What Bower's Mill was for.

Lead Smelting

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Early methods of separating the lead from the waste products were primitive. Smelting took place on hilltops facing into the prevailing westerly winds which provided the draught for the fire. It involved building what was essentially a large bonfire on top of the hill, using alternating layers of wood and ore. It worked because lead has a relatively low melting point but it was very inefficient and used large quantities of wood.

Smelting usually took place in the spring when several days of strong wind could be relied upon. Ore and fuel was stockpiled and the process would last until the wind died down or the supplies of timber and ore were exhausted. As the lead melted, it was collected at the base of the fire and channelled into moulds called pigs.

These hilltop hearths were known as boles and their sites live on in the place-name Bole Hill. There is a hamlet named Bolehill between Cromford and Wirksworth. Boles had become obsolete by the end of the 16th century because of a new technological development, the ore hearth.

The ore hearth was similar to a blacksmith’s forge but here the draught was provided by bellows powered by a waterwheel. The smelting sites therefore transferred from the hilltops to the river valleys. These hearths were much more efficient. (They were about 55% efficient.) In fact it became economic to reprocess the slag which had been produced by the boles, and recover more lead as well as smelting new ore.

Hearths still relied on wood as fuel, but it was now specially prepared for the purpose and was known as white coal. The timber was chopped up into small chips and dried over a fire before use. White coal was produced in woodlands which were specially managed for the purpose.

This method of smelting required the mixture to be constantly stirred by the smelters, who consequently worked in an atmosphere of poisonous fumes. A man employed as a lead smelter usually had a relatively short life.

The final technological development was the cupola or reverberatory furnace. This used coal as fuel and was completely enclosed. The fire and the ore were separated by a low wall and the flames and heat were ‘reverberated’ on to the ore from the domed roof. The reverberatory furnace was first introduced into Derbyshire by the London Lead Company in the mid 1730’s at Bower’s Mill, Ashover. The furnace used a tall chimney to provide the draught for the fire. These smelters were often situated on the barren moorland where there was less chance of farm animals being poisoned by the fumes. They were much more efficient than the ore hearth, about 65%.


Thanks to Peakland Heritage website for this article