WO2003091653A2

WO2003091653A2 - Method and processor for removing explosive devices from an area of land

Info

Publication number: WO2003091653A2
Application number: PCT/CA2003/000582
Authority: WO
Inventors: Erich Richter; Richard Conrad Richter; Ralph Sanford; Bill Watts; Jim Macfarlane
Original assignee: Inter-Continental Safety Systems Inc.
Priority date: 2002-04-26
Filing date: 2003-04-23
Publication date: 2003-11-06
Also published as: AU2003218846A1; WO2003091653A3

Abstract

A method and processing machine (60a, 60b) for removing explosive devices from (32) an area of land are taught. The method includes: treating an area of land with a plough (18a, 18) to create a ploughed land area with an exposed ground surface and a ground surface on which a berm (42, 38), containing soil and explosive devices, is deposited by the plough (18a, 18b), processing the berm (42, 38) to substantially remove the explosive devices from the soil and applying pressure to the ground surface of the ploughed land area, the pressure selected to detonate at least some explosive devices in the ploughed land area, and generally exceeding the highest known trigger pressure of the explosive devices at a depth of about 0.5 meters. The processing machine (60a, 60b) is useful for processing earth materials to remove explosive devices therefrom, the processing machine includes an inlet (76) to receive earth materials, processor means (78) to process the earth materials to remove at least some of the unexploded ordinance contained therein, resulting in processed earth materials, and an outlet (79a, 79b) to pass the processed earth materials out of the processing machine.

Description

METHOD AND PROCESSOR FOR REMOVING EXPLOSIVE DEVICES

FROM AN AREA OF LAND

FIELD OF THE INVENTION

The present invention relates to a method and a processor for removing explosives from an area of land and, in particular, a method and a processor for removing landmines and other surface or subsurface-located explosive devices from an area of land.

BACKGROUND OF THE INVENTION

Landmines are generally laid as a component of a hostile conflict. Another consequence of these conflicts is the various missiles, bomblets, mortars, grenades and projectiles, commonly termed unexploded ordnance (UXO), that did not detonate and remain on the surface or are buried in the area of the conflict. In an area of past conflict, it is not unusual to have thousands of these UXO or landmines per square kilometre of land. These various devices have a variety of shapes, sizes, fuses or detonation methods. The landmines' explosive charges can range from one built to injure a person, termed anti-personnel mines, to those constructed to destroy a vehicle, termed anti-tank or anti-vehicle mines.

Landmines are laid as close to the ground surface as possible, to maximize their effect. Anti-personnel landmines are usually laid on the ground surface or within 2 to 5 centimetres of the ground surface. Anti-vehicle landmines are usually laid on the ground surface or within 5 to 10 centimeters of the ground surface. UXO will vary from being exposed on the ground surface to being many meters beneath the ground surface. With time, plus the effects of wind and water action, mines and UXO can move from their original location or have lesser or greater amounts of ground cover.

Millions of landmines have been deployed in countries by numerous armies. Accurate maps and records of where these landmines were placed do not exist. The United Nations estimate in-place landmines range from 50 million to 150 million, afflicting up to 90 countries.

It is often desirable to build roads, pipelines, power lines and utility right of ways through areas containing undetonated explosive devices, or to make those areas safe and productive for activities such as farming, commercial, residential or industrial development. The only way to make the land productive is to remove all the undetonated explosive devices.

Until recently, most demining efforts have centred around the detection of mines through mechanical, animal or human means, followed by the removal or detonation of the mines. Progress to remove the mine and UXO threat can be painfully slow. Success has typically been measured in square meters per day.

Currently, the most widely used landmine clearing technique is the time-intensive manual search nicknamed "Poke and Prod". This involves the use of mine detectors to identify suspicious objects. A trained deminer will then use a probe which is pushed into the ground above and around a suspicious object many times to try and determine the depth, shape, size and "feel" of the buried object. Then the deminer will make the decision whether or not the object is likely to be a mine or UXO. If the object is determined to be of interest, it will be carefully excavated by hand, visually examined and either classified as harmless or explosively destroyed in place. If not, the deminer will continue onward with his mine detector. Using the "poke and prod" method landmines and UXO can be detected to depth of less than about 15 centimetres.

Mechanical methods are also used to clear undetonated explosive devices. Mechanical devices include soil compacters, flails, ploughs, grinders and tillers.

Soil compacters such as heavy rollers or vibrators are bracketed to the front of or towed behind an armoured vehicle, which is slowly driven through a suspected mined area. The weight of the compacter is selected to set off any landmines that are driven over. For anti-personnel mines the effect on the compacter is minimal; however, anti-tank mines will destroy the compacter (rather than the vehicle). Soil compacters are not intended to clear an area; rather they "prove" that the area is safe for surface access.

Flails include a number of heavy chains that are attached to a spindle or axle suspended in front of an armoured vehicle. The flail axle is positioned parallel to and above the ground. The axle is spun at a high speed, which causes the loose end of the chains to be flung away from the axle. The flung chains strike the ground with sufficient force to detonate landmines close to the surface. The large number of moving chains work well on uneven terrain. An exploding antipersonnel mine will have little effect on the flail and an anti-tank mine may destroy a chain or two, but will not seriously affect the efficiency of the unit. The flail works best on mines located near the ground surface and acts as a prover. A military method to clear passages through a minefield is the application of pressure, through the use of explosive devices that are contained within a hose or tube, such as the Viper™.

