Question

12) Describe the role of the following in the process mentioned
(i) Silica in the extraction of copper
(ii) Cryolite in the extraction of aluminium.
(iii) lodine in the refining of Zirconium.
(iv) Sodium cyanide in froth floatation​

Answer 1

Answer:

1. The role of silica in the extraction of copper is to remove the iron oxide obtained during the process of roasting as slag. If the sulphide ore of copper contains iron, the silica (SiO2) is added as flux before roasting. Then, FeO combines with silica to form iron silicate, FeSiO3(Slag). 2. Cryolite reduces the melting point of Al2O3 and increases its electrical conductivity. Aluminium is produced by the electrolytic reduction of fused alumina in the electrolytic cell. Alumina is not an electrolyte. So it is made as an electrolyte by dissolving it in the fused cryolite. The function of cryolite is to lower the fusion temperature. 3. Zirconium crude metal is heated with iodine in an evacuated vapour to separate from impurities and this decomposes at 1800 K to give a pure zirconium metal and iodine. Initially iodine is heated with zirconium to form a volatile compound. 4. Sulphide ores which are concentrated by the froth floatation process. Depressants are used to prevent certain type of particles from forming the froth. NaCN act as a depressant to separate ZnS from PbS.Read more on Sarthaks.com - https://www.sarthaks.com/866703/describe-the-role-of-the-following-in-the-process-mentioned