Copper electrolysis cell

I.S. Laitenen, Modelling, Simulation and Optimization of Copper Electrolysis Cell Group (Thesis, Tampere University of Technology, 2009), 10-13. 

If a current of 0.123 amps is passed through a copper electrolysis cell for one hour, how much copper will deposit ... 

Pure copper for use in electrical wiring is obtained by electrorefining. How many hours are required to transfer 7.50 kg of copper from an impure copper anode to a pure copper cathode if the current passed through the electrolysis cell is held constant at 40.0 A ... 

Figure 11.16 Schematic of copper recovery by coupled transport from dump leach streams. The concentrated copper solution produced by coupled transport separation of the dump leach liquid is sent to an electrolysis cell where copper sulfate is electrolyzed to copper metal and sulfuric acid...

Pt/XC-72R catalyst mixture that was sprayed directly onto one of the graphite separator plates that came with the high-flow rate single-cell electrolysis cell. We have found that the copper(I) oxidation reaction does not require a catalyst (see below). Thus, a catalyst-free graphite separator plate was used as the anode. Nafion membranes were used as the electrolyte for H+ conduction. 

The results from Figure 4 show that a catalyst like Pt is not required to carry out the copper(I) oxidation reaction. Thus, the anode of a single-cell electrolysis cell can be a Pt-free graphite separator plate. A Pt-free anode will reduce the capital cost of a large-scale commercial electrolyser quite significantly. 

It is easy to demonstrate that electrolysis is always accompanied by the transport of material in an electrolysis cell. If for example the blue solution of copper sulphate and the orange solution of potassium dichromate are mixed in equimolar concentrations, a brownish solution is obtained. This solution can be placed in a U-shaped electrolysis cell and topped up with a colourless layer of dilute sulphuric acid on each side (Fig. 1.2). If this solution is then electrolysed, the hitherto colourless solution next to the cathode slowly becomes blue, while... 

Electrolysis is used in a wide variety of ways. Three examples follow (1) Electrolysis cells are used to produce very active elements in their elemental form. The aluminum industry is based on the electrolytic reduction of aluminum oxide, for example. (2) Electrolysis may be used to electroplate objects. A thin layer of metal, such as silver, can be deposited on other metals, such as steel, by electrodeposition (Eig. 14-2). (3) Electrolysis is also used to purify metals, such as copper. Copper is thus made suitable to conduct electricity. The anode is made out of the impure material the cathode is made from a thin piece of pure copper. Under carefully controlled conditions, copper goes into solution at the anode, but less active metals, notably silver and gold, fall to the bottom of the container. The copper ion deposits on the cathode, but more active metals stay in solution. Thus very pure copper is produced. The pure copper turns out to be less expensive than the impure copper, which is not too surprising when you think about it. (Which would you expect to be more expensive, pure copper or a copper-silver-gold mixture )... 

Metals that have been produced by pyrometallurgical methods, such as copper, silver, nickel, and tin, are too impure for many purposes, and electrorefining is used to purify them further. Crude metallic copper is cast into slabs, which are used as anodes in electrolysis cells that contain a solution of CUSO4 in aqueous H2SO4. Thin sheets of pure copper serve as cathodes, and the copper that dissolves at the anodes is deposited in purer form on the cathodes (Fig. 17.18). Impurities that are more easily oxidized than copper, such as nickel, dissolve along with the copper but remain in solution elements that are less easily oxidized, such as silver and gold, do not dissolve but fall away from the anode as a metallic slime. Periodically, the anode slime and the solution are removed and further processed for recovery of the elements they contain. 

Incidentally, the elemental copper formed by Eq. 13.21 is the chief source of the copper present in anode slimes. Electrolyte is continually recirculated through the electrolysis cells to minimize the buildup of impurities. When the copper content of the electrolyte reaches 40-50 g/L (from the initial 12-18 g/L), it must be purified before reuse. The concentrations of copper, arsenic, antimony, bismuth, and nickel must all be substantially decreased. A small portion (ca. 2-3% of the total volume, per day) of the electrolyte stream is continuously bled from the main electrolyte stream for this purpose. 

