The present invention relates to a device for removing explosive material such as old ammunition and the like from soil according to the preamble of claim 1.

Such a device is known form DE-A 3 335 464 in which by means of the spray lances liquid jets are directed to explosive materials such as mines. The object of said known device is to push the mines out of the roadway by liquid jets in such a manner that in case of an explosion there will be no or little damage. Said known device is not suitable for removing explosives from soil in case said explosives cannot be detected by sight and have for example been in the ground since the last world war.

The object of the invention is to provide a device by means of which these explosives can be efficiently separated from the soil, and with which optimum safety for the operating personnel is ensured.

This object is achieved according to the invention by means of the features of the characterizing part of claim 1.

The soil is emptied into the collection bin of the device by means of a conventional excavator which is armoured against possible explosions. A powerful jet of water is then directed on the soil with the spray lance, so that sand and mud are taken through the perforated plates to the collection tank situated underneath the collection bin. Larger pieces and possible explosive objects remain behind in the collection bin and can be removed from it. Explosive objects can be recognized as such and rendered harmless. During the flushing away of the soil, the personnel are in the armoured cab of the machine and run practically no risk in the process, while still being able to have a good view of the work.

It has to be noticed that from US-A 3 395 798 a collection bin is known for separating materials. In this known collection bin the materials are vibrated and washed in order to separate the larger materials from the smaller materials. In the device according to the invention it is important that the explosive materials can be recognized as such and therefore the mud and soil is sprayed away by means of the liquid jets, the soil being discharged from said device by means of a pump.

It is preferable to have disposed along the side of the walls of the collection bin a spray pipe, which is connected by means of a valve to the water supply pipe of the spray lance. This spray pipe is for flushing the grid and the collection bin clean.

In a preferred embodiment of the invention, one or more spray nozzles are disposed in the collection tank, and are connected to the water supply pipe of the spray lance. These spray nozzles are for the purpose of maintaining water circulation when the spray lance and the spray pipe are not in operation. This prevents the discharge pump accommodated in the discharge pipe from running dry.

The spray nozzles are preferably connected to the water supply pipe by means of an excess pressure valve.

When the spray lance and the spray pipe are not in operation, the pressure in the water supply pipe will increase, and this rise in pressure causes the valve to the spray nozzles to open, so that a water supply to the discharge pump is automatically ensured.

The walls of the collection bin are preferably clad on the inside with wood, so that if an explosion takes place, ricocheting of shell splinters and the like against the walls is avoided. The wood also provides effective protection for the walls. Since the perforated plates forming the bottom of the collection bin are detachable, they can easily be replaced if damaged by any explosion.

The invention is explained with reference to the appended drawing, in which:

• Fig. I shows a schematic cross section of the device according to the invention; and
• Fig. 2 shows a top view of the device of Fig.l.

As can be seen in particular from Fig.1, the device according to the invention comprises a mobile frame which is provided with caterpillar tracks I, a control cab 2, and a collection bin 3. The cab 2 is provided with panels 4 of armour-plated glass, and is designed in such a way that operating personnel in it are virtually fully protected against a possible explosion.

The collection bin 3 is rectangular in top view, with upright walls 5, which are clad with wood on the inside, preferably with deal about 2.5 cm thick. The wood cladding provides effective protection of the upright walls, on the one hand, while the ricocheting of shell splinters against the walls is avoided, on the other. The bottom of the collection bin 3 consists of a grid 6, which is formed by a number of perforated plates which are disposed detachably and can thus easily be replaced in the event of damage. Under the collection bin 3 is a collection tank 7, which is trough-shaped with downward-sloping side walls. Near the bottom of the collection tank 7 is a discharge pipe 8, in which a discharge pump is accommodated, suitable for pumping a water and soil mixture, and driven by a hydraulic motor 10. The discharge pipe 8 extends to the rear side of the device and a discharge pipe (not shown) can be connected to it. If the water and soil mixture has to be transported over a distance of more than I km, extra pumps of the same type as pump 9 will have to be disposed in the discharge pipe.

The device is also provided with a water supply pipe II which extends forwards from the rear side thereof and divides near the front of the cab 2 into a pipe 12 which leads to a spray lance 13, disposed above the collection bin 3, and an essentially through pipe 14. The spray lance 13, which can be controlled from the cab, is of a known type and need not be described in detail here. Connected to the pipe 12 is a branch pipe 15, which extends along the inside of the walls 5 of the collection bin 3 and is provided at regular intervals with openings. The pipe 15 thus forms a spray pipe for flushing away the material through the grid 6.

The through pipe 14 leads to a spray nozzle 16, which is provided inside the collection tank 7 under the grid 6, and the object of which will be clear in the description of the working of the device. Disposed in the pipes 12, 15 and 14 are valves 17, 18 and 19 respectively. Connected to the pipe 12 is another pipe 20 for feeding a screen washer for the windscreen of the cab.

The vehicle is driven by a diesel engine 21, which also drives the hydraulic motor 10 and hydraulic pumps 22 for placing the water supplied by the pipe II under pressure.

The device according to the invention works as follows:

• Ground in which possibly explosive objects could be present is excavated using a conventional excavator, which is provided with suitable safety facilities, and is emptied into the collection bin 3. By means of the spray lance 13, a powerful jet of water is directed onto the soil in the bin 3, so that sand and mud and other small particles are flushed away through the grid 6 to the collection tank 7. The large parts and possibly explosive objects remain sprayed clean on the grid 6. Any explosives can be recognized as such and rendered harmless. The collection bin 3 is then emptied, and a new load of soil is emptied into the collection bin 3. During the examination for explosives left behind on the grid 6 and the removal thereof, the spray lance 13 is stopped by means of the valve 17, and the spray pipe 15 by means of the valve 18. This gives rise to the danger that the pump 9 for discharge of the soil and water mixture will run dry, which could lead to damage to it. However, the shutting off of the spray lance 13 and the spray pipe 15 gives rise to an increase in the pressure in the water supply pipe II. If the valve 19 is designed as an excess pressure valve, this increase in pressure results in the valve 19 opening and water being fed through the spray nozzle 16 into the collection tank 7. In this way the water circulation is maintained when the spray lance 13 and the spray pipe 15 are out of action, and damage to the pump 9 is avoided.