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Sieves & Screens Flour power

Modern screener in old water mill produces high quality flour If visitors from centuries past returned to a familiar footpath by

the River Gowry in northern England, they might be shocked by changes that have taken place, but there would be one comforting sight—the old mill with its large water wheel (although our visitor would probably be surprised to see a steel wheel rather than a wooden one). Powered by a stream diverted from the river, the wheel works through gears to grind wheat into flour for making bread.

Inside the mill the wheat is ground between two flat, 135 cm dia millstones, a method employed for hundreds of years. However, our time traveler would likely be puzzled by some of the equipment, in particular an electrically driven centrifugal screener. The Centri-Sifter centrifugal sifter, as it is called, was supplied by Kason Corp. (Millburn, New Jersey, USA) and recovers the mill’s two basic products: white and whole meal flours. There has been a water mill at the site since the 13th century, but the present building—Walk Mill—is no older than the screener, despite its aged appearance. Rebuilt as a replica of an earlier mill, the new facility started up in 2008. The last mill on the site ceased production in 1915 and only

the footprint of the building was left, says Ben Jones, a partner in the family-owned business, who is in charge of mill operations. “We dug the foundations to find the footprint of the building and we also had a lot of photographs of the old mill. From the footprint and the pictures we were able to construct a building that is exactly like the old mill on the outside.”

Wheat is at hand

Located on the fertile Cheshire plain, close to the historic city of Chester, Walk Mill is surrounded by roughly 405 hectares of wheat fields that were acquired by the Jones family some years ago. “We have always been farmers, says Ben Jones, “and after we bought this land we decided to rebuild the mill.” Wheat is harvested from the fields, dried to reduce the moisture content and cleaned to remove chaff. It is then taken to the mill in a sealed trailer and loaded into a hopper on the first floor. The hopper has a capacity of 2,000 kg, which is enough to meet the mill’s needs for four to six days, depending on the rotation speed of the water wheel.

From the floor hopper the wheat is moved by an auger conveyor to a smaller feed or transit hopper of 50 kg capacity, located above the millstones. The grains fall from the bottom of the feed hopper to the millstones, where they are ground into flour. Walk Mill uses two burr stones, made of hard, dense French granite. The stones are positioned horizontally, one above the other. The lower stone, called a bedder, is fixed, while the upper one (the runner stone) rotates. Wheat from the hopper falls into a hole in the centre of the upper stone and gradually moves to the periphery of the stones via shallow grooves in the stones. The tiny gap between the stones is adjusted to produce white or whole meal flour, the latter being more coarse because it contains bran.

40 Solids & Bulk Handling • May 2012

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