White Calcium Oxide Price: Composition, Classification, and Industrial Applications

Types of Calcium Oxide

Calcium oxide (CaO), commonly known as quicklime, is a versatile industrial chemical used in construction, environmental management, steel production, and water treatment. It is produced through the thermal decomposition of limestone (calcium carbonate) in a process called calcination. Depending on the manufacturing method and intended application, calcium oxide is available in several physical forms—each with distinct properties, reactivity levels, and handling characteristics.

Powdered Calcium Oxide

Also known as quicklime or lime powder, this form is created by heating limestone (CaCO₃) in high-temperature kilns, driving off carbon dioxide (CO₂) to leave behind fine CaO particles.

Advantages

• High surface area enhances reactivity
• Easy to mix and disperse in chemical processes
• Efficient for rapid neutralization reactions
• Widely used in flue gas treatment and soil stabilization

Limitations

• Dust formation poses inhalation risks
• Requires careful storage to avoid moisture absorption
• Can be challenging to handle in humid environments

Best for: Industrial chemical processing, pollution control, and applications requiring fast reaction kinetics

Hydrated Calcium Oxide

Formed when calcium oxide reacts with water in a controlled exothermic process, resulting in calcium hydroxide (Ca(OH)₂), also known as slaked lime. It typically appears as a dry, fine white powder or a milky suspension (lime milk).

Advantages

• Non-caustic and safer to handle than quicklime
• Stable in storage with lower reactivity
• Ideal for pH adjustment in water and wastewater treatment
• Used in food preparation (e.g., nixtamalization of corn)

Limitations

• Lower reactivity compared to CaO
• Less effective in high-temperature applications
• Requires more material for equivalent neutralization

Best for: Water treatment, agriculture, food industry, and pH regulation

Pelletized Calcium Oxide

Quicklime granulated into small, uniform pellets using a controlled amount of water during processing. This form improves handling and reduces dust.

Advantages

• Reduced dust and improved worker safety
• Easier to meter and automate in industrial systems
• Consistent size enhances controlled release
• Suitable for continuous feed applications

Limitations

• Slower initial reaction due to lower surface area
• Requires specialized equipment for pelletizing
• May need crushing before high-speed reactions

Best for: Industrial automation, steelmaking, and large-scale environmental remediation

Fast-Slaking Calcium Oxide

A high-reactivity form of quicklime produced through precise calcination and fine milling to remove impurities and maximize surface area. Also known as reactive lime.

Advantages

• Rapid hydration (slaking) with water
• High efficiency in time-sensitive processes
• Excellent performance in water and flue gas treatment
• Minimizes unreacted residue

Limitations

• Higher production cost
• Requires careful handling due to heat generation
• Sensitive to moisture during storage

Best for: Emergency water treatment, chemical manufacturing, and high-efficiency industrial processes

Granular Calcium Oxide

Processed into larger granules through drying, crushing, and sifting. Offers a coarser texture with reduced surface area compared to powdered forms.

Advantages

• Minimal dust generation
• Easy to transport and store
• Controlled reactivity ideal for slow-release applications
• Excellent flow characteristics in bulk systems

Limitations

• Slower reaction rate
• Not suitable for rapid chemical processes
• May require grinding for full utilization

Best for: Landfill stabilization, long-term soil treatment, and controlled-release industrial applications

Expert Tip: Always wear appropriate PPE (gloves, goggles, respirator) when handling powdered or fast-slaking calcium oxide due to its caustic nature and potential for exothermic reactions with moisture. Store in a dry, sealed environment to prevent premature hydration.

Features of White Calcium Oxide

Calcium oxide (CaO), commonly known as quicklime, is a versatile inorganic compound widely used in industrial, agricultural, and environmental applications. Its unique chemical and physical properties make it essential in processes ranging from steelmaking to water treatment. Below is a detailed breakdown of its key features, including composition, reactivity, purity, and storage considerations.

Chemical Composition and Crystal Structure

Calcium oxide is an ionic compound composed of calcium (Ca²⁺) and oxide (O²⁻) ions in a 1:1 ratio, giving it the chemical formula CaO. It forms a face-centered cubic (FCC) crystal lattice, also known as the rock-salt structure, where each calcium ion is surrounded by six oxide ions and vice versa. This arrangement contributes to its high thermal stability and rigidity.

