From mine to metal

Ore, the raw material of copper, is mined from open pit or underground mines. Ore , which contains 0.3-3% of copper, is crushed and milled and valuable minerals are separated from ore by concentrating. In addition to copper, ores contain for example noble metals like gold and silver, and molybdenum, selenium, cobalt and nickel. Waste rock and tailings, rest materials that have no economical value are returned into mine or landscaped to the vicinity of mine.

Copper concentrates containing 25-35% of copper are smelted in Scandinavia at Boliden smelters mostly with flash smelting technology developed by Outokumpu. Energy required for the flash smelting process is obtained from reaction energy of concentrates. Iron and sulphur contained in copper minerals are burned with oxygen enriched air, which releases heat that is sufficient to smelt the concentrate to copper matte. Process gas heat is recovered in a waste heat boiler and produced steam is used for example for concentrate drying and electricity production. Sulphur dioxide gas generated in the process is converted into sulphuric acid. Production of sulphuric acid also generates heat, which is used for district heating. After flash smelting the copper matte is yet converted by blowing oxygen enriched air into the melt to oxidize remaining sulphur and iron. Iron oxides form slag with added sand. After converting the blister copper is fire refined in anode furnace and finally cast to anodes.

The specific emissions of Boliden copper smelters are among the lowest in the world. Emissions are constantly being decreased, even though production volumes have increased. Slag from smelting is utilized for example in infrastructure construction and the rest is landscaped in vicinity of the smelter.

The smelter product, anode copper, is refined to pure copper in electrolytic refinery. Here also the precious metals are recovered as by-products, i.e. gold, silver, platinum/palladium alloy and selenium. Other by-products include copper tellurium and nickel and copper sulphate. Typical for copper smelting and refining process is that all valuable materials are recovered and further refined into products. In order to achieve as effective recovery of valuable materials as possible, many intermediate products are recycled internally to earlier process stages or to other metal producing plants for reuse. 

Copper cathodes are melted in foundries and cast to desired shape for further processing. Alloying takes also place in foundries when bronzes, brasses or other alloys are produced. Major part of copper cathodes go to the manufacturers of electrical cable rods.

The cast shapes are further fabricated to sheet, strip, tube, wire or profiles. In the manufacture of copper products Luvata uses technologies developed in-house and those commonly used throughout the world. Own modern technologies are generally more energy-efficient and environmentally friendly than competing processes, and require fewer production steps to reach the dimensions of the end product.