WO2010068967A1

WO2010068967A1 - Apparatus and method for mineral recovery using particulate ion exchange media

Info

Publication number: WO2010068967A1
Application number: PCT/AU2009/001489
Authority: WO
Inventors: Noel Priestly
Original assignee: Ripril Process Holdings Pty Ltd
Priority date: 2008-12-18
Filing date: 2009-11-17
Publication date: 2010-06-24
Also published as: WO2010068967A8; ZA201103697B; AU2009328620A1

Abstract

The present invention relates to an apparatus (10) for batch mineral recovery using ion exchange resin including, a contactor vessel (12) in fluid communication with a source of leachate (14) containing mineral ions, the contactor vessel (12) being configured to hold a mixture of said ion exchange resin (54) and leachate (60) therein, a device for forming a closed loop flow path (26) within said contactor vessel (12), and at least one elution vessel (28) in fluid communication with said contactor vessel (12), wherein, the leachate and resin are movable along the closed loop flow path (26) to assist mineral ion exchange between said leachate (60) and ion exchange resin (54), the mineral ion depleted leachate (90) being separated from the ion exchange resin thereafter and the resin being treated within the elution vessel (28) with a reagent to remove said mineral ions therefrom. The present apparatus and associated method provide a way of separating mineral ions from a leachate using ion exchange resin, wherein the loss of resin from the system is minimised.

Description

Apparatus and method for mineral recovery using particulate ion exchange media

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for mineral recovery using particulate ion exchange media. In one particular aspect the invention relates to a batch ion exchange apparatus and method for mineral recovery using ion exchange resin that includes a contactor circuit and at least two elution tanks. It should however be appreciated that the apparatus and method could equally be used with respect to other particulate ion exchange media.

BACKGROUND OF THE INVENTION

Hydrometallurgical methods of mineral recovery that utilise leaching solution to extract metal from an ore body are known in the mining industry. The leaching process can be undertaken in situ where a reagent, such as acid, is pumped into the ore body and the pregnant leachate is extracted for further processing. Alternatively, the ore can be mined, crushed and treated in large tanks or vats containing a leaching solution in what is often referred to as a mineral leach circuit.

The leaching solution varies according to the ore deposit and the target mineral being extracted. For instance, when extracting copper, acids are generally needed to enhance solubility of the mineral within the solution, while for uranium ores the leaching solution may be acid or sodium bicarbonate. The so-called pregnant leachate is treated with a lixiviant for extraction of the desired mineral ions. Various types of lixiviant have been used including carbon, clay and montmorillonite. A more recent development is the use of ion exchange resins produced within the petrochemical industry. These resins are used in resin-in-pulp (RIP) and resin-in- leach (RIL) mineral recovery processes to recover base and rare earth minerals, such as nickel, uranium, gold, copper and nickel.

Ion exchange resins are an organic insoluble matrix or support structure that can be unselective, or have binding preferences for certain mineral ions or classes of ions, depending on their chemical structure. The organic ion exchange resins are typically in the form of beads or pellets having a diameter of between 0.2-1.2mm, and consist of functional groups bound to different polymeric frameworks, most commonly to cross-linked polystyrene.

Typical mineral exchange methods that utilise ion exchange resin include a sorption or contactor stage and an elution stage. Prior to the contactor stage the pregnant leachate is graded to ensure that the maximum particle size of the leachate is smaller than the diameter of the resin beads to enable physical separation of the resin from the leachate after the contactor stage.

During the contactor stage leachate slurry containing the target mineral ions is passed slowly through a reactor vessel and the target mineral ions exchange to the resin. The leachate and resin are mixed within the reactor vessel to ensure that the resin comes into contact and exchanges with the target ions. The depleted leach slurry is then separated from the so-called loaded resin using a mesh or screen, having generally uniform sized apertures. The loaded resin is eluted or stripped of the target ions using a reagent and the resultant eluted solution, which includes the target ions, is removed for further processing. The regenerated resin can then be reused.

Currently there are two typical processing methods utilising resin that are used within the mining industry. One involves the use of continuous counter-current ion exchange techniques, wherein a stream of pregnant leachate flows in an opposite direction to a stream of resin. The other method involves a series of batch-processing tanks that include large propeller blades adapted to mix a slurry of resin and leachate. The slurry is pumped through the system in a cascade route to ensure the target mineral ions are extracted from the leachate.

Due to the nature of the ion exchange resins they are vulnerable to chipping during use. This reduces their overall diameter and therefore permits the resin to pass through the screens and be lost from the system. Conventional processing methods can have high resin wear and attrition, resulting in reduced resin life. This loss of resin can be as much as 30%, which due to the high cost of the resin significantly increases the operational costs of the processing methods currently available. Resin wear is generally caused in batch processing units by the action of the agitation blades, wherein the resin beads violently impact the surface of the blade or the turbulence caused by the blades results in wear. On the other hand, in the continuous counter-current ion exchange techniques, pulp particles can cause abrasion and results in wear of the resin. Resin wear can also result from contact with pump components during movement through the currently available systems, such as during transfer between the series of tanks in the continuous counter-current ion exchange method.

