Wohlwill process

Wohl-Aue synthesis Wohlwill process Wolff-Chaikoff effect... 

Treatment of impure gold is largely via the Miller process (30) in which chlorine is bubbled through the molten metal and converts the base metals to chlorides, which volatilize. Silver is converted to the chloride, which is molten and can be poured. The remaining gold is less pure (99.6%) than that produced by the Wohlwill process and may require additional treatment such as electrolysis. If platinum-group metals (qv) are present, the chlorine process is unsuitable. 

Wohlwill process An early electrolytic process used to refine gold. It used crude gold as the anode and pure gold as the cathode with a solution of gold chloride in hydrochloric acid as the electrolyte. By applying an electrical current across the electrodes, pure gold... 

Balbach A variation of the Moebius process for electrolytically removing gold from silver, in which the anodes are placed horizontally in wooden trays lined with canvas to retain the slimes. The silver is deposited as crystals on graphite cathodes at the base of the cell. Invented by E. Balbach. See also parting, Parkes, Thum, Wohlwill. 

Moebius An electrolytic process for removing gold and platinum from silver. The crude metal, known as Dore, is used as the anode. The cathodes are of silver or stainless steel. The electrolyte is a diluted solution of silver nitrate and nitric acid. Gold and other metals collect as anode slimes. Invented in Mexico by B. Moebius, first operated there in 1884, and subsequently widely operated in Germany and the United States. See also Balbach, Thum, Wohlwill. 

Wittig reaction, 2 64-65, 19 65 Wobbe Number, 12 378-379 Wohl-Aue synthesis, 2 787 Wohlwill refining process, 22 647 Wolff-Chaikoff effect, 14 373 Wolff-Kichner reduction, 13 569-570,... 

An acceptable industrial process for the electrorefining of gold was first developed and implemented at the Norddeutsche Affinenie, Hamburg, 1878, by Wohlwill. The Wohlwill cell is broadly similar to the Moebius celt for silver, as it... 

While the Wohlwill type of process is still applied in small installations and for secondary refining, its large-scale use in primary refining has been superseded by other process routes which allow a smaller 1ockprocess involves chemical dissolution of gold as a chJoro-complex via CI2 bubbled through the liquor. 

In 1908, Wohlwill modified his process by the use of a pulsed current, in fact a low-frequency a.c. superimposed on the normal d.c. supply. This pulsing allowed insoluble chloride films to flake oflF the anode, facilitating the treatment of higher silver content gold at elevated current densities. 

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