RELATED APPLICATIONS

This application derives priority from New Zealand patent application number 782913 filed on 30 November 2021 with WIPO DAS code 4B2D incorporated herein by reference.

TECHNICAL FIELD

Broadly described herein is vacuum separation system and method. More specifically, a solid material vacuum separation system is described that consists of an extraction system and cyclone separator with an airlock that allows solid material to be discharged during vacuum separation system operation with minimal or no substantial loss in vacuum pressure within the vacuum separation system.

BACKGROUND

Cyclone separators are widely used as a means to convey and separate solids from a gas e.g. an air stream. Examples of applications for cyclones include use in food manufacture, excavation, dredging, wood pulp, pellet manufacture and so on.

Soil vacuum excavation is referred to hereafter for brevity however, similar issues to soil vacuum excavation arise in other industries and hence, reference to soil vacuum excavation should not be seen as limiting and the same principles may be applied to other vacuum separation systems.

Vacuum excavation is a safe way to remove soil, especially in the presence of services including power lines, fibre cables and water pipes and so on. Damage to these service lines can be costly to repair and disruptive hence, vacuuming the soil, as opposed to use of diggers or other machinery to excavate, lowers the risk of damaging such service lines.

The main art vacuum extraction devices collect excavated solids in a large container such as a truck mounted vacuum cavity. This approach is common for collecting the solid slurry as this allows a continuous vacuum to operate. The collected material must then be emptied in a batch manner to a tipping site. Thus, each time the truck is filled, excavation must stop and the collected solids (and often substantial amounts of water) then transported to a refuse site and discharged. This approach inherently leads to significant breaks in work flow during transport and associated costs with transporting and refuse site fees. Separation of solids from a gas, or gas/slurry, or liquid and solid mixed together, may be useful to reduce waste and avoid transportation of water instead of actual soil waste. Vacuum excavators have therefore integrated cyclone separators for solid separation. Cyclone separators (cyclones hereafter) separate solids from the conveyor air stream using centrifugal force and gravity, and are typically specified when solid materials are comprised of larger particle sizes that are not prone to dusting. Although filters are uncommon, they can be incorporated as a secondary means of capturing airborne solids.

Existing cyclone systems can have significant drawbacks. For example, solids collected must be removed from the cyclone once separated and removal often involves shutting down the cyclone altogether to allow equilibration of pressure and subsequent opening of a door to a collection chamber to remove the collected solids. This batch style of processing is disruptive and not ideal for work flow.

Rotary airlocks have been used in one form of vacuum extractor cyclone, an example of which is shown in Figure 1 comprising a cyclone marked B and rotary airlock with vanes marked A in Figure 1. Rotary airlocks are common to cyclones and operate by rotating vanes continuously collecting and discharging solids while maintaining a vacuum seal. Rotary airlocks are useful to move solids and keep an airlock however, rotation of the vanes may be prone to blockages and leakage of air pressure from solids or grit captured by the cyclone in the airlock. Soil collected in vacuum excavation may comprise many different particle sizes and relatively hard particles that do not easily crush or move when compressed. Blockages of vane movement may lead to processing shut downs and increased labour and capital expense to clear blockages and broken parts.

Single flaps and doors may be used to gain access to collected cyclone contents however these are not airlocks and, opening of the flap or door to the cyclone interior immediately disrupts vacuum suction/pressure.

Some specific examples of art vacuum extraction devices are now described.

US 6,470,605 describes a typical known truck mounted vacuum excavator. The removed slurry is collected in a tank on the truck. There is no cyclone or airlock used at all.

US 2020/149,245 describes a vacuum extraction system that incorporates a cyclone separation system and an airlock in the form of rotating vane valve, a standard type of airlock like that noted above and shown in Figure 1. US 5,295,317 also uses a cyclone separator and a vane valve airlock. US 5,295,317 in one alternate example shows an airlock involving two rams that operate two sliding plates. US 5,295,317 recognises the problem of handling abrasive material and the solution taught is to provide a modified airlock using a pair of hydraulic cylinders each having piston rods coupled to slidable plates mounted in channels affixed to side walls at an airlock housing unit. The cylinders are actuated simultaneously by means of a four-way two position valve of the solenoid operated type. The cylinder actuated plates move in opposite directions to open and close ducts in communication with the interior of the cyclone separator. Material and water discharged from the cyclone separator is deposited onto a first plate from which it is eventually discharged downwardly towards a second plate which then moves to a duct closed position. At all times, a reverse or upward flow of air into the base of the cyclone separator is prevented by either plate. Valve opening is activated at intervals determined by a timer.

