WO2003031019A1

WO2003031019A1 - Filtering device

Info

Publication number: WO2003031019A1
Application number: PCT/AU2002/001375
Authority: WO
Inventors: Simon Gerard Ryan
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-09
Filing date: 2002-10-09
Publication date: 2003-04-17
Anticipated expiration: 2004-04-09
Also published as: AUPR818101A0

Abstract

A filtering device (10) adapted to filter or concentrate solids from fluids, the filtering device (10) characterised by at least one filter member (12) and a housing (14), the filter member (12) having both an inlet (16) and an outlet (18) and a passage defined therebetween, at least a portion of the walls (20) of which are fluid permeable, the housing (14) adapted to enclose at least the fluid permeable portion of the filter member (12) and having at least one outlet (24), the filter member outlet (18) further comprises an outlet valve (30), adapted to be able to vary pressures and fluid velocities within the housing (14) and within the filter member (12).

Description

"Filtering Device"

Field of the Invention

The present invention relates to a filtering device. More particularly, the filtering device of the present invention is intended to facilitate filtering or concentrating of solids in fluids.

Background Art

There are a large number of instances where the filtering of fluids or slurries to remove solids, such as suspensions or precipitates, is of benefit. This may be desirous because of a need to remove chosen solid matter from the fluid and collection of the filtered fluid or for recovery or concentration of the solid matter. Depending on the nature of the materials to be filtered, it may simply be necessary to remove some of the liquid matter from the slurry to provide a concentrated slurry. Used in this fashion, a filtering device may also be known as a concentrating device.

Most filtering devices function by passing a liquid to be filtered through a membrane that impedes that flow of the solid material whilst allowing the fluid to pass through it. Over time, solids build up on the membrane, thereby impeding the flow of the fluid through the membrane. Eventually the flow of fluid through the membrane may cease completely.

Generally, a filter membrane needs to be cleaned by either a method of removal or by back flushing/cleaning. This results in unnecessary "down-time" which can become a significant cost.

Some mechanisms are known that employ a moving member that passes over the surface of a filter in a way that provides a cleaning mechanism while in use. Mechanisms such as these comprise large numbers of moving parts which can result in increased maintenance, costs and chance of breakdown. There is a need for a filtering device that provides a useful alternative to those already known in the industry. It would be an advancement in the art to provide a filtering apparatus that can filter fluids whilst they are pumped from one location to another. A further advancement would be the provision of a filter able to be set to continually self-clean without stopping the flow of fluid through the filter.

The present invention has one object thereof to overcome substantially, or to at least provide a useful alternative to, the abovementioned problems associated with the prior art.

The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention

In accordance with the present invention, there is provided a filtering device adapted to filter or concentrate solids from fluids, the filtering device characterised by at least one filter member and a housing, the filter member having both an inlet and an outlet and a passage defined therebetween, at least a portion of the walls of which are fluid permeable, the housing adapted to enclose at least the fluid permeable portion of the filter member and having at least one outlet, the filter member outlet further comprises an outlet valve, adapted to be able to vary pressures and fluid velocities within the housing and within the filter member.

Preferably, the filtering device further comprises a pump, adapted to pump fluids and solids to the filter member inlet. Preferably, the outlet valve is adapted to operate in an open position or a closed position, whereby in the closed position, solids and fluids may pass through the valve and in the closed position the flow of solids and liquids is impeded.

Preferably, the filter member is of substantially circular cross section.

The filter member may preferably be provided with a support device to retain the shape thereof. In one form of the invention, the support device may be provided in the form of a screen mesh. In an alternate form of the invention, the support device may be provided in the form of support rods.

In one form of the invention, the filter member is provided in the form of a woven hose. The woven hose may be comprised of monofilament fibres, multifilament fibres or a combination of monofilament and multifilament fibres.

In one embodiment of the invention, the filter member may be in the form of a multifilament polyester synthetic yarn with warp of about 12.1 strands per 2.5 cm and weft of about 10.2 strands per 2.5 cm.

