What is Quartation?
Quartation is an important step in the refining of gold and other precious metals. It involves mixing impure metals with base metals to reduce their purity before further refining. The term comes from “quartering” or reducing the precious metal to a quarter of its original purity.
Purpose of Quartation
The purpose of quartation is to make it easier to separate precious metals like gold and silver from other impurities in the next stages of refining. When gold is mixed with other metals, its melting point is lowered significantly. This makes it easier to dissolve the metal in acids for chemical purification.
Quartation also causes impure metals to become more brittle. This allows them to be more finely pulverized and exposed to greater surface area for chemical reactions during refining. Overall, lowering the purity makes impure metals more workable and separates them from contaminants.
Quartation is an important step in the refining of gold and other precious metals. It involves mixing impure metals with base metals to reduce their purity before further refining.
The Process
There are two main ways quartation is carried out:
Addition of Base Metals
The impure gold can be melted together with copper, zinc or tin which dilute the gold to about 25% purity. The added base metals bond with impurities in the gold.
Silver Inquisition
With impure gold-silver alloys, silver is added to lower gold to 25% purity. The silver bonds with the gold, leaving impurities behind in the slag.
Parting Process
After quartation, the metal must undergo the parting process. This separates the precious gold or silver from the base metals added during quartation.
Parting is typically done by heating the quarted metal in nitric acid. The acid dissolves the added base metals, leaving only gold and silver behind. These precious metals can then undergo further refining to reach pure form.
Importance in Refining
Quartation allows large quantities of impure metals to be refined efficiently on an industrial scale. Without the initial step of reducing purity, refining certain metals would be difficult or impossible.
This indispensable process makes use of base metals to facilitate the purification of precious metals. It is a vital intermediate step between smelting impure metal and producing assayed pure gold or silver.
