With regard to Cobba's comment on Daw Mill being able to break records, I was lucky enough to visit Daw Mill in 1981 as part of an Inter-area visit (thanks to wonderful NCB!).
We went on to what was then the largest coal face installation in the country in the Warwickshire Thick Coal. This is a series of seams which combine to give a total thickness of over 7m.
Extraction was done in 2 "takes", the first being a 250m long advance face taking around 3.5m of the top coal. The 2nd take is by a narrower retreat face in the distressed area below the waste of the upper workings.
The whole operation was an eye opener compared with the tackle I was used to in N. Staffs. The supports were 4x450 tonne shield supports, with 2 Anderson Strathclyde shearers. As the coal is known for spalling, especially when taking such thickness, both machines were fitted with lump breakers, which certained had to work hard to enable the coal to clear the shearer underframes, and operated via remote-control for operator safety.
What with private enterprise, improving technology & machinery, no wonder they keep sending out the black stuff in such quantities! :thumbsup:

Photograph:

🔗Daw-Mill-Coal-Mine-Archive-Album-Image-001[linkphoto]Daw-Mill-Coal-Mine-Archive-Album-Image-001[/linkphoto][/link]

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Quote "As the coal is known for spalling,"

Could you please give a defination of "spalling" and possibly include it in the Mining Dictionary of Terms on the website. I've not come across this term in use in lead mining and it's made me curious. With many thanks.

LTCC method looks quite impressive, one cut!

http://www.mining.unsw.edu.au/publications/publications_staff/paper_hebblewhitecai_iccc_2004.htm 

Quote "As the coal is known for spalling,"

Could you please give a defination of "spalling" and possibly include it in the Mining Dictionary of Terms on the website. I've not come across this term in use in lead mining and it's made me curious. With many thanks.

Spalling is basically the exposed coal breaking off along natural fissures & breaks and falling over in large "blocks". These large pieces cause problems with conveying the coal along the face & therefore the use of lumpbreakers was employed to reduce the size. Different coal seams have different characteristics, but the Warwickshire Thick was subject to heavy spalling especially when associated with such thickness of extraction.
Hope this helps. :flowers:

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LTCC method looks quite impressive, one cut!

http://www.mining.unsw.edu.au/publications/publications_staff/paper_hebblewhitecai_iccc_2004.htm 

Had quick look, certainly interesting.
Here's sketch section & plan of how the Daw Mill system worked.
🔗Personal-Album-5532-Image-51620[linkphoto]Personal-Album-5532-Image-51620[/linkphoto][/link]

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Quote "As the coal is known for spalling,"

Could you please give a defination of "spalling" and possibly include it in the Mining Dictionary of Terms on the website. I've not come across this term in use in lead mining and it's made me curious. With many thanks.

This very same term was used in notes on some plans to the Long Rake spar mine (Calcite) near Youlegreave. The calcite ore was reknown for breaking away from the host rockwalls in the large horizontal veins (approx 60' in height 18' in width).

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Was aware that similar problems occured in other types of mining. In gold mining in South Africa they do have "rock bursts" due to the extreme depths, but thats specific to those conditions.

With regard to spalling at Daw Mill the face supports were equipped with a powered foreplole (a beam that can be extended from the tip of the support to give additional roof support especially after roof is exposed after cutting) and also a face sprag. This can be set to the face at any time during the face cycle to give additional protection from spalling coal.

🔗Personal-Album-5532-Image-51629[linkphoto]Personal-Album-5532-Image-51629[/linkphoto][/link]

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The term spalling was certainly (still is) in use in parts of Derbyshire. As already said it was used at Long Rake. Also in quarries and from memory, in the Derbyshire pits.
Common in civil engineering too. eg. spalling brickwork caused by frost damage.

Staffordshirechina - Many thanks for the explanation of "spalling". Also Brakeman for mentioning the reference to it's use in spar mining at Long Rake, Youlgreave which I can appreciate given the crumbly state of the vein.

Before I raised my query I looked the term up both in Nellie Kirkham's "Derbyshire Lead Mining Glossary" published by Cave Research Group in 1949, and Jim Rieuwerts "Glossary of Derbyshire Lead Mining Terms" published by Peak District Mines Historical Society Ltd. in 1998. Neither of the Glossaries include the term hence my curiosity. Thank you, one is never too old to learn!

Glad I could be of assistance Sougher! ::)

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