US 5,791,073 describes a collection hopper with flaps at the hopper base which open when the vacuum pressure is stopped by the remote valve to expel solids collected in the hopper. This is an example of the art batch style operation where vacuum operation must stop to enable removal of solids collected.

Problems exist to achieve continuous vacuum processing, separation and removal of collected solids. It may be useful to also avoid art transport and tip costs and the time needed to clear blockages and breakages or at least it may be useful to provide the public with a choice of vacuum separation system and method of use.

Further aspects and advantages of the vacuum separation system and method will become apparent from the ensuing description that is given by way of example only.

SUMMARY

Described herein is a vacuum separation system that consists of an extraction system and cyclone separator with an airlock that allows solid material to be discharged during vacuum separation system operation with minimal or no substantial loss in vacuum pressure within the vacuum separation system.

In a first aspect, there is provided a vacuum separation system comprising: an extraction system communicating with, a cyclone; and an airlock communicating with the cyclone, the airlock comprising a first flap and at least one further flap, the first flap and at least one further flap opening and closing in a coordinated manner so as to expel collected solids in the cyclone via the first flap and at least one further flap to a positive pressure environment; wherein, during extraction system and cyclone operation, the airlock is configured to allow removal of collected solids from the cyclone with minimal or no substantial loss in vacuum pressure in the extraction system and cyclone.

In a second aspect, there is provided a method of conveying and separating solids comprising: selecting a vacuum separation system substantially as described above; conveying solids from the extraction system to the cyclone and collecting the solids in the cyclone; separating the solids from the cyclone via the airlock by: opening the first flap and closing the at least one further flap to discharge the solids from the cyclone to or about the at least one further flap; subsequently closing the first flap and opening the at least one further flap to discharge the solids from the vacuum separation system; and, during discharge, coordinating movement of the first flap and the at least one further flap so that the first flap or the at least one further flap is closed so as to have minimal or no substantial loss in vacuum pressure from the vacuum separation system.

In a third aspect, there is provided a vacuum soil excavator comprising the vacuum separation system substantially as described above.

In a fourth aspect, there is provided a dredging device comprising the vacuum separation system substantially as described above.

In a fifth aspect, there is provided a solids conveying system comprising the vacuum separation system substantially as described above.

Selected advantages of the above vacuum separation system and method may be that solids may be vacuum excavated and discharged while the vacuum separation system remains under vacuum hence a providing continuous vacuum pressure and continuous processing.

Further, the solid material collected may be discharged into a bin, onto a tipper truck or, on the ground beside where the hole is dug similar to a conventional excavator. The method may not be restricted to collection in a bulky vacuum chamber or vessel, typically located on a truck. The vacuum separation system may be portable and could be located on a trailer chassis or skid frame that may be towed to and used independently at a work site. The vacuum separation system may be located on a small truck bed.

A flap as a vacuum closure or seal may be superior to a rotary airlock or sliding plates in terms of grit/stone movement and interference and avoidance of blockages. Flaps may allow for weight to be used as a trigger for opening of a flap unlike rotary or sliding plates where weight is harder to use as a trigger for airlock movement.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the vacuum separation system and method will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 illustrates a prior art schematic of a cyclone and rotary airlock;

Figure 2 illustrates a prior art workflow using a prior art soil vacuum system;

Figure 3 illustrates a workflow for an example of vacuum separation system and method described herein;

Figure 4 illustrates a modified workflow to Figure 3 above using a conveyer belt;

Figure 5 illustrates a perspective side view of one example of the vacuum separation system described herein with a housing;

Figure 6 illustrates the above example perspective side view of the vacuum separation system with a housing removed to show internal parts;

Figure 7 illustrates a side schematic view of an example of the vacuum separation system described herein in a first configuration corresponding to solids collection in an intermediate volume from the cyclone;

Figure 8 illustrates a side schematic view of the above example of the vacuum separation system in a second configuration corresponding to both flaps closed prior to discharge of collected solids from the intermediate volume;

Figure 9 illustrates a side schematic view of the above example of the vacuum separation system in a third configuration corresponding to the first flap being closed and a second flap open to cause discharge of collected solids from the intermediate volume to the ground or positive pressure environment; Figure 10 illustrates a side schematic view of the above example of vacuum separation system in a fourth configuration corresponding to both flaps closed post discharge of collected solids from the intermediate volume and prior to the first flap opening to move solids collected in the cyclone to the intermediate volume;

Figure 11 illustrates side perspective views of a modified flap example in an open position from below (top) and above (bottom); and

Figure 12 illustrates side perspective views of the above modified flap example in a closed position from below (top) and above (bottom).

