifted above the surface of the body of water, is not quickly lost.

It will be appreciated that the modules forming at least part of the barrier have the greatest exposure to wave and wind action. Accordingly, the modules forming the barrier include a stabilizing wall and thereby shelter the free modules located on a leeward side of the barrier.

It is an object of a third aspect of the present invention to provide a system for reducing evaporative loss from a body of water or a tailings dam that enables, at least to some extent, control of the location of evaporation reduction modules on the surface of a body of liquid. Advantageously, the present invention also improves stability of modules in high winds.

The invention provides, in a third aspect, a system for reducing evaporative loss from a body of liquid, such as a tailings dam or body of water, comprising a multiplicity of buoyant modules for together covering at least a substantial part of the surface of the body of liquid, and buoyant barrier means positioned near at least part of the perimeter of a group of said buoyant modules, for containing said group of modules in a group formation covering at least a predetermined part of the N,\Melbourne\Cases\Patent\59000-59999\P59230.AU.\Specis\P214.STBILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 11 surface of the body of liquid.

It will be appreciated that the barrier means constrains the movement of the multiplicity of modules from a desired location when the modules are subjected to wave and wind action. Constraining the movement of the modules to a predetermined location provides improved control over evaporative loss from the body of liquid.

For example, beaching of modules can be avoided by placing barrier means to catch modules before they move onto an inclined side wall of a dam under wave and wind action.

In the event that movement of the modules is unconstrained, the modules would beach on the dam side wall and would not contribute to reducing evaporative loss. The barrier means thereby improves control over evaporative loss, at least, in windy conditions.

The barrier means preferably confines movement of the modules in at least one direction.

The buoyant barrier means preferably includes one or more arrays of linked buoyant elements that form a barrier for containing said group of buoyant modules and includes anchor means for restricting the movement of the barrier relative to a body of liquid such that the contained group of modules are contained to cover at least a predetermined part of the surface of a body of liquid.

The buoyant elements forming the barrier may be buoyant modules that are linked together by connection to a common tether or to at least one neighboring module.

The or each array forming a barrier means may be anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located. Alternatively, a barrier may be anchored to another barrier that is anchored to a side wall or the bottom of a dam or pond in N,\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specis\P214.STILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 12 which a body of liquid is located.

The applicant has found that the multiplicity of buoyant modules does not need to be tethered to each other when they are contained by a buoyant barrier means.

Accordingly the multiplicity of buoyant modules may be free floating in a group formation within the confines defined by the barrier means. In this arrangement, the labour intensive and uneconomical task of connecting a given module to neighboring modules is avoided.

In locations that have a prevailing wind, the windward side of the group of buoyant modules is subject to significant wave and wind action that can destabilize exposed modules. The remainder of the group of modules is protected from the wind and waves by the windward modules.

Accordingly, the barrier means may comprise, at least on a windward side, buoyant modules that include means for improving the stability of the buoyant modules against the effect of wind and/or waves. Accordingly, the free buoyant modules may not require any form of stabilizer to counter the effects of wave and wind action.

In another form, the barrier means may comprise, at least on a windward side of the group of modules, two or more rows of linked modules.

Each buoyant module preferably comprises a rim portion for extending into a body of liquid and a cover portion extending from the rim portion and covering the surface of a body of liquid encompassed by the rim portion, means for giving buoyancy to the module and wherein the rim is reinforced for linking the module to neighboring modules or to a tether to form a barrier means.

J,\Melbourne\Cases\Patent\5900O-59999\PS9230.AJ.1\Specis\P214-STABILIZR FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 13 The modules are preferably nestable to facilitate transport and handling in the distribution process. The nestability of the modules is not affected by incorporation of the reinforced rim in the module.

The module may be linked to a tether or a neighboring module by a connection means that is secured to the reinforced rim.

The connection means may be secured to the rim by forming a hole in the rim, such as by drilling or by removing a portion defined by a line of weakness, and inserting a connection means into the hole to engage the connection means with the module.

The connection means preferably comprises a universal joint that enables restricted independent movement of a module relative to a linked tether or neighboring module such that the module is able to ride over waves and such that the module is prevented from being lifted by wave action to the extent that the rim leaves the liquid.