Throughout the specification it should be understood by the reader that the term "leachate" includes, but is not limited to, concentrates, solutions, pulps and slurries containing mineral ions. The term "pregnant leachate" or "pregnant pulp" is used to refer to the leachate prior to treatment with the ion exchange resin, when it contains the mineral ions in solution.

It should be appreciated that any discussion of the prior art throughout the specification is included solely for the purpose of providing a context for the present invention and should in no way be considered as an admission that such prior art was widely known or formed part of the common general knowledge in the field as it existed before the priority date of the application.

SUMMARY OF THE INVENTION

In a first aspect of the invention but not necessarily the broadest or only aspect, there is proposed an apparatus for batch mineral recovery using ion exchange resin including, a contactor vessel in fluid communication with a source of leachate containing mineral ions, the contactor vessel being configured to hold a mixture of said ion exchange resin and leachate therein, a device for forming a closed loop flow path within said contactor vessel, and at least one elution vessel in fluid communication with said contactor vessel, wherein, the leachate and ion exchange resin are movable along said closed loop flow path to assist mineral ion exchange between said leachate and ion exchange resin, whereafter mineral ion depleted leachate being separated from the ion exchange resin and said ion exchange resin being treated within elution vessel with a reagent to remove mineral ions therefrom. The elution vessel preferably includes a separation means for separating said mineral ion depleted leachate from said ion exchange resin having the mineral ions bound thereto. In this way the mixture of mineral ion depleted leachate and ion exchange resin are separated and said resin is treated to remove the mineral ion within the same vessel.

The ion exchange resin may be provided as beads and in one form is a hard, spherical gel type bead. Alternatively the ion exchange resin can be of a macroporous structure. A strong or weak cation or anion resin may be used, depending on the type of leachate and the target mineral ion.

In one form said separation means is a screen having generally uniform apertures in a range between 0.2 and 0.5 mm diameter and preferably 0.2mm in diameter. The leachate is therefore screened prior to being introduced into the contactor vessel to remove particles of equal to and greater diameter than the size of the screen apertures. When the apparatus includes screens having an aperture of 0.2mm diameter an ion exchange resin having a bead size larger than 0.2mm is used. This enables the resin to be separated from the leachate using said screen. It should be understood that this pre-screening of the leachate could be undertaken using any method of physically grading and separating the material. For instance existing crushing and grading of material using a mesh having aperture of known diameter could be used to ensure the leachate slurry has a particle size less that the diameter of the resin beads.

In another form the apparatus may include first and second elution vessels configured to store regenerated or new resin for use in the contactor vessel, and receive the ion exchange resin after contact with the leachate for subsequent elution.

The use of first and second elution vessels means that when one of the elution vessels is being used to elute mineral ions, the other elution vessel can potentially be used as a source of regenerated resin for addition to the contactor vessel, or be configured to receive a mixture of leachate and resin from the contactor vessel. This means that a continuous or semi-continuous processing cycle can be used wherein a first batch of leachate can be treated in the contactor vessel and then removed into the first elution vessel for elution, while a second batch of leachate is added to the contactor vessel and treated using resin added from the second elution vessel.

In yet another form the resin may be regenerated using an acid, such as Sulphuric acid. Regeneration is accomplished by passing a given quantity of the acid through the resin, which exchanges sulphate (SO₄) from the acid for the mineral ions. After elution any residue acid can be rinsed off the resin using tailing from a flush tank.

The contactor vessel may be connected to each of the elution vessels by way of first and second pipes. The first pipe is configured to transport the leachate and resin solution from the contactor vessel to the respective elution vessel once the mineral ions are loaded onto the said resin. The first pipe includes a valve for isolation of the contactor vessel from the respective elution vessels.

In still another form tailing from a flush tank may be introduced into the contactor vessel to force the resin/leachate mixture out from within the contactor vessel and into one of the elution vessels. This prevents the resin from coming into contact with pump components during movement into the elution vessel, that could result in deterioration of the resin.

The second pipe may be configured to transport regenerated or new resin into the contactor vessel from the elution vessel. The second pipe preferably includes two valves for isolation of the contactor vessel from the respective elution vessel.

The elution vessels may include tailing outlets for movement of said mineral ion depleted leachate out of the apparatus into a tailing reservoir once the mineral ion have been loaded onto the resin. The elution vessel may further include an eluted solution outlet for movement of the eluted solution containing the mineral ion into a precipitation tank or circuit.

In yet another form the regenerated or new resin may be moved through the second pipe by way of a pressure or vacuum ejector or eductor. The resin may also be entrained by a flow of leachate being introduced into the contactor vessel. In still a further form the contactor vessel may be torus shaped with two inlets for input of leachate into the contactor vessel from the source of leachate. The inlets preferably include screens to inhibit loss of resin out of the contactor vessel.

