Question

(i) Name the method of refining to obtain silicon of high purity?
(ii) What is the role of \[Si{{O}_{2}}\] in the extraction of copper?
(iii) What is the role of depressants in the froth floatation process?

Answer 1

Hint:(i) In metallurgy, refining consists of purifying an impure metal. It is to be recognized from different processes, in refining the last material is actually indistinguishable chemically to the first one, only if it is purer.
(ii) The process used to extract copper from its ores depends on the nature of the ore.
(iii) Froth flotation is a procedure generally utilized in the mining industry.

Complete answer:
(i) Zone refining is the technique for refining to acquire silicon of high immaculateness. This strategy is utilized for the most part to get semiconductors of high immaculateness like silicon.
In the zone refining process, a circular mobile radiator is fixed toward one side of the metal rod which is made up of the impure metal. Presently, the circular versatile radiator is moved gradually over the metal rod. The metallic impurities melt at the temporary position of this radiator. The melt containing the impurities move forward alongside the radiator through the aggregate of the metal rod. The pure metal is left to solidify as the radiator moves along the rod. As the radiator pushes ahead, the concentration of the impurities in the melt increments due to that the impurities are more soluble in their relating melt state. At long last, the impurities are gathered toward one side of the metal rod.
The process portrayed above is repeated many times in a similar way. The end of the rod in which the impurities have now gathered in is cut off, giving up the pure metal.
(ii) During the process of extraction of pure copper from copper pyrite, \[Si{{O}_{2}}\] acts as acidic flux which combines with iron oxide (\[FeO\]) to form iron silicate (\[FeSi{{O}_{3}}\]).
\[FeO+Si{{O}_{2}}\to FeSi{{O}_{3}}\]
(Gangue) (Flux) $\;\;\;\;$ (Slag)
(iii) In the froth floatation process, depressants assist with isolating two sulphide metals by selective prevention of froth formation by one metal and permitting the other to come into froth. For instance, in order to separate two sulphide metals (\[ZnS\] and \[PbS\]), \[NaCN\] is utilized as a depressant. It specifically permits \[PbS\] form froth, however keeps \[ZnS\] from coming to froth.

Note:
(i) Zone refining suggests that when the conditions are set at the solid-liquid limit, the particles of the impurity will in general diffuse into the liquid region.
(ii) The principal motivation behind the flux is to set up the metal surfaces for fastening by cleaning and eliminating any oxides and impurities. Oxides are formed when metal is presented to air.
(iii) Depressants are added to prevent any kind of particles from forming the froth with air bubbles.