The filtering device of the present invention has particular application in the filtering of slurries. The slurries may comprise solids contents from 0 % to a maximum % determined by the pumping capacity of the pump of the filtering device.

Preferably, the length of the filtering device is between 24 and 100 m.

Preferably, the filter member inlet comprises a valve, adapted to vary pressures within the filter member and the housing.

Preferably, at least one of the or each housing outlets has provided therein a valve, adapted to be able to vary pressures within the housing. Preferably, each of the housing outlets have a valve provided therein.

In one form of the invention the filtering device is further characterised by an inlet manifold and an outlet manifold, the inlet manifold being in fluid communication with the filter member inlet and the outlet manifold being in fluid communication with the filter member outlet.

The inlet manifold preferably comprises at least one inlet and at least one outlet. Preferably, the number of inlet manifold outlets is the same as the number of filter members and are in fluid communication therewith.

The outlet manifold preferably comprises at least one inlet and at least one outlet. Preferably, the number of outlet manifold inlets is the same as the number of filter members and are in fluid communication therewith.

Preferably, the inlet of the inlet manifold has provided therein a valve. Each of the outlets of the inlet manifold may have valves provided therein.

Preferably, the outlet of the outlet manifold has provided therein a valve. Each of the inlets of the outlet manifold may have valves provided therein.

In one form of the invention a means for modifying the dynamics of fluid flow within the filter tube is utilised. Preferably, this means is located within the filter tube. In one form of the invention, this means may comprise a propeller or number of propellers.

In accordance with the present invention there is provided a method for the continuous self cleaning of a filtering device as described above, the method characterised by the step of:

(a) Providing a flow of fluid along the filter member that is sufficient to remove a quantity of particulate matter adhering to the filter member.

In accordance with the present invention there is further provided a method for cleaning the filtering device by a sequential cleaning mode, the method characterised by the steps of:

(a) opening the filter member inlet valve; (b) opening the housing outlet valve;

(c) closing the filter member outlet valve;

(d) thereafter opening the filter member inlet valve;

(e) opening the filter member outlet valve;

(f) closing the housing outlet valve; and

whereby the filter member is flushed.

In accordance with the present invention there is further provided a method for cleaning the filtering device by a back pressure mode, the method characterised by the steps of:

(a) closing the filter member inlet valve;

(b) opening the housing outlet valve; and

(c) opening the filter member outlet valve whereby fluid is passed into the housing outlet and solid passes out the filter tube outlet.

In accordance with the present invention there is further provided a method for the mixing of two or more fluids in the filtering device, the method characterised by the step of:

(a) reversing the filtrate flow and injecting fluids into the filter member and housing outlets.

In accordance with the present invention there is further provided a method for the simultaneous filtering and transport of a fluid from one location to another, the method characterised by pumping that fluid into the filter tube member of the filtering device. Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to five embodiments thereof and the accompanying drawings, in which:-

Figure 1 is a cross-sectional view of a filtering device in accordance with a first embodiment of the present invention;

Figure 2 is a sectional view of the filtering device of Figure 1 ;

Figure 3 is a sectional view of the filtering device of Figure 1 ;

Figure 4a is a sectional view of the filter member of Figure 3;

Figure 4b is a sectional view of a filter member with device to retain shape;

Figure 4c is a sectional view of a filter member of variable shape with devices to retain shape or to increase surface area;

Figure 5 is a cross sectional view of the filtering device of Figure 1 , showing a means for modifying the dynamics of the fluid flow, the means being located in the filter tube of the filtering device in an effort to increase the performance of the filtering device;

Figure 6a is a cross sectional view of a filtering device in accordance with a second embodiment of the present invention;

Figure 6b is a cross sectional view of a filtering device in accordance with a third embodiment of the present invention;

Figure 6c is a cross sectional view of a filtering device in accordance with a fourth embodiment of the present invention;

Figure 6d is a cross sectional view of a filtering device in accordance with a fifth embodiment of the present invention; Figure 7 is a cross sectional view of the filtering device of Figure 1 depicting a continuous mode cleaning mechanism;

