Electrolytic cell refining copper

The copper obtained from this process is about 99% pure, yet this is not pure enough for most uses, especially those involving electrical conductivity. To refine the copper further, it is made the anode of an electrolytic cell containing copper sulfate solution. With careful control of the voltage to regulate the half-reactions that can occur, the copper is transferred from the anode (where it is about 99 % Cu) to the cathode where it can be deposited as 99.999% Cu. At the anode there is oxidation of copper,... 

Copper used in electrical wires and circuits should be very pure. Crude copper is refined electrochemically by using electrolytic cells. Impure copper is given a positive charge (anode), and pure copper is given a negative charge (cathode). 166 Heat, Chemical Kinetics and Eiectrochemistry... 

An electrochemical cell in which electrolysis takes place is called an electrolytic cell. The arrangement of components in electrolytic cells is different from that in galvanic cells. Typically, the two electrodes share the same compartment, there is only one electrolyte, and concentrations and pressures are far front standard. As in all electrochemical cells, the current is carried through the electrolyte by the ions present. For example, when copper metal is refined electrolytically, the anode is impure copper, the cathode is pure copper, and the electrolyte is an aqueous solution of CuS04. As the Cu2f ions in solution are reduced and deposited as Cu atoms at the cathode, more Cu2+ ions migrate toward the cathode to take their place, and in turn their concentration is restored by Cu2+ produced by oxidation of copper metal at the anode. 

Copper is refined electrolyticallv by using an impure form of copper metal called blister copper as the anode in an electrolytic cell (Fig. 12.14). The current supply drives the oxidation of the blister copper to copper(II) ions, Cu2+, which are then reduced to pure copper metal at the cathode ... 

Advantages 1. More impurities can be tolerated in the copper anode since the electrode distances are relatively large. 2. The fabrication of anodes and the operation of the electrolytic cell is relatively simple. 3. More suited for refining copper of varied impurity contents. Advantages 1. Energy losses are comparatively less because of small interelectrode distances and contacts are practically eliminated. 2. The refining cycle is shorter due to higher number of electrodes and the anodic residue is relatively small. 

It consists in a deposition of ions from an electrolyte onto the cathode in an electrolytic cell, under the influence of an applied potential. Usually the process is accompanied by material dissolution from the anode. The electrowinning from aqueous solutions is an important commercial method for the production (and/or refinement) of many metals, including, for instance, chromium, nickel, copper, zinc. As for the electrodeposition from non-aqueous solutions, the primary production of aluminium, electrodeposited from a solution of A1203 in molten cryolite, is a typical example. Other metals which may be regularly reduced in a similar way are Li, Na, K, Mg, Ca, Nb, Ta, etc. 

This electrolytic cell is used to refine copper. The anode is impure copper, and the cathode is pure copper. During electrolysis, the impure copper anode dissolves, and pure copper is plated onto the cathode. The resulting cathode is 99.99% pure metal. Most impurities that were present in the anode either remain in solution or fall to the bottom of the cell as a sludge. 

Metallic copper obtained above is purified by electrolytic refining. The electrolytic cell consists of a cathode made of thin sheets of very pure copper connected to the negative terminal of a direct-current generator, and a lump of extracted impure copper from the ore serving as an anode. A solution of cop-per(II) sulfate in sulfuric acid is used as electrolyte. Electrolysis causes trans-... 

For the production of superpurity aluminum on a large scale, the Hoopes cell is used. This cell involves three layers of material. Impure (99.35 to 99.9% aluminum) metal from conventional electrolytic cells is alloyed with 33% copper (cutcctic composition) which serves as the anode of the cell A middle, fused-salt layer consists of 60% barium chloride and 40% AlF 1.5NaF (chiolite), mp 72(TC. This layer floats above the aluminum-copper alloy. The top layer consists of superpurity aluminum (99.995%). The final product usually is cast in graphite equipment because iron and other container metals readily dissolve in aluminum. For extreme-purity aluminum, zone refining is used. This process is similar to that used for the production of semiconductor chemicals and yields a product that is 99.9996% aluminum and is available in commercial quantities. 

FIGURE 18.19 Electrorefining of copper metal, (a) Alternating slabs of impure copper and pure copper serve as the electrodes in electrolytic cells for the refining of copper, (b) Copper is transferred through the CuS04 solution from the impure Cu anode to the pure Cu cathode. More easily oxidized impurities (Zn, Fe) remain in solution as cations, but noble metal impurities (Ag, Au, Pt) are not oxidized and collect as anode mud. 

A constant current of 100.0 A is passed through an electrolytic cell having an impure copper anode, a pure copper cathode, and an aqueous CuS04 electrolyte. How many kilograms of copper are refined by transfer from the anode to the cathode in a 24.0 h period ... 

An electrolytic cell contains a solution of CU8O4 and an anode of impure copper. How many kilograms of copper will be refined (deposited on the cathode) by 150 A over 12.0 h The copper deposited on the cathode comes from the solution however, that copper deposited is replaced from the anode. This is a technique of separating the copper from the impurities in the anode (refining). 

