Question

Desirable percentage of copper in matte resulting from smelting of sulphide ore of copper is about

• A. 10
• B. 30
• C. 40
• D. 80

Hint:

Remember the progression of copper concentration during extraction:

• Ore Concentrate: 25-35% Cu

• Matte: 30-60% Cu

• Blister Copper: 98.5-99.5% Cu

• Refined Copper: > 99.95% Cu

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
In the pyrometallurgical extraction of copper from sulfide ores (like chalcopyrite, CuFeS\(_2\)), the first major step is smelting. In this step, the ore concentrate is melted with a flux (like silica) to produce two immiscible liquid phases: a molten iron silicate slag and a molten copper-iron sulfide mixture known as

matte. The "grade" of the matte is its weight percentage of copper.

Step 2: Detailed Explanation:
The purpose of the smelting stage is to remove as much of the gangue and iron as possible into the slag, while concentrating the copper and valuable metals into the matte. The grade of the matte produced is a key operational parameter.

• If the matte grade is too low (e.g., < 30%), it means not enough iron has been removed, putting a heavy load on the next stage (converting).

• If the matte grade is too high (e.g., > 65-70%), there is a risk of significant copper losses to the slag.
Therefore, smelter operators target a specific matte grade that balances iron removal with copper recovery. A typical range for matte grade in traditional copper smelting is between

30% and 60% Cu. The value of

40% falls squarely within this common industrial operating range.

• 10% is too low.

• 30% is at the lower end but plausible.

• 80% is too high for matte; this is closer to the composition of "white metal" (Cu\(_2\)S) or blister copper.

Step 3: Final Answer:
A desirable and typical percentage of copper in the matte produced during copper smelting is about 40%.