Figure 8a is a cross sectional view of the filtering device of Figure 1 depicting a sequential cleaning mode;

Figure 8b is a cross sectional view of the filtering device of Figure 1 depicting a sequenced cleaning mode;

Figure 8c is a cross sectional view of the filtering device of Figure 1 depicting a sequenced cleaning mode;

Figure 9 is a cross sectional view of the filtering device of Figure 1 depicting a reverse flow cleaning mode;

Figure 10 is a cross sectional view of the filtering device of Figure 1 depicting the mixing of two or more fluids;

Figure 11 is a circuit for a filtration system incorporating the filtering device of Figure 1 ;

Figure 12 is a plot of feed flow rate versus time in a circuit for a filtration system incorporating the filtering device of Figure 1 ;

Figure 13 is a plot of filtrate flow rate versus time in a circuit for a filtration system incorporating the filtering device of Figure 1 ;

Figure 14 is a plot of % solids in a circuit for a filtration system incorporating the filtering device of Figure 1 ;

Figure 15 is a circuit for a filtration system incorporating a second example of the filtering device of Figure 1 ;

Figure 16 is a plot of % solids in a circuit for a filtration system incorporating a second example of the filtering device of Figure 1 ; Figure 17 is a plot of % difference solids in a circuit for a filtration system incorporating a second example of the filtering device of Figure 1 ;

Figure 18 is a schematic for a filtration system incorporating a third example of the filtering device of Figure 1 ;

Figure 19 is a plot of size distribution of input solids for a filtration system incorporating a third example of the filtering device of Figure 1;

Figure 20 is a plot of pressure measurements in a circuit for a filtration system incorporating a third example of the filtering device of Figure 1 ;

Figure 21 is a plot of flow rate measurements in a circuit for a filtration system incorporating a third example of the filtering device of Figure 1 ; and

Figure 22 is a plot of % difference solids in a circuit for a filtration system incorporating a third example of the filtering device of Figure 1.

Best Mode(s) for Carrying Out the Invention

The filtering device of the present invention will now be described, by way of example only, with reference to five embodiments thereof.

In Figures 1 to 10 there is shown a filtering device 10 comprising a filter member, for example a filter tube 12, and a housing 14. The filter tube 12 comprises an inlet 16, an outlet 18 and a wall 20. The housing 14 comprises an outlet 24 and encloses a portion of the filter tube 12 that is fluid permeable, as will be described hereinafter.

The filter tube inlet 16 has a valve 26 provided therein. The housing outlet 24 has a valve 28 provided therein. The filter tube outlet 18 has a valve 30 provided therein. The filter tube 12 and the housing 14 are of substantially circular cross-section 32, best seen in Figure 3. At least a portion of the wall 20 of the filter tube 12 is composed of a fluid permeable portion 34, best seen in Figure 4a.

The filter tube 12 may conform to any cross sectional shape 36 and may comprise a support device for example a screen mesh 38 to aid in retaining that shape, as shown in Figure 4b. In Figure 4c the support device is provided in the form of support rods 37 extending along at least a portion of the length of the filter tube 12.

In Figure 6a there is shown a filtering device 39 in accordance with a second embodiment of the present invention. The filtering devices 10 and 39 are substantially similar and like numerals denote like parts. The filtering device 39 further comprises a plurality of filter tubes 42. The housing 14 further comprises an inlet manifold 44 and an outlet manifold 46. The inlet manifold comprises an inlet 48 and a plurality of outlets 50. The outlet manifold comprises a plurality of inlets 52 and an outlet 54.

In Figure 6b there is shown a filtering device 55 in accordance with a third embodiment of the present invention. The filtering devices 10 and 55 are substantially similar and like numerals denote like parts. The filtering device 55 comprises a serpentine filter tube 56 which passes through the housing 14 a multitude of times.

In Figure 6c there is shown a filtering device 57 in accordance with a fourth embodiment of the present invention. The filtering devices 10 and 57 are substantially similar and like numerals denote like parts. The filtering device 57 comprises a serpentine filter tube 58 contained entirely within the housing 14.

