Affinerie

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An affinery (also a refinery ) is a facility in which metals are separated in a very pure form by leaching out impurities . It is a separation process for metals from metal alloys , especially precious metals . Affination is often done electrolytically or “wet” using concentrated acids. A common affination process is the aqua regia separation. Aqua regia is an acid mixture of hydrochloric acid and nitric acid in a ratio of 3: 1. Most precious metals such as gold, silver and some platinum metals dissolve in this and can later be individually precipitated. Another method uses hot concentrated sulfuric acid to dissolve copper and silver and convert them into salts. However, it is not possible to produce high-purity metals with sulfuric acid. The task of an affinery is the separation of precious metals and the production of fine metals of particularly pure quality. The goal is a purity of 4N = 99.99% or better.

term

The term has been used in German since the 18th century and refers to an earlier French term that was used for an older technique of metal separation. The name is best known for the Norddeutsche Affinerie , since April 2009 Aurubis in Hamburg , one of the largest copper producers in the world. During the extraction of pure copper, other impurities previously present in the raw copper go into solution, including precious metals.

In addition, the term “refining” is also used for the refinement through maturation and care of cheese, see Maître fromager affineur .

Affinage / affination

The affinage ('refining, maturing') or affination carried out in an affinery comprises various refining processes in metallurgy . Affinage is divided into electrolytic (e.g. gold , silver or copper ), wet (e.g. platinum , palladium , iridium , rhodium ) and dry processes (with chlorine in the melt, e.g. gold and silver) .

• The largest gold refinery is near Johannesburg in South Africa . There are a total of 51 gold refineries worldwide.
• The largest European copper refinery is Aurubis (formerly Norddeutsche Affinerie AG)
• The largest European gold refinery is AGOSI (part of the Umicore Group )

literature

• Ralf Banken: precious metal shortage and large-scale robbery. Akademie Verlag, Berlin 2009, ISBN 978-3-05-004380-7 .
• Carl Schnabel: Handbook of metallurgy. Second volume, published by Julius Springer, Berlin 1904.

See also

• Precious metal separation
• Refinement (metal)
• Separation process (process engineering)

Individual evidence

1. ↑ IN Plaksin: Metallurgiia blagorodnykh metallov . Moscow 1958. In: The Great Soviet Encyclopedia. 3rd edition (1970-1979).

Web links

• Refiners in Transition (accessed August 15, 2019)
• OECD Guidelines for Due Diligence (accessed August 15, 2019)
• Processing and recovery of precious metals (accessed on August 15, 2019)
• The history of Degussa in Wesseling (accessed on August 15, 2019)
• In Search of Clean Gold (accessed August 15, 2019)