Question

Write the principles of the following methods.
A.Froth floatation method
B.Electrolytic refining

Answer 1

To answer this question the concepts in metallurgy should be known. Metallurgy is a process that is used for the extraction of metals to obtain them in their pure form. The compounds of metals mixed with rocks, soil, sand, and impurities are referred to as minerals. These minerals are called ores.

Complete step by step answer:
There are so many processes to purify metals, among them some efficient processes are,
1.Froth floatation method: Froth flotation method is used to concentrate only sulfide ores; this is because pine oil (Froth collector) selectively wets the sulfide ore and brings it into froth This process based on the difference in wetting qualities of gangue and the sulfide ore. In this process, Depressants are used in the froth flotation process, which selectively allows sulfides to come with froth. For example; NaCN (sodium cyanide). In the case of lead ore PbS, there is an impurity of ZnS that is present. In this case, NaCN reacts with ZnS selectively and does not allow ZnS to come with froth.

2.Electrolytic refining: In this process, the impure metal and pure metal are taken as anode and cathode respectively. A salt of that particular metal is taken as an electrolyte. When electricity is passed the impure metals get oxidized and converted into ions. On the other hand, metal ions from the solution get reduced at the cathode. In this way, metal gets purified and the impurities get separated and get collected under an anode electrode. By this process copper (Cu) metal gets purified.

Additional information:
There are some other methods explained below,
1.Zone refining: when the solubility of the impurities is greater in the molten state than in the solid-state of the metal, this process is used. In this process, an impure metal rod is heated by a moving heater from one end to another. When one end of the metal melts the impurities get soluble and concentrated into that particular melted area, and when the heater moves forward it leaves pure solidified metal behind. In this way, all impurities get collected into one end of the metal rod. By this process Zinc (Zn) metal gets purified.
2.Van Arkel method: this method is also called Vapour Phase refining. In this process, a volatile impure metal is heated. As a result, the metal gets vaporized and impurities left behind as solid. By this process titanium (Ti) metal gets purified from iodine.
3.The Mond process: in this process the impure metal reacts with CO and forms gaseous metal carbonyl. The impurities are left unreacted.by this process nickel (Ni) metal get

Note: Purified In the case of the ore, the percentage of metal is greater than other minerals. For example, the ore of aluminum is bauxite. From bauxite, aluminum can be extracted cheaply and profitably. But aluminum is also found in clay, but it is not possible to extract aluminum from clay cheaply and profitably. That is why bauxite is the ore of aluminum.
To extract metals from ore the steps are,
1.The concentration of ore.
2.Conversion of the concentrated ore into metallic oxide.
3.Reduction of metallic oxides.
4.Refining the impure metal.