DETAILED DESCRIPTION

As noted above, described herein is a vacuum separation system that consists of an extraction system and cyclone separator with an airlock that allows solid material to be discharged during vacuum separation system operation with minimal or no substantial loss in vacuum pressure within the vacuum separation system.

For the purposes of this specification, the term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise ¹ and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

Reference is made hereafter to the term 'solids' and grammatical variations thereof herein. It should be appreciated that reference to the term 'solids' should not be seen as limiting to only solids. Solids collected from a vacuum separation system described may comprise liquids or semi-liquids as well with the solid particles and may not be purely solid streams. Gases may further be entrained in the solids and/or solid/liquid mixtures or slurries.

The term 'in unison' or 'coordinated' and grammatical variations thereof as used herein refers to the airlock first flap and at least one further flap moving substantially together or simultaneously so as to minimise or avoid a substantial drop in vacuum pressure that would lead to discontinuation in solids conveying and collection in the extraction system and cyclone.

The term 'minimal or no substantial loss in vacuum pressure' and grammatical variations in reference to the operation of the airlock flaps refers to the measured vacuum pressure. While the airlock described may avoid all loss of vacuum, in some examples, there may be some loss in vacuum when the top flap opens to the vacuum. It may take a very small amount of time for the cyclone to draw back to the previous vacuum pressure before the top door opens. In practice, this small variation in vacuum is not enough to stop a vacuum process but could result in a slight reduction in suction momentarily when the machine goes through an airlock flap movement cycle.

The terms 'vacuum' or 'vacuum pressure' or grammatical variations thereof refers to a pressure less than atmospheric pressure.

Vacuum separation system

In a first aspect, there is provided a vacuum separation system comprising: an extraction system communicating with, a cyclone; and an airlock communicating with the cyclone, the airlock comprising a first flap and at least one further flap, the first flap and at least one further flap opening and closing in a coordinated manner so as to expel collected solids in the cyclone via the first flap and at least one further flap to a positive pressure environment; wherein, during extraction system and cyclone operation, the airlock is configured to allow removal of collected solids from the cyclone with minimal or no substantial loss in vacuum pressure in the extraction system and cyclone.

Gravity movement through the flaps

The collected solids during vacuum system operation, may be conveyed via the extraction system and collected in the cyclone, and further conveyed, via gravity, from the cyclone through the airlock and to the positive pressure environment. Airlock movement actuation

Airlock flap opening and closing may be actuated at a specific time interval. Flap opening and closing may be actuated by time and/or alternate flap position and movement. Time in this case may be at an instant of time or a time period. The timing of opening may be dependent on a rate of vacuum separation system operation and/or a rate of solids collected.

Airlock flap opening and closing may be actuated at a specific measured weight.

Weight measurement may be completed mechanically by use of a bias mechanism tuned to keep the flap closed until a certain weight is reached and the bias force of the bias mechanism may then be overcome by the weight of solids on the flap.

Weight measurement may alternatively be completed electronically via a weight sensor.

In the above weight measurement example, the timing of flap operation may be a function of the weight of solids on the flap or flaps and, after a certain weight of solids is collected on the flap, the flap opens. It is envisaged that a flap held shut purely due to vacuum pressure may be challenging to ensure reliable operation hence why alternatives such as use of a bias force or alternate weight sensing may be useful.

Alternatively, the whole vacuum separation system, cyclone, or a part thereof may be mounted on scales such as on a load cell. In this example, the tare weight could be set prior to solids collection in the cyclone and, when the overall weight increases to a pre-set amount, then the airlock flap(s) would open to discharge collected solids. This weight approach to actuation may be useful in an application for measuring out grain or food products into measured bags for bagging bulk product.