The connection means may include a body with at least one formation for locking the connection means to the rim. In one embodiment, the formation includes a hook insertable through a hole formed in the rim and which prevents the connection means from pulling free of the rim and includes a flange located adjacent to the hook for limiting the extent to which the connection means extends through the hole.

A connection means for linking a module to a neighboring module preferably includes a body having two opposed formations for locking the connection means to the rim, each formation being as described above.

Ni\Melbourne\Case8\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 14 A connection means for linking a module to a tether preferably includes a body with at least one formation for locking the connection means to the rim as described above and a tether connection. The tether connection may be formed as a ring associated with the body or may be any other suitable form for receiving a tether, such as a cable.

By using air-filled buoyancy pocket(s) as the buoyancy means, the module can be molded from a suitable plastics material, or constructed from other suitable material, to enable commercially viable mass production.

The cover portion is usually provided with an air vent to equalize the pressure in said air space between the cover and the surface of the water. The cover portion is in most cases at least slightly domed to facilitate water run off while not significantly interfering with stackability.

The rim portion is preferably circular to provide the most efficient coverage according to random stacking theory. While hexagonal, triangular and square profiles could be adopted, the randomness of the deployment of the modules onto the surface of the liquid, typically water, means that accurate alignment is difficult to achieve. It has been found that a circular profile achieves a higher consistency of coverage of the surface of the water, and for this reason is preferred. In any event, it is believed to be preferable to leave at least a small part of the water surface exposed to maintain water quality.

Brief Description of the Drawings In order that the invention may be more readily Ni\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 15 understood, embodiments will now be described with reference to the accompanying drawings in which: Figure 1 is an isometric view of an evaporation reduction module, without a stabilizer, and having a portion of the rim and cover cut away to reveal the shape of the module.

Figure 2 is a vertical cross-section of an evaporation reduction module, without a stabilizer, floating in a body of water.

Figure 3 is a vertical cross-section of the module in Figure 2 with a stabilizer in accordance with an embodiment of the present invention.

Figure 4 is a vertical cross-section of the module in Figure 2 with a stabilizer in accordance with another embodiment of the present invention.

Figure 5 is a cut-away isometric view of the module in Figure 2 with a stabilizer in accordance with a further embodiment of the present invention.

Figure 6 is a vertical cross-section of a containment barrier in accordance with an embodiment of the present invention formed with a plurality of modules in Figures 1 and 3.

Figure 7 is a top plan view of a system for containing a group of modules in accordance with an embodiment of the present invention.

Figure 8 is a top plan view of a system for containing a group of modules in accordance with another embodiment of the present invention.

N:\Melbourne\Casea\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 -16-

C-

SFigure 9 is a top plan view of a system for containing a group of modules in accordance with a further 0 embodiment of the present invention.

Figure 10 is a side plan view of an anchored module of the system in Figure 3.

SFigure 11 is an alternative anchor arrangement to the anchor arrangement in Figure 4.

Figure 12 is an isometric view of a module formed in accordance with an embodiment of the present invention with a cover partially cut away.

Figure 13 is an exploded isometric view of an embodiment of modules and a connection means for connecting neighboring modules in accordance with an embodiment of the present invention.

Figure 14 is an isometric view of another embodiment of a connection means for connecting neighboring modules.

Figure 15 is an isometric view of a further embodiment of a connection means for connecting a module to a tether.

Figure 16 is a top plan view of a barrier means formed of interconnected and tethered modules.

Description of Embodiments for the Invention Referring to Figures 1 and 2, a floating water N,\Melbourne\Casea\Patent\59000-59999\P59230.AU.l\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 17 surface cover module 10 has a rim 12, and a shallow domed Scover 14, formed with a vent 16 of sufficient size to allow equalisation of the pressure of the air under the 0 cover 14 when the module is immersed in water W as illustrated, while not allowing for the escape of a significant amount of water vapour. The module is suitably injection molded from a UV-treated plastic and the underside of the module is formed with strengthening ribs S(not shown) extending from the center of the cover 14 to the rim 1.

To provide the module 10 with the required buoyancy, it is formed with six closed cavities 18 spaced evenly about the rim 12.

Each module sits in the water W as illustrated in Figure 1 by the suitable selection of the buoyancy provided by the cavities 18.

The module 10 was tested in a wind tunnel under conditions to simulate a partially covered water surface with a 200 meter fetch.

