Which of the following statement is incorrect about the extractive metallurgy of copper?a)Matte chiefly consists of cuprous sulphide and some ferrous sulphide.b)Most of the impurity of iron sulphide is removed as fusible slag during roasting.c)The copper pyrites is concentrated by froth floatation process.d)self reduction and electrolysis respectivelyCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Incorrect Statement: Most of the impurity of iron sulphide is removed as fusible slag during roasting.

Explanation:
Extractive metallurgy of copper involves several steps including concentration, roasting, smelting, and refining. Let's analyze each statement:

a) Matte chiefly consists of cuprous sulphide and some ferrous sulphide.
Matte is the intermediate product obtained during the smelting process. It is a mixture of metal sulfides. In the case of copper, matte mainly consists of cuprous sulfide (Cu2S) and some ferrous sulfide (FeS). Therefore, statement a) is correct.

b) Most of the impurity of iron sulphide is removed as fusible slag during roasting.
During the roasting process, copper sulfide ores are heated in the presence of excess air to convert them into copper oxide and sulfur dioxide. This step is carried out to remove impurities, mainly sulfur. However, the impurity of iron sulfide (FeS) does not form a fusible slag during roasting. Instead, it remains in the roasted ore as iron oxide (FeO) and is further removed in subsequent steps. Therefore, statement b) is incorrect.

c) The copper pyrites is concentrated by froth floatation process.
Copper pyrites (CuFeS2) is the most common copper ore. It is concentrated by froth flotation process, which is based on the differences in the physical and chemical properties of the ore and gangue particles. In this process, the finely crushed ore is mixed with water and a frothing agent. Air is blown into the mixture, causing the copper mineral particles to attach to the bubbles and rise to the surface, forming a froth. The froth containing the copper mineral is collected and further processed. Therefore, statement c) is correct.

d) Self-reduction and electrolysis respectively.
After the concentration and roasting steps, the roasted ore is smelted in a furnace to obtain crude copper. In the smelting process, self-reduction takes place, where copper oxide (Cu2O) is reduced to copper (Cu) by the remaining iron sulfide (FeS) present in the roasted ore. The resulting crude copper is then purified by electrolysis, where an electric current is passed through a solution of copper sulfate, and pure copper is deposited on the cathode. Therefore, statement d) is correct.

In conclusion, the incorrect statement is b) Most of the impurity of iron sulfide is removed as fusible slag during roasting.

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