How does hydrometallurgical leaching remove mercury from ore?

Hydrometallurgical leaching removes mercury from ore by dissolving the mineral—typically cinnabar—into a chemical solution. The ore is treated with a solution of sodium hydroxide and sodium sulfide, or alternatively, sodium hypochlorite.12

Once the mercury is dissolved into the solution, it is recovered through one of two primary methods:
* Precipitation: The mercury is precipitated out of the solution using aluminum or zinc.12
* Electrolysis: The solution undergoes an electrolytic process to isolate the metal.12

While this process is explored as a safer alternative to traditional pyrometallurgical methods due to the high toxicity of mercury and the need for strict pollution control, it is generally more costly than furnacing and is not effective for ores with irregular compositions.12