The inlets may further include valves for isolating the contactor vessel once the leachate has been introduced into the contactor vessel.

In another form the contactor vessel preferably has a rounded cross-sectional profile and comprises a circular or oval loop. The internal surface of the contactor vessel is regular to reduce the formation of eddies or dead areas along the closed loop flow path. This enables the leachate and resin to continuously circulate along the flow path within the contactor vessel to ensure ion exchange is undertaken. The capacity of the contactor vessel may be between 1-2 millions litres, however larger or smaller contactor vessels could be used depending upon the application.

In yet a further form the device for forming the closed loop flow path includes a plurality of pressurised air outlets spaced at regular intervals along the flow path to provide sufficient movement and mixing of the leachate and resin. The pressurised air outlets may be angled upwardly towards one side of the contactor vessel to produce a helical flow path. In an alternate form the closed loop flow path is formed by the introduction of flow of leachate into the contactor vessel by way of feed pumps that are isolated from the resin.

In still another form the contactor vessel may be maintained above atmospheric pressure during the contactor stage. In such an embodiment the apparatus will include pressure relief devices to maintain a balance of correct operating pressures and to protect against the dangers resulting from over pressurisation of the apparatus.

In use, due to the continuous suspension action along the closed loop flow path, the ion exchange resin beads experience effective contact with the leachate that results in the increased exchange opportunities and therefore maximum mineral ion loading onto the ion exchange resin. When a particular batch of resin is exhausted, in that it is fully loaded with the target mineral ions, the mixture is transferred into one of the elution vessels. The resin is retained within the elution vessel by the screen and the spent leachate is allowed to pass through and out of the apparatus to the tailings tank. The loaded ion exchange resin can then be eluted using a selected reagent chemical. The eluted solution is transferred to a precipitation tank for mineral precipitation and solidification. The remaining resin can then be washed to remove any residue reagent. The regenerated resin is then stored within the elution vessel for future reuse within the contactor vessel.

The leachate may be treated a number of times within the contactor vessel to extract different minerals. In such an embodiment different elution vessels can be loaded with different resins to target specific minerals. The leachate is reintroduced back into the contactor vessel after a first elution stage and then treated with a different resin to recover another mineral.

The apparatus may include various sensors and measuring devices for determining the duration that the leachate/resin mixture should be retaining within the contactor vessel to thereby enable the mineral ions to bind with the resin. The sensors may also be used to calculate the length of the elution stage and flushing of the resin. Furthermore the sensors may be used to assist in maintaining a preferred environment within the contactor and elution vessels, such as pH and temperature.

The apparatus may include as many elution vessels as to ensure the continuous operation of the apparatus. This is particularly important when the elution stage is of a longer duration than the contactor stage. As the reader would appreciate, in such as situation, if only two elution vessels were connected to the contactor vessel the sorption process within the contactor vessel would need to be discontinued until regenerated resin from one of the elution vessels became available for reuse. Therefore in such a situation it would be useful to include 3 or 4 elution vessels to ensure there is a constant source of regenerated resin available.

The number of elution vessels and capacity of the contactor vessel can be configured to meet the required flow rates for treatment of the leachate. The contactor vessel can have a capacity to hold several million litres of pregnant solution and a necessary volume of ion exchange resin to complete the mineral exchange and loading process.

In a second aspect of the invention there is proposed a method for mineral recovery using a particulate ion exchange media, including the steps of: introducing a leachate solution containing mineral ions and said particulate ion exchange media into a first container; moving the mixture of leachate and particulate ion exchange media along a loop flow path within said first container whereby the mineral ions bind with said media; transferring the mixture of leachate and particulate ion exchange media into a second container, whereby the mineral ion depleted leachate is separated from the particulate ion exchange media and said media is treating to remove said mineral ions therefrom.

In one form the particulate ion exchange media is an organic resin.

In one form the method of mineral recovery using an ion exchange media, preferably an organic ion exchange resin, may include the steps of: introducing a leachate solution containing mineral ions and said ion exchange media into the contactor vessel, the contactor vessel, having a device for forming a closed loop flow path within said contactor vessel, and in fluid communication with at least one elution vessel; moving mixture of said leachate solution and ion exchange media along the closed loop flow path to thereby blend said mixture; transferring said mixture into the elution vessel wherein the mineral ion depleted leachate is separated from the ion exchange media to which said mineral ion are bound; treating said ion exchange media with a reagent to remove said mineral ions therefrom; and separating the ion exchange media from an eluted solution containing the mineral ions.

In another form the leachate may be introduced into the contactor vessel using a feed pump. The feed pump is separated from the internal space of the contactor vessel by a screen. The screen has apertures of a size to inhibit the larger ion exchange resin coming into contact with the feed pump components since this would increase wear and attrition of the resin.

