Allen Smelt Mill and Allenheads Mine Yard
At its peak, Allen Smelting Mill was a noisy factory full of fire, fumes and smoke. It is rather hard to imagine such a scene when you visit the site today. Only puzzling fragments remain of the mill which in the 1850s, was one of the largest in the country. It had the capacity to process over 2,000 tons of lead ore each year and would have generated enormous wealth for this valley.
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| Illustrated reconstruction of Allen Smelt Mill (1800s) |
The Smelting Mill was demolished in the 1950s and 1970s. All that remains are flue openings, the ore hearths, the wheel pit and roasting furnaces which have only recently been uncovered. The flues can be described as long horizontal chimneys, which end at chimneys high up on the moors above Allendale, over two miles away. The flue system here is the best preserved in England.
These illustrated reconstructions are the product of a close partnership between myself, Steve Pardue of
Differentia Design and Tim Crump of
www.wildlight.co.uk. With the help of local experts, we worked together to research and collate historical information from a range of sources including books, old photographs and drawings and written descriptions to help us reconstruct these two lead mining and lead processing sites. The task of reconstructing the lead smelting mill took us several months and is to date, one of the most complicated visual reconstruction projects I have attempted, requiring the use of 3D computer modelling to plot the locations of the various buildings, sheds and complex network of flues designed to carry the highly toxic lead fumes away from the site.
This project required us to research and understand the lead smelting and refinement process which is a subject I had very little knowledge of before embarking on this project. Smelting and refinement was carried out in different furnaces at Allendale. Roasting would prepare the ore for smelting; ore hearths would ‘sweat out’ pure lead from the ore; slag hearths would re-smelt slag from the ore hearths; and silver was refined from lead in the separating house.
The lead ore or
galena, was transported to this factory from lead mines across the North Pennines, including that of Allenheads just a few miles up the valley and which I have also reconstructed as part of this project. At the Allenheads mine yard, teams of men and boys operated
jiggers and
buddles to sift and wash the mined minerals in order to extract every available ounce of lead ore. The process required vast quantities of water. The ore was then taken from here to the smelting mill at Allendale on the backs of small, rugged horses known as
Galloways, then deposited into storage bays here called
bingsteads, where the material would then await refinement.
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| Illustrated reconstruction showing the extent of Allenheads Mine Yard and Washing Floor (1800s) |
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| Close-up of the Allenheads Mine Yard reconstruction |
First, sulphur in the lead ore was burnt off in the roasting furnace and this prepared the ore for smelting. A coal fire at the front of the furnace was kept separate from the lead ore by a brick shelf or a 'fire bridge'. Heat was drawn through the furnace by the flues at the back.
A draught created by mechanical bellows powered by a giant central water wheel, kept the fires in the Ore hearths hot enough to slowly sweat the lead out of the ore. It provided the oxygen needed for the chemical processes to convert lead ore into lead. Tiny bits of the parent rock, including fragments of ore, were left behind as slag. This was crushed and smelted again in the slag hearths to recover any remaining lead.
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| Illustrated reconstruction showing a cutaway view of Allendale Smelt Mill. A central water wheel drives mechanical bellows which fed a supply of air to the factory's ore hearths. Fumes from the furnaces used to burn off sulphur and other impurities in the lead ore, are carried away from the factory by a complex network of flues. |
A complex network of flues carried the toxic fumes away from the site but were also a way of ensuring every last bit of lead was collected. As the fumes cooled, lead and silver particles condensed on the walls. The mill shut down its smelting operations in order for this ‘fume’ to be scraped off and collected from time to time.
The final part of the lead smelting process was to separate out silver. Although it is only a tiny part of lead ore, its value still made it worth the effort of extracting. The silver was separated from the lead in a separate part of the mill by melting it in a line of pots, each about five or six feet across.
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| Detailed cutaway view of building where silver was separated from the lead by melting it in a series of pans. |
As it melted the purified molten lead was ladled into moulds to cool into bars of lead called ‘pigs’ and were then transported down the valley to Newcastle, to be shipped to the rest of the country, or exported overseas.
My reconstructions are to be mounted on new interpretation boards and these will be installed on site at Allendale Mill and at Allenheads mine yard.
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| This is the only plan drawing we have of Allen Smelt Mill in the 1800s showing the layout of its buildings and the route of its horizontal flues. |
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| The ore hearths and flue openings are all that remains of Allen Smelt Mill today. |
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| The remains of a fire pit - which belonged to one of the many furnaces at Allendale Mill. |
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| A final draft of the 3D model which I made to help work out the arrangement of buildings and the network of horizontal flues (highlighted in green) |
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| The equipment for washing the iron ore of unwanted material were called 'Brunton Buddles'. I made a 3D model of these to try and understand how they functioned. Material was loaded through a hopper at the top and then passed on to a canvas belt where water washed away the unwanted material leaving lead-rich ore to drop into a large tank for collection. |
