Closed open-cast pit and demolished headframe tower of the Vehka area within the former Kotalahti nickel-copper mine, Leppävirta.
The Vehkan kaivos was one of two open-cast mining areas forming part of the Kotalahti nickel-copper mine complex at Oravikoski in Leppävirta, North Savo, operated by Outokumpu Oy from 1959 to 1987. Ore was extracted both from a deep underground mine reaching 680 metres and from two surface open-cast pits, of which the Vehka area was one; the other was the Huuhtijärvi pit. The Vehka pit was later backfilled with tailings following a collapse that occurred during operations.
A mine headframe tower — the Vehkan kaivostorni — stood at the site after closure as a residual structure, remaining in Outokumpu ownership after the surrounding land was largely sold. By 2025 the tower had deteriorated to a point where it presented a safety risk, and Outokumpu obtained a demolition permit jointly with the current landowner. The tower was demolished in autumn 2025 and the mine shaft sealed with a protective cover.
The Kotalahti nickel-copper mine deposit was identified in 1954 when a local man from Leppävirta brought a rock sample containing ore to Outokumpu Oy for analysis. Prospecting confirmed a significant nickel-copper deposit, and construction of the mine complex began in 1957. Production commenced in 1959, with Outokumpu Oy as the operating company throughout the life of the mine. The ore body yielded nickel at a grade of approximately 0.7 per cent and copper at around 0.2 per cent, with total ore extraction over the operational period reaching approximately 12 to 13.7 million tonnes. The mine complex was designed by the architectural practice of Märta Blomstedt and Matti Lampén, who oversaw both the production buildings and the residential settlement built for the workforce.
The main underground shaft and headframe, a 77-metre reinforced concrete tower completed in 1958, stood at the primary pithead area. The Kotalahti complex also included two open-cast pits: the Huuhtijärvi pit and the Vehka area pit. Ore from these open-cast workings and from the underground mine was crushed and processed through the on-site concentrator, with the resulting concentrate transported by road to Varkaus and from there by rail to Outokumpu Oy's refinery at Harjavalta. The underground workings were progressively deepened, ultimately reaching 680 metres, making Kotalahti at one stage the deepest mine in Finland. In its most productive years the mine employed over 300 people. The Vehka area open-cast pit experienced a collapse during the operational period, after which it was backfilled with tailings.
The mine reached the end of its economically recoverable ore and was closed in April 1987. Post-closure environmental monitoring, required under the applicable Finnish environmental legislation, was carried out by Outokumpu on a continuing basis. A wastewater treatment plant was constructed in 2001 at the outfall of the drainage ditch to address elevated nickel concentrations in water flowing from the former mine area into the Oravilahti arm of Lake Koirusvesi. Further remediation works followed over subsequent decades, including improvement of the tailings impoundment cover and the treatment basin.
The Kotalahti mine settlement — comprising residential apartment buildings, terraced housing, a school, a community hall, a cinema and retail premises — was recognised as a nationally significant built cultural heritage environment (valtakunnallisesti merkittävä rakennettu kulttuuriympäristö, RKY) by the Finnish Heritage Agency (Museovirasto) in December 2009. Outokumpu retained ownership of a portion of the former mine land, including the Vehkan kaivostorni, while most of the site had passed to other owners. In autumn 2025 Outokumpu carried out remediation and demolition works at the closed mine area under a programme of environmental aftercare. The Vehkan kaivostorni was demolished for safety reasons following the grant of a demolition permit obtained jointly with the current landowner. The mine shaft at the Vehka site was subsequently sealed with a robust protective cover.