The ion exchange resin may be introduced into the contactor vessel by way of pressure or vacuum ejectors/eductors that are powered by the incoming flow of leachate from the feed pump.

The leachate/resin mixture may be impelled into the elution vessel by the introduction of a flushing solution into the contactor vessel.

The method for mineral recovery may further include the step of screening the leachate prior to its introduction into the contactor vessel.

In yet another form the elution vessel may include a screen that inhibits the movement of loaded resin therethrough while allowing the mineral ion depleted leachate to pass therethrough and be transferred to a tailings tank.

The method for mineral recovery may further include the step of rinsing the resin contained within the elution vessel after it has been treated with the reagent. The regenerated resin can then be subsequently introduced into the contactor vessel for the treatment of another batch of leachate.

The method for mineral recovery wherein at least first and second ion exchange resins are used to recover different mineral ions.

In still another form the method further includes the steps of introducing the leachate solution and the first ion exchange resin into the contactor vessel. The mixture is then transferred and treated within a first elution vessel to recover first target mineral ions. The leachate solution is then reintroduced back into the contactor vessel and treated a second time with the second ion exchange resin. The mixture is then transferred to a second elution vessel and treated for recovery of a second mineral ion. Alternatively, the different mineral ions can be recovered using different reagents. For instance the ion exchange resins may be able to bind with a number of different mineral ions. In such a situation the loaded resin is sequentially treated with different reagents to extract the various mineral ions.

The ion exchange resin may also be a mixture of resins having differing properties to enable the recovery of a number of different mineral ions.

In a third aspect of the invention there is proposed a software program for controlling the operation of the preceding apparatus and method. The software program may be implemented as one or more modules for undertaking the steps of the present invention. In one form the modules are parts of a computer program that usually performs a particular function or related functions. Alternatively the modules can be packaged functional hardware units for use with other components or modules.

A central processing unit (CPU) may be used to control the operation of the apparatus. The CPU is in communication with the apparatus by way of a communication means such as, but not limited to, a modem communication path, a computer network such as a local area network (LAN), Internet, or fixed cables. This means that a user can control the operation of one or more apparatus from a single location.

In one form the processor and the memory cooperate with each other and with other components of a computer to perform all of the functionality described herein. In another form the processor executes appropriate software to perform all of the functionality described herein. In an alternate form, some of all of the functionality described herein can be accomplished with dedicated electronics hardwired to perform the described functions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description and claims, serve to explain the advantages and principles of the invention. In the drawings, Figure 1 is a perspective view of a first embodiment of an apparatus for mineral recovery using ion exchange resin of the present invention;

Figure 2 is a cross-sectional view of the contactor vessel of figure 1 ;

Figure 3 is a schematic view of the apparatus of figure 1 illustrating introduction of the pulp leachate into the contactor vessel;

Figure 4 is a partial schematic view of the apparatus of figure 1 illustrating the resin being introduced into the contactor vessel from the first elution vessel;

Figure 5 is a partial schematic view of the apparatus of figure 1 illustrating mixing of the pulp leachate and resin;

Figure 6 is a partial schematic view of the apparatus of figure 1 illustrating movement of the pulp leachate/resin mixture into the first elution vessel;

Figure 7 is a partial schematic view of the apparatus of figure 1 illustrating treatment of the pulp leachate/resin mixture in the first elution vessel and second batch of pulp leachate and resin being added into the contactor vessel;

Figure 8 is a partial schematic view of the apparatus of figure 1 illustrating mixing of the second batch of pulp leachate/resin and extraction of the eluted solution from the first elution vessel;

Figure 9 is a partial schematic view of the apparatus of figure 1 illustrating mixing of the second batch of pulp leachate/resin and the regenerated resin being held in the first elution vessel;

Figure 10 is a partial schematic view of the apparatus of figure 1 illustrating the pulp leachate/resin mixture being added to the second elution vessel; Figure 11 is a partial schematic view of the apparatus of figure 1 illustrating treatment of the pulp leachate/resin mixture in the second elution vessel and introduction of a third batch of pulp leachate and resin into the contactor vessel;

Figure 12 is a partial schematic view of the apparatus of figure 1 illustrating mixing of the third batch of pulp leachate/resin and extraction of the eluted solution from the first elution vessel;

Figure 13 is a perspective view of a second embodiment of the apparatus for mineral recovery using ion exchange resin of the present invention; and

Figure 14 is a schematic view of a CPU configured to control operation of the apparatus.

DETAILED DESCRIPTION OF THE ILLUSTRATED AND EXEMPLIFIED EMBODIMENTS

Similar reference characters indicate corresponding parts throughout the drawings. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration.