Mine ploughs, also known as mine rakes, are the current standard of many armies for breaching minefields. The plough has a row of tines that are spaced from each other a distance less than the size of any known anti-vehicle landmine. This distance is often less than the size of most anti-personnel landmines and UXO. The plough is pushed forward through the suspected minefield lifting anti-vehicle landmines out of the ground and pushing them to the side away from the vehicle. The plough acts to clear ordnance from its path except for the smallest devices or devices deeper than the plough tines. Mine ploughs can be fitted with chains and/or magnetic field generating devices to detonate some mines before the mines are ploughed. Some mines will detonate by engagement against the plough. The plough is constructed to withstand explosion of anti-personnel and some anti-tank mines without significant damage. As the ploughs are designed to clear anti-tank mines, they are usually modular in construction so that damage due to explosion of an anti-tank mine can be addressed by replacement of a component rather than the entire plough. The undetonated explosive devices lifted by the plough remain in a spoil berm formed by the plough at the side of the vehicle and need to be separated from the berm to make the area safe for use and transport thereover. A grinder is a large drum with cutting bits on its surface and a tiller device is a large axle with arms attached (like a roto-tiller) that have been fitted with cutting edges. The armoured vehicle pushes the grinder or tiller through the ground. As the grinder or tiller is pushed through the ground the cutting teeth cut the casing of the mines and UXO rendering these devices harmless as the mine is cut to pieces. Neither the grinder nor the tiller systems are modular.

Similar to the flail, the direction of rotation for these devices is typically from between the device and the driving tank, underneath the axle of the grinder or tiller and then up and forward. The result is the mines or UXO very close to the surface may be lifted out of the ground and "kicked along" by the grinder or tiller rather than being cut to pieces.

At least one grinder system has the grinder drum hinged on one end and pushed on the other end while the vehicle remains stationary. This results in the grinder sweeping the soil and grinding debris off to one side to form a berm. This berm would need to be searched to ensure that all the explosive devices have been rendered safe, particularly the devices that may have been "kicked along".

SUMMARY OF THE INVENTION

A method and a processing machine have been invented for removing explosive devices, such as unexploded ordnance (UXO) and landmines, from earth materials in an area of land.

In accordance with a broad aspect of the present invention, there is provided a processing machine for processing earth materials to remove explosive devices therefrom, the processing machine comprising: an inlet to receive earth materials, processor means to process the earth materials to remove at least some of the unexploded ordinance contained therein, resulting in processed earth materials, and an outlet to pass the processed earth materials out of the processing machine.

The processing machine can include a collection means, such as for example, a scoop, a pickup drive, a material conveyor, etc., for collecting the earth materials and moving them to the inlet. Alternately, earth material can be transported by other means to the inlet.

The processing machine can be mobile, fixed or self-propelled.

The processing means can include one or more means for rendering explosives safe. In some embodiments, the processing means also includes means for sorting the earth materials to best handle the various components with consideration as to enhance safety and throughput and to select appropriate handling.

In one embodiment, for example, the processing machine includes a means for sorting the earth materials into a first portion selected to be substantially free of unexploded ordinance and a second portion selected based on the possibility of containing unexploded ordinance, prior to the introduction of the earth materials to the inlet, such that only the second selected portion is deposited into the material processing machine and handled by the processor means. In another embodiment, the first portion and the second portion are processed by components of the processor means. For example, the first portion is processed to remove metal contaminants therefrom, while the second portion is processed to render safe any unexploded ordinance.

Sorting components can be used as a part of the processing means. For example, the second portion can be sorted to separate more powerful unexploded ordinance from those easier to handle or the second portion can be sorted to remove harmless materials from unexploded ordinance.

The sorting can be, for example, on the basis of size, visual inspection, material density, material content, material electrical, thermal, magnetic or radioactive signatures.

The processing means includes components for removing the unexploded ordinance. These components can physically remove the unexploded ordinance or render them safe against explosion, but leave the materials therefrom in the earth materials. For example, the processing means can include one or more of magnets, sieves, crushers, flail, spaced gears, housing cutters, shredders, cutting torches, sound wave generators, water jets and/or explosive destroyer/detonators using pressure, freezing, chemicals or explosives.

In one embodiment, the processing machine comprises a collection means to collect earth materials from a ground surface, a first conveyer that conveys the collected earth materials to the inlet and deposits it therein, a size sorting means to separate the earth materials into a first selected portion and second selected portion, between the time that the material is collected from the ground surface and the time that it is deposited into the inlet, such that only the second selected portion is deposited into the material processing device, one or more processor means to process the second selected portion, as by rendering safe at least some of the unexploded ordinance contained therein, to create a processed portion; and additional conveyers that convey the first selected portion and the processed portion past one or more magnets that remove metal from the first selected portion and the processed portion, and then deposit both portions onto the ground surface through one or more outlets. The first portion generally includes small harmless components from the earth material, such as soil and rocks. The second portion can include small explosive devices, which are processed to remove, destroy and/or detonate the explosive devices.

If large explosive devices are suspected to be present in the area that is being cleared, the processing machine can comprise second size sorting means that removes from the second selected portion a third selected portion, before said second selected portion is processed by the processor means. These larger explosive devices can be collected and destroyed or detonated, for example, by flails, spaced gears, a crusher, a housing cutter, a shredder, cutting torch, sound waves, water jet, freezing, chemicals or explosives.

