Cobalt

Cobalt is a metal that has been used for centuries for colouring ceramics and glassware. In the 20th century, cobalt began to be used increasingly in modern technologies such as aircraft turbines due to its high wear resistance, high temperature strength and unique magnetic properties. It is now highly in demand for the use in lithium-ion batteries for electric vehicles and portable devices such as mobile phones.

The electric vehicle market is developing rapidly. The International Energy Agency forecasts that there will be 200 million electric vehicles on roads across the globe by 2030, which translates to a cobalt demand growth for electric vehicle batteries from 160 000 tonnes in 2021 to 250 000 tonnes in 2030. Despite considerable efforts to reduce the cobalt content in batteries due to its high price and supply risks, it is difficult to substitute its unique properties and it is likely to play an important role in the battery technologies of the near future.

Figure 1 Dominant cobalt uses over time and increasing demand from electric vehicle (EV) batteries. BGS © UKRI. Data from Harper et al., 2012; IEA, 2022.

The second-largest use of cobalt is in batteries for portable devices. Such devices chiefly use batteries with a high cobalt content (lithium-cobalt oxide chemistry with 89 per cent cobalt) that have a high energy density and give them a long run-time. Cobalt is also used in many other applications, including various alloys such as superalloys for the aerospace industry and in hard metals (cemented carbide) for hard-wearing cutting and grinding tools. It is also used as a catalyst in oil and gas refinineries to remove sulphur and it is still used for colour pigments in ceramics, enamels, inks and glass, for which it has been used since antiquity. Other uses include magnets for wind turbines and motor sensors, hard facing, energy storage, tyres, soaps and paint driers.

Figure 2 Cobalt Institute (2023a). Data from Benchmark Mineral Intelligence.

Acquiring cobalt

Supply chain

Exploration

Cobalt has become a popular exploration target due to the need for new sources of this key battery raw material. The International Energy Agency (IEA) predicts that global cobalt demand will increase from 160 000 tonnes in 2021 up to 250 000 tonnes per year in 2030 (IEA, 2022). Exploration projects are widely distributed across the globe, with rapid developments of several new projects, especially in Indonesia (Cobalt Institute, 2023b).

Figure 4 Global map of cobalt mines, deposits and occurrences, with approximate locations indicated. The cobalt endowment of each deposit shown exceeds 0.05 million tonnes of cobalt metal, with the exception of some exploration projects in Europe. Other deposit types include: black shale-hosted nickel-copper-zinc-corbalt; iron-copper-cobalt skarn and replacement deposits; iron oxide-copper-gold (IOCG); metasedimentary rock-hosted cobalt-copper-gold; Mississippi Valley-type (MVT) sulphide deposits; cobalt-rich vein deposits, and volcanogenic massive sulphide (VMS) deposits. Note: the approximate location of sea-floor deposits is shown by a number only, without an accompanying symbol. Modified after Petavratzi et al. (2019).

There are several different deposit types that can contain and extract cobalt, with three types accounting for about 85 per cent of terrestrial global cobalt resources (Mudd and Jowitt, 2018):

magmatic nickel-copper-cobalt (with or without platinum-group elements (PGEs)) sulphides
stratiform, sediment-hosted copper-cobalt
nickel-cobalt laterite deposits

Cobalt is usually a by-product of these deposits, as the main commodities are chiefly copper or nickel. Other target commodities include gold, PGEs and silver.

Magmatic nickel-copper deposits are an important source of nickel, with nearly 40 per cent of world production in 2017. Major deposits are located in Russia, Canada and Australia. Stratiform sediment-hosted copper-cobalt deposits are the main source for cobalt, mainly extracted from the Central African Copperbelt in the DRC and Zambia. Large deposits of this type also occur in Europe (Kupferschiefer) and Russia (Udokan Basin), but cobalt concentrations are much lower and copper is the main commodity.

