China in your hand

At first glance, it's almost like being on the surface of the moon. Great, undulating dunes of white sand stretch away as far as the eye can see, occasionally pitted with pools of a strangely luminous blue water. The only hints of human life are the diggers which crawl across the landscape like giant insects...

However, this is right here on planet earth. In Cornwall, to be precise, where enormous tranches of the county's countryside have been buried beneath the waste from two and a half centuries of mining and quarrying china clay. In the industry's heartland, around the town of St Austell, over 500 million tonnes of waste have been tipped, occupying over 1,700ha. And with an extra 20 million tonnes of waste created each year by the china clay industry, this amount will only grow.

This represents a vast, largely untapped aggregates resource, which the construction industry is slowly becoming aware of. It's potential has been spotted by Bardon Aggregates, a subsidiary of Aggregate Industries, which is working to develop its market potential with Imerys Minerals, formerly known as English China Clays and the biggest producer of china clay in this country.

"China clay waste has been used as a construction material for years in Cornwall, but with the advent of the Aggregates Levy its market is expanding rapidly," explains Tom Hilton, general manager of Bardon's Cornwall & Plymouth area business.

Exempt from levy

Though technically a by-product of a primary aggregate, china clay waste is exempt from the levy. This has caused a few murmurings of discontent elsewhere in the aggregates industry, but Bardon and Imerys are getting on with the job of selling the product.

They are being encouraged by a progressive county council, which has promoted extensive use of recycled and secondary aggregates within Cornwall over the past decade.

"Our policy has been to encourage its use as far as possible," explains David Owens, minerals planning officer for Cornwall County Council. "The use of china clay waste within the county has more than doubled since 1993 to 1.7 million tonnes, and last year, secondary aggregates (principally china clay waste) accounted for more than half of all aggregates used in Cornwall." This compares to a national average of just 10%.

"We see it as killing two birds with one stone," continues Owens. "Providing a cheap and potentially enormous source of aggregates; and at the same time, cleaning up the environment around the china clay quarrying areas."

The amount of waste generated by china clay extraction is considerable. For every tonne of clay extracted - around 2.5m last year - nine tonnes of waste are generated as a by-product. This comprises roughly six tonnes of granular sand and gravel, two tonnes of stent (crushed rock), and a further tonne of micaceous waste.

According to Bardon's Hilton, the waste products have "a wide range of uses".

"The sand has been used mainly as a readymix concrete sand," he continues. "We're only in the second year of exploiting the potential of the stent. Some of the materials are slightly weaker than virgin aggregates, but mostly, it's as good as any granite."

China clay waste has proved particularly popular as an alternative material for use in roads. For example, on the A30/A39 Fraddon-Indian Queens bypass in mid-Cornwall, china clay waste accounted for 30% of the concreting sand used and 90% of the sub-base.

It was also used in the foundations of the Eden Project, which was actually sited on a former china clay quarry.

Cornwall County Council has been keen for china clay waste to gain wider recognition and use as a construction material nationally, recognising the economic benefits for the county of developing the product's 'export market'. It even commissioned a study into the possible benefits of using china clay waste in the construction of the Second Severn Crossing, though this ultimately proved unsuccessful.

Tackling the transport problem

The major problem for furthering the use of china clay waste around Britain is transport - being in the far south west of the country, costs of transporting the materials are huge. What little material has been sold outside of Cornwall and Devon has been transported by rail.

But there is another option that is being explored - sea transport.

Most of the china clay quarrying areas are close to the port of Par, and the plan is to construct a new £20m freight terminal there, which would allow china clay waste to be transported to other parts of the country cheaply and efficiently. Bardon Aggregates and Imerys are both keen to push the plan forward.

"We want to build a new jetty, add two more shipping berths and add rail links to the china clay pits," says Clive Kessell, sales manager at Imerys Minerals. "If we could build the port, then it would potentially add another 750,000 tonnes a year to the 1.6m we sold last year."

Imerys owns the land on which the terminal would be built, and the plan is backed by the county council, with other financing likely to come from Cornwall's (European) Objective 1 Funding. However, the Strategic Rail Authority's decision last month to cap Freight Facilities Grants may put the brakes on the project; Bardon and Imerys were counting on a significant chunk of funding from the SRA to help pay for the rail link.

That hitch notwithstanding, the potential for further growth in use of china clay waste remains good, given the direction of local, national and European environmental policy. The government's MPG6 (Minerals Planning Guidance) publication of 1994 set a target of 40m tonnes of aggregates to come from secondary or recycled sources by 2001, rising to 55m by 2006.

As Kessell says: "In terms of cost, china clay waste is on a par with primary aggregates, but it's the green label you can put on it that makes it particularly attractive for clients like local authorities. It fits in with their sustainability objectives." n