What are the Methods of Extraction of Cobalt?

Cobalt-extraction-plant

Cobalt is a key strategic metal used across battery technologies, specialty alloys and high-tech applications. While hydrometallurgical and pyrometallurgical refining paths dominate much of the global market, many cobalt-bearing ores — especially those associated with copper, nickel, iron or manganese systems — are best served by robust ore-beneficiation or "pre-treatment" methods. These methods include gravity separation, magnetic separation, flotation, and re-selection (re-processing of tailings or lower-grade material).

In this article we present the main ore-processing routes and show how each fits into a cobalt extraction strategy.

Gravity separation exploits differences in specific gravity (SG) between usable mineral (ore) and gangue. While gravity alone cannot produce final battery-grade cobalt, it is an excellent pre-concentration method in many cobalt systems.

When is it applicable?

• Cobalt hosted in coarse, well-liberated mineral forms (e.g., oxide/hydroxide, manganese/cobalt oxides) where density differences exist.

• Tailings or coarse rejects where gangue fines and slimes dominate and the heavy cobalt-bearing minerals remain.

• Systems where the liberation size is amenable to gravity devices (e.g., > 0.1 mm).

Typical methods

• Shaking tables: effective for fine-to-medium size heavy minerals.

• Spiral concentrators: for coarse/heavy fractions with continuous feed.

• Jigs: for stratification and heavy material recovery.

• Dense media separation (DMS): sometimes used if feed quantity and size justify.

Benefits

• Low operating cost (low reagent use).

• Simple to operate and maintain.

• Good for coarse recoveries and tailings re-processing.

Limitations

• Not suitable for very fine liberation sizes (< 0.05 mm) or for heavily disseminated cobalt minerals.

• Cannot remove all the gangue; needs subsequent flotation/magnetic separation for higher concentration.

In a typical beneficiation flow for a manganese-cobalt oxide ore (asbolite), you might apply gravity separation first to recover the heavy cobalt-manganese minerals, then follow with flotation or magnetic separation for further purification.

Magnetic separation exploits the magnetic susceptibility of minerals to separate magnetic from non-magnetic materials. It is particularly useful when cobalt is associated with iron minerals (magnetite, pyrrhotite) or other magnetic gangue/host minerals.

Typical scenarios

• Iron-cobalt deposits where cobalt is hosted along with magnetite, pyrrhotite, or other sulfides.

• Where a coarse magnetic/ferrous gangue can be removed to upgrade the feed prior to flotation.

• Where processing tailings with residual magnetic/iron minerals makes sense.

Methods

• Wet high-gradient magnetic separators (WHIMS): For fine particles of magnetic minerals.

• Drum magnetic separators: For coarser particles.

• Magnetic cleaning/scavenging: Once initial concentrate is made, further magnetic circuits remove residual iron minerals.

Benefits

• Effective removal of iron and ferrous gangue, improving downstream processing (less interference, fewer reagents).

• Reduction in volume of material needing flotation, lowering cost.

• Pre-concentration benefits: e.g., you may remove a large part of the mass while keeping most of the cobalt.

Limitations

• If cobalt is present in non-magnetic minerals, then magnetic separation alone is insufficient.

• For fine sizes or complex matrices, magnetic separation may lose efficiency.

A combined flow might first apply magnetic separation to remove iron/magnetite, then flotation on the remaining fraction to recover cobalt minerals.

Flotation is one of the most versatile beneficiation techniques, especially suited to sulphide-rich cobalt ores (e.g., copper-nickel-cobalt systems, copper-cobalt polymetallic ores).

Why flotation?

• Cobalt is often locked in sulphide minerals (e.g., cobaltite, arsenopyrite, chalcopyrite). These exhibit distinct surface chemistry and can be floated.

• Flotation allows selective separation of cobalt (or copper-cobalt mixed concentrates) from gangue.

• Combined circuits (differential flotation, mixed flotation) enable separation of multiple valuable metals (Cu, Ni, Co) from the same ore.

Typical flotation flow types

1. Mixed flotation: Copper, nickel and cobalt are floated together to form a bulk Cu-Ni-Co concentrate. This is often used for copper-nickel-cobalt sulphide ores.

2. Differential flotation: Copper is floated first, then cobalt (or cobalt sulphide) is floated in a second stage. For copper-cobalt deposits.

3. Selective flotation: Adjusting collectors, inhibitors and pH to preferentially float cobalt (or copper) depending on target. In copper-cobalt systems lime, sodium silicate, xanthates etc are used.

4. Flotation after magnetic/ gravity pre-concentration: To improve feed grade and reduce reagent consumption.

Key reagents and conditions

• Collectors: e.g., xanthates, D-series fatty acids or mercaptans for sulphides.

• Inhibitors: Lime to depress unwanted minerals, sodium silicate to suppress gangue silicates.

• pH control, aeration, cell type (mechanical/flotation cell) and residence time all play a role.

Pros

• High enrichment of cobalt in concentrate.

• Flexibility to handle polymetallic ores.

• Good for processing sulfide cobalt ores and improving value before metallurgical refining.

Cons

• Reagents cost and tailings management.

• Fine grinding may be required to liberate cobalt minerals (higher energy cost).

• Some complex ores require extensive optimization (e.g., arsenic-rich, extremely fine disseminations).

  
  

  

Re-selection refers to the process of re-processing existing tailings, coarse rejects or lower-grade ore stockpiles to recover residual cobalt (and associated metals) that was previously unrecoverable or uneconomic.

Why re-selection?

• Many historic cobalt (or copper/cobalt) operations left behind substantial losses in tailings or coarse rejects.

• With improved beneficiation technology (gravity, advanced flotation, magnetic separation) the residual cobalt may now be economically viable.

• Re-selection lowers the need for fresh ore and may reduce environmental footprint and permitting burden.

Our approach

• Tailings characterisation: grain size, mineralogy, liberation by size, residual cobalt grade.

• Gravity separation (shaking table, spiral, jig) to recover coarse heavy cobalt-bearing minerals.

• Flotation/magnetic separation as required to upgrade finer fractions or magnetically distinct minerals.

• Circuit design for low-grade feed, variable tonnage, retro-fitting into existing infrastructure.

Benefits

• Lower capital cost vs new mining development.

• Rapid pay-back due to higher head grades (from leftover material).

• Enhanced sustainability credentials (minimising waste, re-using tailings).

Thus, for a company looking to implement a cobalt processing plant built around beneficiation rather than full metallurgical refining, re-selection is an ideal first phase.

The extraction of cobalt is a complex but critical process in modern metallurgy. Each method has its own technical and economic strengths.

As the global demand for cobalt continues to grow — driven by electric vehicles and renewable technologies — efficient, sustainable extraction methods will be vital. Combining traditional expertise with modern green technologies offers the most promising path toward sustainable cobalt production.