The reader should appreciate that different types and sizes of resin can be used depending upon the mineral ion being extracted and the type of ore. For instance uranium can be extracted from two main leach types, namely acid and carbonate leaches. In sulphuric acid leach solutions the uranium can be present as UO₂ ²⁺ cations or [UO₂(SO₄)J^2" and [UO₂(SOJ₃]^4" anions. In carbonate leaches, the uranium is present as the complex anion [UO₂(CO_j)₃]⁴. In acid leaches the uranium can be extracted in both the cationic and anionic form while only in the anionic form in carbonate leaches. In the present embodiment strong or weak anion resins are used for the extraction of mineral ions, such as uranium. It should however be appreciate that the present invention is not limited to the extraction of uranium or to the use of anionic resins. The following embodiments will be described with reference to a resin-in-pulp (RIP) process whereby the ion exchange resin is added to a pulp leachate. It should however be appreciated that the embodiments can be used with respect to resin-in- leach processing methods or other forms of mineral extraction using ion exchange resin. Accordingly the term "pulp" should be given in its broadest definition as referring generally to a leachate.

Referring to the drawings for a more detailed description, an apparatus 10 for mineral recovery is illustrated, demonstrating by way of examples arrangements in which the principles of the present invention may be employed. As illustrated in figure 1 , the apparatus 10 for mineral recovery using ion exchange resin includes, a contactor vessel 12 for fluid communication with a source of pulp 14 containing mineral ions.

The contactor vessel 12 has a rounded cross-sectional profile and comprises a generally oval loop. The internal surface of the vessel is regular to reduce the formation of eddies or dead areas along the flow path. This enables the pulp/resin slurry to continuously circulate along the flow path within the contactor circuit 12 to ensure ion exchange is accomplished. The capacity of the contactor circuit may be between 1-2 million litres, however larger or smaller contactor vessels could be used depending upon the application. It is envisaged that the contactor vessel will be maintained above atmospheric pressure during the contactor stage, to reduce the evolution of carbon dioxide gas within the slurry.

The source of pulp 14 may be a mineral leach circuit currently used in the mining industry. In this way the apparatus 10 can be connected to existing mine infrastructure, which reduces the cost of installation.

The leaching can be done in different ways, known to the person skilled in the art. This includes high pressure leaching, agitation leaching, heap leaching, or a combination of these methods. The objective of the leaching process is to solubilise the mineral ions in the ore to thereby form leachate residue slurry containing the mineral ions. The leaching can be accomplished using a mineral acid selected from the group consisting of sulphuric acid, hydrochloric acid, nitric acid, and mixtures thereof.

The source of pulp 14 is connected to the contactor vessel 12 by way of input pipes 16 and 18 that include respective feed pumps 20. The feed pumps 20 are separated from the internal space of the contactor vessel by a screen. The screen has apertures of a size to inhibit the larger resin beads coming into contact with the feed pump components since this would increase wear and attrition of the resin.

The contactor vessel 12 is configured to hold a mixture of the ion exchange resin and pulp therein and includes a device 22 for forming a closed loop flow path 26 within the contactor vessel 12. As illustrated in figure 2, the device 22 may be in the form of pressurised air injector or jets 24. Although only a single row of air jets is illustrated it should be appreciated that multiple rows of injector could be used depending upon the size of the contactor vessel 12.

The reader should however appreciate that other forms of current forming means are possible within the scope of the invention. The mixing of resin and pulp ensures high resin contact with pulp and maximum kinetic activity for mineral loading onto the resin. This process can be assisted by both air and pulp flow and also additional pulp from the pulp source 14 to ensure the resin is fully loaded to its exhaustion point so that its operational capacity is maximised.

The apparatus 10 further includes a first elution vessel 28 and a second elution vessel 30 in fluid communication with said contactor vessel 12 by way of respective passageways 32. In the present embodiment the respective passageways 32 include pipes 34, 36 and 38, 40.

The contactor vessel 12 and elution vessels 28, 30 are connected to a tailing flush tank 42 by way of input pipe 44 and discharge pipes 46, 48. The elution vessels are furthermore connected by way of branched outlet pipe 50 to a precipitation circuit

52.

In use the pregnant pulp and resin are moved along the closed loop 26 within the contactor vessel 12 to allow the target mineral ions to bind with the ion exchange resin. When the batch of ion exchange resin is exhausted, in that it is fully loaded with the required mineral ion, the slurry mixture is transferred to one of the elution vessels 28, 30 by way of respective pipes 34 or 38.

The spent pulp is then separated from the loaded resin using of a screen, such that the resin is retained within the elution vessel and the spent pulp is allowed to pass through and out of the elution vessel into the tailings tank 42 or simply to waste. The pregnant resin is then treated within the elution vessel 28 or 30 with a reagent to chemically remove the mineral ions. The resultant eluted solution is then transferred to the precipitation circuit 52 by way of outlet pipe 50 for further processing.

The reader should appreciate that the first and second elution vessels 28 and

30 are configured to both receive pregnant resin after contact with the pulp, for the purposes of elution and also for the storage of regenerated or new resin for use in the contactor vessel 12.