Airlock movement timing

Movement of the flaps may be coordinated to be approximately in unison. Unison movement may ensure that both the first flap and the at least one further flap are not simultaneously open. Unison movement may be completed to ensure the cyclone and extraction system remain under vacuum and to prevent both the first flap and at least one further flap being simultaneously open thereby limiting or avoiding equilibration in pressure to the positive pressure environment. An aim of the airlock may be to always ensure the cyclone and extraction system remain under vacuum or sufficient vacuum to not interrupt vacuum separation operation. This means the airlock flaps may never both (or all) be open otherwise, equilibration to the surrounding environment may occur.

The first flap may communicate directly with the cyclone and the at least one further flap may communicate indirectly with the cyclone via the first flap. Flap movement may be confined to configurations selected from: both the first flap and the at least one further flap closed; or the first flap is open and the at least one further flap is closed; or the at least one further flap is open and the first flap is closed.

Movement between flap positions may be carefully timed so that when one flap opens the other is closed. The phrases 'coordinated' and 'approximately in unison' are used however, it should be appreciated that there may be some variation in movement so that first or at least one further flap shutting occurs slightly ahead of alternate flap opening to ensure a continuous airlock exists at all times.

Any loss in vacuum during an airlock cycle may be minor. This may be because the volume of air in the airlock volume may be very small in comparison to the volume of air in the vacuum portion and the strength of the vacuum pull may be very high e.g. over 400 litres of air per second. It is anticipated that any variation in vacuum, if measurable, during airlock discharge may be less than 20, or 15, or 10, or 5, or 4, or 3, or 2, or 1% of the normal operating vacuum. For example, if the vacuum pressure in the cyclone under normal operation is O.latm, then the variation in vacuum during airlock first flap opening would alter the vacuum pressure from O.lOlatm (1%) to 0.120atm (20%). As may be appreciated however, this variation could be greater should certain events occur. For example, the vacuum may vary depending on the type of material being conveyed and the type and operation of the pump used to draw the vacuum. If a large rock were to block a section of the excavation hose, this would increase the vacuum and greatly affect the variation in vacuum described above. In the application of grain conveying, the air flow from the vacuum source may not need to be as much compared to soil excavation hence, the time or extent of vacuum change would be different for each application. Expressed another way, the variation in pressure may be a function of time. The time duration of any vacuum change may be less than 5, or 4, or 3, or 2, or 1 second. Flap surface

The first flap and/or the at least one further flap may have a smooth or low friction surface or coating on which solids collect. The first flap and/or the at least one further flap smooth or low friction surface may be configured to enable sliding movement of the collected solids on or about the first flap and the at least one further flap when the first flap and the at least one further flap opens.

The upper surface of each flap on which solids are collected and discharged from may have a low friction surface or coating.

In a vertically orientated cyclone unit, the cyclone may be located above the first flap and the first flap located above the at least one further flap. Solids collected on either the first flap or at least one further flap may slide from the flaps as the flaps open via gravity.

Pivoting

Pivoting may occur to open the first flap and the at least one further flap. Each flap may pivot relative to a housing. The housing may be located about a base of the cyclone. Each flap may pivot from one side of the flap. The pivot point may be a rotating axis or hinge. Each flap may pivot relative to a housing. The housing may be located about a base of the cyclone.

Pivoting of the first flap and the at least one further flap may cause the flaps to rotate approximately 30-100 degrees relative to a sealed or closed flap position. The first flap and at least one further flap(s) may pivot on opening approximately 10, or 20, or 30, or 40, or 50, or 60, or 70, or 80, or 90 or more degrees relative to the sealed or closed position. For example, the closed or sealed position may be in an approximately horizontal plane and the flap(s) may pivot downwards relative to the horizontal plane about the pivot axis by up to 90 (or more) degrees.

In an alternative example, the first flap and the at least one further flap may pivot to one side of the cyclone base outlet or intermediate volume outlet. Pivoting in this example may be via a pivot point located distant to the cyclone base or an intermediate volume described further below. For example, the pivot point may be located above the cyclone outlet and to the sides of the cyclone. An arm or arms may be linked to the airlock flap and may actuate movement of the flap away from the cyclone outlet. The pivot point may be located above the intermediate volume outlet and to the sides of the cyclone. An arms or arms may be linked to the airlock flap and may actuate movement of the flap away from the intermediate volume outlet. Other pivot point positions may be used well.