In Figure 6d there is shown a filtering device 59 in accordance with a fifth embodiment of the present invention. The filtering devices 10 and 59 are substantially similar and like numerals denote like parts. The filtering device 59 comprises a coiled filter tube 60. In Figure 5 there is shown the filtering device 10 in which a means for altering the dynamics of fluid flow, for example a propeller 61 , has been provided in the filter tube 12 thereof. The propeller 61 may act on the dynamics of fluid flow within the filter tube and impact favourably on the filtering action thereof. It is envisaged that other means of modifying fluid flow within the filter tube 12 might also be utilised with beneficial effects.

In use, a mixture of fluid and solid 62 passes into the filter tube 12 via the filter tube inlet 16, best seen in Figures 6. The liquid 64 is free to pass through the fluid permeable portion 34 of the filter tube 12. Depending on the size of the solid particles and the porosity of the fluid permeable portion 34 of the filter tube 12, at least a portion of the solid matter 66 is unable to pass through the fluid permeable portion 34 of the filter tube 12. The filtered fluid 64 is collected at the housing outlet 24. The solid material or concentrate 66 is collected at the filter tube outlet 18.

Depending on the materials used, the filtering device 10 may be operated in a continuous cleaning mode, best seen in Figure 6. In this mode, both the housing outlet valve 28 and filter tube outlet valve 30 are in the open position. A mixture of fluid and solid 62 passes into the filter tube 12. The fluid 64 passes through the filter tube wall 20 and is collected at the housing outlet 24. At least a portion of the solid 66 remains inside the filter tube 12. As the amount of solid material 66 inside the filter tube 12 increases, it may be moved along the tube by the flow of fluid 62 entering the filter tube 12. The solid or concentrate 66 may be collected at the filter tube outlet 18. In this manner, the filter tube is continuously self- cleaned. Performance may be adjusted by varying the pressures in the filter tube and housing by adjusting the openness of all or any of the valves, depending on the materials used and the requirements required.

The filtering device 10 may be operated in a sequenced cleaning mode, best seen in Figures 8a-c. In this mode the housing outlet valve 28 is set is the open position whilst the filter tube outlet valve 30 is closed. Fluid and solid 62 enter the filter tube 12 and the fluid portion 64 passes through the filter tube wall 20 and out of the housing outlet 24. Solid material 66 builds up inside the filter tube 12. When there is sufficient solid material, the filter tube outlet valve 30 is opened and the solid material 66 passes through the filter tube outlet 18 and can be collected. The housing outlet valve 28 may be closed at this stage if desired.

The filtering device 10 may be operated in a reverse-flow cleaning mode, best seen in Figure 9. In this mode, the filter tube inlet valve 26 is closed whilst the housing outlet valve 28 and the filter tube outlet valve 30 are opened. Fluid 68 is passed into the housing outlet 24, causing an increase in pressure within the housing 14, resulting in deformation and collapse of the filter tube 12, squeezing the trapped solids 66 from the filter tube outlet 18.

The filtering device 10 may be used to mix two or more fluids by introducing a first fluid 70 through the filter tube outlet 18 and introducing a second fluid 72 through the housing outlet 24, best seen in Figure 10. The second fluid 72 is able to permeate the wall 20 of the filter tube 12 and the two fluids 74 are brought together within the filter tube 12 before exiting through the filter tube inlet 16.

The following Examples serve to more fully describe the manner of using the above-described invention, as well as to set fourth the best modes contemplated for carrying out various aspects of the invention. It is understood that these Examples in no way serve to limit the true scope of this invention, but rather are presented for illustrative purposes.

Example 1

In Figure 11 there is shown a circuit for a filtration system incorporating the filtering device 10 of the present invention. The circuit comprised a Warman 2/2.5 slurry pump 76 with variable speed drive 78. The filter tube 12 had a diameter of 48 mm and a length of 4.23 m. The circuit further comprised a flowmeter 80 to measure the flowrate of the slurry 82 and a flowmeter 84 to measure the flowrate of the filtrate 86. Pressure gauges 88, 90, 92, 94 and sample taps 96, 98, 100, 102, 104, 106 were further provided throughout the circuit for the collection of necessary data and samples respectively. A trial of the circuit shown in Figure 11 was conducted over a 21 hr period with a pump 76 pressure of 150 kPa.

