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More than 100,000 weapons were handed to police during a national knife amnesty. But how did they get rid of them?
Police attended the crushing
The aim was to get as many knives handed in as possible, but the five-week national knife amnesty left police with another problem - disposal.
The weapons handed to police included cut-throat razors, samurai swords, axes, machetes, meat cleavers and a bayonet from 1880. On Friday, the Metropolitan Police disposed of the knives, but how was it done?
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The weapons were recycled at a specialist metal recycling plant in Hertfordshire. The company - H Williams and Sons - offers a secure "mutilation service" for sensitive products like knives.
It guarantees the knives are destroyed beyond recognition so they do not get back onto the streets.
The service operates under tight security. To destroy the weapons the company secured the site, so no one could walk in off the street, and police officers attended the actual mutilation process.
More than 100,000 weapons is a sizable amount but the company has machines capable of processing 250,000 tonnes of material per year.
"All the knives took about five minutes to mutilate," says George Bond, director of the recycling company.
"We have a purpose-built processor for breaking down steel-based products, it has a 6,000 horsepower electric drive. It can crush 10 cars in one minute."
The pulverised particles of steel were sorted to remove all non-metal material, like crushed plastic handles. The steel was then sent on a train to Cardiff and by the end of Monday will have been melted down and made into reinforcement rods for concrete blocks in new buildings.
The knives will become rods
The secure process is used by a lot of companies and government departments, as well as the police. The jobs include disposing of highly-secret prototype designs to make sure they are not copied and potentially useful parts do not get into the commercial market.
"We do work for Jaguar, the Ministry of Defence, a lot of people who need stuff securely disposed of," says Mr Bond. "The worst job I have had to do is crush 27 Lotus sports cars, they were beautiful and it was really hard."