AU4385700A - Apparatus and method to at least partially separate components from a fluid feedstream - Google Patents

Description

WO 00/67873 PCT/AUOO/00435 1 TITLE APPARATUS AND METHOD TO AT LEAST PARTIALLY SEPARATE COMPONENTS FROM A FLUID FEED STREAM FIELD OF THE INVENTION 5 This invention relates to an apparatus and a method which uses host materials such as absorbent materials within a continuous or intermittent process to selectively collect and remove suspended and/or dissolved components such as contaminants within a fluid feed stream such as a liquid feed stream. 10 BACKGROUND ART It is well-known in many industrial applications that materials present in liquid feed streams can be regarded either as waste, process contaminants, or as potentially useful materials if they are able to be concentrated, separated, and collected in a useful condition and quantity. As 15 an example, many waste water streams from industrial applications contain potentially valuable amounts of metals except that, to date, a practical method to remove the metals has not found commercial applicability. Zeolites are aluminosilicate materials, are well-known and are known for their ability to trap various components in a liquid or gas stream. 20 For example, in the treatment of waste water, natural zeolites such as clintoptilolite is used to remove ammonia and ammonium ions, and can reduce their concentration by over 90%. An advantage in using zeolites is that they can be regenerated and cleaned for re-use. In a further example, it is known that hydrated aluminosilicate 25 materials are able to selectively absorb ions and small molecules. These materials find commercial application in oil cracking and waste treatment including nuclear waste treatment. Zeolites are known to remove caesium and strontium radioisotopes from nuclear waste. In a further example, zeolites are used in household and 30 industrial detergents including washing powder which can contain at least 15 to 30% zeolites, the role of the zeolites being to remove calcium and magnesium ions from the washing water.

WO 00/67873 PCT/AU00/00435 2 Zeolites have a three dimensional structure formed by an open framework of [SiO4]4- and [Al 04]5- tetrahedra linked together. These linked tetrahedra generate the formation of rings and cages. These rings and cages form channels within the structure and are often called "oxygen windows", 5 they give zeolites their characteristic features. Although zeolites are a preferred host material to remove contaminants or undesirable components in a liquid stream, other materials are also used depending on the process requirements. These materials include activated-charcoal, synthetic micro porous tubules, diatomaceous 10 earth, natural or synthetic clay-like materials, synthetic or natural fibers. In order for these host materials to work efficiently, the liquid source material must be intimately mixed with the host material as quickly as possible. For instance, it is known to use flow-through columns filled with 15 zeolite or other host material and through which the liquid source material passes. In these columns, natural zeolites are preferred as they have a larger structure compared to the very small crystals (approximately 1 micron or less) found in synthetic zeolites, the small crystals creating a column too dense for the liquid source material to pass through in commercial time 20 scales. Known natural zeolites used in columns include clintoptilolite or mordenite. It is also known to use agitator tanks which bring the host zeolite material or other suitable absorbent materials in contact with liquid feed streams containing contaminants or components which are to be removed. A 25 disadvantage with the use of agitator tanks is that it is necessary to separate the zeolite from the liquid feed stream such that the zeolite can be treated to remove the entrapped component. If the liquid feed stream contains an appreciable amount of suspended solids, separation may be quite difficult. For this reason, it is known to use porous containers such as 30 fabric bags in which the zeolite material is held and through which the liquid feed stream is passed. It is also known to use static filter beds containing a layer of zeolite or other suitable host material and through which the liquid WO 00/67873 PCT/AU00/00435 3 stream is passed. A disadvantage with the fabric bags or filter bed arrangements is that these require to be taken off-line to replenish or regenerate the zeolite or other host material. 5 SUMMARY OF THE INVENTION One form of the present invention is directed to an apparatus which can at least partially overcome the abovementioned disadvantages. Another disadvantage with existing zeolite or other host materials is in the general inability to vary the properties of the host material. 10 To make the host material able to absorb variable components and the like, it is generally necessary to provide mixtures of host materials. These mixtures can be difficult to keep homogenous and regeneration may also be more difficult for complex mixtures of host materials. Therefore, another form of the present invention is directed to 15 various means whereby the effectiveness and properties of the host material can be modified. In this form of the invention, it has been realised that the attraction/absorption selectivity can be controlled by charge modification of bridging and/or terminal hydroxyl ions associated with alumino-silicate amorphous and crystalline structures. This can enhance and/or augment a 20 charge already inherent on the surface and/or within the structure of a suitable host material such as a hydrated aluminosilicate. In one form, this has been achieved by the realisation that by using IR analysis, two types of hydroxl groups exist within the aluminosilicate framework. For example, at 3740cm-1 there are terminal hydroxyls that 25 extend from the surface or from a defect site, the second group appears between 3650cm-1 and 3550cm-1 and are bridging hydroxyls. Using IR data, it can be said that the higher the acid strength the weaker the bond and therefore the lower the IR frequency. This suggests that terminal hydroxyls are not polarized by Al and have an acid strength approximately equal to, for 30 example, ethanoic acid, whereas bridged hydroxyls are more acidic and have an acid strength similar to concentrated sulfuric acid. In an embodiment, these hydroxyls and particularly the bridging WO 00/67873 PCT/AUOO/00435 4 hydroxyl (OH-Al tetrahedral) bonding mechanism can be manipulated to control the selectivity of the host material. For instance, the neutralization, disruption or enhancement of binding energies inherent within these hydroxyl ions by ionic and/or electronic means can vary the selectivity of the zeolite 5 material. To further understand the significance of hydroxyl reactions within aluminosilicate systems it may be helpful to know that a synthesis of hydrated aluminosilicates can be achieved under hydro-thermal conditions (i.e. with temperature < 100C) and at normal atmospheric conditions. Such a lo synthesis can be initiated by an inhomogeneous aluminosilicate gel, produced from an alumina source and a "reactive" silica source combined with water at a high pH (this can be achieved by using a high alkali/alkali-earth metal hydroxide ion). This mechanism creates mainly aluminium rich zeolite structures. 15 The type of hydroxyl reactions involved in the process according to the invention can be understood using the Lewis acid-base theory as a convenient model. For example, a hydrated ion such as [Al(H 2 0) 6