The modules 10 were stable for wind speeds up to 96 kilometres per hour. Above this wind speed, the wave troughs exposed the lower extremity of the rim 12 above the surface of the water. Wind flowing underneath the rim 12 lifted the module 10 off the water.

The modules 10 were fitted with an extension wall to form a stabilized module 20 (Figure 3).

The extension wall 30 is fitted on the module by snap-on attachment formations (not shown) such that the extension wall can be retro-fitted to an existing module N:\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 18 The extension wall 30 has a shape that complements the shape of the perimeter of the module Typically, the modules 10 have a rim 12 with a circular profile to optimise surface coverage with random packing of the modules. However, the rim 12 may be formed in other profiles as required, e.g. hexagonal, triangular or square.

The extension wall 30 extends into the water to a depth that is 80 millimetres beyond the lower extremity of the rim 12 under quiescent water conditions in the absence of waves). Modules 20 incorporating the extension wall 30 were tested under the same conditions that modules were tested. The modules 20 were stable up to 107-115 kilometres per hour and wave heights of up to 0.36 meters.

It was also observed that the modules 10 and suppressed wave action in sections of the pond covered entirely with modules 10 and 20. The wave suppressing effect of the modules 20 including extension wall indicates that only the wind-exposed modules, i.e.

typically the windward 3 rows of exposed modules, require an extension wall 30. Modules 10 without stabilizers can be located on the leeward side of modules 20 without significant stability problems because the modules suppress wave action and shelter the leeward modules This configuration is shown in Figure 6 with the windward stabilised module 20 anchored to a concrete block 80 to prevent movement of the modules 10, 20 across the water surface under wind and wave action.

Improved stability of the modules 20 is expected for extension walls 30 that extend 50-500mm beyond the lower extremity of the rim 12 into the water W. While it is expected that modules can be stabilized with extension walls 30 that extend more than 500mm beyond the rim 12, such extension walls 30 so dimensioned will be difficult N,\Melbourne\Caaes\Patent\59000-59999\P9230.AU.1\Speci\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 19 to transport. Therefore, the extension walls 30 are preferably formed to extend up to 500mm beyond the level of the rim 12 into the water W.

Module 50 (Figure 4) includes an alternative form of stabiliser including an extension wall 30 and an open annular channel in the form of a return portion 60. The return portion 60 includes a floor panel 62 extending inwardly from the lower extremity of the extension wall toward an opposing side of the extension wall 30. The return portion 60 further includes an inner panel 64 formed as a wall in the shape of an annulus extending upwardly towards the cover 14 from an innermost edge of base panel 62.

The return portion 60 increases the resistance of the module 50 to movement under wave and wind action by increasing the effective surface area of the module 50 in the water at a depth where the water is relatively calm.

Another embodiment of a stabilised module 70 is shown in Figure The module 70 is based on module 10 and includes a snap on extension wall 30 having a return portion 60, as described above in relation to module 50, and a top panel 66 extending from an upper extremity of inner panel 64 to the extension wall 30 to form a closed annular channel.

The top panel 66 and a floor panel 62 of the module 70 each include a plurality of apertures 68. The apertures 68 are evenly spaced about the top panel 66 and floor panel 62. In the particular embodiment of module the top panel 66 and bottom panel 62 each include six apertures 68 that are 5 millimetres in diameter.

The number and size of the apertures are selected Ni\Melbourne\Casee\Patent\59000-59999\P59230.AU.1\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 20 to prevent water contained in the closed annular channel from draining quickly. In the event the return portion is above the surface of water W, for example in a trough between wave crests, the water in the return portion will not have sufficient time to drain from the closed annular channel. The water, therefore, will act as ballast to prevent the module 70 being lifted from the water surface by wind and wave action. Additionally, the apertures 68 enable the water to be drained over a period from the closed annular channel so the module 70 can be transported.

In other words, the number of apertures and the size of the apertures may be varied to achieve on a desired flow rate of water into and from the closed annular channel.

It will be appreciated that the extension wall does not need to extend around the entire perimeter of modules 20, 50, 70. The extension wall 30 may extend about a portion of the perimeter of the modules 20, 50, only. For instance, the extension wall 30 may extend about a windward side of the modules 20, 50,70.

