The Hautalampi nickel-cobalt-copper (Ni-Co-Cu) project is an underground mine development in Finland. It is being developed by FinnCobalt (formerly Vulcan Hautalampi), a private Finnish company, and Eurobattery Minerals, a mining company based in Sweden.
All the ground and mining rights of Hautalampi are owned by FinnCobalt. Eurobattery Minerals completed the acquisition of a 40% stake in the company in July 2022.
Eurobattery announced a second acquisition in March 2023 to increase its stake in the company to 70%. The transaction is expected to be completed in the second quarter of 2023. Eurobattery plans to acquire 100% of FinnCobalt’s shares in a phased manner by May 2024. The project will strengthen Eurobattery’s plans to supply critical raw materials for EV battery manufacturing in Europe.
A pre-feasibility study (PFS) on the Hautalampi property was completed in March 2023. The study estimated an initial development capital of €65.07m ($69.4m) and a mine life of 12 years.
The Hautalampi property is located in the Outokumpu mining camp area in the Outokumpu municipality of eastern Finland, which is approximately 350km north-east of Helsinki. The project area sits on the historic Keretti mine site.
The mining concession encompasses a mining area of 114.95ha and an auxiliary area of 168.55ha.
Geology and Mineralisation
Hautalampi is a volcanogenic massive sulphide-type deposit characterised by a hanging-wall NiCoCu mineralised body extending up to 200m above the historic Keretti mine. The deposit lies above the Keretti copper ore in a quartz rock-skarn zone interbedded by serpentinite and mica schist.
Mineralisation occurs as disseminated bands that have formed due to metamorphosis, with the mineralised zone having close contact with the wall rocks in some instances. The banded rock formation is attributed to variation in grain size and the presence of CaMg minerals in dust-like sulphides and microcrystalline graphite and chromite.
The main part of the mineralisation occurs 70m‐120m below the surface, while the deepest parts of the known mineralisation zone occur at up to 150m below the surface.
The proven and probable mineral reserves at Hautalampi are estimated at 4.56 million tonnes grading 0.30% nickel, 0.24% copper, and 0.08% cobalt. They contain 13,700t Ni, 11,000t Cu and 3,500t Co, as of March 2023.
Mining Method at Hautalampi Project
Hautalampi will be developed as an underground mine using the long hole stoping (LHS) method and up‐hole benching. The longitudinal LHS will be mainly mined as 40m-long stopes, varying between 20m and 60m in length depending on the shape of the ore body. Ore extraction will be maximised by using consolidated hydraulic backfilling.
Mining will be performed using bottom-up excavation with primary and secondary stopes. Primary stopes will be mined first, followed by secondary stopes after the backfilling of adjacent primary stopes. The secondary stopes will also act as rock pillars to improve stope stability.
Underground access for all mining-related traffic will be provided through an existing 5mx5m decline with an inclination varying from 1:6 to 1:14.
Up‐hole benching will be used as the secondary mining method in areas with no access drift above and where the LHS method is not suitable. The size and the shape of the stopes will also vary according to the dimensions of the orebody.
The Hautalampi processing plant will have a nominal output of 500 kilotons per annum. The run-of-mine ore will be crushed in a two-stage crushing circuit comprising a primary jaw crusher and a secondary cone crusher. The crushed ore will undergo grinding in a primary rod mill operating in an open-circuit and a secondary closed-circuit ball mill to achieve a target particle size of 68µm.
The feed from the grinding circuit will be conditioned prior to being fed to the copper flotation circuit comprising a scavenger flotation and two cleaning flotation stages.
The copper flotation tailings will feed the nickel and cobalt flotation circuit, while the copper concentrate product will be thickened in a 4m thickener. The thickened concentrate will pass through a disc filter to reduce the moisture content to 12% and will be held in a concentrate storage.
The nickel and cobalt flotation circuit will consist of a rougher flotation and three cleaning flotation stages. The concentrate product from the third cleaning stage will be dewatered, while the tailings will feed the sulphur removal flotation circuit. The nickel/cobalt concentrate will be thickened in a 4.5m thickener and disc filtered to reduce the moisture content to 12% and stored.
The sulphur from the nickel/cobalt flotation tailings will be further reduced using an additional sulphur flotation stage consisting of one rougher flotation stage. The sulphur flotation concentrate will feed the mine backfill feed hopper or the tailings thickener.
The Hautalampi property is accessible throughout the year via a tarred road that runs through the centre of the claim. The mine access road covering 1km will be upgraded and paved to accommodate mining traffic.
The total power requirement for mining equipment, ventilation and dewatering works is estimated to be 1.65MW, which will be sourced from the national grid via a local supplier.
Potable water will be sourced from a potable water network operated by the municipal network, which is situated in the proximity of the mine site. An underground pipeline system will be installed to connect to the municipal water network.
Contractors Involved in the Hautalampi Project
FinnCobalt engaged AFRY, an engineering, design and advisory services company based in Finland, to prepare the PFS for the Hautalampi Ni-Co-Cu project.
The process plant design parameters were largely based on pilot test work conducted by GTK Mintec laboratories and the prior experiences from the former Keretti mining operation.
The underground mine design was prepared by JK Kaivossuunnittelu, a consulting company.
Leaching test works with Hautalampi Ni-Co concentrates were carried out by Metso Outotec (formerly Outotec), a technologies and services provider for the mining industry, in 2019.
Source: Mining Technology