Problem 12 - A Complete Resource Book in Chemistry for JEE Main

Question

Wolframite ore is separated from tinstone ore by the process of (a) smelting (b) calcination (c) roasting (d) electromagnetic

Step-by-Step Solution

Answer

(d) electromagnetic

Step 1: Understand the Ores

Wolframite is an ore of tungsten, while tinstone is an ore of tin. These ores often occur together and need to be separated effectively to extract the individual metals.

Step 2: Identify the Separation Challenge

The challenge here is to separate two different ores, each with distinct properties, but often present in the same mineral deposits.

Step 3: Review the Separation Techniques

Review the given separation techniques: Smelting is used for extracting metal from ore at high temperatures, calcination involves heating to remove volatile substances, roasting involves heating in presence of air, and electromagnetic separation exploits differences in magnetic properties.

Step 4: Find Specific Properties of Ores

Consider the specific properties; wolframite is magnetic, whereas tinstone is not. This difference in magnetic property is a key factor in choosing the separation method.

Step 5: Determine the Suitable Method

Given the magnetic nature of wolframite, the most effective method to separate it from the non-magnetic tinstone is electromagnetic separation.

Key Concepts

Magnetic Properties

Understanding magnetic properties is crucial when separating ores like wolframite and tinstone.
Magnetic properties refer to the ability of a material to be attracted or repelled by a magnetic field. Materials are broadly categorized as either magnetic (attracted to magnets, like iron) or non-magnetic (not attracted, like aluminum).
Wolframite, an ore of tungsten, exhibits magnetic properties, meaning it can be drawn towards a magnetic field.

• Magnetic materials like wolframite get attracted to magnets due to their internal magnetic moments aligning in the direction of the external field.
• In contrast, non-magnetic materials like tinstone (ore of tin) do not exhibit such properties, possibly due to the absence of unpaired electrons or specific atomic structure.

Recognizing these differences allows for effective use of separation techniques, particularly electromagnetic separation, which utilizes these inherent properties.

Electromagnetic Separation

Electromagnetic separation is a key method used for separating magnetic materials from non-magnetic ones.
This technique exploits the differences in magnetic properties between various ores, making it ideal for separating wolframite from tinstone.
Here's a simple breakdown of how electromagnetic separation works:

• The process involves passing a stream of ore particles over a moving belt or drum that carries a magnetic field.
• Magnetic ores like wolframite are attracted to the magnet and separate from the non-magnetic ones like tinstone.
• This separation process is precise and can handle large quantities of material, making it efficient for industrial use.

Essentially, electromagnetic separation is highly effective for ores with distinct magnetic differences, allowing for the extraction of pure metals like tungsten and tin in subsequent processing steps.

Tungsten and Tin Extraction

Once wolframite and tinstone are separated through electromagnetic methods, the extraction of tungsten and tin can occur efficiently.
The separated wolframite undergoes further processing to extract tungsten, while the non-magnetic tinstone is processed to extract tin.
This extraction involves several steps:

• Tungsten Extraction: Wolframite undergoes a series of chemical reactions, starting with its conversion to tungsten oxide through calcination or direct leaching. Tungsten oxide is then reduced, usually using hydrogen, to yield pure tungsten metal.
• Tin Extraction: Tinstone, primarily containing tin oxide (cassiterite), is reduced, often with carbon, in a smelting process to produce tin metal. Because tin does not respond to magnetic fields, its extraction relies entirely on chemical conversion processes.

The initial separation step using electromagnetic fields is thus critical, setting the stage for the straightforward extraction of each metal, ensuring high purity and usability in various industries.