The snap on attachments 40 for connecting the extension wall 30 to modules 20, 50, 70 may be any conventional snap-on arrangement or other attachment means that enables the extension wall 30 to be quickly fitted and removed from a module 10 as required. While it is preferable for the extension wall 30 to be formed separately to the module 10 for retro-fitting to facilitate stacked transportation, it will be appreciated that the wall 30 may be integrally formed with the modules in other embodiments.

The embodiments described above satisfy the requirements of facilitating mass production and enabling N\Melbourne\Casaes\Patent\59000-59999\P59230.AU.l\Speci\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 21 efficient storage and distribution for use as a useful device for the reduction of water evaporation from water storage facilities exposed to hostile environments.

An embodiment of a system and apparatus for reducing evaporative loss from a body of liquid, such as a dam filled with water or a tailings pond, is shown in Figure 7.

The system comprises barrier means in the form of containment barriers 110 and a multiplicity of buoyant modules in the form of any one or more of modules 10, or 70 described above.

The containment barrier 110 is formed of four cables 114, each having buoyant pods 112 located at regular intervals along the cables 114. The cables 114 are anchored at each end either to the bottom (Figures and 11) or side walls of a dam 104. The anchored cables 114 each confine movement of the modules 10 in one direction. Collectively, the cables 114 define a containment area 118 that retains the modules 10 in a close-packed arrangement to cover the surface of the dam defined by the containment area 118.

Another embodiment of the system and apparatus for reducing evaporative loss is shown in Figure 8. In this embodiment, like features to the features in Figure 7 are denoted with like reference numerals.

In this embodiment, the containment barrier 110 defines a generally circular containment area 118 in which free floatable modules 10 are contained in a close-packed arrangement. The containment barrier 110 comprises a perimeter cable 116 with buoyant pods 112 located at intervals along the perimeter cable 116.

Ni\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specis\P214.STABILIZER POR EVAPORATION REDUCTION MODULES.doc 19/04/07 22 The perimeter cable 116 and modules 10 are prevented from moving under wave or wind action and so cover a predetermined part of the surface of the water by virtue of the perimeter cable 116 being attached to anchored cables 114. Again, the anchored cables 114 are anchored either on the bottom of the dam 104 or on side walls of the dam (not shown).

A further embodiment of the system and apparatus for reducing evaporative loss in accordance with the present invention is shown in Figure 9. In this embodiment, like features to the features in Figure 7 are denoted with like reference numerals.

The system in Figure 9 replaces the buoyant pods 112 in Figure 8 with outer modules 10 (shaded) that are threaded on the perimeter cable 116. The outer modules define a generally circular containment area in which free floating modules 10 are contained in a close-packed arrangement.

In the circumstances that the dam is subject to a prevailing wind, the outer modules 10 may be supplemented by a second or further inner rows of modules 10 linked to the outer row of modules 10 to form a broad band of linked modules 10 on the windward side of the group of modules The broad band of modules 10 shelters the modules 10 located in the containment area 118 behind the containment barrier 110. Additionally, the outer modules of the containment barrier preferably include a stabiliser in the form of modules 20, 50 or 70 above to stabilise the modules 10 against the effects of winds and/or waves.

It will be appreciated that the free floating N\\Melbourne\Casee\Patent\59000-59999\P59230.AU.\Speci\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 23 modules 10 in the systems shown in Figures 7-9 may be interconnected to form a raft of modules that is contained within the containment barrier 110.

In the circumstances that the anchored cables 114 are anchored to the bottom of the dam 104, the anchor may comprise a concrete block 130 resting on the bottom 4 of the dam 104 and an anchor line 132 extending from the concrete block 30 to the containment barrier 110 (Figures 10 and 11). Optionally, the anchor line 132 forms part of a perimeter cable 116. In particular, the anchor line 132 of a perimeter cable 116 may include a buoy 134 (Figure 11).

The rim 12 of the modules 10 includes reinforced sections 24 that receive a connecting means for linking a module 10 to a neighboring module 10 (Figure 12).

The reinforced sections 24 comprise regions of the rim 12 that have a thickness greater than the thickness of the remainder of the rim 12. The reinforced sections 24 improve the hoop strength of the rim 12 such that the modules 10 can be towed or pushed across the surface of a dam to a desired location. Additionally, the reinforced sections 24 are formed so as to not interfere with the nestability of modules 10. Accordingly, the modules 10 can be stacked to facilitate handling and transport during distribution.

