Existing comment:
In the 1890's, a processing method was developed that could recover almost every atom of gold found in tailings, waste and low grade ore.
Crushed gold-bearing sands were mixed in a dilute sodium-cyanide solution, dissolving the gold. This liquid was run through beds of fine zinc shavings, the gold settling out as a black sludge. This mixture was then heated in a retort to remove the zinc impurities.
The process was so simple anyone could process gold at the digging site. Many miners ran old tailing heaps through their vats in this manner to recover any remaining gold particles. |