During the test, the initial feed flow rate was 235 L/min, which rose to a maximum level of 245 L/min after 8 hr, then gradually decreased to a steady value of 230 L/min after 21 hr, as represented in Figure 12. The decrease in flow resulted from a decrease in line pressure possibly as a result of a rise in temperature of the slurry. The temperature of the slurry rose from 16.5 °C to approximately 38 °C over the 21 hr test due to the slurry continually being recycled through the pump. Over this time, the pressure dropped from 150 kPa to 110-130 kPa.

The flowrate 84 of the filtrate 86 showed an increase in flow from 1.2 to 2.5 L/min after 8 hr, followed by a decrease to a steady value of 2.2 L/min after 21 hr, as represented in Figure 13, following a similar trend to the feed flow rate. When the pump speed was increased and returned to 35 Hz, the filtrate flow also increased but returned to the steady state flow value, or slightly higher.

The feed density was found to increase with time. If the layer of solids on the wall of the filter tube 12 reaches a steady thickness and hence mass, then the increase in percent solids must result from a loss of water from the system. Each hour approximately 500 mL of slurry were removed from each of the three streams 82, 86, 108 as a sample and the solids content measured. A calculation of the effect of this solid and water loss on the sump slurry density indicated that an increase in slurry % solids will result. This is shown in Figure 14, plot 1. This indicates an increase from 28 - 30 % solids over a period of 17 hr. The initial jump from 28 to 29 % solids has been estimated from an approximately 15 L hold up of water in the pipework of the test rig. At start up, there will be some dead space in the housing 14 that is filled before water will start to flow from the filtrate pipe back into the sump. This dead volume of water is effectively removed from the sump and will increase the % solids of the reconstituted pulp in the sump. There will also be some solids held up on the inner wall of the filter tube 12 but this is expected to be small. Plot 2 in Figure 14 shows the measured change in feed density as measured at the inlet sampling point 96. This also shows an increase in % solids with time but at a greater rate than predicted by loss of solid and water during sampling. It is believed that there must be some additional water loss in the system.

Plot 3 in Figure 14 shows the increase in % solid for the discharge stream 108 over time. The difference between the measured feed % solids (plot 2) and the discharge stream (plot 3) gets smaller as the filtration test proceeds. The difference was approximately 4% at the beginning of the test and approximately 2 % after 21 hr.

The test showed that there is a small variation in feed 82 and filtrate 86 flow with time but a steady state is established over a 21 hour period with only a minor drop off in flow rate. Prolonged pumping does not appear to be detrimental to the filtration performance as the high turbulence of slurry flow maintains a steady cake thickness build up on the inside of the filter tube 12.

Example 2

In Figure 15 there is shown a circuit for a filtration system incorporating the filtering device 10 of the present invention. The filtering devices of Examples 1 and 2 are substantially similar and like numerals denote like parts. The filter tube in Example 2 had a length of 96 m and was divided into two 48 m halves 110, 112. A sample tap 114 was incorporated into the junction 116 at the half way point to be able to check the performance along the filter tube length.

The test conditions slightly exceeded the nominal conditions with the feed pressure at 160 kPa and the feed density at 43 - 45 % solids.

After initial high flowrates which decreased over the first hour as solid was introduced to the sump, the flow at 82 and 86 then reached steady values of approximately 130 and 50 L per minute respectively. Figure 16 shows the % solids discharges after 48 m and 96 m and Figure 17 shows these values plotted as a difference from the % solids in the input.

The results show an increase in % solids from approximately 44 % in the feed to approximately 53 % after 96 meters of pumping. The % solids increases by about 2 - 3 % after the first 48 meters and 5 - 6 % increase over the second 48 meters.