]

3 + complex is formed as a result of a Lewis acid-base reaction. In this case the metal cation is the Lewis acid, and the hydrating water molecules are the Lewis 20 bases. Although H 2 0 has two lone pairs, only one is shared with the metal cation and is a one metal-oxygen bond (the second lone electron pair are forced to point in the wrong direction unable to form a second bond with the metal atom). Bronsted acid-base equilibrium theories offer yet another means to highlight the mechanisms at work within the process. Proton 25 donating and proton accepting are dynamic applied processes within the method used in the invention to modify the properties of the host material. For a cation to behave as a Bronsted acid it must have protons to donate. This would appear to rule out acid behaviour of simple cations such as Na* and Al 3 +, however, metal ions are hydrated in solution, and the 30 resulting hydrated ion can act as a Bronsted acid. This happens if an 0 - H bond in one of the hydrating H 2 0 molecules is weakened enough by electron withdrawing influence of the cation. A relevant example is A[ 3 *, which exists in WO 00/67873 PCT/AUOO/00435 5 solution as [Al(H 2 0)6] 3 + . This complex is a Bronsted acid: the small, highly charged Al" ion polarizes the 0 - H bonds of the hydrating H 2 0 molecules and makes it possible for at least one or two protons to be lost: [Al(H 2 0) 6

]

3 * + H 2 0 5o [AI(H 2

O)

5 0H] 2 * + H 3 0* 5 In another example, H 2 0 acts as a Bronsted acid and donates a proton, for example to NH 3 , becoming an OH- ion in the process: NH 3 + H 2 0

NH

4 + OH The properties of hydronium ions H 3 0* and the behaviour of protonated water molecules in the invention processes should be appreciated. It should also be noted that any acid that is a stronger proton io donor than H 3 0* would donate its proton to an H 2 0 molecule; and any base that is a stronger proton acceptor than OH- will remove a proton from an H 2 0 molecule and produce OH- ions in aqueous solution. In practice the aforementioned mechanisms of ion generation and proton donating or accepting, can be related to reduction-oxidation 15 (redox) reactions within the electrolytic systems of the invention processes. For example, oxidation is electron loss as when H 2 is oxidized to H* : - H 2 -+ 2H* + 2e Oxidation is brought about by an oxidizing agent, which accepts the electrons (and is reduced in the process). Reduction is electron gain, as 20 when H* is reduced in the reaction:- 2H* + 2e- -+ H 2 . Reduction is brought about by a reducing agent, which donates the electrons (and is oxidized in the process). For example, in an electrolysis process, electrons (from an external current supply) enter the cell through the cathode causing reduction there, electrons are removed from the cell through 25 the anode the oxidation site. An embodiment of the invention is directed to the ability to dynamically control the aforementioned neutralization, disruption or enhancement of binding energies inherent within these hydroxyl ions. Switching or sequencing said neutralization, disruption or enhancement of 30 binding energies is used to facilitate selective adsorption/de-sorption of target materials (that may or may not have been sensitised to optimise their attraction/adsorption capacity).

