Question

Name the sulphide ore of Copper. Describe how pure copper is extracted from this ore?

Answer 1

Hint: Copper having a symbol,Cu is a chemical element with atomic number as 29. Copper exists in a range of minerals like copper sulfides having the formula \[C{u_x}{S_y}\]. The method employed to extract copper from its ores entirely depends upon the nature of the ore. The copper (II) ions in the sulphide ore are first reduced to copper (I) sulphide which is later on reduced further to produce copper metal in the final stage.

Complete step by step answer:
Sulphide ore of copper is copper sulphide or chalcocite \[C{u_2}S\].
In case of sulphide ores, the method of Froth floatation is employed to concentrate the ore by taking out gangue particles from it. Generally, the extraction of copper from the ores include three major steps which are:
(i) Concentration of the ore: Collectors as well as froth stabilisers are added to an aqueous suspension of the powdered ore. Collectors are added to improve hydrophobicity (non-wettability) of the mineral particles (like pine oil) whereas froth stabilisers are added to stabilise the froth (like aniline). The mineral particles become moist by oils and the gangue particles become moist by water. On agitation via a rotating paddle, the solution mixture draws air forming froth. This froth holds the mineral particle and being light gets skimmed off from the surface. On getting dried, ore particles are recovered. The obtained product, \[C{u_{2}}S\] may also contain iron or FeS, therefore it is now mixed with silica and given a heat treatment in a reverberatory furnace. During the heat treatment, iron oxide slags off as iron silicate while copper is formed in the form of copper matte. The reactions are mentioned below:
\[{2FeS{\text{ }} + {\text{ }}3{O_2} \to {\text{ }}2FeO{\text{ }} + {\text{ }}2S{O_{2}}} \\
{FeO{\text{ }} + {\text{ }}Si{O_2}{\text{ }} \to {\text{ }}FeSi{O_3}\;\left( {slag} \right)}\]
(ii) Isolation of metal from the concentrated ore: \[C{u_{2}}S\] and \[FeS\] Copper matte are charged into a silica lined converter. Moreover, some silica is also appended. Hot air blast is blown, thus converting the remaining \[C{u_{2}}S/C{u_{2}}O\;\]into the metallic copper as shown below:
\[{2C{u_2}S{\text{ }} + {\text{ }}3{O_2} \to {\text{ }}2C{u_2}O{\text{ }} + {\text{ }}2S{O_2}} \\
{2C{u_{2}}O{\text{ }} + {\text{ }}C{u_2}S{\text{ }} \to {\text{ }}6Cu{\text{ }} + {\text{ }}S{O_2}}\]
The obtained solidified copper has a blistered appearance owing to the evolution of \[S{O_2}\]. As a result, it is called blister copper.
(iii) Purification of the metal: Blister copper can be converted to pure copper through electrolytic refining. Pure copper strips are used as an anode. In addition to this, acidic \[CuS{O_4}\] acts as an electrolyte. When current is made to pass through the cell, pure copper starts depositing at the cathode whereas impure copper starts collecting into the solution from anode. The impurities of \[Au,{\text{ }}Ag{\text{ }}and{\text{ }}Sn\] get deposited below the anode as anode mud. The deposited pure copper at the cathode is scraped off.

Note: With electrolytic refining, it is even possible to yield 99.99% pure copper. The electrolytic refining of copper generates the high quality or high purity copper required by industries.