Quicklime

Quicklime is one of the few bulk materials that can injure someone who simply gets it on damp skin.

Reactivity

Contact with water produces calcium hydroxide, heat and expansion.

In a silo this means a blocked, hard mass; on a person it means a deep burn that develops slowly.

• Dried venting and conveying air, with the dryer treated as critical equipment.
• Weatherproof filling connections and sealed silo tops.
• Immediate washing facilities and dust-tight protective clothing at every manual point.

Flow behavior

Lump quicklime flows freely and abrades; ground quicklime is cohesive and bridges.

Plants handling both need outlets and discharge aids sized for the ground material and wear protection sized for the lump.

Dust control

The dust is strongly alkaline and damages eyes and airways.

Enclosed transfer, extraction at loading and bag emptying and well-maintained filters are the practical controls.

Dosing into a process

Flue gas treatment and water treatment need a stable rate from a cohesive, reactive powder.

Loss-in-weight feeding with a conditioned, agitated inlet and a short residence time gives repeatable dosing.

What to establish before buying equipment

• Form and particle size on delivery, lump or ground.
• Reactivity grade, which affects both heat release and flow.
• Air dryness available for venting and conveying.
• Emergency washing and first aid provision at every manual interface.

Quicklime is the one material in this list that is dangerous because of what storage does to it.

It reacts with water, and the reaction releases a great deal of heat. A leak into a quicklime silo does not make a lump; it makes steam, pressure and a hot mass that expands.

• Keep water out as a safety requirement, not a quality one, and design the vent accordingly.
• Seal against humid air; even atmospheric moisture slakes the surface of the bed over time.
• Ground grades consolidate and bridge, so size the outlet for the stood condition.

The design has to cope with an abrasive, caustic, reactive material.

Lump quicklime flows and wears; ground quicklime bridges and reacts. Both need closed transfer with dry air and materials chosen for abrasion rather than for cost.

• Dry, filtered conveying air with a stated dew point.
• Wear-resistant surfaces for lump handling, aerated discharge for ground grades.
• Closed transfer throughout; this dust must not be in the room.

Quicklime burns skin and eyes, and it does so more aggressively when it meets moisture, including sweat.

The combination of a caustic dust and an exothermic reaction with water makes personal protection and water discipline the two controls that matter.

• Full skin and eye protection wherever the material is open, with eyewash available.
• No water near storage or transfer unless the reaction has been accounted for.
• Confined space entry only with the atmosphere tested and the material condition known.