Chemistry - Metallurgy Question with Solution | TestHub

The commercial extraction of pure copper from chalcopyrite ore (CuFeS₂) involves several key processes. Let's examine the options provided:

A. Froth flotation: This is the INITIAL step in concentrating the ore. Chalcopyrite ore is crushed and then treated with chemicals that selectively make the copper sulfide particles hydrophobic. Air is then bubbled through the mixture, and the hydrophobic copper sulfide particles attach to the air bubbles and float to the surface, forming a froth which is skimmed off. This process separates the copper sulfide from unwanted rocky material (gangue).

B. Roasting: After froth flotation, the concentrated copper sulfide ore is roasted in the presence of excess air. This converts the copper sulfide (CuFeS₂) to copper oxide (Cu₂O) and iron oxide (Fe₂O₃), and sulfur dioxide (SO₂). The reactions are as follows:

$$2CuFe{S}_2(s)+O_2(g)\to C{u}_{2}S(s)+2FeS(s)+S{O}_2(g)$$

$$2C{u}_{2}S(s)+3O_2(g)\to 2C{u}_{2}O(s)+2S{O}_2(g)$$

$$2FeS(s)+3O_2(g)\to 2FeO(s)+2S{O}_2(g)$$

C. Poling: After roasting and reduction, the copper obtained is not pure; it contains impurities like copper(I) oxide (Cu₂O). To purify it further, the molten copper is stirred with green wood logs. The hydrocarbons in the wood reduce the copper oxide to copper metal. This process is called poling.

$$C{u}_{2}O(s)+C(s)\to 2Cu(s)+CO(g)$$

D. Carbon reduction: Carbon reduction is NOT typically used directly for copper extraction from chalcopyrite. While carbon can reduce metal oxides, the process is not efficient or selective enough for copper extraction from its sulfide ore on a commercial scale. Carbon reduction is more commonly used for metals like iron.

Therefore, Froth flotation, Roasting, and Poling are all involved in the commercial extraction of pure copper from chalcopyrite ore.

Final Answer:

A, B, C

Froth flotation, Roasting, and Poling are all involved in the commercial extraction of pure copper from chalcopyrite ore.

Froth flotation is used to concentrate the ore.

Roasting converts copper sulfide to copper oxide.

Poling is used to reduce any remaining copper oxide to pure copper.

Carbon reduction is not used.