WO 00/67873 PCT/AUOO/00435 6 The apparatus of the invention can incorporate a means whereby such modified host materials can be brought into contact with liquid sources that contain components that are selectively attracted to the modified host material and/or are themselves changed because of contact or proximity 5 with said host materials. To optimise the effectiveness of any change applied or modified material, it may be necessary to pre-treat or sensitise said liquid sources by chemical or physical means. This may take the form of surface charge and/or surface area modification. A surface charge can be applied as an electrostatic 1o emf of between 500 - 50,000 volts with a preferred voltage of 20,000 volts, as a continuous application via a spreader unit. The spreader unit is typically electrically insulated. The liquid source material may be chemically treated to modify its pH and/or encouraged to change its surface activity by ionic, electronic, 15 electrostatic, or magnetic means. A preferred pretreatment may comprise an 'acid digestion' step. For example, when using nickel bearing ores concentrated H 2

SO

4 can be used as a 30 % volume addition to an equal volume of dry ore and water. A soak time of between 10mins., and 3 hours (depending on ore condition, 20 constituents and temperature )can be used, with a preferred soak time of 45 mins at 850C, with a subsequent dilution of this treated ore fluid by at least 50% water as a feed stream. In another form of the invention, the host material can have its properties changed by changing the properties of the hydroxyl ions present in 25 the liquid feed stream. This form is particularly suitable for use with a metal or carrying aqueous feed stream where the binding energies of the hydroxyl ions in the feed stream can be neutralized, disrupted or enhanced to optimise the effectiveness of the host material. Both liquid source and modified host material may require 30 temperature adjustment to achieve optimum selectivity of certain liquid source target components. This can be achieved as a pretreatment step, or conducted as part of the method, or on the apparatus. For instance, the fluid WO 00/67873 PCT/AUOO/00435 7 stream can be heated, say to 65*C. The controlled interaction of charge modification on the host material and/or charge modification within the metal or contaminant aqueous feed material offers a means whereby said metals or contaminants can be 5 more easily isolated/extracted from liquid/slurry sources. The modification and control of binding energies using an intermediary selective medium to promote ionic mobility of a target component within a liquid source material may be further enhanced by the use of specific charge relaying electrode materials. Such electrode materials lo are able to supply gases, ions and electric field to the host material and/or liquid feed source, that appropriate neutralize, disrupt or enhance binding energies inherent within the hydroxyl ions present. In a preferred embodiment, a host material may be used to encapsulate a suitable electrode. Alternatively, a porous electrode material 15 may be used to encapsulate a suitable host material thereby reducing the need for high surface area electrodes. Or the host material may be used to partition a cell thus providing the opportunity to continually "feed" one surface of the host material with a suitable "replenishing" chemical/electrolyte. The establishment of such an ionic "gradient" may further assist target component 20 selectivity. A suitable host material for use in conjunction with said invention device should otherwise be chemically and physically stable. Preferred materials can be amorphous and/or crystalline alumino-silicates, swelling type clays, natural or synthetic zeolites, carbon, hydrated silicates, 25 metal oxides, and the like. Such materials may be in pulverised, powdered, or a mixture of sand-like particles and powder. In one form of the invention, there is provided a method for at least partially separating at least one component from a fluid stream containing the component, the method comprising the steps of: 30 providing an endless conveyor which moves through a plurality of stations, the conveyor having host material localised thereon such that the host material moves with the conveyor, the host material able to trap the WO 00/67873 PCT/AUOO/00435 8 component, the plurality of stations comprising: a liquid feed station to apply a liquid feed onto the conveyor and in contact with the host material, a contact station where the liquid feed and the host material 5 remain in contact such that the host material can trap the component, a drainage station where the component depleted liquid is at least partially removed from the host material, and, a stripping station where the component is at least partially removed from the host material. 