Finncobalt mine plan targets decades of pollution in Outokumpu

A planned battery-minerals mine could help clean up pollution left by a copper mine that closed decades ago in Outokumpu, northern Karelia, Yle reports. The city has already spent millions of euros cleaning contaminated soil, while environmental authorities remain unconvinced that the new project will eliminate the risks.

Outolampi, a pond near the centre of Outokumpu, contains waste sand from the former copper mine. Its water is highly acidic and contains metals, with a pH of 2.7, close to the acidity of lemon juice.

Finncobalt plans to extract cobalt, nickel and copper from old mine tunnels in the Hautalampi mining area. The tunnels are currently filled with water containing high concentrations of metals.

When Finncobalt bought the mining area, it also assumed responsibility for the old mining waste located there. The company says the new mine could remove some of the waste and improve the environmental condition of the area.

Environmental expert Mari Heikkinen from the Permit and Supervisory Authority said acidic water continues to flow into nearby waterways because Outolampi has no bottom structures. The water contains high concentrations of sulphates and metals, and acidification has intensified in recent years.

Heikkinen said the greatest risks in the new mining project are connected to the old waste. If nothing is done to it, the pollution will continue.

Pollution has continued since the 1940s

Mining extensively polluted Outokumpu’s groundwater in the 1940s. The problems began when weak dams at Outolampi broke, allowing contaminated mine water to flow into nearby waters. Contaminated water then seeped into the soil and polluted the groundwater.

Within a few years, all the fish in nearby Lake Sysmäjärvi had died. The lake began to recover after surface waters were treated with lime in the 1960s. Liming ended in the early 2000s, and the situation has since deteriorated again.

The Outokumpu company operated from 1910 to 1989. It brought wealth to the city, which grew around the copper mine and took its name from it, but also left extensive environmental problems.

Company plans to control emissions

Finncobalt’s environmental impact assessment for the Hautalampi project was completed in 2023. The authorities concluded that the environmental studies were insufficient and needed to be continued.

Finncobalt Chief Executive Ilari Kinnunen said the assessment had mainly served as guidance for the issues that must be addressed in the company’s environmental permit application. He said understanding how water moves through the area was one of the most important issues.

The environmental permit application has been under consideration for more than two years and is still pending. The permit will determine how much the mine must invest in environmental protection.

Another major source of emissions is the waste rock from the old mine, which releases metals into the environment. Finncobalt plans to use the waste rock to fill mine workings and is also examining whether the rock could be used to produce metals.

Kinnunen said the copper content of some of the waste rock may be high enough to make copper processing profitable. He estimates that around 250,000 tonnes of waste rock lies at Outolampi and on the slope of Mökkivaara.

He described the slope as the largest single source of emissions because rainwater can flow directly through the mining waste, dissolving metals into the water.

Not all pollution caused by the old mine is likely to be prevented.