The process that involves the removal of sulphur from the ores is
(a) smelting
(b) roasting
(c) leac

Q: Why can't we just melt the sulphide ore to get the metal?

Melting is just a physical phase change. If you melt Zinc Sulphide, you just get liquid Zinc Sulphide. The chemical bond between the metal and sulphur remains intact. We need a chemical reaction (oxidation) to break that bond and remove the sulphur as a gas.

Q: What is the exact difference between roasting and calcination?

This is a classic point of confusion! Roasting is done in the *presence* of a regular supply of air and is primarily used for sulphide ores to remove sulphur as $SO_2$. Calcination is done in the *absence* or limited supply of air and is used for carbonate or hydrated ores to remove $CO_2$ or water.

Q: Is roasting an exothermic or endothermic process?

While you need to supply initial heat ($\\Delta$) to start the process, the oxidation of sulphur is highly exothermic. Once the roasting starts, the heat released by the reaction itself often sustains the process without needing much external fuel.

Q: What happens to the $SO_2$ gas produced? Isn't it harmful?

Yes, $SO_2$ is a major pollutant that causes acid rain. In modern metallurgical plants, this gas is not released into the atmosphere. Instead, it is captured and used as a raw material to manufacture Sulphuric Acid ($H_2SO_4$) via the Contact Process.

Q: Can roasting be used for oxide ores like Bauxite or Haematite?

No. Oxide ores already have their metal bonded to oxygen. The whole point of roasting is to replace sulphur (or other volatile impurities) with oxygen. Roasting an oxide ore would be chemically redundant.

Question

The process that involves the removal of sulphur from the ores is

Options:

(A) smelting

(B) roasting

(C) leaching

(D) refining

Sigma Percentile · Accepted Answer

### The Challenge of Sulphide Ores

Imagine you are an ancient metallurgist, and you have just mined a beautiful, shiny rock. This rock is a sulphide ore, such as Zinc Blende ($ZnS$) or Galena ($PbS$). Your ultimate goal is to extract the pure metal hidden within. However, there is a major obstacle: the metal is tightly bonded to sulphur.

Before you can even think about extracting the pure metal, you must first break this bond and remove the sulphur from the solid matrix. You cannot simply melt the rock, as that would just give you liquid metal sulphide. You need a chemical transformation. You need a way to make the sulphur "fly away."

### Enter Roasting: The Breath of Fire

This is where the process of **roasting** comes into play. Roasting is a foundational pyrometallurgical process. The ore is placed in a reverberatory furnace and heated strongly. But heat alone is not enough. The critical ingredient here is a regular, abundant supply of air (specifically, oxygen).

There is a catch, though: the temperature must be carefully controlled. It must be high enough to initiate the chemical reaction but strictly **below the melting point** of the metal. If the ore melts, the surface area exposed to the oxygen drops drastically, and the reaction chokes. We want the solid ore particles to be bathed in hot oxygen.

### The Chemistry of Transformation

When the hot oxygen hits the sulphide ore, a beautiful chemical exchange occurs. Oxygen is highly reactive and essentially "steals" the sulphur away from the metal, forming a gas, while simultaneously bonding with the metal to form a solid oxide.

Let's look at the mathematics of this fiery breath. For Zinc Blende, the reaction is:

$$ 2	ext{ZnS} + 3	ext{O}_2 \xrightarrow{\Delta} 2	ext{ZnO} + 2	ext{SO}_2 \uparrow $$

For Galena (Lead Sulphide), the exact same logic applies:

$$ 2	ext{PbS} + 3	ext{O}_2 \xrightarrow{\Delta} 2	ext{PbO} + 2	ext{SO}_2 \uparrow $$

And for Copper Glance (Copper(I) Sulphide):

$$ 2	ext{Cu}_2	ext{S} + 3	ext{O}_2 \xrightarrow{\Delta} 2	ext{Cu}_2	ext{O} + 2	ext{SO}_2 \uparrow $$

The common thread in all these reactions is the evolution of **Sulphur Dioxide ($SO_2$) gas**. By converting the solid sulphur into a volatile gas, it simply floats away out of the furnace chimney, leaving behind a solid metal oxide. The sulphur has been successfully removed!

### Why Not the Other Methods?

To truly master a concept, you must know why the other options are incorrect.

**Smelting** is the next step in the journey; it involves taking the metal oxide we just created and reducing it (usually with carbon) to get the pure metal.

**Leaching** is a hydrometallurgical process where the ore is dissolved in a liquid chemical solvent (like an acid or cyanide), not roasted in air.

**Refining** is the very last step, where the crude, impure metal obtained after smelting is purified to 99.9% perfection.

Therefore, the specific process dedicated to the removal of sulphur from ores is undeniably roasting.

Animated Solution for Chemistry - Metallurgy: The process that involves the removal of sulphur from the ores is

Select Answer:

Visualized Solution

$The Objective: Removing Sulphur$

$The Process: Roasting$

$Chemical Reaction: Zinc Blende$

$Chemical Reaction: Galena$

$Chemical Reaction: Copper Glance$

$Conclusion$

$Analyzing Other Options$

The Sigma Insight: Principles of Metallurgy and Extraction

The Challenge of Sulphide Ores

Enter Roasting

The Chemistry of Transformation

Why Not the Other Methods?

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