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Electrolytic reduction is a method of electrolysis where electric current passes through an ionic material in a dissolved or molten form. This causes the electrodes to react chemically. The materials tend to decompose allowing the oxides, chlorides, and hydroxides present in a combined state in the materials to be electrically reduced. Electrolytic reduction is used to carry out the extraction and purification of metals. Some metals that are extracted through this method are potassium (K), Sodium (Na), and Aluminium (Al). At the cathode stage, the metals so reduced are gathered. The reduction is due to the electrons present in the materials.
Electrolytic Reduction
1.Electrolytic reduction is a process used to extract and purify metals, such as Sodium, Magnesium, Aluminium, and Calcium.
2.An electrolytic reduction is a form of electrolysis. An electric current is made to pass through ionic substances in their dissolved or molten state and is done for the electrodes or electrons present in it to react chemically.
3.The materials’ hydroxides, oxides, and chlorides present in a combined state are reduced from their original state electrically.
4.Copper is extracted by performing pyrometallurgy.
5.Gold and silver are obtained by hydrometallurgy.
6.Electrolytic reduction is made to ensure the purity of metals. It is done for the extraction and purification of metals.
Electrolytic Refining
Electrolytic refining is a process in which metals are refined using the method of electrolysis.
In electrolysis, a large amount of impure metal, such as a thick strip of impure copper metal, is used as anode, and a thin strip of pure metal is used as cathode.
An electrolyte such as a metal salt aqueous solution is used for this process, although it depends on the metal to be used. Electrorefining is another name for electrolytic refining.
Metal’s electrolytic refining
This is another way of the extraction and purification of metals.
Before carrying out the electrolytic refining of a particular metal, it is important to decide on an electrolyte and other pre-requisites to ensure efficiency while proceeding with both anodic dissolution and metal deposition. It is necessary to ensure that no impure metals move from the anode to the cathode. The aim of metallic electrolytic refining is to deposit some amount at the cathode, in good quality, and sometimes extremely crystalline properties also work. The anode must not be passive. To ensure the right behaviour on both sides of the electrodes, additives are applied to the electrolyte when needed. The refining of copper metal is an example of electrolytic refining.
Metals | The concentration of components in electrolyte/g dm¯ | I/Ma cm ¯ | -cell voltage/V | T/°C | Current Efficiency/ % | Impurity metals | |
Slime | Solution | ||||||
Sn | Na2SnO3(40-80) NaOH (8-20) | 5-15 | 0.3-0.6 | 20-60 | 65 | Pb, Sb | —– |
Co | CoSO4(150-160) Na2SO4(120-140) NaCl (15-20) H3BO3(10-20) | 15-20 | 1.5-3.0 | 60 | 75-85 | — | Ni, Cu |
Pb | Pb2+(60-80) H2SiF6(50-100) | 15-25 | 0.3-.0.6 | 30-50 | 95 | Bi, Ag, Au, Sb | —- |
Cu | CuSO4(100-140) H2SO4(180-250) | 10-20 | 0.15-0.30 | 60 | 95 | Ag, Au, Ni, Pb, Sb | Ni, Se, Fe, Co |
Ni | NiSO4(140-160) NaCl (90) H3BO3(10-20) | 15-20 | 1.5-3.0 | 60 | 98 | Ag, Au, Pt | Cu, Co |
Electrorefining of Copper
Copper is extracted and mined from its ore, called blister copper. Blister copper is 98 to 99% pure. The process of electrorefining copper makes it 99.95% pure, and because of this purification, this newly refined copper is used for electrical components.
For the electrorefining of copper, a thick strip of impure copper metal is used as an anode.
Acidified copper sulphate is created using sulphuric acid, and this acidified copper sulphate is used as a graphite-coated electrolyte, with a combination of pure copper tubes, as a cathode or negative electrode.
During electrolysis, this copper sulphate divides itself into one positive ion of copper and a negative ion of sulphate. The positive copper ion moves towards the negative electrode.
The newly refined Cu is accumulated at the graphite layer of the cathode. This is a prime example of electrolytic refining.
The cathode has a graphite coating so that the material that is concentrated can be easily removed in the process of electrorefining.
An anode’s metallic properties are also combined with sulphate to create metallic sulphate and dissolve.
The by-products such as gold and silver settle down as dust because they are not produced by the solution of copper sulphate and sulphuric acid.
Electrorefining of minerals
The process of refining minerals is as follows –
Gold
Hydrochloric acid is used as an electrolyte for the electrorefining of gold. An alloy of gold is made as to the anode, and a thin sheet of gold acts as a cathode. During the transportation of ions, pure gold with a high level of purity is deposited in the cathode.
Silver
The anode creates crude silver, and the cathode creates a more purified version of silver. The process of electrorefining silver is the same as gold. The only difference is that a nitric acid bath is used when the silver anodes dissolve themselves.
Conclusion
Electrolytic reduction is the primary way of extraction and purification of metals. Extraction of metals such as magnesium, aluminium, and calcium is done through electrolytic reduction. This process involves the basis of electrolysis. Electrorefining is a part of the electrolytic reduction and gives the highest purity to metals.
