Ajka alumina plant accident

science Thursday, October 7, 2010. Post by David Bradley

UPDATE (Nov 24): Most sludge reservoirs in Slovakia pose no threat, according to Ministry.

Ajka is a town in Hungary, 100 miles southwest of Budapest, with about 35,000 inhabitants. It is situated in the hills of Bakony and has a history dating back to the Celts who lived there 1000 BCE. If the name of this place sounds familiar it’s because on October 4, caustic sludge from a red mud reservoir at a metals plant  was spilled across the town and has killed at least four people. Three people are still missing and 120 were injured in the wake of the torrent.

The accident happened when a dam wall collapsed, freeing about a million cubic metres of liquid “red mud” from the Ajkai Timföldgyár alumina plant.

Images of the red sludge, a waste product of aluminum production, have been spattered across news media and concerns are today being voiced that the sludge could enter waterways including the famed Danube river, which could spread the problem across national borders, although the addition of water and acid has lowered the caustic pH from 12 to 10 (safe levels would be 6-8). Ecosystems in Hungary, Croatia, Serbia and Romania, could be affected. A criminal negligence investigation is now underway.

What is the red mud? It is a waste product of the so-called Bayer process for purifying bauxite (aluminum ore) into pure alumina, aluminum oxide. The red mud contains the impurities from the bauxite ore and is red because of the presence of iron(III) oxide, but also contains titanium and vanadium compounds as well as lower concentrations of other heavy metals. The alkaline red mud is stored in large open-air reservoirs and observers estimate there are 30 million tonnes of red mud at the Ajkai Timföldgyár plant.

A report published after this article in C&EN, discusses the potential for finding alternative uses for the vast quantities of waste.

Related articles on the Ajka red sludge

• Race on to stop toxic sludge from reaching major European river
• Hungary battles to prevent sludge contamination
• Sludge Flood Like Hungary’s Unlikely in US
• Hungary Opens Criminal Probe Into Toxic Sludge Spill
• Hungary toxic sludge spill reaches Danube

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