Why were mercury salt and copper sulfate added during the patio process?

In the patio process, mercury, salt, and copper sulfate were added to the crushed silver ore to facilitate the extraction of the metal. These substances were essential for triggering the chemical reactions necessary to free the silver from its compounds, allowing it to dissolve into the mercury to form an amalgam.1

Once the silver was successfully amalgamated, the mixture was washed to remove the mud, and the remaining amalgam was heated to evaporate the mercury, leaving behind the pure silver. This method was a primary technique for silver processing for over three centuries, particularly in regions like Mexico, before being replaced by the cyanide process in the early 20th century.1