Winter 2016

Water treatment of mining waste

TenCate Geotube® technology has been used in the treatment and storage of water that has been seriously contaminated as a result of extracting nickel in Talvivaara (Finland), Europe’s largest nickel mine.

In 2008, the Finish mining company Talvivaaran Kaivososakeyhtiö Oyj began extracting nickel at Kuusilampi and Kolisoppi (near Sotkamo, Finland). Owing to extreme rainfall in 2012, Talvivaara was forced to store approximately 8 million cubic metres of excess water in lakes on the 61 km2 site. This precipitation was contaminated. In that same year, extraction came to a halt because a huge quantity of contaminated water had collected in the lowest-lying part of the mine. In November, a leak was discovered in a basin with gypsum sediment. By the time the leak had been localised and sealed, some 220,000 cubic meters of water contaminated with nickel and cadmium had leaked away into the surrounding natural environment. Operations were shut down. To prevent more wastewater disappearing into the environment, Talvivaara erected dams around the basins.   

4 geosynthetics Turva-altaat-_paljaalla_maaperällä_-_Ilmakuva_2013
The nickel mine in 2013 (Turva altaat paljaalla maaperällä Ilmakuva)

The environmental and water treatment experts of Talvivaara wanted a cost-effective solution with sufficient treatment capacity. Sito, a leading company in infrastructure and consultancy, introduced the dewatering technology based on TenCate Geotube®: tubular-shaped geotextile containers, in this case with the addition of polymers to bond the contamination. Because of its experience in using TenCate Geotube® the contractor Vesirakennus Ojanen was involved in the project. The cleaning operation began in March 2013. 

4 geosynthetics nickel mine ilmakuva
(Ilmakuva, 2013)

From the beginning, the use of TenCate Geotube® technology for the treatment of sludge and mine waste turned out to be more successful than expected – so much so that Talvivaara could restart operations after only a few months. 
Nevertheless, serious leakages also occurred in the years following, starting on 8 April 2013. It was found that, of 620,000 m3 of stored wastewater, 250,000 m3 of contaminated liquid had leaked into the environment. Shortly afterwards, permission was requested to discharge another 820,000 m3 of wastewater – on top of the 1.8 million m3 for which authorisation had been granted. One thing after another resulted in the bankruptcy of Talvivaaran Kaivososakeyhtiö Oyj, and in 2015 it was taken over by the Finish company Terrafame, part of a state-owned enterprise. 

4 geosynthetics Kipsisakka-altaat_laittomassa_tilassa_-_Ilmakuva_2013
(Kipsisakka altaat laittomassa tilassa Ilmakuva, 2013)

In 2016, The Finish government announced that the mine would be dismantled and closed down under supervision.  There are currently some 10 million m3 of wastewater on the site, and water is still running in the abandoned mine shaft. The water treatment in progress is not sufficient to handle all the contamination, and Terrafame is therefore seeking a definitive central wastewater purification system to deal with the problems once and for all. TenCate Geotube® may well be part of this operation.

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