Amalgamation in Metallurgy

Amalgamation in Metallurgy 

a method of extracting metals with the aid of mercury. When wetted with mercury, other metals form amalgams with it, and they are separated from dirt and sand. Amalgamation is called internal when it is effected simultaneously with pulverization of the ore (in mulling basins, mills, and so on). It is called external when carried out in concentration sluices; as the mixture of triturated ore and water moves forward in the sluice, the metals are caught by the mercury that is spread over copper (sometimes silver-plated) sheets. A different version of this method is active amalgamation, where the ability of metals to combine with mercury is increased by preprocessing the ore with a dilute sulfuric acid solution or by using a zinc amalgam in a sulfuric acid solution. Elec-troamalgamation is also utilized to increase the metal’s ability to combine with mercury by treatment of the ore in the sluices under the action of direct current (the mercury is given negative polarity). Amalgamation is employed for the extraction of precious metals from their ores in conjunction with technically more advanced extraction processes—for instance, cyanidation. It is also used for processing the tailings of lightweight metals (in secondary metallurgy), for electrolytic extraction of rare elements, and so on. More than 2,000 years ago amalgamation was employed for the extraction of gold.

REFERENCE

Plaksin, I. N. Metallurgiia blagorodnykh metallov. Moscow, 1958.