Table 1 Overview of the characteristics of different cobalt deposit types. Source Brown (2016).
Deposit type	Description	Typical size (Mt ore)	Co-bearing minerals	Examples (with Co ore grade)
Magmatic Ni-Cu-(Co-PGE)	Massive to disseminated sulphides hosted in mafic to ultramafic igneous rocks	5 to >500	Pentlandite Pyrrhotite Millerite Carrollite-linnaeite	Norilsk-Talnakh, Russia (0.061%) Voisey's Bay, Canada (0.13%) Kambalda, Australia (0.21%)
Stratiform sediment-hosted Cu-Co	Hydrothermal sulphide deposits loosely bound to a siliciclastic or carbonaceous unit(s)	10 to 500	Carrollite-linnaeite Cobaltite Cattierite (Heterogenite and sphaerocobaltite in weathered zones)	Tenke Fungurume, DRC (0.245%) Kisanfu, DRC (1.08%) Nchanga, Zambia (0.026%)
Ni-Co laterite	Supergene weathering products of mafic to ultramafic rocks	10 to 800	Erythrite Heterogenite Asbolane 'Garnierite' Co-rich clays	Moa, Cuba (0.13%) Goro, New Caledonia (0.11%) Murrin Murrin, Australia (0.078%)
Black-shale hosted	Disseminated sulphides in dominantly sulphur-rich black shales	Very large mineable deposits (1525 Mt at Sotkamo)	Co-bearing pyrite Pentlandite Pyrrhotite	Sotkamo, Finland (0.02%)
Metasediment-hosted Co-Cu-Au	Massive to disseminated sulphides in stratabound zones, lenses, veins, breccias; mainly in rift-related environments	<1 to 31	Co-arsenides Co-sulphides Co-sulpharsenides	Blackbird, USA (0.42%) Modum district, Norway (0.26%)
Polymetallic Co-rich veins	Hydrothermal sulphide veins; some known as 'five element vein' deposits (Ni-Co-As-Ag-Bi)	<20	Co-arsenides Co-sulphides Co-sulpharsenides	Bou Azzer, Morocco (1.0%)
Iron-oxide Cu-Au (Ag-U-REE-Co-Ni) (IOCG)	Magmatic (?)-hydrothermal, structurally-controlled replacement deposits; usually in an intracratonic setting	5 to >9 000	Co-bearing pyrite Cobaltite Glaucodot	Olympic Dam, Australia (0.02%)
Volcanogenic massive sulphide (VMS)	Massive sulphides formed in a submarine volcanic environment; cobalt concentrations may be high where hosted in ultramafic to mafic rocks	<10 to 300	Cobaltite Cobaltpentlandite	Windy Craggy, Canada (0.066%) Kylylahti, Finland (0.15%)
Mississippi Valley-type (MVT)	Epigenetic hydrothermal deposits hosted typically in dolostone or limestone; cobalt is rarely enriched	7 (median deposit size)*	Siegenite Bravoite Gersdorffite Pyrite	Higdon, USA (0.14% Co)
Skarn and replacement deposits	Sulphides associated with calc-silicate minerals	100 to 500	Cobaltite Carrollite-linnaeite Pyrite Safflorite	Cornwall, USA (0.03%) Goroblagodat, Russia (0.02%)

Reserves of cobalt

Cobalt reserve data from the United States Geological Survey (USGS) indicate a total of 8.3 million tonnes of cobalt, with almost 50 per cent situated in the DRC in sediment-hosted copper-cobalt deposits.

Australia also contains a significant proportion of cobalt reserves in magmatic nickel-copper deposits as well as nickel-cobalt laterite deposits; there are also substantial investments into new exploration projects concerning cobalt.

Indonesia currently holds the third-largest reserves, with many new nickel-cobalt laterite deposits being developed in the last few years that plan to produce cobalt as a by-product.

Figure 5 Global distribution of cobalt reserves expressed as tonnes of cobalt. Diagram shows global distribution of cobalt reserves, with the rest of the world (RoW) comprising countries with reserves of less than 200 000 tonnes, including Morocco, Papua New Guinea, Turkey, USA, Madagascar and China. Data source: USGS (2023).

Extraction

Processing

The vast majority of cobalt ores are first crushed and milled to a finer grain size, so that the 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:

sediment-hosted copper-cobalt deposits
nickel-cobalt laterite deposits
magmatic nickel-cobalt deposits

Figure 6 Cobalt processing for the three main deposit types that produce cobalt as a by-product. Figure after Dehaine et al. (2021).

Sediment-hosted copper-cobalt deposits

Sediment-hosted copper-cobalt deposits are mined and processed in the DRC and Zambia and generally produce copper, with cobalt as a by-product. There are two different ore types, sulphide and oxide ores, 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 the copper and cobalt and remove impurities. Sulphide 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 also be used to produce pure cobalt metal.

Nickel-cobalt laterite deposits

Laterite deposits generally consist of two different ore types: saprolite (silicate-dominated)and limonite (oxide-dominated). The ratio between the two in a single deposit determines the best processing technologies for optimal recovery.

