Ball clay

Highley, D.E.. 1975 Ball clay. London, UK, HMSO, 37pp. (Mineral Dossier No. 11)

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Abstract/Summary

Ball clay is a fine-grained, highly plastic, mainly kaolinitic, sedimentary clay, the higher grades of which fire to a white or near white colour in an oxidising atmosphere. They consist of varying proportions of kaolinite, clay mica and quartz, with small amounts of organic matter and other minerals, and are commercially valued because they increase the workability and dry strength of various ceramic bodies and have white or near white firing characteristics. Ball clays are used mainly in the manufacture of pottery and refractories, but have important non-ceramic applications as a filler in rubber and plastics, as an anti-caking agent in fertilisers and for pelletising animal feedstuffs. Commercial ball clay deposits are confined to three Lower Tertiary basins in south-west England; the Bovey Basin of south Devon, the Petrockstow Basin of north Devon and the area around Wareham in southeast Dorset. Similar Tertiary clays also occur in Northern Ireland but have too high an iron content to be of commercial value as ball clays. Ball clay is produced by both opencast quarrying and underground mining, the latter method being largely confined to a limited range of high grade clays. The largest pits are 40 m deep and the largest mines, in the Bovey Basin, extend to depths of 135 m. Abandoned pits are either backfilled or fill with water and quickly revert to nature; the underground mines, which are generally inconspicuous, may cause some subsidence, although this is not usually serious. Processing consists essentially of shredding or drying and grinding, but because of the wide variation in the properties of ball clays, blending is of the utmost importance in producing uniform and consistent grades. United Kingdom production of ball clay is recorded under the heading 'Potters' clay (including ball clay)'. Production under this heading in 1973 was 755,000 tonnes, mostly consisting of ball clay with the remainder consisting of other clays used in the manufacture of coarse pottery. Imports of ball clay are negligible, but exports, principally to Europe, amounted to 404,720 tonnes in 1973 with an f.o. b. value of £2,836,820. Trade has, therefore, a favourable effect on the balance of payments. Of the three producing areas the Bovey Basin has the greatest output, accounting for about two-thirds of total production and 70 per cent of total exports. Three companies produce ball clay in the United Kingdom: Watts, Blake, Bearne and Company Limited, probably the largest ball clay producer in the world, ECC Ball Clays Limited (a member of the English China Clays Group) and The Wareham Ball Clay Company, a small independent producer operating in Dorset.

Item Type:	Publication - Report
Programmes:	BGS Programmes > Economic Minerals
Funders/Sponsors:	Institute of Geological Sciences
Additional Keywords:	Mineral, Ball clay
NORA Subject Terms:	Earth Sciences
Date made live:	25 Jul 2025 16:55 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539901

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