Precious metals refining


Precious metals refining

Precious metal refining is a superordinate term for the separation from noble-metalliferous materials. The precious metals are won for example from used catalysts, electronics, ores or alloys. The refining is a very expensive and complex procedure, but as prices rise recycling of precious metals becomes ever more attractive.

Procedure

In order to isolate noble-metalliferous materials, pyrolysis procedures, hydrolysis or a combination of both are used. In pyrolysis, the noble-metalliferous products are released from the other low materials, by becoming in a melt as cinder poured off or simply only oxidized. In the hydrolysis the noble-metalliferous products are solved either in Aqua regia (consisting of hydrochloric acid and nitric acid) or brought in hydrochloric acid/chlorine gas in solution. One speaks also therefore of the explanation procedure. Subsequently, certain metals can be precipitated or reduced directly in connection with a salt, gas or an organic and/or a Nitrohydrat connection. Afterwards they go through still certain cleaning stages or are again recrystallized. At the end the precious metal from the precious metal salt connection is separated by calcination from the connection. Both procedures for the employment in most cases come. The noble-metalliferous materials are hydrolyzed first, thermally prepared (Pryolyse) and thereafter. Straight if it around catalysts from the chemistry sector acts or the customer special a high purity of the metals wishes, because these materials contain different metals and foreign matter those as a rule also the sheath - process disturb or into the length pull. Also the catalysts themselves can consist of several precious metals. From this reason, step by step a precious metal from the recycling product are removed in each case and driven several times in the cycle.

Products

To a large extent silver and gold become divorced, afterwards follow platinum, palladium and rhodium. Iridium, ruthenium, osmium as well as rhenium are recycelt rather rarely. At present however rises the demand for ruthenium, which is used it for the coating of smaller and more efficient non removable disks.

The companies from this business

Only on it specially companies with good ratings of banks have, should one these materials and work leave. One of the reasons therein, which precious metals are treated such as foreign exchange also the metals become daily again evaluated (Fixing). The most of this companies have an internal precious metal trade, which functions similarly in principle as a bank. There so-called precious metal becomes - accounts led, on which there is even partial interest. In the international area these companies are well-known: W.C. Heraeus GmbH & CO KG (Germany), Engelhard (since short to the BASF Group) and Johnson Matthey PLC.


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