Saprolite ore is chiefly smelted to produce ferronickel, which is used in the stainless steel industry, and cobalt is not recovered during this process.

High-pressure acid-leaching (HPAL) is the most popular processing route for deposits that chiefly contain limonite ore, as the recovery rates for nickel are higher. Cobalt is also recovered with recoveries of more than 90 per cent for both metals. After leaching of the ore in an autoclave under high pressure and temperature, and additional steps to remove impurities, a mixed nickel-cobalt sulphide or hydroxide is precipitated; this can be a sellable product on its own, or it can be 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. This process is used in active operations at Punta Gorda, Cuba.

Magmatic nickel-copper (cobalt-platinum-group elements) deposits

In magmatic nickel-copper sulphide 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 sulphide matte is then leached, followed by solvent extraction to recover nickel and cobalt. The overall recovery of cobalt is relatively low at only 40 per cent and depends strongly on the dominant mineral host of cobalt. Current operations that undergo this pyrometallurgical processing route are Sudbury, Canada, and Norilsk, Russia.

Drivers and alternatives

Secondary sources

Secondary sources can form an important part of the future cobalt supply, as large quantities of cobalt end up in waste streams at different stages in the value chain. As cobalt is mainly a by-product of copper and nickel production, metallurgical processing routes are not optimised for cobalt recovery and a significant proportion ends up in mining wastes. Manufacturing waste (new scrap) can be recirculated to ensure more efficient use of cobalt components. However, the largest secondary future cobalt resource is most likely end-of-life (EOL) products, particularly lithium-ion batteries in electric vehicles, which will gradually become more available for recycling.

Mining and refining waste

In many mining operations, cobalt is not prioritised for recovery as it only makes up a small proportion of the revenue compared to the main commodities of copper or nickel. It is estimated that between 40 and 60 per cent of cobalt is lost during ore processing to make a concentrate. Equally, smelting of sulphide ores from magmatic nickel-copper-cobalt sulphide deposits only recovers roughly 60 per cent of cobalt, but 80 per cent of nickel. The remainder will end up in the waste streams in mine tailings or as slag from smelting. There are several projects in central Africa that attempted to recover cobalt from tailings (Petavratzi et al. 2019). A successful example is the Kasese project in Uganda, which recovered cobalt from pyrite-rich mine tailings via a bioleaching process on an industrial scale. The facility produced 800 tonnes of cobalt per year from 1998 to 2014 (BRGM, 2023).

Another study at Nkana, Zambia, investigated the reprocessing of slag to produce a cobalt-rich alloy that can be further refined into cobalt metal. The Nkana site contains 20 million tonnes of slag with an average cobalt content of 0.76 per cent, higher than cobalt grades in many cobalt-producing mines. However, the process was never fully implemented and the operator decided to use a less expensive technology with no cobalt recovery (Petavratzi et al. 2019).

Recycling

The IEA forecasts that the amount of spent lithium-ion batteries will surge after 2030, with 1 TWh reaching their end of life by 2040 (SDS scenario) (IEA, 2021). An electric vehicle battery contains between 5 and 33 per cent cobalt (amongst many other valuable materials). Successful recycling depends on the collection of end-of-life products, battery types and cobalt prices. Battery recycling involves mechanical recovery, pyrometallurgy and hydrometallurgy or a combination of the three. Recycling efficiency of cobalt from lithium-ion batteries are relatively high at more than 85 per cent (Tkaczyk et al. 2018).

Other important waste streams include scrap from superalloys and nickel-cobalt alloys, as well as catalysts. These are often recycled in existing or secondary smelting facilities (pyrometallurgy). Spent cemented carbide (cobalt-bearing hardwearing tools) can be recycled via the zinc method and produce cobalt metal powder (Petavratzi et al. 2019).

The United Nations Environment Programme (UNEP) estimates an overall end-of-life recycling rate of 68 per cent cobalt, but the recycled content in newly fabricated cobalt metal is only 32 per cent (UNEP 2011).

The main challenges to increase cobalt recycling are:

economics of the scrap material, that is, the presence of other valuable materials and uncertainty material composition, making large-scale and efficient recycling difficult
poor end-of-life collection rates, which affects the viability of the recycling sector
hibernating stocks of, for example, consumer electronics, and lack of consumer engagement associated with waste management

(Petavratzi et al. 2019)