10 The effectiveness and/or properties of the host material can be varied and modified by at least one treatment step, which can be a pretreatment of the host material prior to addition to the conveyor, and/or may comprise at least one treatment step on the conveyor. In another form, there is provided an apparatus for at least 15 partially separating at least one component from a fluid stream containing the component, the apparatus having an endless conveyor which moves through a plurality of stations, the conveyor having host material localised thereon such that the host material moves with the conveyor, the host material able to trap the component, the plurality of stations comprising: 20 a liquid feed station to apply a liquid feed onto the conveyor and in contact with the host material, a contact station where the liquid feed and the host material remain in contact such that the host material can trap the component, a drainage station where the component depleted liquid is at 25 least partially removed from the host material, and, a stripping station where the component is at least partially removed from the host material. The effectiveness and/or properties of the host material can be varied and modified by at least one treatment step, which can be a 30 pretreatment of the host material prior to addition to the conveyor, and/or may comprise at least one treatment step on the conveyor. The method and apparatus can be used to separate many WO 00/67873 PCT/AUOO/00435 9 different types of components from different types of fluid streams by varying the host material and possibly also the stripping station. Thus, it is found that the method and apparatus can be used to remove metals from a metal containing solution although the apparatus is not limited to this use only. 5 The method and apparatus has an endless conveyor which moves through a plurality of stations. The endless conveyor typically has an upper forward loop portion and a lower return loop portion. The size of the conveyor including its length and width will of course vary depending on the amount of material which is to be loaded onto the apparatus, the type of 10 component which is to be trapped by the host material and the like. The host material will of course vary depending on the component to be trapped by the host material. Typical host materials can be amorphous and/or crystalline aluminosilicates, swelling-type clays, natural or synthetic zeolites, carbons including activated carbons, hydrated silicates, metal oxides which can be 15 pulverised, powdered or mixtures thereof. The host material is localised on the conveyor such that it moves with the conveyor. As the conveyor has a return loop portion, if it is desired to have the host material re-used several times, it is preferred that the host material is localised in such a manner that it does not fall away from the 20 conveyor on the return loop portion. In one form, this can be achieved with the use of a plurality of pockets in which the host material can be placed. These pockets can comprise porous mesh, membranes and the like such that the liquid feed stream can pass efficiently through the pockets and through the host material. 25 In another form, the conveyor may be formed from two layers being an outer layer and an inner layer and the host material can be sandwiched between the two layers. In this arrangement, the outer layer and the inner layer can be formed from porous sheet material such as membranes which are tough enough ( or are reinforced) to be driven like a conveyor belt 30 and which will trap the host material and prevent the host material from passing through the layers. It is also envisaged that the conveyor may itself comprise the WO 00/67873 PCT/AUOO/00435 10 host material and may for instance be formed from felt, fibrous material, wool, canvas or other materials which can function as a host material (the conveyor may need to be impregnated to facilitate this function). The conveyor may be driven by one or more drive rollers or 5 other suitable type of drive means. The method and apparatus has a plurality of stations including a liquid feed station whereby a liquid feed can be poured onto the conveyor and in contact with the host material. In a simple form, the liquid feed station may comprise a liquid feed spreader extending transversely across the moving 1o conveyor to provide an even flow of pregnant liquid onto the conveyor. A contact station is provided downstream from the liquid feed station and where the liquid feed and the host material remain in contact such that the host material can trap the component in the liquid feed. The contact station typically comprises a substantially horizontal area through which the 15 conveyor passes. The length of the horizontal area will depend upon the amount of residence time required between the host material and the liquid feed and the speed of the conveyor. Typically, a residence time of from a few seconds to up to a few minutes is considered suitable. A drainage station is provided on the apparatus and in the 20 method to at least partially remove the component depleted liquid from the host material. This may be in the form of a drainage trough underneath the forward loop portion of the conveyor. The method and apparatus further includes a stripping station where the component is at least partially removed from the host material. 