Most of the excess copper present in spent electrolyte is electrolytically removed from solution in liberator cells, which are very similar to the electrolysis cells used for electrowinning. These have a pure copper cathode, on which copper is deposited (Eq. 13.20), and a lead anode, rather than the copper anode used in electrorefining. The lead anode reforms sulfuric acid from the hydrogen ions released from water, instead of contributing dissolved lead to the electrolyte (Eq. 13.22). 

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.

Electrolysis is used in a wide variety of ways. Electrolysis cells are used to produce very active elements in their elemental form. Electrolysis may be used to electroplate objects. Electrolysis is also used to purify copper, making it suitable to conduct electricity. 

To illustrate the Hittorf method for measuring the contribution of the individual ions to the current, we consider the electrolysis cell shown in Fig. 31.4. Suppose that the solution contains copper sulfate and that the anode is copper. We examine the changes that occur in each compartment if one mole of electricity passes. These changes are summarized in Table 31.4. If a quantity of electricity Q passes, this is Q/F moles, so all of the changes are... 

Figure 5.1 The Knowles water electrolysis cell Key A, steel cell tank B, temperature control tubes C, electrodes D, leads E, gas collection bells F, insulating sleeves G, sealing and safety tubes H, J, insulating caps (top, bottom) K, copper connections M, gas take-off pipes N, drain tubes O, S-pipes ...

When copper is extracted, in a process similar to that happening in the blast furnace, it is very impure. To purify the copper, it is used as the anode in a very large electrolysis cell containing copper sulfate solution as the electrolyte and a pure copper rod as the cathode. During the process, the anode dissolves and pure copper is deposited on the cathode. The impurities settle at the bottom of the cell. A simplified version of this process can be carried out as a class practical. 

M Figure 23.11 Electrolysis cell for refining of copper. As the anodes dissolve away, the cathodes on which the pure m l is deposited grow in size. 

Make a sketch of an electrolysis cell that could be used to electroplate copper onto other metal surfaces. Label the anode and fhe cathode and show the reactions that occur at each. 92. Make a sketch of an electrolysis cell that could be used to electroplate nickel onto other metal surfaces. Label the anode and the cathode and show the reactions that occur at each. 

Copper metal used for electrical wire must be quite pure otherwise its electrical resistance it too large. More than 90% of the copper produced by reduction of copper ores is further refined, or purified, by electrolysis. The electrolysis cell consists of two electrodes, one of impure copper connected to the positive pole of a battery and the other of pure copper connected to the negative pole. The electrodes dip into a solution of copper ions. Copper(II) ions from the solution combine with electrons from the negative pole of the battery, leaving copper atoms that plate out onto the pure copper electrode. 

The conductivity of copper increases by a factor of 10 when it is more than 99.9% pure. The impure copper is made the anode of an electrolysis cell and pure copper is the cathode. Impure copper contains small amounts of gold and silver. They drop off the anode as the copper around them dissolves, and fall to the bottom as anode sludge . Gold and silver can be extracted from the filtered sludge. 

A fluidized bed electrolysis cell with copper particles of 0.5 mm is used for removing traces of copper ions from waste water. The minimum fluidization velocity of these particles appears to be 0.03 m/s see eq. (4.45), When the flow rate is not higher than 3 times the minimum fluidization velocity, the fluid bed is still "homogeneous, i.e. without bubbles. In the pilot plant tests with a superficial velocity of 0.04 m/s, the Cu-content of the waste water is reduced from 100 ppm to 26 ppm when the bed height is 0.35 m, and from 100 to 7 ppm when the bed height is 0.70 m. 

The impure copper is used as the anode of an electrolysis cell. The cathode is pure copper, and the electrolyte is copper(II) sulphate solution. 

Make a sketch of an electrolysis cell that electroplates copper onto other metal surfaces. Label the anode and the cathode and indicate the reactions that occur at each. 

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