The kiln, above, can reach temperatures in excess of 1000CThe Lafarge cement works is a burning issue in Westbury and Wiltshire Times reporter Ed Mezzetti went on a tour of the plant which has been a key feature of the town for over 40 years.

TOURING Westbury cement works may not sound like the most interesting way to spend a Friday morning, but it turned out to be a real eye-opener.

Guided by communications manager Alistair Gale, I followed the cement making process from quarry to bag and got up close and personal with a 1,000-degree kiln.

While the factory's existence is unmissable by its towering chimney that dominates the skyline, the location of its chalk quarry near the White Horse is rather more hidden.

But when you realise that cement is 80 per cent chalk, its importance cannot be under-estimated.

A trip to the site revealed what you might expect in terms of diggers and trucks scurrying around. What is not immediately apparent is that the chalk slurry is transported down to the works via an underground pipeline that carries 1m tonnes of it every year.

Works manager Real Simard explained that Westbury chalk has 20 per cent moisture and therefore making cement was a 'wet process,' and different from the 'dry' quarries Lafarge has elsewhere.

He said: "Our process has advantages because it is more stable and produces better quality cement.

"But we also need 40 per cent more energy to evaporate the water so we have to make sure that the fuel costs are less."

The chalk is then mixed with clay, which is extracted much nearer to the plant, and a few other raw materials. This slurry is fed into the two kilns fired by coal with old tyres inserted half way down for an extra energy boost.

Although a controversial addition to the heating process, an Environment Agency trial revealed tyre burning reduced the works' impact on the environment by a quarter.

Mr Gale said: "As of July 2003 whole tyres could no longer be put into land fill sites. The UK gets rid of 40m tyres a year and Lafarge deals with 3m of them, which is a pretty good percentage."

The trial burning of recycled liquid fuel (RLF) next year will further reduce the amount of coal used and Lafarge says it will also have environmental benefits.

At its peak the mix reaches 1,450C before exiting as a hard, gritty material called clinker. This is ground with gypsum to make the cement powder, which is bagged or loaded straight into tankers.

My tour also included much of the 'behind the scenes' work like the plant's central control room. From here a computer network monitors over 6,000 sensors across the works and collects emissions data fed directly to the Environment Agency.

Next door in the laboratory I met chemist Chris Easton, who has been at the works for 37 years. One of his main jobs is to x-ray pellets of the product at each stage to check for quality.

He said: "The raw materials are tested every 30 minutes for a period of eight to 10 hours a day. Next month we will be using a new £115,000 machine and there has been a total investment of nearly £200,000 for the laboratory side.

"Since I've been here the workforce has gone from 400 to 130. I've seen a lot of changes, but I still enjoy it."

FACTFILE

Lafarge is a French firm with a presence in 75 countries and 75,000 employees worldwide.

In Westbury, Lafarge employs 130 staff and 95 per cent live within five miles of the plant.

The works opened in 1962 and a second kiln was added in 1965. It produces over 700,000 tonnes of cement a year and contributes £10m to the local economy.

The company bought out Blue Circle in July 2001 to become the world's largest cement manufacturer, but continues to use the Blue Circle name for its cement products.

The Westbury works is under-going a £10m refurbishment, which includes replacing over 90m of the two kilns' steel shells.

The peak temperature the cement mix reaches in the kilns is 1,450C, more than six times hotter than a standard oven.

The works burns 250,000 tyres a month and 3m a year and these are delivered from across the south of England.

The chalk quarry has nine years' reserves remaining and if the extension is permitted this will increase to 28.

One of the other raw materials added into the slurry is pulverised fuel ash, a by-product of power stations.

The record number of cement bags produced in an eight-hour shift at Westbury is 27,500.

The plant is the only cement works in the south west and its product has been used in major buildings including Cribbs Causeway Shopping Mall.