An advantage of this pivot point position may be to reduce the overall height of the extraction system. This pivot point position may also move the airlock flap well away from the outlet to avoid any build-up of material about a flap pivot axis and may provide the flap(s) with more closure force when the flap(s) return to an outlet closed position hence, the ability to move away any material obstructing the interface between the airlock flap surface and outlet surface.

Pivoting of the flaps may be from a common side of the cyclone, or a 90 degrees offset, or from opposing sides. The exact location of the pivot axis and alignment may not be limited to one configuration or alignment.

Intermediate volume

An intermediate volume may be located between the flaps. The intermediate volume may be sized to receive solids collected in the cyclone over a predetermined time period or weight.

The intermediate volume may alternately communicate with an interior of the cyclone and the positive pressure environment external to the vacuum separation system depending on first flap and at least one further flap position.

Three or more flaps

The vacuum system may comprise a first flap and two (or more) further flaps, the first flap and the two (or more) further flaps defining two (or more) intermediate volumes between the first flap and the two further flaps. The first flap and the two (or more) further flaps may work together in a coordinated manner to expel collected solids to the positive pressure environment via the two (or more) intermediate volumes.

The two or more intermediate volumes may be a way of increasing the airlock reliability and introduces redundancy so that if one flap fails and remains open, the other flap or flaps remain closed and hence the vacuum pressure is retained in the extraction system and cyclone. This may be appropriate when handling dangerous goods conveyed using inert gases, reactive solids, toxic chemical or biological compounds.

An alternative arrangement may be where the first flap or at least one further flap is made of two parts that collectively act like a single flap. For example, the first flap or one of the at least one further flaps may be made up of two flaps or partitions that seal together when in a closed position and which separate to open. A clamshell flap design may be used to form the first flap or at least one further flap e.g. with opposing flaps that abut together to seal and which move apart to open.

Transportable

The vacuum separation system may be transportable/portable to and from a worksite. The vacuum separation system may be configured to be left at a worksite during operation. The vacuum separation system may not need to be transported during separation operation to a remote site for solids discharge.

Portability may be possible from the described vacuum separation system compared to art systems which lack such portability. This is because there is no inherent need for a large recovery container under vacuum. Consequently, the vacuum separation system described may be more compact and may not need a storage vessel at all since separated solids may be dumped. Dumping may be to the ground about a work site or to a conveyer to transport the solids elsewhere. By removing the need for a large storage vessel, the vacuum separation system may be made compact and portable. The described vacuum separation system could for example be mounted on a trailer chassis and driven to a site and detached and left at a worksite for the time needed and then relocated easily, without trucks, cranes or heavy machinery, to another site. There is also no need to periodically stop vacuum separation as in art systems to have the collected solids (and integral vacuum system) transported away from the work site for disposal. This makes a substantial difference to work flow and efficiency.

Positive pressure environment

The positive pressure environment may be ambient atmospheric pressure. The positive pressure environment may be selected from: the ground about a worksite, a conveyer belt, a vehicle, a room or enclosure, and combinations thereof.

As noted, the positive pressure environment may be the ambient atmospheric pressure or, may be any pressure greater than the vacuum pressure of the extraction system and cyclone. As noted previously, solids collected may be expelled to the ground about a worksite, a conveyer belt or a separate vehicle such as a truck to transport collected solids from the work site. The positive pressure environment may also be a collection vessel (not under vacuum) or a room under positive pressure (greater than ambient pressure) such as a laboratory or dangerous goods enclosure.

Continuous operation

The vacuum separation system may run continuously during extraction, collection and discharging the collected solids to the positive pressure environment.

As noted above, there is no need to stop and start vacuum separation system excavation when discharging collected solids from the vacuum separation system, such as when a collection vessel integral to the vacuum separation system is full and needs to be driven to a waste dump thereby interrupting vacuum separation operations.

Method of conveying and separating

In a second aspect, there is provided a method of conveying and separating solids comprising: selecting a vacuum separation system substantially as described above; conveying solids from the extraction system to the cyclone and collecting the solids in the cyclone; separating the solids from the cyclone via the airlock by: opening the first flap and closing the at least one further flap to discharge the solids from the cyclone to or about the at least one further flap; subsequently closing the first flap and opening the at least one further flap to discharge the solids from the vacuum separation system; and, during discharge, coordinating movement of the first flap and the at least one further flap so that the first flap or the at least one further flap is closed so as to have minimal or no substantial loss in vacuum pressure from the vacuum separation system.