In accordance with another broad aspect of the present invention, there is provided a method for removing explosive devices from an area of land, the method comprising treating an area of land with a plough to create a ploughed land area with an exposed ground surface and a ground surface on which a berm, containing soil and explosive devices, is deposited by the plough, processing the berm to substantially remove the explosive devices from the soil and applying pressure to the ground surface of the ploughed land area, the pressure selected to detonate at least some explosive devices in the ploughed land area, and generally exceeding the highest known trigger pressure of the explosive devices at a depth of about 0.5 meters.

In one embodiment the pressure is applied to the ploughed land area on either side of the berm, before the berm is processed. In another embodiment, the pressure is applied to the ploughed land area on either side of the berm after the berm is processed. In yet another embodiment, the pressure is applied to the ground surface on which the berm had been located, the pressure selected to exceed the highest known trigger pressure of the explosive devices remaining in the ground surface on which the berm had been located.

The method is useful to detonate and/or remove various explosive devices such as, for example, anti-personnel landmines, anti-tank landmines or unexploded ordnance. The area of land can be in any condition that will support the passage thereover of heavy equipment and that is loose enough to be worked by the plough.

In the step of treating an area of land with a plough, the area of land is ploughed to separate some explosive devices from the area of land and push them to the side to form the berm. In so doing, some explosive devices may be detonated. In one embodiment, the plough is a mine plough and includes a ploughing blade and a plurality of tines disposed to dig into the ground below and forwardly of the ploughing blade. The tines are spaced apart a distance less than the width of one or more different types of selected explosive devices, such that the explosive devices cannot pass between the tines, but are lifted by them and moved to the side of the plough and into the berm. Other ploughs can be used such as a standard grader, a bulldozer or other machines, available for example from Bofors Defense (Karlskoga, Sweden).

The berm may be pushed to one or both sides of the area being ploughed. In one embodiment, one or more ploughs are passed over the area such that the berm is deposited on a ground surface between two or more ploughed ground surfaces. In the step of applying pressure, the pressure can be applied over substantially the entire exposed ground surface of the ploughed land area or to selected portions thereof. The pressure applied is preferably selected to be sufficient to detonate at least some of the explosive devices in the area of land. In one embodiment, the pressure applied is selected to be sufficient to detonate at least some of the anti-tank landmines. Pressure can be applied in various ways including applying or dropping weights, hitting the ground surface such as by use of heavy rollers, vibrating ground compactors, flails or explosive devices.

The berm formed in the method of the present invention is processed to remove the explosive devices from the soil contained in the berm. In one embodiment, the berm contents are processed to remove explosive devices from the soil. In another embodiment, the berm contents are further processed to remove metal materials, such as detonated explosive devices, explosive shrapnel, discarded metal tools, and such, from the soil. The soil that is separated from other berm materials in this step can be returned to the area of land.

The berm can be processed manually or by machine. In one embodiment, a berm processing machine is used that is moved along to collect the berm material. The processing machine includes an inlet to receive berm materials, processor means to process the berm materials to remove at least some of the unexploded ordinance contained therein, resulting in processed berm materials, and an outlet to pass the processed berm materials out of the processing machine.

The processing machine can include a collection means to collect the berm material from a ground surface, a first conveyer that conveys the collected berm material to a material processing device and deposits it therein, a size sorting means to separate the berm material into a first selected portion and second selected portion, between the time that the material is collected from the ground surface and the time that it is deposited into the material processing device, such that only the second selected portion is deposited into the material processing device, one or more processor means to process the second selected portion, as by rendering safe at least some of the unexploded ordinance contained therein, to create a processed portion; and additional conveyers that convey the first selected portion and the processed portion past one or more magnets that remove metal from the first selected portion and the processed portion, and then deposit both said portions onto the ground surface through said one or more outlets. The first portion generally includes small harmless components from the berm material, such as soil and rocks. The second portion can include small explosive devices, which are crushed to destroy and/or detonate the explosive devices.

If large explosive devices are in the area that is being cleared, the processing machine can comprise second size sorting means that removes from the second selected portion a third selected portion, before said second selected portion is processed by the processor means. These larger explosive devices can be collected and destroyed or detonated, for example, by flails, spaced gears, a crusher, a housing cutter, a shredder, cutting torch, sound waves, water jet, freezing, chemicals or explosives.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flow chart showing one embodiment of the method of the present invention.

Figure 2 is perspective view of a mine plough useful in the present invention.

Figure 3 is a schematic sectional view of a ploughing operation useful in the present invention.

^* Figure 4a is a schematic of a step of ploughing an area of land useful in the present invention.

Figure 4b is a schematic of the steps of applying pressure to a ground surface of a ploughed land area, collecting berm materials and applying pressure to the ground surface on which the berm was located, which are useful in the present invention.

Figure 5 is a side elevation of a berm processor according to the present invention and useful in a method according to the present invention. Figure 6 is a side elevation of another berm processor according to the present invention and useful in a method according to the present invention.

Figure 7 is a top plan view of a coarse sieve and oversize handling arrangement useful in the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring to Figure 1 , a flow chart is shown that summarizes a method for removing explosive devices from an area of land. As used herein "explosive devices" includes undetonated explosives such as anti-personnel mines, anti-tank mines, anti-vehicle mines and various UXO's, including missiles, mortars, grenades and projectiles. "Soil" or "earth materials" includes sand, top-soil, mud, rocks and other types of loose ground material.

