This bizarre contrivance is a slime thickener, which was part of a coal washery, the only remaining part of the former Hafodyrynys colliery.

A colliery had been in operation at Hafodyrynys in the 1870’s, and another opened in 1914 which operated until the 1950’s. The old shafts were closed and three drifts were sunk, with new surface infrastructure built. The Northern Mine Research Society describes it thus:

“The new colliery buildings and washery were designed with modern buildings and equipment for maximum efficiency. Architecturally, they were influenced by the functionalism of pre-war collieries in Germany designed by the Bauhaus architect Peter Behrens, by the sinuous forms of the Festival of Britain, and possibly by the nearby Brynmawr Rubber Factory. All the buildings had reinforced concrete frames filled with brick or glass panels and flat, curved or waveform concrete roofs. Washery plants were key elements in post-war efficiency improvements, as only half of British coal output was being washed in 1945. The washery at Hafodyrynys contained equipment for extracting coal dust from slurry and drying the remaining waste before tipping: processes that were rare before the 1950s. It was built entirely of reinforced concrete with continuous glazed panels.“

Source:https://www.nmrs.org.uk/mines-map/coal-mining-in-the-british-isles/swales/abercarn/hafodyrynys-colliery/

The entire complex cost £5.5million pounds and opened in 1959. However, it ran at a loss and in 1966 was closed. The washery remained in use for processing coal from other collieries in the area before it closed in 1985 and the site was cleared. According to the Coflein website, the ‘slimes thickener at the washery was retained at the request of Sir Richard Hanbury-Tenison of Pontypool Park Estate, to which the site reverted. Plans were drawn up at the time to adapt the building as a restaurant.’ This didn’t happen and it now stands isolated in a field, and used as a shelter by horses.