© UNMAS/Giovanni Diffidenti
© UNMAS/Giovanni Diffidenti

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Stockpile Destruction

Stockpiled landmines far outnumber those actually laid in the ground. In accordance with Article 4 of the anti-personnel mine-ban treaty, State Parties must destroy their stockpiled mines within four years after their accession to the convention. Sixty-five (65) countries have now destroyed their stockpiles of antipersonnel landmines, destroying a combined total of more than 37 million mines. Another 51 countries have officially declared not having a stockpile of antipersonnel mines and a further three countries are scheduled to destroy their stockpiles by the end of the year.

There are many options available to states in destroying their stockpiles. Stockpiles are usually destroyed by the military, but an industrial solution can also be employed. The techniques used vary depending on the make-up of the mines and the conditions in which they are found. The complete destruction cycle involves aspects such as transportation and storage, processing operations, equipment maintenance, staff training and accounting, as well as the actual physical destruction.

The United Nations has a general responsibility to encourage and support the effective management of stockpile destruction programmes. Accordingly, the International Mine Action Standards developed under UN auspices, also deal with stockpile destruction.

 

Technology

Overview

The techniques used for stockpile destruction are varied, representing the differences which exist in the make-up of anti-personnel mines and the diverse conditions in which they are found. Detailed cost-benefit studies must be done by states to determine the most efficient, safest and cost-effective means to carry out the destruction of their stockpiled AP mines. For more information on International Mine Action Standards, visit IMAS' site.

Pre-Process

It is may be necessary to disassemble or breakdown anti-personnel mines prior to the destruction process. This is necessary because of limitations on the amount of contained explosive that can be incinerated, the anti-personnel mine design or the requirement for different components to have separate destruction methods. All of these methods require the movement of exposed bare explosive to the final destruction facility. Available technology includes: manual disassembly, mechanical disassembly (pull apart, defuzing and depriming), robotic disassembly, mechanical breakdown (bandsaw, guillotine, cracker mill, rock crusher, punch), cryofracture, hydro abrasive cutting, laser cutting, and microwave explosive melt-out. The following are brief descriptions of these techniques:

Manual Disassembly

This technique implies the use of human resources to physically dismantle APM by manual labour using simple hand tools. It has the advantage of requiring limited capital investment required, but is a labour intensive process which results in relatively slow production rates. This method requires well-trained, yet semi-skilled staff.

Mechanical Disassembly

The use of mechanically operated systems to dismantle APM. The different technologies are available, as noted above are: Pull Apart, Defuzing and Depriming. In contrast to manual disassembly, mechanical disassembly has the advantages of high production rates, it is an efficient system of work and has low staff requirements. It is environmentally friendly for this stage of the demilitarisation cycle and the technology is readily available. A major disadvantage, however, is the requirement for high capital investment. This is further complicated by the need for a wide range of equipment necessary to cope with all pre-processing requirements.

Robotic Disassembly

A fully automated disassembly system. Similar advantages and disadvantages to mechanical disassembly, however the initial capital costs are much greater. This system would only be economically efficient for very large production runs due to the high start-up costs.

Mechanical Breakdown

This process is mainly concerned with techniques required to expose the explosive fillings of APMs prior to the destruction phase. There are low staff requirements for mechanical breakdown, and it is an environmentally friendly operation during this stage of the demilitarisation cycle. The technology is now readily available and there is no secondary waste stream, which reduces scrap salvage and disposal costs. A major disadvantage is the requirement for high capital investment. This is further complicated by the need for a wide range of equipment necessary to cope with all pre-processing requirements. Production rates per machine can be slow and there is always te danger of induced initiation of the target APM during processing.

Cryofracture

This process is used to break down an APM into small enough pieces to be processed through an incineration destruction method. It involves the use of liquid nitrogen to change the mechanical properties of the munition casing to a more brittle phase by cooling it to -130 C. The munition can then be easily shattered using simple mechanical shear or press techniques. A cryogenic wash out system is in the early stages of development. The principle is similar to cryogenic fracture; except that the filling is attacked with liquid nitrogen in order to make its removal easier.

Cryofracture is an environmentally friendly technique during this stage of the demilitarisation cycle with low staff requirements. The technique can also be used for any other type of munition, explosive or propellant with limited pre-preparation of the munition required. There is no secondary waste stream, hence cutting final disposal costs. In financial terms low capital investment only is required for set up costs. Sensitivity tests have shown that even at -196C there is little change to the insensitiveness of the munition.

The disadvantage of high operating costs for liquid nitrogen usage must also be considered, however. Unfotunately, today there is only one proven production system in place. APMs with metal or aluminium casings are not susceptible to embrittlement and variations in the shear forces or pressures are required to fracture the munition casing. Further trials are necessary, as analysis has shown that the failure modes for the munition casings involved a mixture of brittle fracture, plastic deformation and shearing. Results are currently unpredictable and there is an obvious low temperature hazard to personnel.