In order to link modules 10 to neighboring modules 10, a hole 28 is made in the reinforced section 24 so a coupling 40 (Figures 13 and 14) can be secured to the module The hole 28 may be made by drilling through the reinforced section 24. Alternatively, a line of weakness N,\Melbourne\Cases\Patent\S9000-59999\P59230.AU.1\Specis\P214STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 24 is formed in the reinforced section to enable a plug to be punched out, thereby forming a hole 28, typically circular in profile, in the reinforced section 24.

The coupling 40 (Figures 13 and 14) comprises an elongate body 42 and an arrow-shaped head 44 on each end of the body 42. The arrow head 44 includes resilient limbs 48 that extend in a direction away from the tip of the arrow head 44. The limbs 48 flex to a small extent to enable the arrow head to be forcibly inserted through a hole 28 formed in a reinforced section 24 of a rim 12.

Once inserted through the hole 28, the limbs 48 flex outwardly to abut a portion of the rim 12 surrounding the hole 28 such that the arrow head cannot be pulled back through the hole 28 without deflecting the limbs 48 inwardly.

The coupling 40 includes a flange 46 adjacent to and spaced from the arrow head 44. The flange 46 restricts the extent to which the coupling 40 can be inserted through the hole 28 in the reinforced section 24.

The portion of the coupling 40 between the flange 46 and the arrow head 44 has a cylindrical shape with a diameter slightly smaller than the diameter of the hole 28 in the reinforced section 24 such that the coupling loosely fits in the hole 28. The loose fitting provides universal movement between the coupling 40 and the module The coupling 40 includes the same arrow head 44 and flange 46 formations on an opposed end. This end is inserted into a hole in a neighboring module 10 to link neighboring modules 10 together (Figure 16).

The loose fitting of the coupling 40 in the respective holes 28 in the rims 12 provides universal movement between the linked modules 10, but restricts the extent to which the linked modules 10 can move away from N,\Melbourne\Cae \Patent\59000-59999\P59230.AU.I\Speci\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 25 each other. The maximum and minimum distance between respective holes 28 of linked modules 10 depends upon the spacing of the opposed arrow heads 44 and flanges 46 of the coupling In an alternative form, the coupling 40 (Figure 14) comprises arrow head 44 and flange 46 formations on opposed ends of the body 42 and an arm 80 extending perpendicularly from the body 42 between the flanges 46.

A free end of the arm 80 includes a ring 82. This configuration enables neighboring modules 10 to be linked together and enables the coupling 40 to be connected to tethers, such as cables 114 and 116, forming part of the containment barrier 110.

In a further embodiment, the coupling 40A (Figure comprises an arrow head 44 and flange arrangement 46 on one end of the body 42 and a ring 82 on an opposed end of the body 42. The ring 82 is formed to receive a cable or other form of tether therethrough for linking the coupling 40 and an associated module 10 to a cable, such as anchored cables 114 or perimeter cable 116 (Figure 16).

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

In the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

NI \Mebourne\Canea\Ptent\59000 59999\PS9230.AU. \Spe \P214 .STATIZER POR EVAPORATION REDUCTION MODtLES.doc 19/04/07 26 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

N:\Melbourne\Casee\Patent\59OOO-S9999\P59230.AU.1\Specis\P214.STAILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07

Claims (39)

1. An apparatus for reducing evaporative loss from a body of liquid, such as a tailings dam or body of water, the apparatus comprising: a plurality of loose buoyant modules for together covering at least a substantial part of the surface of the body of liquid; and a plurality of linked buoyant modules positioned near at least part of the perimeter of a group of the loose buoyant modules, for containing said loose modules in a group formation covering at least a predetermined part of the surface of the body of liquid.

2. An apparatus as defined in claim 1, wherein the linked buoyant modules confines movement of the loose modules in at least one direction.

3. An apparatus as defined in claim 1 or claim 2, wherein the linked buoyant modules includes anchor means for restricting the movement of the linked buoyant modules relative to a body of liquid such that the contained group of modules are contained to cover at least a predetermined part of the surface of a body of liquid.

4. An apparatus as defined in any one of the preceding claims, wherein the linked buoyant modules are linked together by connection to a common tether or to at least one neighbouring module. An apparatus as defined in any one of the preceding claims, wherein the linked buoyant modules are anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located. N\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specie\P214.STAILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 28

6. An apparatus as defined in any one of the preceding claims, wherein the linked buoyant modules are anchored to another barrier that is anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located.

