How can ammonia be used to process nickel concentrates?

In the context of nickel processing, ammonia is utilized as a chemical agent to extract nickel from concentrates through a process known as leaching.1

Ammonia Leaching Processes

• Direct Leaching: Nickel concentrates can be leached directly using ammonia to dissolve the metal from the ore.1
• Ammonia Pressure Leach: This method is used to treat nickel matte. During this process, nickel is recovered from the resulting solution through hydrogen reduction. A significant environmental benefit of this technique is that the sulfur present in the material is recovered as ammonium sulfate, which can then be utilized as fertilizer.1

Recovery of By-products

When using ammonia pressure leaching to process nickel, other valuable metals such as cobalt can also be recovered. In this specific leaching environment, cobalt is extracted from the solution by reduction with hydrogen under pressure.2