In one embodiment, the method includes ploughing 10 an area of land with a plough to create a ploughed land area with an exposed ground surface and a ground surface on which a berm, containing berm materials including explosive devices, is deposited by the plough, applying pressure 12 to the ground surface of the ploughed land area, the pressure selected to detonate at least some explosive devices in the ground beneath the ploughed land area, processing 14 the berm to remove at least some of the explosive devices from the berm materials and applying pressure 16 to the ground surface on which the berm had been located, the pressure selected to detonate at least some of the explosive devices remaining beneath the ground surface on which the berm had been located.

In the step of ploughing 10, a plough is passed over the area of land to form a ploughed land area and a berm. The land to be treated by the plough is preferably open, as for example of desert, savannah or field, so that the plough can move freely over the entire area. The area from which explosive devices are to be removed generally contains loose and/or sandy soil. The explosive devices can be buried, partially buried or on the surface of the ground.

The berm is generated by a mine plough, plough, bulldozer, or other machine (all generally referred to as a "plough") that can lift and/or sift through soil. The berm contains berm material that includes explosive devices, detonated explosive devices, soil, and other natural and foreign materials. In one embodiment the plough includes a blade and/or tines that lift the explosive devices, and possibly also soil, and pushes them aside out of the path of the plough, forming the berm.

5 For example, a mine plough known as a Pearson Landmine Plough™ (Pearson

Engineering Ltd.; England) may be used in the present invention.

To facilitate understanding of the operation of a mine plough an exemplary plough 18 useful in the present invention is shown in Figures 2 and 3. The mine plough 18 is carried on a vehicle 20 that can push it though the soil 21 of the area to be 10 treated. The vehicle can be tracked or wheeled and manually or remotely operated. A useful vehicle is an armoured vehicle, since it can withstand many kinds of explosions without significant damage thereto. A vehicle useful in the present invention is a humanitarian demining vehicle (HDV), an ex-military vehicle that is modified for humanitarian use.

15 The mine plough includes a blade 22 and a plurality of spaced apart tines 24. The tines extend below and forwardly of the blade. As is known, the blade and tines are formed to dig into the ground and lift and push aside the explosive devices 26 in the path of the blade and tines. The tines are spaced apart a distance "D" that is selected to be less than the smallest dimension of most explosive devices, so

20. that most explosive devices will be lifted by the tines rather than passing therethrough. In one embodiment, the tines are spaced a distance smaller than all known anti-tank mines. The mine plough or other plough is designed to survive large explosions (i.e. anti-vehicle mines) and can cause certain devices such as magnetic triggers, seismic triggers, tilt rod devices, sensitive triggers or other

25 devices to detonate. While a mine plough including tines and a blade is shown, ploughs, bulldozers and the like can be used herein that have tines or a blade, without the other.

A bracket arrangement 28 connects plough 18 to vehicle 20. The bracket arrangement can include means, such as skids 29 and associated arms and

30 hydraulics, for adjusting the position of the blade relative to the ground surface, so that a consistent depth of soil can be treated by the plough, regardless of variations in the terrain. In one embodiment, the blade is positioned so that it strips off a top portion such as, for example, about 10 to 20 cm of the soil over which the plough is passed and pushes this stripped off material to the side or sides of the plough. This generally will include most of the soil area in which mines were originally laid and on which UXO landed. The tines dig into the ground below the blade and lift explosive devices from below the level of the blade to the surface. In one embodiment, the tines are positioned to dig about 0.5 meters into the ground. The stripped off soil, unearthed explosive devices and other natural or manmade materials are pushed to the side to form the berm. The passage of the plough removes some, if not all, of the explosive devices located within about 50 centimeters of the ground surface and some if not all of those which were in the ground at normal mine laying depths. The explosive devices that are removed from the ploughed land area are located in the berm.

In one embodiment, a chain or other weight is suspended from the plough to contact the ground surface ahead of the plough as it advances. This acts to cause the detonation of some explosive devices prior to contact by the plough.

After the area is ploughed, pressure may be applied 12 to the ploughed land area about the berm. The ground that was ploughed may contain explosive devices that were located below the depth reached by the plough, and/or were too small to be picked up by the tines of the plough. The pressure applied is selected to be sufficient to detonate at least some explosive devices while they remain in place in the ploughed land area. In one embodiment, a pressure that will result in about three times any known landmine trigger pressure at a depth of about 0.5 meters, is applied to the ploughed ground surface. Pressure can be applied over substantially the entire exposed ground surface of the ploughed land area or to selected portions thereof. Pressure can be applied in various ways, such as by applying or dropping weights or by hitting the ground surface such as by use of heavy rollers, vibrating ground compactors, flails, shock waves, pressure waves or explosives. These devices are known in the art as "provers", and have many and varied industrial applications. The provers can be moved over the area of land by any means. In one embodiment, the provers are pushed or towed by armoured vehicles. One means of proving in the method of this invention is the use of a vibratory compactor, such as available from Caterpillar (Peoria, Illinois, USA).

The vibratory compactor has been found to be particularly useful for detonating ratchet mines, as it sends a series of pulses into the ground, that activate the ratchet mine.