7. An apparatus as defined in any one of the preceding claims, wherein at least one of the linked buoyant modules include means for improving the stability of the buoyant modules against the effect of wind and/or wave action.

8. An apparatus as defined in any one of the preceding claims, wherein the linked buoyant modules include two or more rows of linked modules and adjacent rows are linked together.

9. An apparatus as defined in any one of the preceding claims, wherein each buoyant module has a rim portion for extending into a body of liquid and a cover portion extending from the rim portion and covering the surface of the body of liquid encompassed by the rim portion and means for giving buoyancy to the module.

10. An apparatus as defined in any one of the preceding claims, wherein the linked modules are linked to a tether and/or to a neighboring module by a connection means.

11. An apparatus as defined in claim 10, wherein the connection means enables restricted universal movement of a module relative to a linked tether or neighboring module such that the module is able to ride over waves and such that the module is prevented from being lifted by wave action to the extent that the rim leaves the liquid. NJ\Nelbourne\Caseo\Patent\59O00-59999\P59230.AU.1\Specis\P214.STABILrZER FOR EVAPORATION REDUCTDN MODULES.doc 19/04/07 29

12. An apparatus as defined in claim 10 or claim 11, wherein the connection means attaches to the rim of the linked buoyant modules and the rim of the linked buoyant modules is reinforced for linking neighboring modules and/or linking the buoyant module to a tether.

13. An apparatus as defined in any one of the preceding claims, wherein the buoyant modules are nestable to facilitate transport and handling of the buoyant modules.

14. A stabilizer for an evaporation reduction module that has a rim, a cover extending from the rim to enclose an air space above the surface of a body of liquid and means for giving buoyancy to the module such that in use the rim is submerged in the liquid, wherein the stabilizer extends from the module for location into a body of liquid, the stabilizer in use extending to a depth where the liquid is calm relative to the surface of the liquid such that the stabilizer located in the relatively calm liquid resists movement of the module caused by wave and wind action at the surface of the liquid. A stabilizer as defined in claim 14, wherein the stabilizer is a wall that extends from the module beyond the level of the rim into the body of liquid by a distance in the range 5

16. A stabilizer as defined in claim 15, wherein the wall extends beyond the level of the rim into the body of liquid by a distance in the range 8

17. A stabilizer as defined in claim 15 or claim 16, wherein the wall includes attachment means that are co- operable with attachment means on the rim for fitting the wall to a rim. Ni\Melbourne\Cases\Patent\59000-59999\PS9230.AU.1\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 30

18. A stabilizer as defined in any one of claims Sto 17, wherein the wall has a shape that complements the shape or a portion of the shape of a rim.

19. A stabilizer as defined in any one of claims to 18, wherein the rim is circular and the wall has a semi-circular profile for fitting to a module on a _windward side of the module.

20. A stabilizer as defined in any one of claims Sto 19, wherein the wall includes a formation for increasing resistance of the module to vertical movement.

21. A stabilizer as defined in claim 20, wherein the formation is located at a lower extent of the wall such that the formation is in the calmest water reached by the wall.

22. A stabilizer as defined in claim 20 or claim 21, wherein the formation is a return portion that extends from the wall and toward the module to define an open channel.

23. A stabilizer as defined in claim 20 or claim 21, wherein the formation is a return portion that extends from the wall and toward the module to define a closed channel for retaining liquid in the channel as ballast.

24. A stabilizer as defined in claim 23, wherein the channel includes a plurality of apertures for allowing liquid to flow into and out of the channel. A stabilizer as defined in claim 24, wherein the apertures are sized to permit a small flow of water from the channel such that the ballast effect of the liquid remaining in the channel is not lost if the channel is lifted above the surface of the body of water. NW\Melbourne\Cases\Patent\59000-59999\PS9230.AU.\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 31

26. A system for reducing evaporative loss from a body of liquid, such as a tailings dam or a body of water, the system comprising a multiplicity of buoyant modules for together covering at least a substantial part of the surface of the body of liquid, and buoyant barrier means positioned near at least part of the perimeter of a group of the buoyant modules, for containing the group of modules in a group formation covering at least a predetermined part of the surface of the body of liquid.

