Question

In the extraction of copper, its sulphide ore is heated in a reverberatory furnace after mixing with silica to:

• A. remove \(FeO\)as \(FeSiO _3\)
• B. separate \(CuO\) as \(CuSiO _3\)
• C. decrease the temperature needed for roasting of \(Cu _2 S\)
• D. remove calcium as\(CaSiO _3\)

Answer 1

The Correct Option is A

The extraction of copper from its sulfide ores involves several steps, one of which includes heating the ore in a reverberatory furnace. The purpose of mixing the ore with silica and heating is to remove impurities, specifically iron, in the form of slag.

1. During the extraction process, copper is often found as a sulfide ore associated with iron as an impurity (e.g., CuFeS₂ - Chalcopyrite).
2. When the copper sulfide ore is heated in the presence of silica (SiO₂) in a reverberatory furnace, it undergoes a process called smelting.
3. Iron sulfide (FeS) present in the ore gets oxidized to form iron oxide (FeO).
4. This iron oxide reacts with silica to form iron silicate (FeSiO₃), which is a slag. The reaction is given by:

\(FeO + SiO_2 \rightarrow FeSiO_3\)

1. The slag (FeSiO₃) formed is less dense and can be easily separated from the molten copper sulfide, thereby purifying the copper.
2. This process ensures that iron, an unwanted impurity, is removed efficiently from the ore, improving the quality of the extracted copper.
3. Given the options, the correct answer is to remove \(FeO\) as \(FeSiO_3\).
4. Let's analyze the other options to understand why they are incorrect:

• Separating \(CuO\) as \(CuSiO_3\) is not part of the process as copper typically doesn't form silicates during this phase.
• The process does not aim to decrease the temperature needed for roasting \(Cu_2S\) as the primary goal is impurity removal.
• Removing calcium as \(CaSiO_3\) is irrelevant to this context since calcium compounds typically aren't significant in copper ores.

Hence, the intention of mixing silica with the sulfide ore in a reverberatory furnace is to remove iron as iron silicate slag, thereby purifying copper.