The process steps will now be discussed in greater depth with reference to figures 3-12. To assist in explanation within the following discussion the term "contactor vessel 12" will be replaced with "contactor circuit 12" and the term "elution vessels 28, 30" will be replaced with "elution tanks 28, 30". It should however be appreciated by the reader that this is not intended to limit the invention in any way.

Before initiating the process using the apparatus 10, resin beads 54 having a diameter greater than 0.2mm are loaded into the elution tanks 28, 30. The resin beads 54 are retained within elution tanks 28, 30 by way of a 0.2mm screen 56 positioned at a lower portion of the vertical tanks and a valve 58 adapted to control the flow of material through respective pipes 36 and 40 into the contactor circuit 12.

The contactor circuit 12 is then loaded with a first batch of pregnant pulp 60 through input pipes 16, 18 by means of respective pumps 20, as illustrated in figure 3. Inlets 62, 64 include respective 0.2mm screens 68 that inhibit loss of resin 54 from the apparatus 10. As illustrated in figure 4, valves 58 and 70 of pipe 36 are then opened to allow the resin 54 held within elution tank 28 to be entrained into the flow of pregnant pulp 60 thereby forming a first batch of pulp/resin slurry 72. The resin 54 can be introduced into the contactor circuit 12 under the influence of gravity or be compelled by way of pressure or vacuum ejectors that may be powered by the incoming pulp flow from the feed pumps 20.

The respective valves 74 adjacent inlets 62 and 64 are then closed, as illustrated in figure 5, to isolate the contactor circuit 12. The device 22 includes a series of air jets 24 located around the contactor circuit 12, as previously illustrated in figure 2, are then operated to mix the resin and pulp.

In one form the air jets 24 are spaced at regular intervals around the contactor circuit 12 and are adapted to form the flow path 26 to provide sufficient movement and mixing of the pulp and resin. The air jets 24 may be angled upwardly towards one side of the contactor vessel to produce a helical flow path.

Due to the continuous suspension along the flow path created by the air jets means the resin beads experience good contact with the pulp. This therefore results in the greatest amount of exchange opportunities and maximum mineral loading onto the resin beads.

Figure 6 illustrates movement of the first batch of pulp/resin slurry 72 into the first elution tank 28. Pipe 34 is configured to transport to the pulp/resin slurry 72 from the contactor circuit 12 to the first elution tank 28 once the mineral ions have bonded with the resin.

Accordingly, once the mineral ions have been loaded onto the resin, valve 78 is closed and valve 80 of pipe 34 is opened to provide a return passageway to the first elution tank 28. Valve 82 within pipe 44 is then opened and a tailings solution 84 from the tailing flush tanks 42 is pumped by way of feed pump 86 into the contactor circuit 12.

The input of the tailings solution 84 forces the first batch of pulp/resin slurry 72 out through pipe 34 and into the elution tank 28. As the reader would appreciate this means that the resin does not come into contact with the pump which would result in wear and attrition of the resin.

The loaded resin 88 is entrapped within elution tank 28 by screen 56 and the spent pulp 90 passes through open valves 92, 94 and pipe 46 into the tailing flush tank 42. This physical separation of the larger resin beads from the finer leach residue solids and barren liquid means that the loaded resin is separated from the mineral- depleted leach slurry 90. Alternatively the spent pulp may exit through an outlet to waste.

As illustrated in figure 7, valves 80, 82, 92 and 94 are then closed, and valve 78 and valves 74 of respective pipes 16, 18 are opened so that a second batch of pregnant pulp 98 can be introduced into the contactor circuit 12.

At the same time a reagent 100 is added to the loaded resin 88 held within the first elution tank 28. The reagent may be a dilute mineral acid solution, such as HCL or H₂SO₄. The strength of the acid solution is envisaged to be between 0.5-4 mol/L. Regeneration is accomplished by passing a given quantity of the acid through the resin, which exchanges hydrogen from the acid for the mineral ions.

As further illustrated in figure 7, the resin 54 held within the second elution tank 30 is then added to the second batch of pregnant pulp 98 through open valves 58 and 70 of pipe 40, in the manner discussed above. The second batch of pulp/resin slurry 102 is then circulated throughout the contactor circuit 12 as illustrated in figures 7 and 8. As the reader will now appreciate this means that the contactor circuit 12 is in constant use and there is no "down time" for processing of leachate, other than during flushing cycles.

As further illustrated in figure 8 the eluted solution 104 passes through screen 56, open valve 106 and pipe 50 to the precipitation circuit 52. The eluted solution 104 is transferred to a precipitation circuit 52 for mineral precipitation and solidification. Once the eluted solution 104 has been removed the resin may be washed to remove any residual reagent 100. As illustrated in figure 9, valve 106 is closed and the regenerated resin 54 is retained within the first elution tank 28 for reuse. Simultaneously the second batch of pulp/resin slurry 102 is mixed by way of the movement generated from the air jets 24 to ensure mineral ion transferral to the resin beads.