The technical process of copper refining is an important example of an electrolytic concentration cell. Two copper electrodes operate in the same Cu++-containing electrolyte, one as anode, the other as cathode. Clearly, at equilibrium, E - 0. The current flow at the anode will dissolve Cu as Cu++, raising the concentration there. On the other hand, at the cathode, Cu++ deposits as Cu. Consequently, near the cathode, the Cu++ concentration decreases. Thus, a cell voltage will establish that opposes the applied voltage and leads to a loss of energy. Note that the aim of the process is the... 

The copper from this process contains many impurities and must be refined, so the molten copper is cast into large, thick plates. These plates are then used as an anode in an electrolytic cell containing a solution of copper(II) sulfate. The cathode of the cell is a thin sheet of pure copper. As current is passed through the cell, copper atoms in the impure anode are oxidized to copper(II) ions, which migrate through the solution to the cathode where they are reduced to copper atoms. These atoms become part of the cathode while impurities fall to the bottom of the cell. 

Electroplating Objects can be electroplated with a metal such as silver in a method similar to that used to refine copper. The object to be silver plated is the cathode of an electrolytic cell that has a silver anode, as shown in Figure 21-21. At the cathode, silver ions present in the electrolyte solution are reduced to silver metal by electrons from an external power source. The silver forms a thin coating over the object being plated. The anode consists of a silver bar or sheet, which is oxidized to silver ions as electrons are removed by the power source. Current passing through the cell must be carefully controlled in order to get a smooth, even metal coating. 

Several elements are produced commercially by electrolysis. In Sections 21-3 to 21-5, we described some electrolytic cells that produce sodium (the Downs cell), chlorine, hydrogen, and oxygen. Electrolysis of molten compounds is also the common method of obtaining other Group lA metals, HA metals (except barium), and aluminum (Section 22-3). Impure metals can also be refined electrolytically, as we will describe for copper in Section 22-8. 

The impure copper is refined using an electrolytic cell like the one shown in Figure 22-12. Thin sheets of very pure copper are made to act as cathodes by connecting them to the negative terminal of a dc generator. Chunks of impure copper connected to the positive terminal function as anodes. The electrodes are immersed in a solution of copper(II) sulfate and sulfuric acid. When the cell operates, Cu from the impure anodes is oxidized and goes into solution as Cu ions Cu ions from the solution are reduced and plate out as metallic Cu on the pure Cu cathodes. Other active metals from the impure... 

Figure 22-12 A schematic diagram of the electrolytic cell used for refining copper (a) before electrolysis and (b) after electrolysis, (c) Commercial electrolysis cells for refining copper.

Should the anode or the cathode be made of pure copper in an electrolytic cell designed for refining copper metal Explain. 

Electrolytic refining. Lead of very high purity can be produced from the electrolytic process. Most electrolytic refineries utilize the Betts process [17]. In this process, lead bullion is cast into anodes and placed in an electrolytic cell which contains an electrolyte of fluorosilicic acid and lead fluorosilicate. The cathode is a thin sheet of high-purity lead referred to as the starter sheet . Lead is deposited on the cathode while the impurities form an adherent, but porous, slime layer on the anode. The slimes are collected for recovery and refining as they contain valuable impurities such as silver, gold, copper, and bismuth. 

The impure copper is refined using an electrolytic cell like the one shown in Figure... 

Fixed or porous-bed electrodes. Fixed bed flow-through electrodes consisting of finely divided graphite chips have been used for electrodeposition of copper in for example substitute for liberator cells, in copper tankhouse bleed streams in South Africa [19]. This concept used two parallel particulate beds separated by an ion exchange membrane with upflow of electrolyte through the beds. One bed acted as the cathode for electrodeposition while the other was the anode for simultaneous anodic dissolution of the electrodeposit. The Kennecott Copper Corporation developed a thin disposable particulate coke bed cathode for the same purpose [20]. This product is smelted in a furnace to separate the coke and then molten copper is fire refined to produce a saleable product. 

Figure 26-12 A schematic diagram of the electrolytic cell used for refining copper.

As an example, we inspect electrolytic copper refining, which utilizes the electrochemical dissolution of an impure copper anode in an electrolytic cell containing a... 

The final processing in tire production of high-purity metals is often carried out electrolytically and is referred to as electrorefining. In this process the metal to be refined, such as copper or silver, has a typical initid purity of 95 to 99% and the aim is to reduce the impurity level to less than 0.1%. Conventional purification processes are often either inadequate or too expensive for this purpose. In electrorefining, the impure metal, e.g., copper, is placed in an electrolytic bath as an anodic plate that is paired with a cathode on which the purified metal is deposited electrolytically. The electrolyte typically consists of an aqueous solution of a salt of the metal to be purified, for example, copper sulfate, and the electrolytic cell is composed of an array of closely spaced alternating cathodes and anodes. A sample electrode pair and the configuration of the electrolytic cell are shown in Figure 3.2a. 

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