25 The type of stripping station will depend upon the host material and the component. If the host component is a zeolite which has adsorbed or otherwise trapped a metal cation, the stripping station may comprise an electrolyte cell to plate out the metal component. Various other types of stripping stations are envisaged depending upon the component. For 30 instance, the component may be dissolved out or stripped out of the host material using another liquid stream which absorbs the component. A forced air draft may be suitable to remove components which have appreciable WO 00/67873 PCT/AUOO/00435 11 volatility and where the host material is not appreciable volatile. Solvent extraction techniques can be used. Other types of gradients can be applied such as a magnetic gradient to remove the component from the host material. If the host material is sponge-like, squeeze rollers or squeeze pads can be 5 used to squeeze out the component if the component is a liquid. It can be appreciated that other types of component removing techniques can also be used. If necessary, the conveyor can pass through a conveyor treatment station such as a wash and neutralizing bath which can prepare the io conveyor for further contact with the liquid feed. If the conveyor is formed from two layers which sandwich the host material, the conveyor treatment station is usually present to prepare and neutralize the outer and the inner layers of the conveyor prior to re-use. For some separations, the host material has a finite life which 15 may be a single use or only a limited number of re-uses. If the host material is used once, it needs to be separated from the conveyor and fresh host material has to be placed on the conveyor prior to moving into the liquid feed station. If the host material is used a finite number of times, one option is to remove only a portion of the host material after each pass and to replace this 20 portion with fresh host material. BRIEF DESCRIPTION OF THE DRAWING An embodiment of the apparatus according to the invention is illustrated with reference to Figure 1. DETAILED DESCRIPTION 25 Figure 1 illustrates the following features with the following reference numerals: 10 Porous membrane in contact with the support mesh of the device, having a mesh size less than the smallest particle present amongst the absorbent material, for example <75ptm, 30 and suitably of a polypropylene, silicone, nylon, P.T.F.E, or rayon. In less aggressive applications such materials as calico, wool or the like may be used. In extreme applications it may be WO 00/67873 PCT/AU0O/00435 12 advantageous to use a 3161L stainless steel mesh of similar mesh size, or such that has been coated with resistant polymeric materials. 11 Porous membrane in contact with membrane (a), and having a 5 mesh size less than the smallest average particle of the absorbent material for example <150pm, 12 Motorized roller providing motion to membrane (a), with sufficient variable speed torque to keep said contact membrane in motion when fully loaded. 10 13 Electric motorized roller providing motion to membrane (b), with sufficient variable speed torque to keep said contact membrane in motion when fully loaded, and independently controllable to maintain a differential speed in relation to membrane (a) so that there is no shear between the two membranes when in full 15 operation. 14 Liquid feed spreader and flow control assembly. 15 Combined membrane, support and liquid feed contact area. 16 Feed liquid drain area. 17 Feed liquid drain reservoir. 20 18 Feed liquid reservoir outlet valve. 19 Membrane surface particulate remover (brush). 20 Excess particulate collector trough (with outlet valve). 21 First electrolyte cell, with electrode connection (L,) & contact guide (L 2 ). This cell incorporates a removable cathode plate of 25 suitable surface area to accept metal deposition. The cell structure may be fabricated using polypropylene, glass reinforced plastic, polymer coated steel, or the like. 22 Membrane preparation & neutralizing bath. 23 Membrane separator assembly. 30 24 Absorbent material loading & replenishing mechanism. 25 Membrane compression roller guides. Referring to Figure 1, while the two membranes 10, 11 are in WO 00/67873 PCT/AUOO/00435 13 motion, an appropriate absorbent material (e.g. zeolite) is introduced as a constant even stream across the membrane width at a point between the separated membranes. Said appropriate absorbent material may be introduced in one preferred embodiment as an even stream from a worm 5 driven extruder 26 or other feeder device, in such a way as to create a known thickness/weight of material across (and between) a predetermined width of membrane. As the membranes are in motion the absorbent material will become encapsulated between said membranes as it passes between pinch rollers 27, 28 and is subsequently carried between them until the complete 10 length of the membrane contains the predetermined thickness/weight of material. It should be noted that said worm-driven absorbent material extruder delivery device may be used to extract spent material as well as introducing said material. This expedient allows an optimum amount of material to always be available for absorption activity without interrupting the 15 continuous operation of the device. The host material can be pretreated to increase its effectiveness. As an option, a preferred pretreatment is an electrolytic process whereby the electrolyte is a (room temperature) saturated NaCl solution in water, and ion receiver is a hydrated aluminosilicate host material. 