Lime Technology – Slaking Process Slaking (hydration) of quicklime to form lime putty or hydrated lime primarily occurs under which action or condition?

Introduction:
Slaking of lime is the chemical hydration of quicklime (calcium oxide) to produce hydrated lime (calcium hydroxide). The question tests understanding of the practical condition that drives slaking on site and in materials processing.

Given Data / Assumptions:

• Material: quicklime (CaO) to be converted to hydrated lime (Ca(OH)2).
• We compare typical field conditions: air exposure, immersion in water, mechanical crushing.
• Goal: identify which action actually causes slaking.

Concept / Approach:

The hydration reaction is CaO + H2O → Ca(OH)2 with heat release. Without water, slaking cannot proceed substantially. Therefore, options involving water contact will be correct.

Step-by-Step Solution:

Verification / Alternative check:

Observe field practice: pits or drums are used for slaking by controlled water addition to avoid violent reaction and ensure complete hydration.

Why Other Options Are Wrong:

Air exposure: leads to carbonation, not hydration. Crushing: physical process only. Dry sand: inert and does not hydrate lime. 'None of these': incorrect because immersion in water is correct.

Common Pitfalls:

Adding too much water too quickly (violent reaction), confusing carbonation with hydration, and assuming size reduction equals slaking.

Final Answer:

Immersing the quicklime in water (controlled hydration)