Listen as Andreas Vallmark, development engineer and environmental coordinator for closed mines, explains his work with the Holmtjärn project, which is making just that a reality.
In the early 1990s, the Holmtjärn Mine in Västerbotten was reclaimed in accordance with the standard at that time, but due to environmental impact, Boliden made the decision to undertake new measures.
“The reclamation is a process that we do not want to repeat again in 20 years’ time. Instead, what we do today needs to last forever,” says Andreas Vallmark, development engineer and environmental coordinator for closed mines.
He explains that at many of Boliden’s former mines there are heaps of material containing sulphides. This material affects local adjacent watercourses leading to a low pH, when it oxidises and produces acid. To investigate, conduct and prioritize actions for this effect is an ongoing responsibility for Boliden.
“We carried out a fairly extensive sampling of the rock deposited at Holmtjärn and discovered that it contains enough gold to make concentration viable. The mission is to transport all the waste rock from Holmtjärn to the concentrator in Boliden and, in doing so, remove the major source of environmental impact, while also making a financial profit instead of purely a loss.”
“Getting to work with improvement measures like this is very exciting. It’s great to work for a company that takes its responsibilities seriously. Responsibility doesn’t end when you stop mining activities. In fact, responsibility continues forever.”
The water is purified to 99 percent
Once the waste rock has been removed, any residual metals at the site will gradually be washed out of the soil and water. In order to prevent these from spreading, an ultramodern water treatment plant will be used.
“We want purification that is effective, requires little supervision and is mobile. Based on these requirements, we started a project group within Boliden which included various departments from our technology and environment sections in order to design a water treatment plant specially adapted for closed mines where we have no power supply.”
In summary, the plant offers a high degree of purification and efficient use of chemicals, is remote controlled and regulated, is mobile and to some extent self-sufficient in terms of power supply.
“We will be able to precipitate 99 per cent of the metals in the water. Once we see the levels fall at Holmtjärn to a good level, the plant will be moved to the closed mine where it can do the most good,” concludes Andreas.
