Name: Self-Reduction Process
Uploaded: 2019-07-19
Duration: 5 min 13 s
Description: Sulphide ores of less electropositive metals such as mercury are heated in the presence of air to convert a part of ores into oxides or sulphates. Watch the...

Question

Explain Zone refining method for refining of metals.

Accepted Answer

Zone refining is a technique to get highly pure crystals of impure elements (specially metals) by using melting and crystallization processes. In this a narrow region of the crystal is heated so that impurities get melted and forms a molten zone which moves along the crystal.

In the zone refining process, a mobile heater is fixed at one end of the impure metal rod which we want to purify. Now an impure metal rod fitted with a circular mobile heater is fixed in a column filled with inert gas. This circular heater heats the rod radially and produces a region in which the temperature is uniformly elevated to the melting point in a plane perpendicular to the axis of the rod. As the heater moves along the rod, the molten zone also propagates down the rod. We make the heater move very slowly. Because of this impurities and pure metal both get melted but atoms of pure metal recrystallize while molten impurities move with heater or molten zone. Thus, after the process impurities get collected at one end while solid pure metal remains at another end. The process is repeated many times to get pure metal.

Explain Zone refining method for refining of metals.

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