Slaked Lime

What is Slaked Lime?

Slaked Lime, also known as Hydrated Lime or Calcium Hydroxide (Ca(OH)₂), is a versatile inorganic compound formed by reacting quicklime (Calcium Oxide, CaO) with water. It serves as a critical raw material in industries ranging from construction to pharmaceuticals due to its unique properties:

• High Alkalinity: pH 12–12.4 in aqueous solutions.
• Low Solubility: 1.65 g/L in water at 25°C, ideal for suspensions.
• Reactive Surface: Efficiently absorbs CO₂, SO₂, and acidic pollutants.

Physical & Chemical Properties of Slaked Lime

Physical Properties

• Appearance: Fine white powder, free of visible impurities.
• Density: 2.21 g/cm³ (true density), 0.5–0.7 g/cm³ (bulk density).
• Particle Size: Adjustable from 20 mesh (coarse) to 200 mesh (ultra-fine).

Chemical Properties

• Thermal Decomposition: Breaks down at 580°C into CaO and water vapor.
• Reactivity:
  • Neutralizes acids: Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O.
  • Captures CO₂: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O (used in carbon sequestration).

Advanced Production Process of Slaked Lime

Modern manufacturing ensures high purity and consistency:

1. Hydration Control: Water-to-lime ratio maintained at 0.33:1.
2. Temperature Management: Reactor kept at 65±5°C to prevent overheating.
3. Precision Grinding: Jet mills produce particles with D50=5µm (CV <5%).

Quality Advantages

Parameter	Industry Standard	Our Specification
Purity	≥90%	≥95%
Free CaO	≤1.5%	≤0.8%
Heavy Metals	<50 ppm	<10 ppm

Industrial Applications of Slaked Lime

① Water Treatment & Environmental Remediation

• pH Adjustment: Neutralizes acidic wastewater (pH 2–4) at 30% lower cost than NaOH.
• Heavy Metal Removal: Binds to Pb²⁺, Cd²⁺ (removal rate >99.5%).
• Flue Gas Desulfurization (FGD): Achieves 98.5% SO₂ capture at Ca/S ratio 1.03.

② Construction & Building Materials

• Mortar Additive: Enhances workability and reduces cracking by 25%.
• Soil Stabilization: Increases clay soil CBR value from 3 to 8.5.

③ Chemical Manufacturing

• Plastic Filler: 15% Slaked Lime in PVC improves tensile strength by 18% (ASTM D638).
• Pharmaceutical Synthesis: Used in aspirin production with >92% yield.

④ Food & Agriculture

• Food-Grade (E526): Anti-caking agent in powdered products (≤0.3% dosage).
• Soil pH Correction: Raises acidic soil pH from 5.0 to 6.8, boosting crop yields.

Safe Handling & Storage of Slaked Lime

Operational Safety

• PPE Requirements:
  • Respiratory: FFP2 masks (EN 149 standard).
  • Eye Protection: ANSI Z87.1-rated goggles.
• Spill Management: Use inert absorbents (e.g., sand), never water.

Optimal Storage Conditions

Grade	Temperature	Humidity	Packaging
Industrial	<30°C	<60% RH	25kg moisture-proof bags
Food/Pharma	15–25°C	<45% RH	10kg vacuum-sealed pouches

FAQs – Slaked Lime Usage & Safety

Q1: Is Slaked Lime corrosive?

A1: Yes, its high alkalinity can irritate skin and eyes. Always wear PPE during handling.

Q2: Can Hydrated Lime be used in drinking water?

A2: Yes, food-grade Calcium Hydroxide is certified for water treatment (WHO-compliant Ca²⁺ levels <100 mg/L).

Q3: How does Slaked Lime differ from quicklime?

A3: Slaked Lime (Ca(OH)₂) is hydrated, less reactive, and safer than quicklime (CaO).

Reference

https://en.wikipedia.org/wiki/Calcium_hydroxide

https://www.britannica.com/science/calcium-hydroxide

https://cameo.mfa.org/wiki/Slaked_lime