Figure 10 illustrates movement of the second batch of pulp/resin slurry 102 into the second elution tank 30. The pipe 38 is configured to transport to the pulp/resin slurry 102 from the contactor circuit 12 to the second elution tank 30 once the mineral ions have been loaded onto the resin.

This is accomplished by closing valve 108 and opening valve 80 of pipe 38 to provide a return passageway to the second elution tank 30. Valve 110 within pipe 44 is then opened and a tailings solution 84 is pumped by way of feed pump 86 into the contactor circuit 12. The input of the tailings solution 84 forces the second batch of pulp/resin slurry 102 out through pipe 38 and into the elution tank 30.

The loaded resin 88 is entrapped by screen 56 and the spent pulp 90 passes through open valves 112, 114 and pipe 48 into the tailing flush tank 42. Alternatively the spent pulp may exit through an outlet to waste.

As illustrated in Figure 11 the loaded resin 88 is then treated with a reagent 100 within the second elution tank 30. At the same time valve 80 of pipe 38 and valves 110, 112 and 114 are closed, and valve 108 and valves 74 of respective pipes 16, 18 are opened so that a third batch of pregnant pulp 116 can be added to the contactor circuit 12.

The regenerated resin 54 held within the first elution tank 28 is then added to third batch of pregnant pulp 116 through open valves 58 and 70 of pipe 38, in the manner discussed above.

The resultant third batch of pulp/resin slurry 118 is then circulated throughout the contactor circuit 12 as illustrated in figure 12 for eventual treatment within first elution tank 28. As further illustrated in figure 12 the eluted solution 104 produced in elution tank 30 passes through screen 56, open valve 120 and pipe 50 to the precipitation circuit 52, for mineral precipitation and solidification. Once the eluted solution 104 has been removed the resin may be washed to remove any residual reagent 100. The regenerated resin 54 is then stored in the second elution tank 30 for future reuse.

The apparatus 10 may also be used for the recovery of different mineral from a single batch of pulp. For instance a pregnant pulp may contain both uranium and gold. In such as situation elution vessel 28 is filed with a strong base anion resin for the recovery of the uranium and elution vessel 30 is filled with a weak base anion resin for the recovery of the gold.

The pulp is treated using resin from elution vessel 28 to extract the uranium ions in the method discussed above. However the spent pulp that is transferred to the tailings flush tank, as illustrated by arrow 90 in figure 6, still contains small concentrations of dissolved gold. The partially spent pulp is treated with a chemical to create a gold complex and the pregnant pulp is pumped back into the contactor circuit 12 along with the weak base anion resin from elution vessel 30 for the recovery of the gold ions. Different reagents may be used within elution vessels 28 and 30 to strip the ions from the respective resins.

It should be appreciated that the apparatus 10 may include a number of elution tanks to undertake the recovery of several different minerals. In this way the pulp can be retreated in the contactor circuit 12 multiple times to extract different mineral ions.

In another embodiment the apparatus 10 may include a separate treatment tank (not shown) that is connected to the contactor circuit 12. The separate treatment tank can be used as the intermediate storage and treatment device when the pulp is being treated a number of times within the contactor circuit 12 to extract different minerals. This means that the tailings flush tank can house the completely spent pulp while the separate treatment tank can house the partially spent pulp that may still contain one or more target minerals. As illustrated in figure 13, the apparatus 10 may include a number of elution tanks to ensure the continuous operation of the apparatus or for the recovery of different minerals. There may be eight elution tanks 122, 124, 126, 128, 130, 132, 134 and 136 connected to a single contactor circuit 12. Such a configuration may be required when the elution stage is of a longer duration than the contactor stage. As the reader would appreciate, in such as situation, if only two elution tanks were connected to the contactor circuit the process would need to be discontinued until the resin from one of the elution vessels become available for use after being regenerated.

It should be appreciated that the number of elution tanks and capacity of the contactor circuit can be configured to meet the required flow rate for treatment of the pulp. The contactor circuit can have a capacity to hold several million litres of pregnant solution and a necessary volume of resin to complete mineral exchange and loading process.

The configuration of the apparatus 10 means that it can be easily scaled up. This means that the process from the initial testing and construction of a pilot plant to the final construction of the production plant is simplified.

The adaptability of the apparatus means that is can be used in various environments and for the processing of different amounts of material or flow rates. The apparatus can therefore be modified so that its configuration and dimensions are site or application specific.

As illustrated in figure 14 the apparatus 10 includes a plurality of sensors and measuring devices 138 that are used to control the movement of material through the apparatus and control such things as pH, cycle time, removal or addition of resin, temperature and other factors. The sensors 138 are connected to a central processing unit 140 by way of a communicate means 142. The communication means such as a modem communication path, a computer network such as a local area network (LAN), Internet, or fixed cables.