Applications

In a third aspect, there is provided a vacuum soil excavator comprising the vacuum separation system substantially as described above.

In a fourth aspect, there is provided a dredging device comprising the vacuum separation system substantially as described above. In a fifth aspect, there is provided a solids conveying system comprising the vacuum separation system substantially as described above.

As may be appreciated form the above applications, the vacuum separation systems described may be used in a variety of environments and for a variety of different conveyed solids.

Advantages

Solids may be vacuum excavated and discharged while the vacuum separation system remains under vacuum hence a providing continuous vacuum pressure and continuous processing.

Further, the solid material collected may be discharged into a bin, onto a tipper truck or, on the ground beside where the hole is dug similar to a conventional excavator. The method may not be restricted to collection in a bulky vacuum chamber or vessel, typically located on a truck.

The vacuum separation system may be portable and could be located on a trailer chassis or skid frame that may be towed to and used independently at a work site. The vacuum separation system may be located on a small truck bed.

A flap as a vacuum closure or seal may be superior to a rotary airlock or sliding plates in terms of grit/stone movement and interference and avoidance of blockages. Flaps may allow for weight to be used as a trigger for opening of a flap unlike rotary or sliding plates where weight is harder to use as a trigger for airlock movement.

The description above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the examples relate, such known equivalents are deemed to be incorporated herein as if individually set forth.

WORKING EXAMPLES

The above described vacuum separation system and method are now described by reference to specific examples and the following items and item numbering:

1 Vacuum excavator 2 Truck

3 Vacuum vessel

4 Hose

5 Ground

6 Pump

7 Refuse site

8 Slurry

9 Driving

10 Vacuum separation system

11 Truck

12 trailer

13 Airlock system

14 Extraction hose

15 Cyclone

16 Vacuum source

17 Soil

18 Ground

20 Vacuum separation system

21 Housing

23 Outlet

24 Piston linkage

25 Cyclone

26 First flap

27 Linkage actuator

28 Intermediate volume 29 Further (second) flap

30 Positive pressure environment

50 Vacuum separation system

51 Cyclone

52 Rocks and large soil particles

53 Intermediate volume

54 Hydraulic cylinder

55 First flap

56 Rubber seal

57 Large rock

58 Second flap

59 Further hydraulic cylinder

60 Solids inlet

61 Air outlet

62 Discharge material

100 Vacuum separation system

110 Modified flap

120 Cyclone

130 Outlet

140 Pivot point

150 Arms

200a Conveyer belt stored position

200b Conveyer belt in-use position EXAMPLE 1

In this example, process flow diagrams are shown of a prior art vacuum excavator Figure 2 compared to the equivalent flow diagram for the above described vacuum separation system shown in Figure 3 and Figure 4.

Referring to Figure 2, the vacuum extractor 1 comprises a truck 2 mounted vacuum vessel 3 and hose 4 from the vessel 3. Soil is vacuumed as a slurry from the ground 5 and collected in the vacuum vessel 3. A vacuum is produced via a large pump apparatus 6 also located on the truck 2. When the vessel 3 is full, extraction stops while the truck 2 and vacuum extractor 1 drives 9 to a refuse site 7, dumps the collected slurry 8 and returns back to the work site 5. This may take up to 2 hours (or more) depending on how remote the work site 5 is from a refuse point 7. The truck 2 used is a dedicated bespoke unit and only produced by a small number of manufacturers. Due the truck 2 size, site access can also be an issue.

Figure 3 and Figure 4 shows the work flows for the above described vacuum separation system 10. In this example, a small truck 11 tows a trailer 12 mounted vacuum extraction system 11 to a site. A vacuum is produced from a vacuum source 16 to an extraction hose 14 and cyclone 15 and soil 17 vacuumed via a hose 14 linked to the cyclone 15. Solids collected in the cyclone 15 are separated out via the airlock system 13 described and, as shown, may be dumped to the ground 18 (Figure 3) or dumped to a conveyer belt 200a, 200b (Figure 4) immediately below the cyclone 15 and about the work site 17. This dumped material 18 can then be used to re-fill the work site excavated area 17 and does not have to be taken away and dumped hence saving transport and dump fees. Note that the conveyer belt 200a, 200b may be rotated for use from a truck bed conveyer 200a position for transport to an in-use conveyer 200b position to relocate discharged material 18.

