Pan amalgamation

The pan amalgamation process is a method to extract silver from ore, using salt and copper(II) sulfate in addition to mercury.

[1] The amount of salt and copper(II) sulfate varied from one-quarter to ten pounds of one or the other, or both, per ton of ore treated.

Each tank ("pan") was circular, and commonly held 1,200 to 1,500 pounds of ore that had been crushed to sand size.

A circular iron plate called a muller was mounted on a vertical shaft and lowered into the pan, and was rotated to provide both agitation and additional grinding.

The Washoe process was found not to work well for ores with arsenic or antimony sulfides, or with galena or sphalerite.