Your phrase "paying ore" is important. Where was the market? When was the market? The extra investment to separate and process the zinc would have to be matched by a certain and specific market. It makes your search more laborious, but looking at particular fields in particular decades to try and match a customer to the produce would give some indication whether the sphalerite ores were dumped as waste, or processed into zinc. We know that subsequent workings of fields previously abandoned often involved "mining" the waste tips first for material for which there was now a market - and improved technology. Best wishes Steve Gray
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From: mining-history [mailto:[log in to unmask]] On Behalf Of mining-history automatic digest system
Sent: 05 July 2011 12:05 AM
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Subject: mining-history Digest - 1 Jul 2011 to 4 Jul 2011 (#2011-91)
There are 4 messages totaling 226 lines in this issue.
Topics of the day:
1. Lead/Zinc dressing (4)
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Date: Mon, 4 Jul 2011 11:10:04 +0100
From: Phil Newman <[log in to unmask]>
Subject: Re: Lead/Zinc dressing
Thanks everyone,
The picture I am getting from these responses, in terms of the archaeology, is that in the early 19th century, zinc from sphalerite, when associated with galena could be separated either by picking or as an operation within standard lead dressing processes. But there would be no way of knowing (other than documentary record or sampling of dressing waste) if it was collected as paying ore or discarded. Archaeological evidence for specific zinc recovery might therefore be difficult to distinguish from that of a mine dealing only with lead. It was not until the later 19th and early 20th century that froth flotation was used to recover zinc, in which case evidence of this technology at such a mine would imply zinc was being recovered as a paying ore.
Is this a valid summary? Is it also the case that waste dumps at former lead-only mines might have been re-worked for zinc at a later date?
Thanks
Phil
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Date: Mon, 4 Jul 2011 14:38:22 -0400
From: Bernard Moore <[log in to unmask]>
Subject: Re: Lead/Zinc dressing
Dear Phil,
Not quite. May I refer you to the Mins.Stats. (Burt. et al), since zinc production - & it's increase (pertinent to a gradualy increasing importance and value as a commodity), is clearly evident via this source of info..
Frongoch Mine in Wales for example, gained many years of production. The Taylor's left considerable reserves to be reaped by Kitto. As to Derbs., well, one or two mines did well out of the mineral.
Regards, Bernard
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Date: Mon, 4 Jul 2011 20:25:08 +0100
From: Peter Claughton <[log in to unmask]>
Subject: Re: Lead/Zinc dressing
At 19:38 04/07/2011, Bernard Moore wrote:
>Dear Phil,
>Not quite. May I refer you to the Mins.Stats. (Burt. et al), since zinc
>production - & it's increase (pertinent to a gradualy increasing
>importance and value as a commodity), is clearly evident via this source of info..
Yes - but can that be determined from the archaeological record? What you have cited is the documentary record which Phil is aware of - as he stated -
>But there would be no way of knowing
>(other than documentary record or sampling of dressing waste) if it
>was collected as paying ore or discarded. Archaeological evidence for
>specific zinc recovery might therefore be difficult to distinguish from
>that of a mine dealing only with lead.
We know that many lead mines shifted to zinc to maintain production but that was achieved by manipulating the existing gravity separation methods of ore preparation. How would that be identified in the physical evidence surviving on the dressing floors? Even the froth flotation process, when introduced, cannot be said to be a symptomatic of a shift to zinc production. It was capable of treating ores from polymetallic deposits and its introduction to what had previously been primarily a lead producer might imply that zinc ores were being separate out from lead but that was not always the case.
Greenside, in what is now Cumbria, introduced froth flotation in the 1930s but zinc is not listed as a product - just lead. See Murphy, Black Gold, (Moiety 1996).
The documentary evidence provides a clearer picture of production but unfortunately the collated statistics you cite (Burt et al.) end in
1913 - too early to pick up on the changes which might have been brought about by the introduction of froth flotation.
Peter
Dr Peter Claughton,
Blaenpant Morfil, nr. Rosebush, Clynderwen, Pembrokeshire, Wales SA66 7RE.
Tel. +44 (0)1437 532578; Fax. +44 (0)1437 532921; Mobile +44 (0)7831 427599
Hon. University Fellow - College of Humanities, University of Exeter http://people.exeter.ac.uk/pfclaugh/about.htm
E-mail: [log in to unmask]
Co-owner - mining-history e-mail discussion list.
See http://www.jiscmail.ac.uk/files/mining-history/ for details.
