As Boliden continues to pursue further development of the Kristineberg underground copper-zinc mine in Sweden, it is increasing its understanding of the use of battery-electric vehicles at its underground operations.

Last month, the company outlined a SEK1.25 billion ($150 million) investment at Kristineberg – most of which is conditional on a production expansion permit – towards further developing the mine towards the Rävliden mineralisation. The expansion is expected to contribute to an increase in milled volumes in the Boliden Area to 1.8 Mt/y.

While this is happening, the company, in partnership with Epiroc, has been testing a 14 t ST14 Battery LHD at the mine.

Testing of the machine commenced in the March quarter and is expected to last 12 months. It has involved the installation of a battery swap and charging station (with overhead crane), and the switching of two batteries on site as testing has ramped up.

Patrik Hansson, Senior Development Engineer of Mining Technology at Boliden Mines, told IM the testing has been limited to a specific part of the mine – the L-Area, 850-1,000 m level. He said the ST14 Battery is the first battery-powered LHD tested across the company.

“We have several KPIs that we are following and evaluating, and comparing to our normal diesel equipment,” Hansson said. Included among the KPI list is tramming distance, driving time, equipment utilisation, equipment availability, production (t/mth), energy consumption (kWh/t), operator acceptance, ambient temperature, air quality (CO, NOx, CO2, diesel particulate matter), humidity level and noise level.

Boliden has submitted an application for expanded production at the Kristineberg mine to the Swedish Land and Environment Court. At the same time, it has decided to make preparatory investments in, among other things, infrastructure and water treatment. Conditional on the application being approved, Boliden will complete the investment, which includes a new ramp and a new crushing station. Production is expected to start in 2023.

In addition to increased mine production, a completed expansion means the life of the Kristineberg mine will be extended and that capacity utilisation in the Boliden Area’s concentrator will be improved.

At Kristineberg, cut and fill mining and drift and fill mining methods are used to mine the mineralised material underground. Generally, levels wider than 10 m are mined with drift and fill mining. In levels with widths between 6-10 m, slashing is used to mine any remaining mineralised material on the walls of the mining room. In the uppermost slices, residual mining is also practiced to mine the sill pillars.