The compound has a molecular weight of 56.08 g/mol and appears as a white to off-white solid. The color variation (gray or yellowish tints) typically indicates impurities such as iron or magnesium compounds. High-purity CaO is bright white and is preferred for pharmaceutical and food-grade applications.

Physical Properties

In its pure form, calcium oxide is a fine, dry, free-flowing powder with a coarse or granular texture. It is odorless and non-combustible, making it safe to handle under normal conditions (with appropriate protective equipment). Key physical characteristics include:

• Density: 3.35 g/cm³ — relatively high, indicating a tightly packed crystal structure
• Melting Point: 2,572 °F (1,412 °C) — exceptionally high, suitable for high-temperature industrial processes
• Boiling Point: 4,631 °F (2,550 °C) — reflects strong ionic bonding within the lattice
• Solubility: Slightly soluble in water (forming Ca(OH)₂), highly soluble in acids, and insoluble in benzene, ethanol, and most organic solvents

Its low solubility in water is due to the high lattice energy of the crystal, which must be overcome during hydration.

Acidity and Basicity (pH Behavior)

Calcium oxide is a **strongly basic** substance, with an aqueous slurry exhibiting a pH greater than 12. When exposed to moisture, it undergoes a hydration reaction:

CaO + H₂O → Ca(OH)₂ + heat

The product, calcium hydroxide (slaked lime), is a weaker base with a pH of approximately 11–12. Due to its hygroscopic nature, CaO readily absorbs atmospheric moisture and carbon dioxide, gradually converting into calcium hydroxide and then calcium carbonate (CaCO₃) over time:

CaO + CO₂ → CaCO₃

This property necessitates careful storage to maintain reactivity and purity.

Reactivity and Chemical Behavior

Calcium oxide is highly reactive, especially in the presence of moisture or heat. Its exothermic reaction with water releases significant heat (approximately 65.3 kJ/mol), which can pose safety risks if uncontrolled. Key chemical reactions include:

With Acids

Neutralizes acids to form calcium salts and water. For example, with sulfuric acid:

CaO + H₂SO₄ → CaSO₄ + H₂O

This makes it useful in flue gas desulfurization and soil pH correction.

With Carbon Dioxide

Forms calcium carbonate in a reversible reaction:

CaO + CO₂ ⇌ CaCO₃

This principle is applied in carbon capture technologies and lime kilns.

At elevated temperatures, CaO acts as a flux in metallurgy, removing acidic impurities like silica (SiO₂) by forming slag (calcium silicate).

Purity and Common Contaminants

High-purity calcium oxide (>98% CaO) is essential for sensitive applications such as food additives, pharmaceuticals, and laboratory reagents. Impurities often originate from the limestone feedstock or incomplete calcination. Common contaminants include:

Quality control through spectroscopy or titration ensures consistency in industrial batches.

Packaging, Storage, and Shelf Life

Due to its hygroscopic and reactive nature, calcium oxide must be stored under dry, airtight conditions. Typical packaging includes:

• Plastic-lined paper bags – for small-scale or retail use
• Multi-wall poly-lined containers – moisture-resistant and durable
• Bulk bags (FIBCs) with moisture barriers – for industrial transport
• Sealed steel drums – for high-purity or hazardous environments

When stored properly in a cool, dry environment away from humidity and CO₂-rich air, calcium oxide maintains its potency for **6 to 12 months**. Prolonged exposure leads to gradual conversion into hydroxide and carbonate, diminishing its effectiveness.

Important: Always use personal protective equipment (PPE) when handling calcium oxide. The exothermic hydration reaction can cause thermal burns, and dust may irritate the eyes, skin, and respiratory system. Store in clearly labeled, sealed containers away from acids and moisture sources. Never mix with ammonium salts, as this can release toxic ammonia gas.

Uses of Calcium Oxide (Quicklime) – A Comprehensive Guide

Calcium oxide, commonly known as quicklime, is a versatile inorganic compound with a wide range of industrial, agricultural, and environmental applications. When reacted with water, it forms calcium hydroxide (slaked lime), a process known as slaking, which further expands its utility. Below is a detailed exploration of the key uses of calcium oxide across various sectors.