Hydro abrasive cutting (HAC)

The use of water and abrasives at pressures from 240 to 1000 BAR to cut open APM bodies by an erosive process. There are two distinct technologies; 1) "entrainment" or 2) "direct injection". Research has now proven that the direct injection technology should be the preferred option for safety reasons. There are low staff requirements for HAC systems and a wide range of target munitions can be attacked. The explosive safety of systems is well proven and it is a cost effective technique in comparison to other pre-processing methods.The major disadvantage is the requirement for initial high capital investment for infrastructure. The systems also produce contaminated waste-water, which requires a complex filtration system to clean it up. In terms of post-process operations, the explosive content is "grit sensitised" and requires careful handling during any further processing or destruction.

Laser Cutting

Still in the research phase in the USA.

Microwave Melt-Out

This technology is also under development in the USA. It utilises microwaves to heat up TNT based explosive fillings. It is a rapid, clean technique but has one major disadvantage, the lack of control over heating can lead to the formation of "hot spots" with a resultant initiation of the filling. Work continues on its development, but it is not yet a feasible production technique. It is more energy efficient that steam and improves the value of any recovered explosives.

Destruction

There are a wide range of industrial technologies available for the final destruction ofanti-personnel mines. The selection of the most suitable principle depends primarily on the pre-processing techniques to be utilised, and vice versa. The system must be designed to result in efficient production rates.

Open-pit Incineration

Waste material is placed on a tiled floor in a purpose built pit equipped with perforated air pipes to supply forced air to the system. A turbulent air current is created above the fire that re-circulates the combustion gases and particulates, which assists in full oxidation of the evolving gases. The principle has been tested, but no large scale trials have yet been conducted.

Rotary Kiln Incineration

This is perhaps the most common, and certainly most mature demilitarisation destruction technology available. The rotary kiln is an unlined rotary furnace originally designed to destroy small arms and bulk explosives. The kiln is made up of four 1.6 metre long, 1 metre outer diameter retort sections bolted together. The 6 to 8 cm thick walls of the kiln are designed to withstand small detonations. The kiln contains internal spiral flights, which move the waste in an auger-like fashion through the retort as the kiln rotates. The flights also provide charge separation for the in-process materials, and discourage sympathetic detonations and scattering of materials. The kiln is equipped with a variable speed drive, which allows varying rotation speeds and material residence time.

Car Bottom Furnace

Used to destroy small amounts of explosive or explosive residue left after flush-out pre-processing techniques.

Directly Heated Retort

Thin walled and ceramic lined in which the feed system uses an auger. Pre-processed by a crusher. Used to process general chemical waste and explosive in solution. A typical production rate of 10,000 tonnes per year.

Plasma Arc

A Plasma torch, at temperatures in the region of 4000C to 7000C, is used to heat a container into which waste products are fed. The plasma is an ionised gas at extremely high temperature, which is used to initiate rapid chemical decomposition by the action of this extreme heat. The material is currently fed in a slurry form, although research is ongoing for the destruction of entire munitions. It is a complex production system that has a high power requirement. 

Mechanical

The use of high strength and capacity commercial crushing or shredding machines. Only suitable for APMs with a very low net explosive content.

"Silver 2"

An electro-chemical oxidation process. The organic waste is treated by the generation of highly oxidising species in an electro-chemical cell. The cell is separated into two compartments by a membrane that allows ion flow but prevents bulk mixing of the anolyte and catholyte. In the anolyte compartment a highly reactive species of silver ion attacks organic material ultimately converting it to CO2, H2O and non-toxic inorganic compounds. 

Biological Degradation

This technology has been demonstrated at the pilot level for the destruction of per chlorate contaminated aqueous streams. The potential exists for bacteria to be used to consume the explosive content of APM, converting it into inert material. It requires extensive storage capacity whilst bio-remediation is taking place and only has limited applications. There is also a requirement for an element of mechanical breakdown prior to the addition of the bacteria.

Contained Detonation

The destruction of ammunition and explosives by detonation in an enclosed chamber. The evolving gases are then processed by an integral pollution control system. Limited pre-processing is required and a wide variety of ammunition natures can be destroyed. However, the available systems are currently limited to 15 Kg Net Explosive Content. There is also a requirement for a donor charge for each detonation, therefore the process is expensive in serviceable ammunition usage.

Molten Salt Oxidation

Only demonstrated at prototype scale. Can destroy finely divided and consistent organic waste, therefore significant pre-processing required. These wastes can be destroyed by incineration anyway.

Scrap Processing

The final disposal of arising from any of the above systems will require some form of scrap processing facility. Commercial advice is required in this area to determine the production rates, technical capability and availability of systems.

Industrial scrap processing systems work by crushing, shredding, cracking or compressing the feed material into an easily manageable form for further salvage or recycling processes. There may be a requirement for a combination of techniques for scrap that is difficult to process.

Policy

Countries that do not have the resources financial, technical or otherwise to destroy all their stockpiles have avenues available to help them ensure that their anti-personnel mines are safely and completely destroyed. Under Article 6 of the anti-personnel mine-ban treaty, nations in need can appeal to other States Parties for assistance in fulfilling their requirements. In order to guide the delivery of assistance from the international community, the United Nations has formulated a consolidated policy framework on stockpile destruction that compliments the efforts of States Parties through the Standing Committee on Stockpile Destruction.