Karaktärisering av morän i Aitikgruvan för användning vid efterbehandling av gråberg

• Main Author: Larsson, Anna
• Format: Others
• Language: Swedish
• Published: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap 2018
• Subjects: Aitik Mine; Characterization; Till; Waste rock; Hydraulic conductivity; Natural Sciences; Naturvetenskap
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-153685

The Aitik Mine is the largest copper mine in Europe and every year, 15 – 20 Mt waste rock is deposited in dumps located close to the mine. This waste rock can contain sulfides, which if exposed to oxygen can cause leeching and formation of acid rock drainage. To prevent this from happening, Boliden has designed a dry cover system to prevent leaching from occurring. The purpose of this study was to characterize existing stockpiles of till at Boliden’s Aitik Mine site in the context of requirements for the closure cover system. The till was evaluated primarily of its suitability for use in a highly compacted layer (HCL), since Boliden has a cover system design that has to provide the necessary control on oxygen diffusion rates to underlying waste rock material over the long term. The sampling took place on three of the stockpiles and a total of 31 test pits were excavated. A total of 27 samples of soil were collected and analyzed for particle size distribution (PSD) testing. Following review of PSD results, select samples were tested for hydraulic conductivity and compaction testing. The PSD results showed that all materials were fine-grained sand with some gravel, cobbles and silt. Results also show the amount of clay particles (0,004 mm) were relatively low across the three stockpiles. The result for the hydraulic conductivity were higher than Boliden’s prescriptive criteria. The results indicate that the sampled till would require addition of sodium bentonite to be able to construct a HCL with a hydraulic conductivity not exceeding Boliden’s criteria.