20 This preferred process comprises an electric current applied via suitable connecting means, in this case Ti metal acting as an anode in contact with the NaCl sol" electrolyte, the other (which can also be Ti) in contact with the ion receiver particle material. Application of 10volts and 0.5amps for 10mins. within a temperature range of 25-450C will increase the level of available Na 25 on the host material by at least 15%. (Current input will vary with surface area/volume of host material, in this case it related to a sample size of approximately 16cm 3 .) The presence of elements such as Ni, Fe, Mg, Co, Mn, & Ca, singularly, in part, or in whole combination, within the electrolyte NaCl sol", has the effect of substantially increasing sodium ion migration and 30 retention on the hydrated aluminosilicate. Alternatively, the host material can be treated on the apparatus, for instance within a trough, and/or indeed as the main task of the apparatus WO 00/67873 PCT/AU0O/00435 14 for desalination purposes. In this case the feed stream would inherently contain sodium chloride. The loaded membrane then moves to a liquid feed station which has a spreader 14 where a liquid feed material is delivered across the width 5 of the membrane. The sandwiched absorbent material between membrane 10, 11 (while still in motion) is allowed to remain in contact with said liquid feed material to facilitate optimum absorption within a trough like area 15 which is the contact station. The trough's dimensions, including length and liquid capacity, are determined by the residence time needed for any chosen lo liquid feed material to be in contact with an appropriate absorbent sandwiched material. A surface charge can be applied as an electrostatic emf of between 500 - 50,000 volts with a preferred voltage of 20,000 volts, as a continuous application via the spreader. The spreader itself being electrically 15 insulated from the rest of the apparatus, and especially the frame. The spreader can optionally contain an electrostatic conductive mesh through which the feed stream passes and which relatively evenly distributes the charge through the fluid stream. The spreader can be part of a spreader unit which can 20 optionally contain other constructions to modify or to treat the fluid stream. For instance, the spreader unit can incorporate a microwave source to increase fluid stream temperature and to apply short wave electromagnetic effects. An ultrasonic resonating means can also be used. In another optional construction, the spreader unit can contain a nozzle arrangement to introduce 25 high pressure steam or other gaseous flow to the feed stream. The length and width of said membranes 10, 11 would therefore be in direct proportion to the aforesaid residence time factors. It should be noted that residence time can be further adjusted by the speed of the membranes and the flow control of the liquid feed stream at 14. 30 After an appropriate traverse interval through trough 15 absorbent material sandwiching membranes are drained at a drainage station 16 of treated liquid feed (and excess liquid feed material). Vacuum may be WO 00/67873 PCT/AUOO/00435 15 applied at this point to assist removal of excess liquid. Sandwiched material now containing selectively absorbed liquid feed target components moves into a stripping zone in the form of a trough 21 containing an appropriate electrolyte or other solution able to either 5 chemically or electrolytically remove said adsorbed components. Metallic components electrolytically removed may be recovered as a deposited film from electrode (L 1 ) cathode. Chemically removed components from said sandwiched absorbent material may be recovered as precipitate and/or coating. 10 It should be noted that trough 21 in an electrolytic or chemical format may be repeated as a sequential process on the same invention device and designed to selectively remove sequentially remove single metallic or chemical absorbed components. The next point of said membrane sandwiched absorbent 15 material traverse is a conveyor treatment station in the form of trough 22 which contains a chemically neutralizing or conditioning bath. Said trough 21 may contain chemicals able to neutralize any electrolyte or chemical used in the previous trough 21. It should be noted that further neutralizing baths may be placed in sequence to allow further chemical treatment of sandwiched 20 absorbent materials. Said treatment may include the introduction of exchangeable ions and/or surfactants. The membrane sandwiched material continues its traverse over motorized roller 12 to pass through the membrane separation and material delivery assembly. Said sandwiched material may be left undisturbed to 25 continue further complete cycles of the invention process or may have a proportion of the material removed and replaced with new absorbent material. It should be noted that said delivery assembly has the ability to completely replace spent absorbent material and replace said with new material without stopping the traverse motion of said invention device. The device is so 30 constructed and controlled that continuous operation is the preferred process method. A scraper 19 is provided adjacent the return loop of the conveyor to scrape off any solids on the surface, and which are scraped into a trough 20 WO 00/67873 PCT/AUOO/00435 16 for disposal or re-use. Preferred invention device & method examples: 1. Membranes 11,12 polypropylene micro-filament fabric mesh, holes 105 microns at 47 per cm 2 , thread diameter 106 microns, 5 fabric thickness 212 microns, weight 78 g/m 2 , air permeability 4270 1/m 2 /sec, water permeability 755 /m 2 /sec, and burst strength 15 kg/M 2 . 