what is meant by refining of metals ? Name four methods used for refining of impure metals
Answers
Answer:
The most widely used method for the refining of impure metals obtained by various reduction processes is electrolytic refining method. Electrolytic refining is a process of purification by electrolysis. Several metals like copper, zinc, tin, lead, nickel, chromium, gold and silver are refined by this process.
Explanation:
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Explanation:
In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer.
1. Distillation Method
This method is useful for purification of those volatile metals which have low boiling points such as zinc and mercury. In this method, the impure metal is heated to its boiling point in a vessel. The vapours of metal thus formed are collected and cooled in a separate vessel Distillation Method
This method is useful for purification of those volatile metals which have low boiling points such as zinc and mercury. In this method, the impure metal is heated to its boiling point in a vessel. The vapours of metal thus formed are collected and cooled in a separate vessel to get pure metal. The impurities being non-volatile remain behind.
2. Liquation Method
By this method, those metals can be purified which have low melting point. In this method, the block of Impure metal is placed on the top side of sloping floor of a furnace and heated gently. Due to high temperature, the fusible metal melts and flows down to the bottom of the sloping floor while the non-fusible impurities remain behind on the floor. Finally, the pure metal is collected from the bottom of the sloping floor.
3. Electrolytic Refining
Many metals like Cu, Zn, Pb, Cr, Ni, Ag, and Au are refined electrolytically for refining of an impure metal by electrolysis.
We shall understand electrolytic refining of metals by taking the example of refining of copper. In case of copper, a thick block of impure copper is made anode and a thin block of pure metal is made cathode and copper sulphate solution is used as an electrolyte. On passing electric current, pure copper metal from the electrolyte solution deposits on the cathode. At the same time, an equal amount of impure copper dissolves from anode into the electrolyte solution. The soluble impurities settle down in the solution below the anode and are called as anode mud. to get pure metal. The impurities being non-volatile remain behind.
By this method, those metals can be purified which have low melting point. In this method, the block of Impure metal is placed on the top side of sloping floor of a furnace and heated gently. Due to high temperature, the fusible metal melts and flows down to the bottom of the sloping floor while the non-fusible impurities remain behind on the floor. Finally, the pure metal is collected from the bottom of the sloping flilling