After applying pressure to the ploughed land area about the berm, the ploughed land area is generally safe for surface access, as the ground pressure exerted by the provers is generally greater than the ground pressure exerted by humans, vehicles or animals. The use of provers can also act to compact the soil of the ploughed land area so that it better serves for transport thereover.

In one embodiment of this invention, pressure is not applied to the ploughed area before processing of the berm, but rather after the berm has been processed as described next herein.

The berm generated during ploughing is next processed 14 to remove the explosive devices and possibly also metal fragments and other foreign materials therefrom. The berm contents can be searched for explosive devices by a number of means, for example, by visual screening, metal detection, thermal separation, magnetic separation, or by differential chemical detection. In one embodiment, the berm is processed manually by digging through the contents of the berm. In another embodiment, the berm processing is automated in whole or in part.

In one embodiment, the berm is processed to remove the explosive devices from the berm and return the soil and other natural materials to the area of land. The explosive devices can be stored, detonated and/or destroyed. In another embodiment, the berm is processed to ensure that no undetonated explosive devices remain therein.

After the berm has been processed, the ground on which the berm is located may have pressure applied 16 thereto. As noted above, the pressure can be applied in various ways. The pressure applied is selected to be sufficient to detonate at least some explosive devices while they remain in place in the ground. As an example, pressure can be applied to the ground surface that will result in a pressure of about three times greater than any known landmine trigger pressure, at a depth of about 0.5 meters.

The ground under the berm can be untreated, meaning that it has not previously been ploughed or proven, or alternately the berm can be placed on a ground surface that has been previously ploughed or proven, such that at least some of the explosive devices have been removed therefrom.

Referring to Figures 4a and 4b, another method is shown for removing explosive devices from an area of land 30 within a region 32 suspected to contain explosive devices. In the method, an area of land 30 along a selected direction 34 is selected for treatment to remove at least a portion of the explosive devices suspected to be contained therein. The location of the area of land 30 within the greater region 32 is recorded by mapping such as with a global positioning system or with other survey methods, so that further areas within the region can be systematically treated to remove further explosive devices. Mapping can be important where it is desirable to treat all areas of land in the region 32.

Mine ploughs 18a, 18b, 18c are moved by armoured vehicles 20a, 20b, 20c to form ploughed area of land 30 along the selected direction 34. The mine ploughs, in the illustrated embodiment, are positioned with respect to each other to provide for some overlap of the area ploughed by ploughs 18a, 18b and 18c, and to push a berm 38, formed by the ploughs, onto a ground surface that has been ploughed and has ploughed areas on each side of it. In particular, a first plough 18a is advanced along the direction of travel 34 forming a first ploughed path 40. Second and third ploughs, 18b, 18c follow first plough 18a and overlap first path 40 and also plough through untreated soil to form area of land 30 which has a width greater than path 40.

Other arrangements, configurations and numbers of ploughs can be used, as desired, to plough the area of land 30 in the greater region 32. As an example, ploughs could be used alone, or in side by side or slightly overlapping arrangement, to clear a ploughed pathway or additional ploughs could move together to replough areas or expand the pathway. However, the illustrated plough arrangement provides a level of redundancy and effectively ploughs an area 30 using three ploughs. It may be desirable, if explosive devices are to be removed from further areas of the region 32, to carry out a second pass in which an area of land adjacent to area 30 is ploughed with, for example, a plough overlapping on a portion of area 30 formed by one of the ploughs 18b and 18c. Where a region 32 is to be treated by making a plurality of passes with the plough, and the following steps, it may be useful to make a plurality of passes over the area at any angle transverse to the original passes.

While plough 18a forms leading berms 42, or a single berm if plough has only a single-directional blade, of materials lifted from path 40, ploughs 18b, 18c may consolidate berms 42 with further materials lifted by them to form the berm 38.

After the ploughs have passed, devices for applying pressure such as provers 44a, 44b towed by armoured vehicles 46a, 46b are moved over the ploughed area adjacent berm 38. The provers 44a, 44b apply pressure to the soil, which at a depth of about 0.5 meters can be three times greater than the trigger pressure of any known explosive device. This causes explosive devices that remain in the ploughed 30 area to explode in place. Proving can also serve to compact the soil, which has been loosened by ploughing. The provers 44a and 44b are manufactured to withstand explosions of various explosive devices at close range and/or are formed to ease repair as a result of damage thereto.

To increase the rate of the step of application of pressure, a pressure applying device can be sized such that it spans the distance from the edge of the ploughed area 30 to the edge of the berm 38. The provers 46a, 46b can then make one pass following the direction of the ploughs. Alternatively, the provers 46a and 46b can be sized to prove only a portion of the ploughed area 30.

Thereafter, a berm processor 48 is moved along, to collect the berm material containing explosive devices, soil and other manmade or natural material. Embodiments of processing machines are shown in Figure 5 and Figure 6 that are useful for berm processing. These processing machines will be discussed in greater detail hereinbelow. The berm processor 48 removes some, and preferably all, of the explosive devices from the berm material. It is also useful to collect the berm materials and process them directly so that the soil and other harmless materials from the berm can be returned to the ground, indicated at 50, to region 32 or area of land 30. The explosive devices are stored, destroyed and/or detonated. The berm processor useful in this method is most useful if it is able to traverse the area of land behind the provers and in one pass collect the entirety of a berm, which can be 3 m wide, 1.5 m high and extend continuously along a length of several kilometers. The processors described below can be used to process any earth materials, such as those deposited in berm 38.