27. A system for reducing evaporative loss as defined in claim 26, wherein the barrier means confines movement of the modules in at least one direction.

28. A system for reducing evaporative loss as defined in claim 26 or claim 27, wherein the buoyant barrier means includes one or more arrays of linked buoyant elements that form a barrier for containing said group of buoyant modules and includes anchor means for restricting the movement of the barrier relative to a body of liquid such that the contained group of modules are contained to cover at least a predetermined part of the surface of a body of liquid.

29. A system for reducing evaporative loss as defined in claim 28, wherein the buoyant elements forming the barrier are buoyant modules that are linked together by connection to a common tether or to at least one neighboring module. A system for reducing evaporative loss as defined in claim 28 or claim 29, wherein the or each array forming the barrier means is anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located. N:\Melbourne\Cases\PaBenc\59000-59999\P59230.AU.I\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.dOC 19/04/07 32

31. A system for reducing evaporative loss as defined Sin claim 28 or claim 29, wherein the barrier is anchored to another barrier that is anchored to a side wall or the bottom of a dam or pond in which a body of liquid is located.

32. A system for reducing evaporative loss as defined _in any one of claims 26 to 31, wherein the multiplicity of buoyant modules are free floating in a group formation within the confines defined by the barrier means.

33. A system for reducing evaporative loss as defined in any one of claims 26 to 32, wherein the barrier means comprises, at least on a windward side of the group of modules, two or more rows of linked modules.

34. A system for reducing evaporative loss as defined in any one of claims 26 to 33, wherein the barrier means comprises, at least on a windward side, buoyant modules that include means for stabilizing the buoyant modules against the effect of wind and/or waves. A system for reducing evaporative loss as defined in any one of claims 26 to 34, wherein each buoyant module comprises a rim portion for extending into a body of liquid and a cover portion extending from the rim portion and covering the surface of a body of liquid encompassed by the rim portion, means for giving buoyancy to the module.

36. A system for reducing evaporative loss as defined in claim 34, wherein the stabilizing means is a stabilizer in accordance with any one of claims 14 to

37. A system for reducing evaporative loss as defined in claim 35 or claim 36, wherein the rim is reinforced for linking the module to neighbouring modules or to a tether N,\Melbourne\Cases\Patent\59000-59999\P59230.AU.1\Specia\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 -33- to form the barrier means.

38. A system for reducing evaporative loss as defined in any one of claims 26 to 37, wherein modules are linkable to a tether or to a neighbouring module by a connection means that is securable to the reinforced rim. _39. A system for reducing evaporative loss as defined Sin claim 38, wherein the connection means is securable to the rim by forming a hole in the rim, such as by drilling or by removing a portion defined by a line of weakness, and inserting a connection means into the hole to engage the connection means with the module.

40. A system for reducing evaporative loss as defined in claim 38 or 39, wherein the connection means comprises a universal joint that enables restricted independent movement of a module relative to a linked tether or neighbouring module such that the module is able to ride over waves and such that the module is prevented from being lifted by wave action to the extent that the rim leaves the liquid.

41. A system for reducing evaporative loss as defined in any one of claims 38 to 40, wherein the connection means includes a body with at least one formation for locking the connection means to the rim.

42. A system for reducing evaporative loss as defined in claim 41, wherein the formation includes a hook insertable through a hole formed in the rim to prevent the connection means from pulling free of the rim and includes a flange located adjacent to the hook for limiting the extent to which the connection means extends through the hole.

43. A system for reducing evaporative loss as defined N\Melbourne\Cases\Patent\59000-59999\P59230.AU.l\Specis\P214.STABILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07 34 in claim 42, wherein the connection means for linking a module to a neighbouring module includes a body having two opposed formations for locking the connection means to the rim.

44. A system for reducing evaporative loss as defined in claim 42, wherein the connection means for linking a module to a tether includes a body with at least one formation for locking the connection means to the rim as and a tether connection. A system for reducing evaporative loss as defined in claim 44, wherein the tether connection is a ring associated with the body for receiving a tether, such as a cable.

46. A system for reducing evaporative loss as defined in any one of claims 36 to 38, wherein the buoyant modules are nestable to facilitate transport and handling. N\Melbourne\Cases\Patent\59000-59999\P5923.AU.1\Specis\P214.STAILIZER FOR EVAPORATION REDUCTION MODULES.doc 19/04/07