Affinage

Affinage

 

a metallurgical process for obtaining noble metals of high purity by separating and recovering them from contaminating foreign matter. It is one of the ways of purifying metals.

Methods of affinage are divided into electrolytic, wet, and dry types. Electrolytic methods are used primarily for refining gold and silver; they involve the deposition of the pure metal on a cathode with the simultaneous separation of impurities in the form of sludge. Gold obtained by this method has a fineness of no less than 999.9. The advantage of electrolytic methods of affinage is in the lower cost of the process, the high degree of purity of the metals, the favorable working conditions, and the possibilities of obtaining metals in the platinum group as by-products by the addition of chemical reagents to the depleted electrolyte.

Wet affinage methods are used to obtain platinum, palladium, iridium, rhodium, and other metals of this group in a complex manner by dissolving the metals in aqua regia and subsequently separating them out of the solution with various reagents (such as ammonium chloride, ammonia, or sugar).

Dry gold affinage methods involve the treatment of the molten metal generally with chlorine. All the base metals then form chlorides and are volatilized, but silver chloride rises to the surface of the pure, molten gold. The fineness of the gold is 996.5, and the fineness of the silver (when recovered from the chloride) is 999.0.

REFERENCE

Plaksin, I. N. Metallurgiia blagorodnykh metallov. Moscow, 1958.
References in periodicals archive ?
According to Fuhrmann, "He's a good cheesemonger but his heart has always been in affinage.
AFFINAGE The French word describes the maturing and ageing of cheese.
The affinage process has become very important to us.
From such activities Republic loses control over accounting and the movement of mined and processed raw materials and also contributes to the loss of profit from value added in the case of deep processing and affinage of gold in the country.
Even rinds that aren't meant to be eaten can enhance the flavor of the cheese within, thanks to the affinage process.
There is also an informative and equally delicious glossary offering not only cheese-y terms like affinage and Bovine somatotropine but also not-so-mainstream social activists like Danny Cohn-Bendit Jose Bove and the punk band Bikini Kill.
A good cheese may benefit from a year or two of affinage, but only after a decade or two (or three or four) does the full wonder of a fine wine emerge--if, that is, it hasn't completely fallen apart in the meantime.
The French practice of affinage means that particular cheeses are ripened in optimum conditions to ensure that the cheese reaches the customer in perfect condition.
Just a few doors away was the affinage, or aging house, of Migneron de Charlevoix, a cheese found listed on restaurant menus throughout Quebec.
Les figures 4A et B referent au secteur manufacturier a faible valeur ajoutee, secteur qui, pour les fins de l'etude, comprend egalement des secteurs lourds << traditionnels >> comme les pates et papiers et la fonte et affinage de l'aluminium.
Within hours Artisanal will fulfill your request, directly from five custom-designed cheese aging caves masterminded by the Artisanal Affinage staff.
They're looking at things like hand cutting curds, affinage [ripening] techniques and building caves and cave-like areas.