After berm 38 is removed from area of land 30, a device for applying pressure such as a prover 44c may be moved over the area on which the berm 38 was located. The prover 44c applies pressure to the surface of the ground, which pressure at a depth of about 0.5 meters can be three times greater than the trigger pressure of any known explosive device. This may cause explosive devices that remain in the ground on which the berm was located to explode in place and can also serve to compact the soil which was distributed on the ground 50, by berm processor 48.

As a final step, a mine detector array (not shown) or a metal detector may be passed over area 30 to determine whether all explosive devices or metal components in that area have been detonated or removed.

Area of land 30, once treated, is deemed generally safe for surface access.

The ploughs 18a, 18b and 18c, provers 44a, 44b and 44c, and berm processor 48 can move separately over an area of land, provided they follow generally the same path, or they can move together such as in a convoy.

Figures 5 and 6 show processing machines 60a and 60b which are useful for processing earth materials, such as those in berm 38 or other loose materials either picked up by the machine or fed to the machine.

In the illustrated embodiments, the processors are mobile and move along by use of tractor conveyors 62 (Figure 5), wheels 64 (Figure 6) or the like. If mobile, the processors should be equipped with consideration as to the terrain that they are intended to traverse. In the illustrated embodiments, the processors move in the directions indicated by arrows "E".

The processors can be powered by an internal combustion engine 66 (Figure 5) or other means. The embodiment of Figure 6 includes a power pack 69. One power pack includes an engine, coolers, generator and drive pump in a unit that can be uncoupled, removed and replaced in a short period of time.

While the processors can be manned, they are preferably remotely operable so that personnel are removed as much as possible from the handling of explosives. Systems for remote operation of machinery are known and can easily be adapted for application to the processing machines. The remote control system would need to have control over the entire operation controlling earth material handling and movement. Cameras can be positioned to facilitate processor operation and driving. A security system can also be provided.

Each processor 60a or 60b includes a material conveyor 70a or 70b such as an auger, a chain or roller driven belt, which moves material from the ground surface and feeds it to the inlet of the processing components 78, wherein the materials are processed and then discharged through outlets 79a, 79b.

The conveyor leading edge 72a, 72b rides along the ground surface and acts to collect earth materials, for example, those of berm 38. In one embodiment of the berm processor, the material collector and conveyor is a modified Star™ pick-up system, the Star™ pick-up system being available from Richard Pearson Limited, UK and is known for use in agricultural applications. In the illustrated embodiments, wheels or skids 74 are provided adjacent to leading edge 72a, 72b to facilitate operation. A funnel arrangement 76 or scoop can also be mounted at leading edge 72b to guide earth materials onto the conveyor. To enhance safety, as much as possible, the conveyor should be selected, as much as possible, to handle and convey the earth materials without detonating the ordinance contained therein.

In one embodiment the earth material is processed while on the conveyor, such that a significant portion is mechanically sorted and returned to the ground 50 through outlet 79b. In particular, with reference to Figure 6, conveyor 70b is formed as a fine sieve through which materials can be sorted based on size. In the illustrated embodiment, the materials passing through the conveyor, termed herein as "conveyor underflow", is passed through a magnetic field generated from a first magnet 84, which collects metal fragments therefrom so that the materials returning to the ground are substantially free of metal contaminants such as shrapnel, bullets, etc. The conveyor underflow can be deposited on the ground in any desired way. For example, in the illustrated embodiment, a baffle plate 80 is positioned below the conveyor to collect the conveyor underflow and pass it to a material conveyor 98, such as a belt, auger, etc. that moves the underflow toward outlet 79a. In one embodiment, the conveyor can be selected to operate on a size selection that retains materials above about 25 to 30 mm and permits smaller materials, which would generally include sand, small rocks and harmless foreign materials, to pass through. The vast majority of the materials in the berm material will be smaller materials that pass through the conveyor sieve. Removing small sized material advantageously reduces the amount of materials that must be handled in the remainder of the processing components 78.

Larger materials, that are retained on the conveyor, are moved up and deposited into material processing components 78. Components 78 can include various sorting or explosives handling devices.

In the illustrated embodiment, larger materials are passed from conveyor onto a sieve plate including a fine sieve 81 and a course sieve 82. Fine sieve 81 is open to baffle plate 80 therebelow so that materials passing therethrough can be handled along with the conveyor underflow. Fine sieve 81 is preferably also selected to size select based on material sizes of 25 to 30 mm. Materials which are unable to pass though sieve 81 are passed, as by sieve orientation, machine vibration or direct vibration, to the coarse sieve. Coarse sieve 82 is also selected to separate materials based on size, for example, to separate large-sized, more powerful explosives from smaller ones, which are easier to handle, detonate and destroy. In one embodiment, coarse sieve 82 has openings selected to retain materials larger than about 100 mm and preferably larger than about 150 mm, termed herein as oversize materials, while smaller materials, termed herein coarse sieve underflow, are permitted to pass through.

The coarse sieve underflow and oversized materials are each handled to remove the unexploded ordinance therefrom.

In the illustrated embodiment, the underflow materials from sieve 82 are directed through a hopper and into a coarse crusher 90, where they are crushed by grinders, hammers, rollers or other means. Coarse crusher 90 is selected to grind rocks, metal and other hard materials and can be, for example, a Komatsu™ rock crusher, modified, as required, to withstand or reduce the effects of explosions generated by the explosive devices to be passed therethrough. Modifications can be, for example, the installation of blast resistant plates or plate configurations.