2. Membrane 10 length 15 m - width 1.2 m membrane 11 16.5 m width 1.2 m. 10 Absorbent material: hydrated aluminosilicate (Clintoptilolite) crushed and washed to a size able to be retained by aforesaid membrane mesh sizes, approximate weight of said material 0.6gm/cm 2 , approximate total traversing weight of absorbent material between membranes 100kg. 15 Traverse speed of invention device between 0.5 - 1.0m/sec., therefore there is approximately 7kg of absorbent material within each meter of traversing membrane. It is known that hydrated aluminosilicates such as clintoptilolite and the like in granular form (>125microns) can exchange/capture a reasonable amount 20 of available and appropriate ions at a ratio of one litre of aqueous ion source to one kilogram of aluminosilicate material. The exact ratio would of course depend on feed material ion concentration and their chemical bonding position within said feed material. The optimum residence time required for any 25 feed material in relation to an appropriate absorbent material can be easily determined. From experiments using a ratio of one litre feed material containing between 150ppm - 900ppm Cu ions to one kilogram of hydrated aluminosilicate granules, a Cu ion reduction of 15% 30 takes place within the first second of contact with a linear reduction in Cu ions of 4% per second over the next 5 seconds. Within a traverse speed of (0.5 - 1.0m/sec) and using the WO 00/67873 PCT/AUOO/00435 17 aforementioned Cu ion containing liquid feed material said invention device (with sandwiched clintoptilolite granules) is able to remove from said clintoptilolite granules adsorbed Cu ions by passing said membrane granule sandwich through trough (1) 5 containing approx. 150 litres of water acidified with HCL to a pH of between 4.5 - 5.5. Other similar acid pH solutions such as sulphuric, nitric, phosphoric, and the like may also be used to generate a suitable electrolyte. Stainless steel electrode plate (12) is adjusted to make good 10 contact with the traversing membrane and connection is made to the positive pole of a voltage source. Insulated stainless steel electrode plate (1,) is likewise connected to the voltage source at the negative pole. Said voltage source has the following specifications: 15 60 volt output 80 amp variable output reverse polarity switch. Using the aforesaid operating parameters and Cu ion containing liquid feed material delivered at a constant rate of 2 litres a 20 second and a current density of 34 amps per m 2 on the stainless steel electrode plates (11) & (12), copper metal was deposited on said cathode electrode plate. The membrane sandwiched absorbent material continued its traverse into neutralization bath (m) which contained 90 litres of water containing sodium 25 hydroxide to a pH level of 8.5 - 9.5. Other similar pH range aqueous solutions such as, potassium hydroxide, lithium chloride, sodium & potassium chlorides and the like may also be used to generate a suitable neutralizing/sensitizing condition in trough (m). It should be 30 noted that a further treatment area may be included after said neutralizing trough which is designed to impart to the absorbent material ion exchange or conductivity enhancing compounds WO 00/67873 PCT/AUOO/00435 18 such metal salts, e.g., silver, platinum, lead, nickel, iron, copper, tin, and the like. Higher than ambient temperatures may be used in this post neutralization area (50 - 90'C). Ion or conductivity enhancing material delivery may take the form of 5 liquid dip saturation, aerosol and/or electrostatic spraying, submersion electrolysis It is envisaged that automatic dosing devices (already commercially available) will maintain all liquid concentrations in the respective troughs and delivery areas. 10 In the other form of the invention, it is now possible to improve the effectiveness of certain host materials by using an electric charge. In particular, it has been found that by connecting feed delivery device 14 to an electric charge source at low amperage (<5amps) and relatively high voltage (>100volts) ion adsorption into a hydrated aluminosilicates such as 15 clintoptilolite can be increased by at least 10%. The following laboratory experiments and their results can be applied to the invention device: 1. An ore containing: 1.36% Ni, 0.39% Co, 4.86% Mg, 19.50% Fe, 0.312% Mn, 0.36% Ca, was mixed in an aqueous solution 20 and brought into contact with a hydrated aluminosilicate such as clintoptilolite, after a suitable residence time (5mins) said hydrated aluminosilicate material was separated and washed to remove any residual ore material not firmly attached or absorbed. Said hydrated aluminosilicate was added to an 25 acidified (HCI) aqueous solution (pH 5.1 electrolyte). Using a titanium mesh anode and a copper cathode, and applying an e.m.f of 8 volts, and a current density of 0.lamps per cm 2 , metal was deposited on the cathode. Metal deposition was also noted on the copper electrode when polarity of the cell was reversed. 30 (It should be noted that copper when used as an electrode material may exhibit anomalies, especially when evolved oxygen bubbles scourer its surface thus removing copper ions WO 00/67873 PCT/AUOO/00435 19 which may render the electrode anodic in relation to its opposite cell electrode). 2. Using the above materials and methodology but substituting the HCI acidified aqueous solution with 35,000ppm NaCl aqueous 5 solution, metal was also deposited on said copper electrode. 3. Using the above materials and methodology but substituting the HCI acidified aqueous solution with H 2

