Vanadium - Otanmäki
The Otanmäki mine complex is located some 30 kilometres south-west of Kajaani in central Finland and was the biggest and most important Finnish iron mine, which provided the domestic raw material base for steel manufacturing and also for the production of ilmenite and vanadium.
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Geology of the Otanmäki area
Mafic layered intrusions in brown, Kylylahti Copper Oy’s claim reservations in black. Red stars show the locations of the Otanmäki and Vuorokas mines. Other Fe-V2O5 prospects are shown as light green circles. Map grid is 10km x 10km. Geology by the GTK.
The Otanmäki and Vuorokas mines are hosted by Paleoproterozoic (2.065 Ga) mafic layered intrusions.
The underground mines were operated by Rautaruukki Oy during 1953-1985 and the total mining at each mine was; Otanmäki 29.8 million tonnes @ 33.9% Fe, 0.46% V2O5, 12.7% TiO2 and Vuorokas 1.35 million tonnes @ 32.5% Fe, 0.46% V2O5, 9.24% TiO2.
The average ore composition was 35-40 vol% magnetite and 27-32 vol% ilmenite. The magnetite contains 0.62 wt% vanadium and ilmenite 0.17 wt% vanadium
At Otanmäki the remaining resource is approximately 19 million tonnes and is located beneath the lowest production level (some 600 metres vertical depth). This resource was not mined due to the high capital expenditure required at the time of operation.
Total production over the mine life was:
- 7.6 million tonnes iron concentrate
- 3.8 million tonnes ilmenite
- 200,000 tonnes sulphur concentrate
- 55,545t V2O5 (produced from magnetite)
A number of other deposits have been discovered in the area and Resource Estimates have been published by GTK and are available on that organisations website.
Resource Estimates published by GTK
| Deposit | Mt | Fe (%) |
V2O5 (%) |
TiO2 (%) |
| Pentinpuro | 2.20 | 34.8 | N/A | N/A |
| Isonkivenkangas | 0.10 | 19.7 | 0.30 | N/A |
| Honkamaki | 0.50 | 37.0 | 0.48 | 13.76 |
| Koski North | 0.25 | 27.7 | 0.36 | 11.68 |