The Kemi Mine is owned by Outokumpu Chrome Oy, a subsidiary of Outokumpu Oyj. It is located in Elijärvi, in the municipality of Keminmaa, to the north of Kemi. The Kemi Mine is the largest underground mine in Finland, with an annual production capacity of 2.7 million tonnes of ore. It is also part of the integrated ferrochrome and stainless steel manufacturing chain owned by Outokumpu in the Kemi-Tornio region. The Kemi mine is the only chromium mine in the European Union.
The company is committed to start the adoption of the new sustainability standard for mining in Finland.
The purpose of the Kemi Mine in the long production chain from chromite ore to stainless steel is to produce concentrates from ore as raw material for the manufacture of ferrochrome at the ferrochrome plant located in Tornio. The chrome contained in the ferrochrome generated as a product at the ferrochrome plant – used as an alloying material in the steel manufacturing process – is what makes the steel manufactured at the Tornio steel plant stainless.
The Kemi Mine opened in 1968, less than ten years after the orebody was found. Chromite ore was extracted from open-pit mines reaching depths of approximately 200 meters until 2005. In 2003, underground mining began. Open-pit mining ended at the Kemi Mine in December 2005 with the final open-pit blasting.
The underground mine is accessible either via an incline ramp or a mine shaft. Ore extraction started at level 500, from which the process proceeds upwards towards the bottom of the open-pit. Fully excavated primary stopes are filled with waste rock. From each stope, the ore is carried to an underground crushing station. The crushed ore is transferred via a conveyor belt to crushed ore silos located close to the mine shaft and further to a skip via a measuring pocket. The ore is hoisted through the shaft to an unloading silo located in a 70-meter-tall lifting tower, from where it is forwarded to the concentration process.
Ore is concentrated at concentration plant located at the Kemi Mine into lump and fine concentrate. In the first phase, the ore is crushed for further processing. At the lump concentration plant, lump concentrate is separated from the crushed ore using the sink-and-float method. After that at fine concentration plant, the ore is grinded with rod mill and concentrated with gravity by spiral separators into fine concentrate. Concentrates are transported to Tornio by trucks. From fine concentrate plant, tailings are pumped into tailings pond area, where solids are deposited and water goes to clarifying ponds. Concentrator plant takes process water from clarifying ponds.
Environmental impacts from Kemi Mine is minimal due to chromium oxide ore, with low leachability and gravity based separation methods with no chemicals and process water recycling.
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Company’s corporate responsibility report http://www.outokumpu.com/fi/vastuullisuus/Sivut/default.aspx