Hafodyrynys Slime Thickener was ormerly part of Hafodyrynys Coal Preparation Plant (NPRN 91477) and is was retained for a proposed conversion to a restaurant. it consists of a concrete drum set on short legs and roofed with a domed concrete cap. The thickener is a remnant of the washery of Hafodyrynys Colliery, which was an expensive scheme from 1954 to 1958, that involved two new drifts and underground links to other pits allowing outputs to be concentrated at fewer places with modern plant. The colliery closed in 1966.

Claire Parry, RCAHMW, 19 July 2011.

Source: A Guide to the Industrial Archaeology of South East Wales, AIA, 2003