The vast majority of cobalt ores are first crushed and milled to a finer grain size, so that cobalt-bearing minerals can be easily separated from surrounding rock and other minerals of no economic interest. Further concentrating and processing of cobalt depends on the type of ore. The main sources of cobalt are three different deposit types, which are sediment-hosted Cu-Co deposits (SSHC), Ni-Co laterite deposits and Magmatic Ni-Co deposits, which are described below.

Processing of sediment-hosted Cu-Co deposits

Sediment-hosted Cu-Co deposits are mined and processed in the Democratic Republic of the Congo and Zambia and produces copper, while cobalt is dominantly a by-product. There are two different ore types, sulfide and oxide ore, which can be treated in different ways to reach the best metal recoveries. Oxide ore is commonly treated by Whole Ore leaching (WOL), where the minerals are dissolved in acid. Subsequently, solvent extraction is used to separate copper and cobalt and remove impurities. Sulfide ores are first concentrated by froth flotation and roasting before leaching, solvent extraction and impurity removal. Final precipitation commonly produces a cobalt hydroxide, but electrowinning, can be used to produce pure cobalt metal.

Processing of Ni-Co laterite deposits

Laterite deposits also generally consist of two different ore types, namely saprolite ore (silicate-dominated)and limonite (oxide-dominated), the ratio between the two in one deposit determines the best processing technologies for optimal recovery. Saprolite ore is chiefly smelted to produce ferronickel, used in the stainless steel industry, and cobalt is not recovered during this process. For deposits that chiefly contain limonite ore, high-pressure acid-leaching (HPAL) is the most popular processing route as the recovery rates for nickel are higher and cobalt is also recovered with recoveries of more than 90% for both metals. After leaching of the ore in an autoclave under high pressure and temperature, and additional steps to remove impurities, a mixed Ni-Co sulfide or hydroxide is precipitated, as a saleable product or it is re-leached to produce a pure cobalt powder via hydrogen reduction or cobalt metal via electrowinning. HPAL is used in Murrin Murrin, Australia and new operations in Indonesia. An alternative is the Caron process, where both limonite and saprolite ore can be treated together by roasting and subsequent ammonia leaching of the ore. However, overall recoveries are lower than in HPAL plants and decrease with higher contents of saprolite ore. An active operation, where this process is applies is Punta Gorda, Cuba.

Processing of Magmatic Ni-Cu (Co-PGE) deposits

At Magmatic Ni-Cu sulfide mines, copper is generally separated from nickel and cobalt via flotation, and the resulting nickel-cobalt concentrate is processed by smelting in a flash furnace or electric furnace. The resulting sulfide matte is then leached, followed by solvent extraction to recover nickel and cobalt. The overall recovery of cobalt is relatively low at only 40%, and is strongly dependent on the dominant mineral host of cobalt. Current operations that undergo this pyrometallurgical processing route are Sudbury, Canada or Norilsk, Russia.