Nikiel otrzymuje się gł. z rud siarczkowych, przerabianych na tzw. kamień niklowy, z którego uzyskuje się tlenek niklu redukowany węglem do metalu
http://slimak.sciaga.pl/prace/praca/12524.htm

At the present time nickel is obtained practically entirely from garnierite and the nickeliferous pyrrhotines. When the former is used it is roasted with calcium sulphate or alkali waste to form a matte which is then blown in a Bessemer converter or heated in a reverberatory furnace with a siliceous flux with the object of forming a rich nickel sulphide.
http://50.1911encyclopedia.org/N/NI/NICKEL.htm

The pyrometallurgy process that nickel goes through is a two-stage process of smelting and then refining. Smelting is a two-stage process, the first in the furnace and the second in the converter. When the pentlandite is in the smelter, oxygen (O2) and silica (SiO2) is added. As a result, the sulfur is oxidized and converted to sulfuric acid, and slag, and iron silicate material, is produced.

The finished product form smelting is Ni3 S2, or the nickel matte. The matte goes to be refined. There, the Ni3 S2 is melted and oxygen (O2) is added, thus creating Ni3 and SO2. The nickel is removed by using electrowinning.
http://www.bishops.ntc.nf.ca/science/chem/nickel2/