Mining History Pages - http://www.people.exeter.ac.uk/pfclaugh/mhinf/
_____________________________________________
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Date: Mon, 4 Jul 2011 17:09:57 -0400
From: Bernard Moore <[log in to unmask]>
Subject: Re: Lead/Zinc dressing
Dear Peter,
Zinc did not feature much at Greenside since there was little to none there in the first place. Likewise Weadale proper, though from Cowshill to the top of Killhope it came to be more prevalent until reaching the Nenthead Mines and westward where it was a significant mineral/metal.
The matter of 'manipulating existing gravity separation methods of ore preparation', produced problems due - in the early days to SG - so mainly hand sorting was resorted to (this will obviously leave little evidence on the ground). The proof in the Frongoch pudding, is in as much that it was not until the 1920's (Nancarrow), that zinc could be treated from the dumps...
indeed, as a specific target (the latter's Plant and aerial ropeway over to the Ystwyth Valley (Electrolytic Zinc. Co. etc., etc.) - footings of plant extant... but Kitto kept the mine working for many years stripping the stopes of zinc that the Taylors' had left... but such well handled, enabled a clean product - and a touch surprisingly left the dumps alone to wait for Nancarrow. The 1870's indeed saw a decreasing lead commodity value, and it was 'handy', to say the least, to some mines, to take on an mineral that otherwise had previously been treated as a nuisance. As to extant Plants; well of course they are not there now, but a little imagination/research into what plants were elsewhere, and how the matter was handled in other areas, will demonstrate eventually what went on in any 'zinc area' of any note anyway.
A slight problem though, England only is sought - Wales is another matter and quite a bit of tech. data. is available (1908 onwards - flotation)...
one can only assume that same was duplicated elsewhere. Mind you, there is much available on the Nenthead Plant and of course Forcecrag - one musn't forget the North Wales Orefield (I enclude the LLanrwst Area), since zinc featured quite a bit there. 1913 is a completely irrelevant date: zinc was an important product twenty years before, and indeed a bit before that, so, with not a great deal of evidence other than Govt. statistics (& Taylor's, Kitto's and Nancarrow's mentioning of handling), one can only resort to documentary and Stats. evidence really... interpretation must be left to educated assessment with what is at and in hand.
Enough rambling.
Regards, Bernard
In a message dated 04/07/2011 20:41:24 GMT Daylight Time, [log in to unmask] writes:
At 19:38 04/07/2011, Bernard Moore wrote:
>Dear Phil,
>Not quite. May I refer you to the Mins.Stats. (Burt. et al), since
>zinc production - & it's increase (pertinent to a gradualy increasing
importance
>and value as a commodity), is clearly evident via this source of info..
Yes - but can that be determined from the archaeological record? What you have cited is the documentary record which Phil is aware of - as he stated -
>But there would be no way of knowing
>(other than documentary record or sampling of dressing waste) if it
>was collected as paying ore or discarded. Archaeological evidence for
>specific zinc recovery might therefore be difficult to distinguish from
>that of a mine dealing only with lead.
We know that many lead mines shifted to zinc to maintain production but that was achieved by manipulating the existing gravity separation methods of ore preparation. How would that be identified in the physical evidence surviving on the dressing floors? Even the froth flotation process, when introduced, cannot be said to be a symptomatic of a shift to zinc production. It was capable of treating ores from polymetallic deposits and its introduction to what had previously been primarily a lead producer might imply that zinc ores were being separate out from lead but that was not always the case.
Greenside, in what is now Cumbria, introduced froth flotation in the 1930s but zinc is not listed as a product - just lead. See Murphy, Black Gold, (Moiety 1996).
The documentary evidence provides a clearer picture of production but unfortunately the collated statistics you cite (Burt et al.) end in
1913 - too early to pick up on the changes which might have been brought about by the introduction of froth flotation.
Peter
Dr Peter Claughton,
Blaenpant Morfil, nr. Rosebush, Clynderwen, Pembrokeshire, Wales SA66 7RE.
Tel. +44 (0)1437 532578; Fax. +44 (0)1437 532921; Mobile +44 (0)7831 427599
Hon. University Fellow - College of Humanities, University of Exeter http://people.exeter.ac.uk/pfclaugh/about.htm
E-mail: [log in to unmask]
Co-owner - mining-history e-mail discussion list.
See http://www.jiscmail.ac.uk/files/mining-history/ for details.
Mining History Pages - http://www.people.exeter.ac.uk/pfclaugh/mhinf/
_____________________________________________
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End of mining-history Digest - 1 Jul 2011 to 4 Jul 2011 (#2011-91)
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