SO

4 (pH 5) aqueous solution, metal was also deposited on said copper electrode. 4. Using the above materials and methodology but substituting the 10 HCI acidified aqueous solution with HNO 3 (pH 5) aqueous solution, metal was also deposited on said copper electrode. Experiments using the same methodology and absorbent material have been carried out using ore type materials containing predominantly lead, and ore materials containing predominantly zinc, in each 15 case metal was deposited on said copper electrode. It was found during these experiments that different proportions of deposited metals could be obtained by varying electrode material especially at the negative pole of the electrolytic cell. For example, using the ore type material and methodology as described in experiment (1.) a 20 significant quantity of silicon was deposited on said copper electrode. However, by replacing said copper electrode with a lead electrode of the same surface area, it was found that significant quantities of magnesium and nickel had been deposited in preference to silicon. The choice of electrode material within the operating 25 parameters of the invention device should not be limited to any one or combination of metals. It should also be noted that said invention device principles exhibit similar effectiveness in metal absorption and recovery when using kaolin, diatomaceous earth, natural swelling clays, silica gel, and synthetic 30 zeolites such as Linde A, Linde B, Silicalite A, Zeolites F & W, and the like. The apparatus of Figure 1 has been shown to be effective when using activated charcoal as a membrane sandwiched absorbent material, for WO 00/67873 PCT/AUOO/00435 20 feed materials containing hydrocarbon/aromatic contaminants. The aforementioned de-sorption troughs of the invention device then contain solvents/de-greasing/stripping agents such as acetone, kerosene, white spirit, and the like, and with subsequent troughs containing stabilizing solutions 5 such as methyl-alcohol, and water. It should also be noted that said invention device is able to sandwich between its membranes materials that can be made temporarily attractive to a range of liquid feed components. For example matrices such as high porosity resin foams, organic and in-organic beads and the like, onto 10 which surfactants and other 'active' or 'sticky' coatings can be applied at the pretreatment/sensitizing areas within invention device. Such coated materials may then traverse with the membranes and be available to attract or treat specific components within a given liquid feed stream, and subsequently be removed within said de-sorption troughs of the invention device. Enzymes, 15 yeasts and other bio-active materials may be linked to suitable substrates or be used alone as a suitable membrane sandwiched material. It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims (18)

1. A method for at least partially separating at least one component from a fluid stream containing the component, the method 5 comprising the steps of: providing an endless conveyor which moves through a plurality of stations, the conveyor having host material localised thereon such that the host material moves with the conveyor, the host material able to trap the component, the plurality of stations comprising: 10 a liquid feed station to apply a liquid feed onto the conveyor and in contact with the host material, a contact station where the liquid feed and the host material remain in contact such that the host material can trap the component, a drainage station where the component depleted liquid is at 15 least partially removed from the host material, and, a stripping station where the component is at least partially removed from the host material.

2. The method of claim 1, wherein the host material is selected from the group comprising amorphous and/or crystalline aluminosilicates, 20 swelling-type clays, natural or synthetic zeolites, carbons including activated carbons, hydrated silicates, metal oxides optionally pulverised or powdered or mixtures thereof.

3. The method of claim 2, wherein the host material has a natural attraction/absorption selectivety which is modified by modifying the charge on 25 hydroxyl ions in the host material.

4. The method of claim 3, wherein the charge is modified by applying an external surface charge to the host material.

5. The method of claim 3 wherein the charge is modified by chemical means applied to the host material. 30

6. The method of claim 1, wherein the fluid stream is treated prior to contact with the host material.

7. The method of claim 6 wherein the treatment comprises applying a charge to the fluid stream. WO 00/67873 PCT/AU00/00435 22

8. The method of claim 6, wherein the treatment comprises a chemical treatment of the fluid stream.

9. An apparatus for at least partially separating at least one component from a fluid stream containing the component, the apparatus 5 having an endless conveyor which moves through a plurality of stations, the conveyor having host material localised thereon such that the host material moves with the conveyor, the host material able to trap the component, the plurality of stations comprising: a liquid feed station to apply a liquid feed onto the conveyor and 10 in contact with the host material, a contact station where the liquid feed and the host material remain in contact such that the host material can trap the component, a drainage station where the component depleted liquid is at least partially removed from the host material, and, 15 a stripping station where the component is at least partially removed from the host material.

10. The apparatus of claim 9, wherein the endless conveyor has an upper forward loop portion and a lower return loop portion.

11. The apparatus of claim 10, wherein the conveyor is provided 20 with a plurality of fluid permeable pockets in which the host material can be placed.

12. The apparatus of claim 10, wherein the conveyor is formed with twofluid permeable layers being an outer layer and an inner layer and the host material is sandwiched between the two layers. 25

13. The apparatus of claim 10, wherein the conveyor is formed of material which comprises the host material.

14. The apparatus of claim 9, wherein the liquid feed station comprises a liquid feed spreader extending transversely across the moving conveyor to provide an even flow of pregnant liquid onto the conveyor. 30

15. The apparatus of claim 9, wherein the contact station comprises a substantially horizontal area through which the conveyor passes.

16. The apparatus of claim 9, wherein the drainage station WO 00/67873 PCT/AUOO/00435 23 comprises a drainage trough underneath the forward loop portion of the conveyor.

17. The apparatus of claim 9, wherein the stripping station comprises an electrolyte cell 5

18. The apparatus of claim 9, including a conveyor treatment station which prepares the conveyor for further contact with the liquid feed .