I don't think the Cornish copper ores would have been any more difficult to
smelt than Lake District ores. The matte smelting process is pretty
robust and will take out many impurities along with iron and sulphur which
are the main ones. Others such as bismuth would not be removed and might
degrade the properties of the copper but no attempts would be made to
remove these.
The evidence suggests that silver removal was not carried out at Neath and
therefore the process was much simpler. Ulrich Frosse, who eventually
went to runn the Neath smeltmill claimed that it could produce copper in 48
hours rather than 6 weeks at Keswick. It has been suggested that the
Neath smeltmill might have had a reverberatory furnace, some 85 years or so
before it was first used for non-ferrous smelting in the Britain.
However, there is no evidence that this was the case. The main reason for
the long cycle times arose from the classical Tyrolean process for roasting
copper ores. This used great lumps of ore (look in Agricola) and was
persisted with into the C19th. Roasting only occurred on the outside of
the piece and repeated processing was necessary. Once roasted either a
blast furnace or reverberatory could be used, although more care would be
needed in putting roasted fines through a BF. We know that Hechstetter
carried out some roasting experiments on finely powdered lead and copper
ores and was able to reduce the smelting cycle dramatically by doing this.
There is no evidence that he did or did not introduce the new process at
Keswick but it could have been used at Neath.
There are a few accounts of the performance of the Neath process in the PRO
but no indication of how this was achieved - I would love to know.
Richard Smith
3M UK Bracknell, B2-3N,
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Tel: 01344-858154 (Trim. 8-230-2154)
Fax: 01344-858367 (Trim. 8-230-2367)
"D.R.Poyner"
<[log in to unmask] To: [log in to unmask]
AC.UK> cc: (bcc: Richard Smith/UK-Europe/3M/US)
Subject: Cornish Copper and the Neath Smelter
15/11/2002 09:40
Please respond to
"The
mining-history
list."
Following on from the discussions about the Mines Royal, for some time
I have been interested in the career of John Weston, who operated
mines under licence in Cornwall and Wales with Thomas Smith in the
early 1580s. He built a smelter at Neath for the Cornish copper. W.
Rees, in Industry before the Industrial Revolution, considered that the
"complex" nature of the Cornish copper ores would have caused
considerable difficulties.
Is Rees correct in stating that smelting Cornish copper ores in the
1580s would have been more difficult than the ores in the Lakes?
Has anyone carried out an analysis of the operation of the Neath
Smelter? Donald in Elizabethan Copper and Rees himself do consider
this, but I wonder if there is more recent work? Weston himself
operated a blast furnace for iron, in addition to his interests in non-
ferrous metals.
Thanks
David Poyner
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