EXAMPLE 2

An example of one design of vacuum separation system 20 is shown in a perspective partially assembled view in Figure 5 and in a cross-section view with a housing removed in Figure 6. Figure 5 shows the vacuum separation system 20 with a housing 21 over it. The top of the system 20 shows an outlet 23 for separated air. Also shown in Figure 5 is an externally located piston linkage 24 to open and shut a lower or second flap (shown further in Figure 6). Figure 6 shows the same system 20 with the housing 21 removed to see the system 20 internal features. As shown, the vacuum separation system 20 comprises a cyclone 25 separator, a first flap 26 and linkage actuator 27 that seals against the base of the cyclone 25 and which pivots and opens to an intermediate volume 28 between the first flap 26 and a second flap 29 that seals the intermediate volume 28 and which pivots open to the positive pressure environment 30 which, in this example, is an enclosed region below the second flap 29.

EXAMPLE 3

Referring to Figures 7-10, the vacuum separation system 50 is described in more detail including the various stages of operation (stage 1-4 equivalent to Figures 7-10 respectively). A cyclone 51 is shown that separates the rocks and large soil particles 52 which collect in the intermediate volume 53 of the vacuum separation system 50 or as shown in Figure 10 in the base of the cyclone 51.

The cyclone 51 has a solids inlet 60 connected to a hose (not shown) and an air outlet 61.

After a set time or weight calculation, the intermediate volume 53 is shut off by a hydraulic cylinder 54 from the cyclone 51 by means of a hinging first flap 55 that forms an airlock seal against the base of the cyclone 51 with a rubber seal 56 that accommodates a small amount of grit or obstruction. Any large rock 57 that was about to enter the intermediate volume 53 would be pushed back into the base of the cyclone 51 when the first flap 55 closes.

As may be appreciated, this design is preferable over a sliding door used in one art system for at least two reasons. Firstly, a sliding door will require clearance for the door to slide, given the fact this machine will be dealing with grit, suitable clearance to accommodate the grit will be too great to create an airlock seal between the sliding door and base of the cyclone. The second reason for not using a sliding door is a large rock part way between the cyclone 51 and intermediate volume 53 when the sliding door closes would obstruct the closing of the sliding door preventing the airlock seal.

Once the base of the cyclone 51 is closed via the first flap 55, (end of 2 ^nd stage), a lower second flap 58 opens by a further hydraulic cylinder 59 to discharge material 62 collected whilst maintaining vacuum in the cyclone 51 and extraction system for the excavation process. This lower second flap 58 closes and seals again, (end of 4 ^th stage), followed by the upper first flap 55 opening to allow the upper collected material 57 to drop into the intermediate volume 53 (the process cycle goes back to stage 1). As this process happens continuously, material collected moves through the cyclone 51 and intermediate volume 53 whist maintaining vacuum for the excavation or material conveying process.

The collected material can be directed onto a conveyor belt (see Fig 4 item 200a, 200b) and moved out of the way, discharged directly onto a tipper truck, or simply discharged or expelled onto the ground.

EXAMPLE 4

Referring to Figures 11-12, an alternative example of the vacuum separation system 100 is described using a flap 110. The flap 110 shown open in Figure 11 and closed in Figure 12 may pivot to one side of the cyclone 120 outlet 130 (or intermediate volume outlet not shown). Pivoting in this example may be via a pivot point 140 located distant to the cyclone 120 outlet 130, in Figures 11-12 the pivot point 140 being located above and to the sides of the cyclone 120. Arms 150 linked to the flap 110 move the flap 110 away from the cyclone 120 outlet 130. As shown in Figures 11-12, this more distant pivot point system moves the flap 110 well away from the outlet 130 to avoid any build-up of material (not shown) about a flap 110 pivot axis and provides the flap 110 with more force when the flap 110 returns to an outlet 130 closed position hence the ability to move away any material obstructing the interface between the flap 110 surface and outlet 130 surface.

Aspects of the vacuum separation system and method have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.