The effect of an increase in feed density in a conventional filter, is to increase the cake deposition rate as there is less water to extract to produce a given cake thickness. As the cake thickness builds up, the filtrate flow will decrease due to the increased resistance. However, in the filtering device 10 of the present invention, the cake thickness should remain constant due to the high shear forces running perpendicular to the cake build up. Hence, the filtrate flow 86 should also be approximately constant with increasing slurry density.

Example 3

In Figure 18 there is shown a schematic for a filtration system conducted on a tailings stream 118 from a gold processing plant and incorporating the filtering device 10 of the present invention. The filtering devices of Examples 1 , 2 and 3 are substantially similar and like numerals denote like parts. The filter tube 12 in Example 3 had a length of 24 m.

Measurements were taken of the feed and discharge pressures and the pressure in the filtrate line and the flow rate of the discharge and filtrate lines. Samples of the slurry were also taken for sizing and % solids determination. The feed stream had the following characteristics (best seen in Figure 19):

Feed Pressure: 320 kPa (average) % Solids: 48.9 % (average) SG of Solids: 3.8

Particle size: p80 of 120 μm p69 of 100 μm p31 of 10 μm (Figure 19) The filtration trial ran for 4 days. On the fourth day a plant shutdown (1.25 hr) caused the filter pipe to sand up. When the plant restarted, the flow was not able to be re-established and without a source of flush water at the dam site, the pipe could not be cleared. At this point, sufficient data had been collected and the test was terminated. The pressure and flow rate measurements are shown in Figures 20 and 21.

The feed pressure fluctuated between 270 - 350 kPa with corresponding flow rates from 115 - 185 L/min. The line pressure was, on average, higher than obtained during laboratory tests (Examples 1 and 2). The filtrate flow was around 5 L/min over the 24 m pipe length compared with 50 L/min over 96 m of pipe length for the laboratory trial of Example 1. This represents a lower flow rate/m of pipe length despite a feed pressure that was double the laboratory pressure. This could arise from a finer particle size in the solids treated but at a p80 of 120 μm this would not be expected to be a problem although the % passing 38 μm was over 50 %. A finer particle size of solid would give a higher cake resistance and hence a lower filtration rate.

Of more significance than the feed pressure is the pressure in the filtrate line. This line has to lift the filtrate over the dam wall 120 before discharging into the tailings dam, and with a 20 meter head on the filtrate line this corresponds to a pressure of around 196 kPa. The experimental value in the filtrate line was an average of 130 kPa which would decrease the effective pressure across the filter wall to around 190 kPa. Thus a combination of pressure head and particle size may explain the reduced filtration rate.

A mass balance calculation on the solids in and out based on the volume flows gives an expected increase of about 1 % in the discharge line. This is consistent with the measured density increase of 1-2% solids (Figure 22) and is also consistent with the 2-3 % increase in % solids observed over the first 48 m of pipe in the laboratory tests (Example 2).

Modifications and variations such as would be apparent to the skilled addressee are considered to be within the scope of the present invention.

Claims

1. A filtering device adapted to filter or concentrate solids from fluids, the filtering device characterised by at least one filter member and a housing, the filter member having both an inlet and an outlet and a passage defined therebetween, at least a portion of the walls of which are fluid permeable, the housing adapted to enclose at least the fluid permeable portion of the filter member and having at least one outlet, the filter member outlet further comprises an outlet valve, adapted to be able to vary pressures and fluid velocities within the housing and within the filter member.

2. A filtering device according to claim 1 , wherein the filtering device further comprises a pump, the pump adapted to pump fluids and solids to the filter member inlet.

3. A filtering device according to claims 1 or 2, wherein the filter member outlet valve is adapted to operate in an open position or a closed position, whereby in the closed position, solids and fluids may pass through the valve and in the closed position the flow of solids and liquids is impeded.

4. A filtering device according to any of the preceding claims, wherein the filter member is of substantially circular cross-section.

5. A filtering device according to any of the preceding claims, wherein the filter member may be provided with a support device to retain the shape thereof.

