Which chemicals can be used to leach mercury from ores and concentrates?

To leach mercury from ores and concentrates, several chemical solutions can be employed as part of hydrometallurgical processes. These methods are often explored as safer alternatives to traditional roasting, which relies on the volatility of mercury and poses significant environmental and health risks due to the metal's toxicity.12

Chemicals used for leaching include:

• Sodium hydroxide and sodium sulfide: A solution containing these two compounds can effectively leach mercury from ores and concentrates.1
• Sodium hypochlorite: This solution is also used to dissolve cinnabar, the primary mercury ore.2

Once the mercury has been leached into the solution, it can be recovered through electrolysis or by precipitation using aluminum or zinc. While these hydrometallurgical techniques offer a way to avoid the hazards associated with mercury vapour, it is important to note that leaching is generally more costly than traditional furnacing and may not be effective for ores with irregular compositions.12