Electrolytic Refining of Copper

Anode copper, produced in the metallurgical process, is used for electrolytic refining. The anodes are placed in an electrolyte containing copper sulfate and sulfuric acid. Between the anodes, thin start plates made of pure copper are inserted as cathodes. In the process the anodes are dissolved and the cathode plates grow by copper precipitation. After electrolysis for 10 days the weight of the cathodes has increased to 145 kg and their copper content is 99.95% or more. This copper is delivered as refined copper. 

There are different commercial qualities within the group refined copper  

During electrolysis an anode sHme is obtained that is processed for extraction of gold, silver, platinum metals and selenium. 

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Silver is also recovered during electrolytic refining of copper. Commercial fine silver contains at least 99.9% silver. Purities of 99.999+% are available commercially. 

Preparation. Selenium is normally extracted as a by-product from electrolytic refining of copper. 

Selenium is recovered from anode muds or slimes in electrolytic refining of copper. Anode mud is treated with sulfuric acid and roasted. Selenium is converted to its dioxide, which vaporizes and is collected in a wet scrubber system. 

Electrolytic Refining of Copper. Immerse a carbon cathode and an anode cut out from a strip of crude copper into a 300-ml beaker. Pour a 20% sulphuric acid solution into the beaker. The current... 

Tellurous acid can be prepared from the residues from the electrolytic refining of copper by treating them with a solution of ammonia. On the addition of acetic acid to the resulting solution tellurous acid is obtained as a precipitate. When this precipitation is carried out in the cold the product obtained is readily soluble in alkali hydroxide, but if the precipitation takes place in a hot solution the product tends to be insoluble in the alkali hydroxides.2... 

In the electrolytic refining of copper, blister copper is used as the anode and oxidized. The copper(II) ion that is produced from its oxidation is then reduced at the cathode to give a metal with a much higher purity. The impurities in the blister copper include iron, nickel, silver gold, cobalt, and trace amounts of other metals. The material that is not... 

These are very unreactive metals. Silver exists mainly as silver sulfide, Ag2S (silver glance). The extraction involves treatment of the pulverised ore with sodium cyanide. Zinc is then added to displace the silver from solution. The pure metal is obtained by electrolysis. Silver also exists to a small extent native in the Earth s crust. Gold is nearly always found in its native form (Figure 10.17). It is also obtained in significant amounts during both the electrolytic refining of copper and the extraction of lead. 

Each industrial chemical process has as its objective the economical production of a particular primary product. It is frequently true that, in attaining this objective, one or more by-products may become available. If these by-products can be disposed of at a profit, this serves to decrease the overall cost of operation and to permit the sale of the primary product at a lower, more favorable, competitive price. Thus, the cost of electrolytically refined copper is dependent on the recovery and sale of the by-products—silver, gold, platinum, and palladium. These precious metals are recovered in large quantities from accumulated anode sludges. Fully one-fourth of the total production of silver, about one-eighth of the gold, and lesser quantities of platinum and palladium are obtained as by-products of the electrolytic refining of copper. 

Large quantities of this acid are used in the metallurgical industries in the pickling of iron and steel, in the production of zinc, in the electrolytic refining of copper and other metals, in electroplating operations, and so forth. 

In the electrolytic refining of copper (p. 249) both silver and gold are deposited in the insoluble sludge at the bottom of the vessel, and are subsequently extracted from this sludge, the silver being dissolved by boiling with sulphuric acid, and subsequently precipitated by copper. 

Electrolytic manufacture of sodium and chlorine. Electrolytic manufacture of aluminum. Electrolytic refining of copper. 

Why does the electrolytic refining of copper purify it from gold From iron ... 

FIGURE 17.18 In the electrolytic refining of copper, many slabs of impure copper, which serve as anodes, alternate with thin sheets of pure copper (the cathodes). Both are dipped into a dilute acidic solution of copper. As the copper is oxidized from the impure anodes, it enters the solution as Cu and migrates to the cathodes, where it plates out in purer form. 

Selenium and tellurium are found in sulfide ores they are also recovered from the anode sludge formed during the electrolytic refining of copper. 

Source From anode slime produced in electrolytic refining of copper and lead. 

Selenium is quite rare (9 X 10 % of the earth s crust). It occurs mainly as an impurity in sulfur, sulfide, and sulfate deposits. It is obtained from the flue dusts that result from roasting sulfide ores and from the anode mud formed in the electrolytic refining of copper. It is used as a red coloring in glass. The gray crystalline allotropic form of selenium has an electrical conductivity that is very light-sensitive, so it is used in photocopy machines and in solar cells. 

Tellurium is used in the metallurgical industry as an alloy constituent. Tellurium improves the acid resistance of lead used in batteries. It is also used in the manufacture of heat- and abrasive-resistant rubber. Tellurium is obtained as a by-product in the electrolytic refining of copper. In the semiconductor industry, the ultra-trace level determination of tellurium in tellurium-doped single crystals is often required. Tellurium species are highly toxic. 

With regard to geochemical cycling (as well as for economic considerations), it is important to distinguish between the abundance of an element and its availability. The availability of an element is related not only to its relative abundance on Earth but also the stability of minerals in which it is a major constituent. Thus, a number of elements (e.g. copper, mercury, tin, and arsenic) that are scarce in terms of their average crustal abundance are easily isolated due to their ability to form mineral deposits. The most unavailable elements are those that form no major minerals of their own. Many of the rarer elements are available for economic use only to the extent that they are obtained as byproducts of the extraction of more abundant elements. Tellurium, for example, is produced during the electrolytic refining of copper. 

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