6. A filtering device according to claim 5, wherein the support device is a screen mesh.

7. A filtering device according to claim 5, wherein the support device is provided in the form of support rods.

8. A filtering device according to any of the preceding claims, wherein the filter member is provided in the form of a woven hose.

9. A filtering device according to claim 8, wherein the woven hose comprises monofilament fibres, multifilament fibres or a combination of monofilament fibres and multifilament fibres.

10. A filtering device according to claims 8 or 9, wherein the woven hose comprises a multifilament polyester yarn with warp of about 12.1 strands per

2.5 cm and weft of about 10.2 strands per 2.5 cm.

11.A filtering device according to any of the preceding claims, wherein the filtering device is adapted for filtering slurries comprising between about 0 % to a maximum % determined by the pumping capacity of the filtering device.

12. A filtering device according to any of the preceding claims, wherein the filtering device is adapted for filtering slurries comprising between about 28 % to 50 % solids.

13. A filtering device according to any of the preceding claims, wherein the filtering device is between about 24 m and 100 m in length.

14. A filtering device according to any of the preceding claims, wherein the filter member inlet comprises a valve, the valve adapted to vary pressures within the filter member and the housing.

15. A filtering device according to any of the preceding claims, wherein the at least one of the or each housing outlets has provided therein a valve, the valve adapted to be able to vary pressures within the housing.

16. A filtering device according to any of the preceding claims, wherein each of the housing outlets have a valve provided therein.

17. A filtering device according to any of the preceding claims, wherein the filtering device further comprises an inlet manifold and an outlet manifold, the inlet manifold being in fluid communication with the filter member inlet and the outlet manifold being in fluid communication with the filter member outlet.

18. A filtering device according to claim 17, wherein the inlet manifold comprises at least one inlet and at least one outlet.

19. A filtering device according to claim 18, wherein the number of inlet manifold outlets is the same as the number of filter members and are in fluid communication therewith.

20. A filtering device according to claim 17, wherein the outlet manifold comprises at least one inlet and at least one outlet.

21.A filtering device according to claim 20, wherein the number of outlet manifold inlets is the same as the number of filter members and are in fluid communication therewith.

22. A filtering device according to claim 17, wherein the inlet of the inlet manifold has provided therein a valve.

23. A filtering device according to claim 18, wherein each of the outlets of the inlet manifold have valves provided therein.

24. A filtering device according to claim 17, wherein the outlet of the outlet manifold has provided therein a valve.

25. A filtering device according to claim 20, wherein each of the inlets of the outlet manifold have valves provided therein.

26. A filtering device according to any one of the preceding claims, wherein a means for modifying the dynamics of fluid flow within the filter tube is provided.

27. A filtering device according to claim 26, wherein the means is located within the filter tube.

28. A filtering device according to claims 26 or 27, wherein the means comprises one or more propellers.

29. A method for the continuous self cleaning of a filtering device as described in any one of claims 1 to 28, said method characterised by the step of:

30. A method for the sequential cleaning of a filtering device as described in any one of claims 15 to 28, said method characterised by the steps of:

(a) opening the filter member inlet valve;

(b) opening the housing outlet valve;

(c) closing the filter member outlet valve;

(d) thereafter opening the filter member inlet valve;

' (e) opening the filter member outlet valve;

(f) closing the housing outlet valve; and

whereby the filter member is flushed.

31. A method for the back pressure cleaning of a filtering device as described in any one of claims 15 to 28, said method characterized by the steps of:

(a) closing the filter member inlet valve;

(b) opening the housing outlet valve; and

32. A method for the mixing of two or more fluids in a filtering device as described in any one of claims 1 to 28, said method characterised by the step of: (a) reversing the filtrate flow and injecting fluids into the filter member and housing outlets.

33. A method for the simultaneous filtering and transport of a fluid from one location to another, the method characterised by pumping that fluid into the filter tube member of a filtering device as described in any one of claims 1 to

28.

34. A filtering device substantially as hereinbefore described with reference to the Examples.

35. A filtering device substantially as hereinbefore described with reference to the Figures 1 to 5 and 7 to 10 or 6a or 6b or 6c or 6d.