About Lime

What is Lime?

Lime — One of Earth's Most Versatile and Ancient Minerals

Lime has been used by civilizations for over 7,000 years — from the ancient Egyptian pyramids to modern steelmaking. It is one of the most important industrial minerals in the world, serving industries as diverse as construction, agriculture, water treatment, pharmaceuticals, and food processing.

At its core, lime is produced by heating limestone (calcium carbonate, CaCO₃) to high temperatures — a process called calcination. The result is quicklime (calcium oxide, CaO), which can be further processed with water to produce slaked lime (calcium hydroxide, Ca(OH)₂).

The Lime Cycle

Understanding the Lime Production Process

From limestone rock to finished lime products — a complete overview of the lime cycle.

1

Limestone Mining

Calcium carbonate (CaCO₃) rock extracted from our own open-cast mines in Tirunelveli, Tamil Nadu. High-purity deposits with CaCO₃ ≥ 90%.

CaCO₃ → Raw Material

2

Calcination (Burning)

Limestone is heated to 900–1200°C in lime kilns. This drives off carbon dioxide (CO₂), leaving behind calcium oxide — quicklime.

CaCO₃ + heat → CaO + CO₂

3

Slaking (Hydration)

Quicklime is combined with controlled amounts of water in a process called slaking, producing calcium hydroxide — slaked lime (hydrated lime).

CaO + H₂O → Ca(OH)₂ + heat

4

Carbonation

When slaked lime reacts with CO₂ in the air, it reverts to calcium carbonate — completing the natural lime cycle. This is what makes lime-based plasters harden.

Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

Lime Products

Types of Lime Products We Offer

Krishna Mines Group produces a comprehensive range of lime products for industrial, agricultural, and consumer applications.

Quicklime (CaO)

Calcium Oxide

Produced by calcining high-purity limestone at 1,000–1,200°C. Available as lump lime, granular lime, and ground quicklime. Key uses: steel manufacturing, water treatment, FGD, chemical production.

Purity: CaO ≥ 85%

Slaked Lime (Ca(OH)₂)

Calcium Hydroxide

Produced by controlled hydration of quicklime. Available as fine dry powder. Key uses: construction, water and effluent treatment, sugar refining, paper manufacturing, food additive (E526).

Purity: Ca(OH)₂ ≥ 90%

Limestone (CaCO₃)

Calcium Carbonate — Raw

High-grade crushed and sized limestone direct from our mines. Available in multiple grades and sizes. Key uses: cement manufacturing, steel flux, chemical feedstock, agriculture.

Purity: CaCO₃ ≥ 90%

Ground Calcium Carbonate

Micronized CaCO₃

Ultra-fine calcium carbonate produced by controlled grinding and classification. Available in multiple particle sizes (D97: 5–150 microns). Key uses: paint, plastics, paper, rubber, pharmaceuticals.

Purity: Brightness ≥ 92%

Agricultural Lime

Soil Amendment Grade

Finely ground limestone for soil pH correction and calcium/magnesium nutrition. Meets FCO standards for agricultural use. Recommended: 1–3 tonnes/acre based on soil testing.

Purity: ENV ≥ 80%

Consumer Lime Products

Alpine White Range

Premium white cement and lime-based consumer products under the Alpine White brand — Wallputty, Wallprimer, Aqua Proof, Floor Fixer, and Primer for construction applications.

Purity: BIS Certified

Applications

Where is Lime Used?

Lime is one of the most widely used industrial minerals in the world, serving over 100 industries across the globe.

Steel Manufacturing

Lime is used as a flux in blast furnaces and basic oxygen furnaces to remove impurities (silica, sulfur, phosphorus) from iron and steel, producing clean steel.

Water Treatment

Lime is used in water and wastewater treatment to adjust pH, precipitate heavy metals, remove phosphates, and disinfect drinking water — making it safe for consumption.

Construction

Lime mortar, lime plaster, and lime-based wall finishes have been used in construction for centuries. Modern applications include wall putty, primers, waterproofing compounds, and tile adhesives.

Agriculture

Agricultural lime corrects soil acidity (low pH), improves soil structure, provides calcium and magnesium nutrition, and enhances the effectiveness of fertilizers — boosting crop yields.

Chemical Production

Lime is a key raw material in the production of calcium carbide, calcium chloride, soda ash, bleaching powder, sodium silicate, and hundreds of other industrial chemicals.

Flue Gas Desulfurization

Lime and limestone are used in power plants to remove sulfur dioxide (SO₂) from flue gases, preventing acid rain and meeting environmental emission standards.

Sugar Refining

Milk of lime (lime + water suspension) is used in sugar manufacturing to clarify and purify cane juice, removing impurities and color to produce white crystalline sugar.

Paper Manufacturing

Lime is used in the Kraft pulping process, bleaching of wood pulp, and in the production of precipitated calcium carbonate (PCC) as a paper filler and coating agent.

Pharmaceuticals

High-purity calcium carbonate and hydroxide are used as excipients in tablets, antacids, calcium supplements, and as processing agents in pharmaceutical manufacturing.