Materials passing from crusher 90 can be further processed such as by conveyance by conveyor 100 to a second, fine crusher 92, where the materials are further crushed to ensure that no harmful explosive devices are left intact. Materials from fine crusher 92 are released onto outlet conveyor 102 which passes the materials past a second magnet 94 before distributing them to the ground 50 though outlet 79b.

An ordnance magnet 86 functions to remove metal from crusher 90, should it become plugged.

The oversize materials remaining on coarse sieve 82 are generally larger than 150 mm, and may include undetonated explosive devices such as anti-vehicle or anti-tank mines. These materials are transferred, as by use of an automated arm or crane, to an ordnance removal unit 88, where they may be examined by remote camera system to determine the best way to dispose of them. The remote arm or crane or other means can be used to remove objects that are obviously non- explosive, such as shrubbery, from unit 88.

Unit 88 may be designed to be a holding device, intended merely to collect explosive devices, after which they will be transferred, for example by a remote crane, to a location where they can safely be detonated, stored or rendered safe. However, it may be advantageous to form unit 88 with an open top that can withstand, yet direct upwardly, the explosive force of a large explosive device such as an anti-vehicle or anti-tank mine. Alternatively, or in addition, unit 88 may be designed to render safe the explosive devices, for example by incorporating a housing cutter, plasma cutter, a shredder, cutting torch, sound wave generator, water jet, freezing mechanism, chemicals, or crusher. Any destroyed explosive housings can be held in the processor for separate disposal. In one embodiment, unit 88 includes a plurality of plasma cutters, spaced apart and configured for redundancy, each selected to be capable of cutting the explosives to a sufficient depth to ignite the explosive filler material.

Figure 7 shows another embodiment of a sieve and oversize handling arrangement. The sieve is positioned to accept materials from conveyer 70c and includes a fine sieve 81a adjacent conveyer 70c and a coarse sieve 82a adjacent the fine sieve. Fine sieve 81 a is formed as a grate with openings of about 50 mm² and coarse sieve 82a is formed as a grate with openings of about 150 mm². The sieve is sloped with sieve 81a at a higher vertical configuration then sieve 82a so that materials that are excluded from passing through the fine sieve tend to move, by gravity, toward the course sieve. In the illustrated embodiment, the sieve is sloped to position one corner 100 thereof in a lowermost position so that oversize materials from the coarse sieve are driven, by gravity, toward that corner.

Four cutting torches 102 (shown in phantom) are positioned at corner 100 to cut all oversize materials that pass into the corner, those materials having been excluded from passing through the fine and coarse sieves. The four cutting torches are spaced to ensure coverage of the area of this corner and to permit redundancy should one or two of the torches fail during operation. Corner 100 opens into a chute 104, such that materials passing under the torches can then be dumped, by gravity into a storage bin (not shown). Chute 104 has mounted therein additional torches 106 to ensure that materials passing into the storage bin have been adequately cut to expose and burn all of the explosive filler. The storage bin can be emptied regularly and the explosives recovered therefrom for disposal, while rocks or other safe materials can be returned to the ground. As is apparent, processors according to the present invention can have only one crusher or, alternatively, two or more crushers. It may have more or fewer sieves, which allow for larger or smaller materials to pass therethrough, and/or it may have more or fewer conveyors, magnets, or outlets and in other configurations. The ordinance removal unit can be modified as desired, or omitted if it is apparent that all ordinance in the area of land can be handled by the other processing components. All of these embodiments are intended to be included in the scope of the invention disclosed herein.

As will be appreciated, many of the processor parts, such as wheels, undercarriage, conveyors, sieves, crushers, etc. can be exposed to intentional or inadvertent explosions. As such, the material handling areas can be of open design to allow any explosive effects to vent. As will be appreciated, it is sometimes also useful to buffer explosions, rather than venting them. As such, to facilitate use it is desirable that the conveyor parts be easily replaceable or repairable, as much as possible, in the event that they are damaged due to an inadvertent explosion. Shielding should be used to protect more sensitive parts, such as generators, electronics, cameras, etc. Ease of repair and durability is also desirable, when considering the normal operating conditions of the processing machine.

Claims

We claim:

1. A method for removing explosive devices from an area of land comprising:

. (a) treating an area of land with a plough to create a ploughed land area with an exposed ground surface and a ground surface on which a berm, containing soil and explosive devices, is deposited by the plough;

(b) processing the berm to substantially remove the explosive devices from the soil; and

(c) applying pressure to the ground surface of the ploughed land area, the pressure selected to detonate at least some explosive devices in the ploughed land area.

2. The method of claim 1 , further comprising the step of applying pressure to the ground surface on which the berm had been located, the pressure selected to detonate at least some explosive devices in the ploughed land area.

3. The method of claim 1 or 2 wherein the pressure applied to the ground surface is sufficient to exceed the highest known trigger pressure of any explosive device at a depth of about 0.5 meters below the ground surface.

4. A method for removing explosive devices from an area of land comprising:

(a) treating an area of land with at least one plough to create a ploughed land area with an exposed ground surface and a ground surface on which at least one berm, containing soil and explosive devices, is deposited by the plough;

(b) processing the at least one berm to substantially remove the explosive devices from the soil; and (c) applying pressure to the ground surface of the ploughed land area, the pressure selected to detonate at least some explosive devices in the ploughed land area.

