The tailings pond above the Willibald treatment plant
Above the Willibald processing plant, which was completed in 1889, there was a thickener and a sludge pond for the ore processing residues. The plant, which was built in 1935, processed up to 1,000 tons of ore every day. Around 90% of this was fine-grained, almost metal-free tailings, which were produced as sludge
, and this sludge was pumped into a thickener measuring around 35 meters. The solids settled there, while the clarified water was reused as process water. The thickened sludge was fed into the 100 x 50 meter sludge pond via a wooden channel. Coarse sand particles were used to build up the surrounding dam, while finer particles settled in the middle of the pond. Excess clear water was drained into a stream, and
with the completion of the new Bilmecke sludge pond in 1955, the thickener and the old tailings pond were decommissioned.