The skilled addressee will now appreciate the many advantages of the illustrated invention. The apparatus reduces the wear of the ion exchange resin that results from the forces of counter current flow, and contact with agitator blades and pump components in currently available devices. The apparatus provides efficient mixing of the pulp and resin that results in mineral ions being loaded onto the resin. Furthermore the recycling of the tailings during flushing means that ionic leakage is also reduced.

The illustrated apparatus provides continuous processes by way of a series of pregnant leachate batches that can be eluted in different elution tanks. This means there in no down time for the apparatus as leachate material is constantly being moved through the system.

The configuration of the apparatus also means that the pulp can be treated several times to recover different minerals using a number of ion specific resins stored in separate elution tanks.

Various features of the invention have been particularly shown and described in connection with the exemplified embodiments of the invention, however, it must be understood that these particular arrangements merely illustrate and that the invention is not limited thereto. Accordingly the invention can include various modifications, which fall within the spirit and scope of the invention. For the purpose of the specification the word "comprise" or "comprising" means "including but not limited to".

Claims

THE CLAIMS DEHNING THE INVENTION ARE AS FOLLOWS:

1. An apparatus for batch mineral recovery using ion exchange resin including, a contactor vessel in fluid communication with a source of leachate containing mineral ions, the contactor vessel being configured to hold a mixture of said ion exchange resin and leachate therein, a device for forming a closed loop flow path within said contactor vessel, and at least one elution vessel in fluid communication with said contactor vessel, wherein, the leachate and ion exchange resin are movable along said closed loop flow path to assist mineral ion exchange between said leachate and ion exchange resin, whereafter mineral ion depleted leachate being separated from the ion exchange resin and said ion exchange resin being treated within said elution vessel with a reagent to remove said mineral ions therefrom.

2. The apparatus in accordance with claim 1 wherein the elution vessel includes a separation means for separating said mineral ion depleted leachate from said ion exchange resin to which the mineral ions are bound, the separation means being a screen having generally uniform apertures.

3. The apparatus in accordance with claim 1 or 2 wherein the ion exchange resin is provided as beads and preferably is a hard, spherical gel type bead.

4. The apparatus in accordance with any one of the above claims wherein the apparatus includes first and second elution vessels configured to store regenerated or new resin for use in the contactor vessel, and to receive the ion exchange resin after contact with said leachate for subsequent elution.

5. The apparatus in accordance with claim 4 wherein the first and second elution vessels include respective outlets for movement of said mineral ion depleted leachate out of the apparatus and into a tailing reservoir once the mineral ions have been loaded onto the resin.

6. The apparatus in accordance with claim 4 or 5 wherein first and second elution vessels include an eluted solution outlet for movement of eluted solution containing the mineral ion into a precipitation tank or circuit.

7. The apparatus in accordance with any one of the above claims wherein the contactor vessel is torus shaped with two inlets for input of leachate into the contactor vessel from the source of leachate.

8. The apparatus in accordance with any one of the above claims further including a plurality of pressurised air outlets spaced at regular intervals along the flow path to provide movement and mixing of the leachate and resin, preferably said pressurised air outlets being angled upwardly towards one side of said contactor vessel to thereby produce a helical closed loop flow path.

9. The apparatus in accordance with any one of the above claims wherein the contactor vessel is maintained above atmospheric pressure during the contactor stage.

10. A method for mineral recovery using an ion exchange media, including the steps of: introducing a leachate solution containing mineral ions and said ion exchange media into the contactor vessel, the contactor vessel, having a device for forming a closed loop flow path within said contactor vessel, and in fluid communication with at least one elution vessel; moving mixture of said leachate solution and ion exchange media along the closed loop flow path to thereby blend said mixture; transferring said mixture into the elution vessel wherein the mineral ion depleted leachate is separated from the ion exchange media to which said mineral ion are bound; treating said ion exchange media with a reagent to remove said mineral ions therefrom; and separating the ion exchange media from an eluted solution containing the mineral ions.

11. The method in accordance with claim 10 wherein the ion exchange media being an organic ion exchange resin, is introduced into the contactor vessel by way of pressure or vacuum ejectors/eductors, powered by the incoming flow of leachate from a feed pump.

12. The method in accordance with claim 10 or 11 wherein said mixture is impelled into the elution vessel by introduction of a flushing solution into the contactor vessel.

13. The method in accordance with any one of claims 10 to 12 wherein the elution vessel includes a screen for inhibiting movement of a mineral ion loaded ion exchange media therethrough, while allowing the passage of mineral ion depleted leachate.

14. The method in accordance any one of claims 10 to 13 further including the step of rinsing the ion exchange media contained within the elution vessel following treatment with said reagent.

15. The method in accordance any one of claims 10 to 14 wherein at least first and second ion exchange medias are used to recover different mineral ions.

16. A software program for controlling the step of the method of any one of claims 10 to 15.