At the invitation of David Smalley, who knew of our interest in brick-making in Mapperley, Christine Drew, Elizabeth and Bobby Robinson and Tom Zadik joined a small group of visitors (mostly interested in the packaging industry) to the Ibstock Brick factory at Dorket Head on Wednesday 9 April.
We were shown round by Mike Chapman, the factory manager and himself a keen local historian.
We know something of the history from the presentations by Elizabeth and Christine. Mike showed us an aerial picture of the Mapperley site at its greatest extent some time before its closure in the 1960s. For orientation, the Belle Vue pub is in the centre of the top of the picture. The circular kilns are clearly visible.
The clay on either side of the Mapperley ridge is plentiful, accessible and of high quality for brick-making. Unlike similar clay at Gunthorpe it is not contaminated with gypsum. The many small brickworks amalgamated in the nineteenth century to form Nottingham Brick, whose shareholders included Jesse Boot, John Player, Robinson (of Home Brewery) and Mellers. The Dorket Head site had been producing bricks since at least 1865, probably longer, and when the Mapperley site closed, a re-development began, with the most recent substantial building some 12 years ago, resulting in one of the largest and most modern and efficient brickworks in Europe.
n 1987 Nottingham Brick was taken over by Marley, which in turn became part of Tarmac in 1993, Ibstock in 1995 and finally CRH, an Irish-based multinational, in 1999, though retaining the Ibstock brand. Ibstock have about 30 – 35% of the UK market, as one of three main manufacturers. There are also a number of small independents, mostly making specialist products, often for restoration.
The Dorket Head factory
The Dorket Head factory employs relatively few direct employees, and works continuously, producing 85 million bricks per year, 80% of which are used within a radius of 60 miles (though some are exported, particularly to Ireland).
The site occupies both sides of Calverton Road on the south side of Woodborough Lane/Lime Lane. The clay pit is on the east side, and the worked-out part is now used for landfill. The methane from the landfill is used by the company for electrical power, with a little extra which is fed into the National Grid (it is not of consistent enough quality to be used in the actual manufacturing process). The factory is on the west side of Calverton Road, and is set in old clay workings, mostly below the level of the surrounding land. We visited the works only.
Mike’s itinerary took us through the brick-making process in sequence, from the clay in the ground, through crushing and grinding it, forming it into bricks by extrusion and wire cutting, drying, firing and packing.
The clay in the ground is beneath a layer of skerry, a soft sandstone which can be crushed and included in the clay in small amounts.
It is brought to the works site by conveyor belt, and some is stored for processing at night when there is no digging.
The crushing and grinding, which is noisy, takes place in a different shed from the rest of the process. Particles of about 1 mm3 are produced and taken by conveyor belt to the main works.
This is highly automated (the workers are those in orange: we visitors are in yellow).
Naturally, the clay has about 12% water in it. To make it plastic, more water is added. Also, sand, and/or anthracite and other pigments may be added to obtain the desired colour and texture.
It is then compressed, shaped and extruded in a continuous strip. It moves from right to left in this picture, the caged machine in the centre impressing a pattern onto it.
Wire cutters then produce the bricks.
These are packed on to pallets …
… which are stacked in frames that take them to the drying process: a full frame can just be seen in this picture trundling along the back wall behind the fourth column from the left.
Drying takes some 30 hours. The bricks are heated to about 120?C by circulating hot air from the kiln. The holes in the bricks increase the surface area and facilitate the process.
The dried bricks are re-packed on to huge trolleys on top of a layer of refractory bricks.
These are slowly moved across the shed to the kiln. This is a tunnel structure about 100 meters long. On the right can be seen a trolley moving away from us to the far end of the kiln. On the far left is part of a trolley just emerging from the kiln after a 55 hour journey.
Peering between the bricks on this emerging trolley one can see the glow of the kiln in the distance. At its hottest point the temperature is in the region of 1050?C, depending on the type of brick being produced. The whole process is tightly controlled by computer.
On top of the kiln we saw the gas and air feeds. Behind Mike on this picture can be seen the pipes through which the waste hot gases are ducted to the dryers.
Here is the final product …
…which is now finally restacked into packs of just under 1 tonne for manipulation by fork-lift trucks.
These are strapped,
… wrapped in plastic, and stacked ready for distribution.
Finally, here are a few samples of the products made at Dorket Head.