5. The method of claim 4, further comprising the step of applying pressure to the ground surface on which the berm had been located, the pressure selected to detonate at least some explosive devices in the ploughed land area.

6. The method of claim 4 or 5 wherein the pressure applied to the ground surface is sufficient to exceed the highest known trigger pressure of any explosive device at a depth of about 0.5 meters below the ground surface.

7. The method of claim 4 wherein two or more ploughs plough two adjacent smaller areas within the ploughed land area, and deposit a berm between the two adjacent smaller areas.

8. A method for removing explosive devices from an area of land comprising:

(a) ploughing a first area of land with a plough, to create a first ploughed land area with an exposed ground surface and two berms containing soil and explosive devices, deposited by the plough, one each on opposite edges of the ploughed land area;

(b) ploughing a second and third area of land parallel to the first area of land, with a second and a third plough, to create a second and a third ploughed land area with exposed ground surfaces, the second and third ploughed land areas each overlapping one of the two berms, said second and third ploughs removing the two berms and depositing a new berm therebetween;

(c) processing the new berm to substantially remove the explosive devices from the soil; and

(d) applying pressure to the ground surface of the second and third ploughed land areas, the pressure selected to detonate at least some explosive devices in the ploughed land area.

9. The method of claim 8, further comprising the step of applying pressure to the ground surface on which the new berm had been located, the pressure selected to detonate at least some explosive devices in the ploughed land area.

10. The method of claim 8 or 9 wherein the pressure applied to the ground surface is sufficient to exceed the highest known trigger pressure of any explosive device at a depth of about 0.5 meters below the ground surface.

11. The method of claim 1 , 4 or 8 wherein the plough is a mining plough.

12. A machine for processing berm material, with an inlet and one or more outlets, comprising:

(a) a collection means to collect the berm material from a ground surface;

(b) a first conveyer that conveys the collected berm material to a material processing device and deposits it therein;

(c) a size sorting means to separate the berm material into a first selected portion and second selected portion, between the time that the material is collected from the ground surface and the time that it is deposited into the material processing device, such that only the second selected portion is deposited into the material processing device;

(d) one or more crusher means to crush the second selected portion to create a crushed portion; and

(e) an outlet conveyer to convey the first selected portion and the crushed portion past at least one magnet for removing metal from the first selected portion and the crushed portion, and then deposit both said portions onto the ground surface through said one or more outlets.

13. The machine of claim 12 wherein the size sorting means is a first size sorting means, further comprising:

(a) a second size sorting means that removes from the second selected portion a third selected portion, before said second selected portion is crushed by said crusher means; and

(b) a means of conveying the third selected portion to an ordnance removal unit and depositing it therein.

14. The machine of claim 12 or 13 wherein the first and second size sorting means are sieves.

15. The machine of claim 12 or 13 wherein the first conveyor is both a conveyor and a size sorting means.

16. The machine of claim 12 or 13 wherein the second and third selected portions comprise one or more explosive devices.

17. The machine of claim 12 or 13 wherein the ordnance removal unit is capable of withstanding the detonation of an explosive device deposited therein.

18. A processing machine for processing earth materials to remove explosive devices therefrom, the processing machine comprising: an inlet to receive earth materials, processing means to process the earth materials to remove at least some of the unexploded ordinance contained therein, resulting in processed earth materials, and an outlet to pass the processed earth materials out of the processing machine.

19. The processing machine of claim 18 further comprising a collection means for collecting the earth materials and conveying means for conveying the earth materials to the inlet.

20. The processing machine of claim 18 further comprising a means for sorting the earth materials into a first portion selected to be substantially free of unexploded ordinance and a second portion selected based on the possibility of containing unexploded ordinance, prior to the introduction of the earth materials to the inlet, such that only the second selected portion is deposited into the material processing machine and handled by the processor means.

21. The processing machine of claim 18 further comprising a means for sorting the earth materials into a first portion selected to be substantially free of unexploded ordinance and a second portion selected based on the possibility of containing unexploded ordinance, and the first portion is handled by the processing means at least in part separately from the second portion.

22. The processing machine of claim 20 or 21 , wherein the means for sorting operates based on size selection.

23. The processing machine of claims 20 or 21 , wherein the means for sorting is a conveyor selected to move the earth materials and formed to permit passage therethrough of the first portion, the materials of the first portion being below a selected size and to retain and convey the second portion.

24. The processing machine of claim 23 further comprising a collection means to collect the first portion after it has passed through the conveyor.

25. The processing machine of claim 21 further comprising a magnet to process the first portion to remove metal contaminants therefrom.

26. The processing machine of claim 21 wherein the second portion is processed to render safe any unexploded ordinance.

27. The processing machine of claim 21 further comprising a sorting means for processing the second portion to separate more powerful unexploded ordinance from those easier to handle.

28. The processing machine of claim 27, wherein the sorting means operates on size selection.

29. The processing machine of claim 18 wherein the processing means includes a crusher.

30. The processing machine of claim 18 wherein the processing means includes a cutter for cutting an explosive housing.

31. The processing machine of claim 18 wherein the processing means includes a magnet for removing metal contaminants from the earth material.

32. The processing machine of claim 18 wherein the outlet configured to return the processed earth materials to a ground surface.