Street cleaners find riches in waste

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It seems Dick Whittington was right: the streets really are paved with gold - and now a company is to start looking for it.

One of Britain's biggest street-cleaning firms says it will "mine" the sweepings it collects from roads and pavements for gold and other precious metals.

Veolia Environmental Services believes it can find at least 1 million ($1.9 million) worth of platinum, palladium and rhodium from the muck swept up from Britain's streets each year.

These metals are commonly used in catalytic converters and tiny amounts can be thrown out by car exhausts which then settle on street surfaces. Fragments can also rub off clothes, shoes and jewellery.

Until now, street sweepings have been sent straight to landfill or compost sites, but Veolia has established the country's first plant to extract precious metals from the material. The rubbish will go through a number of processes, including filtration and chemical washes, to extract the valuable substances.

Richard Kirkman, Veolia's technical director, said: "In the past we have always sent our street sweeping to landfill or compost sites.

"We wanted to find something to do with this material, so we are separating everything out with flotation tanks and mechanical sorting machines. We are left with this fine black dust and we have found palladium, rhodium and platinum at levels they are found in the ore when it is mined from the ground."

Veolia has contracts to sweep streets in 40 towns and cities and collects up to 165,000 tons of sweepings a year. Across Britain, about 440,000 tonnes of street sweepings are collected annually.

The company estimates that up to 1.5 tonnes of rare platinum could be recovered from these each year. Platinum is highly prized for jewellery and is used in electronic equipment.

Veolia also believes it can recover 1.3 tonnes of palladium, which is also in electronics and jewellery. Demand for this metal is increasing as it is a key component in new fuel cells used in hydrogen-powered cars.

There could also be around 0.8 tonnes of rhodium in the sweepings. Shortages of this metal saw its price rise to more than 6000 an ounce in 2008. Veolia hopes to open three extraction centres to mine street sweepings and is looking at other sources of metal, such as waste water.

The practice of searching for precious metals among rubbish began in Mumbai, India, where street sweepers panned for gold dust amid the sewerage pipes in front of goldsmiths' houses. In New York, Raffi Stepanian, a self-styled urban prospector, claimed he could make up to US$800 ($1000) a week collecting fragments of gold, diamonds and rubies from the Diamond District, where merchants accidentally picked them up on their clothes.