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TMF Extension at the Björkdal Mine : Dam Foundation Challenges

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The Björkdal Mine is a gold mine situated 28 km northwest of Skellefteå in Northern Sweden and owned by Mandalay Resources since 2014. Mining operations started in 1988. In 2018 a new permit was granted to extend the life of the tailings management facility (TMF) for an additional 10 years, as well as increase the annual ore production by 30%, up to 1,7 million tonnes per annum. This extension of the TMF includes a 6.5 m raise of an existing dam, dam K1, and major extensions of both abutments. The raise results in approximately a three-fold increase of the total length of dam K1. Construction of the abutments brought specific challenges when it came to foundation works as the south extension involved foundation on saturated silt and the north on complicated bedrock. The silt foundation was required as the silt in this location, close to a waste rock dump, could not be excavated to the required depth. During construction, a control program with pore water pressure measurements was set up to maintain safe and stable conditions. The north extension included extensive excavation work in loose soils (peat and silt) to great depths, where bedrock was encountered. To conduct this excavation, the work had to take place during winter in frozen soils. The depth to bedrock was in line with previous investigations, but the complex surface and the quality of the bedrock became an unexpected challenge, with increased design work and extensive special measurements required. This paper will describe the foundation challenges of extending dam K1, as well as how these challenges affected the project.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86813

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/