Question

What is the commonly used material for stone dusting in mining operation?

• A. Limestone
• B. Granite
• C. Sandstone
• D. Marble

Hint:

The number one health concern with any rock dust in a mine is silicosis.
This is why silica-bearing rocks like sandstone and granite are strictly avoided for stone dusting.
Limestone is the safe, non-siliceous, and effective choice.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the standard material used as "stone dust" in underground coal mines.

Step 2: Detailed Explanation:

Stone dusting is a critical safety measure to prevent coal dust explosions.
The process involves spreading a fine, incombustible dust throughout the mine roadways to dilute the combustible coal dust.
If an ignition occurs, the stone dust is thrown into suspension along with the coal dust, where it acts as a heat sink, absorbing energy from the flame and preventing it from propagating.
The material used for stone dusting must have several key properties:
- It must be incombustible.
- It must not be harmful to health.
Specifically, it must have a very low percentage of free crystalline silica (quartz), as inhalation of silica dust causes the fatal lung disease silicosis.
- It must be light in color to improve visibility.
- It should be readily available and inexpensive.

Limestone dust (primarily calcium carbonate, CaCO\(_3\)) meets all these requirements perfectly and is the most commonly used material for stone dusting worldwide.
Granite and sandstone are unsuitable because they have a high silica content.
Marble, while also calcium carbonate, is not used because it is a more expensive crystalline form.

Step 3: Final Answer:
The commonly used material for stone dusting is Limestone.
This corresponds to option (A).