Among the following bulk materials, which must be stored in silos (enclosed storage) and not in an open yard due to handling, loss, and safety considerations?

Introduction / Context:
Storage strategy affects quality, loss, and safety of bulk solids. Fine fractions and self-heating materials require special handling to prevent wind loss, spontaneous combustion, or contamination. This question tests practical bulk storage knowledge.

Given Data / Assumptions:

• Coke breeze: very fine coke fraction used in sintering or fuel blending.
• High volatile-matter (VM) bituminous coal: prone to oxidation; large stockpiles are common but need care.
• Sand: inert and non-reactive; open storage is typical.

Concept / Approach:
Fine, dusty materials such as coke breeze are highly susceptible to wind losses, environmental emissions, and non-uniform moisture pickup. Enclosed storage (silos/bins) minimizes loss and controls dust. While high VM coal requires fire-preventive practices, it is still commonly stored in engineered open yards with compaction, layering, and temperature monitoring.

Step-by-Step Solution:

Verification / Alternative check:
Iron and steel plants store coke breeze in bins/silos feeding sinter plants to ensure consistent dosing without environmental losses.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming any oxidizable fuel cannot be stored outdoors; ignoring particle size and wind susceptibility as decisive factors for silo storage.

Final Answer:
Coke breeze