Talvivaara mine is one of the most important large-scale nickel mining pits in Finland. It is located in the eastern part of the country, in between the towns of Sotkamo and Kajaani; except for the above mentioned metal, there are also deposits of zinc, copper, cobalt and uranium in this region. The mining operations in the area started in 2004, the initial deliveries of final product were effected in 2008, in 2010 the manufacturing output of the site exceeded 10 000 tons of nickel and 25 000 tons of zinc, the aggregate targeted volume from 2012 onwards is approximately 150 000 tons of metals per annum.
Because of poor concentration of these metals in the low grade ore found in this location, using traditional mining technologies was impossible (these being inefficient with respect to necessary input of resources and potential output volumes) and the mine owner decided to utilize bioheapleaching method instead (extraction of metals based on biological processes – with the help of bacteria). The ore is crushed into fine particles, these are being stacked on heaps, irrigated with acid+bacteria leach solution and exposed to aeration. Chemical reactions running inside the heaps cause the inner temperature to raise, thereby intensifying the actions of bacteria and decomposition of metalcontaining chemical compounds. Total metal extraction efficiency ratio (after 18 months of primary leaching and further 36 months of secondary leaching period) is 90%.
The above manufacturing method is very space-demanding. It was necessary to occupy vast areas of land (that were originally forest covers) in order to establish primary and secondary heaps (plus storage tanks intended to hold the final solution; these had to be safely separated from the surrounding environment by an insulation layer with a high level of chemical resistance and a long life span. This function is being fulfilled by a geosynthetic barrier made from high density polyethylene (PE-HD). In 2011, Juta a.s. became one of two suppliers of this product for Talvivaara mining site. The geomembrane JUNIFOL PEHD for this project was manufactured according to GRI GM13 requirements, the thickness of the material supplied was 2,00 mm and it was delivered both with smooth and structured surface.