Construction Industry

Calcium oxide is a foundational material in construction, primarily used to produce calcium hydroxide through the slaking process. This hydrated lime is essential in traditional and modern building materials.

• Used in the formulation of lime mortar, which offers flexibility, breathability, and self-healing properties in masonry work
• Key component in plaster and stucco, improving workability and adhesion to surfaces
• Incorporated into lime concrete for historical restoration and sustainable building projects
• Enhances durability and resistance to weathering in long-term structural applications

Did you know? Lime-based mortars have been used since ancient Roman times and are still valued today for heritage conservation.

Water Treatment

In municipal and industrial water treatment, calcium oxide plays a vital role in ensuring safe and clean water supplies.

• Acts as a pH adjuster, neutralizing acidic water to prevent pipe corrosion and improve disinfection efficiency
• Facilitates coagulation and sedimentation by removing suspended solids and turbidity
• Effective in precipitating heavy metals such as lead, arsenic, and cadmium, reducing them to safe levels
• Used in wastewater treatment to stabilize sludge and reduce odor

Environmental benefit: Lime treatment is a cost-effective and eco-friendly method for large-scale water purification.

Agriculture and Soil Management

Calcium oxide is widely used in agriculture to improve soil health and manage waste.

• Applied as agricultural lime to neutralize acidic soils, enhancing nutrient availability (especially calcium and magnesium)
• Promotes stronger root development and improves crop yields in acidic conditions
• Used in composting to accelerate decomposition and reduce pathogens in organic waste
• Helps control odors and stabilize manure in livestock operations

Pro tip: Soil testing is recommended before liming to avoid over-application, which can lead to nutrient imbalances.

Sugar and Juice Processing

Calcium oxide is a critical agent in food processing, particularly in the sugar and beverage industries.

• Serves as a clarifying agent in sugar extraction from sugarcane and sugar beets, forming calcium saccharate to remove impurities
• Used in fruit juice clarification to precipitate proteins, tannins, and other suspended particles
• Improves the color, taste, and shelf life of final products
• After clarification, excess lime is removed through carbonation, ensuring food safety

Fun fact: The "milk of lime" process has been used in sugar refining since the 19th century.

Chemical Manufacturing

Calcium oxide is a fundamental raw material in the chemical industry, serving as a precursor to numerous compounds.

• Used to produce calcium hydroxide, calcium carbonate, and various calcium salts
• Essential in the manufacture of cement and glass, where it acts as a flux and stabilizer
• Reacted with coke in electric arc furnaces to produce calcium carbide, which generates acetylene gas when mixed with water
• Acetylene, once a primary fuel for welding and lighting (e.g., kerosene lamps), remains important in organic synthesis

Historical note: Acetylene was the first synthesized hydrocarbon and played a key role in early 20th-century industrial chemistry.

Steel and Metallurgy

In the metal production sector, calcium oxide is indispensable as a flux in smelting and refining processes.

• Used in basic oxygen furnaces (BOF) and electric arc furnaces (EAF) to remove impurities like silica, sulfur, and phosphorus
• Forms slag with impurities, which can be easily separated from molten metal
• Improves the efficiency and purity of steel production, leading to higher-quality alloys
• Also used in the extraction of non-ferrous metals such as aluminum and magnesium from their ores

Industry standard: High-purity lime is required in steelmaking to ensure consistent quality and reduce processing defects.

Expert Insight: Calcium oxide’s reactivity and alkalinity make it a powerful yet manageable chemical in industrial processes. When handling quicklime, proper safety precautions—such as using protective gear and ensuring dry storage—are essential due to its exothermic reaction with water and potential to cause burns.

Additional Applications and Considerations

• Environmental Remediation: Used in flue gas desulfurization to reduce sulfur dioxide emissions from power plants
• Paper Industry: Employed in the kraft pulping process to recover chemicals and regenerate cooking liquor
• Pharmaceuticals: Serves as an excipient or processing aid in some medicinal products
• Safety Note: Quicklime is caustic and reacts vigorously with water—always handle with care and store in airtight containers
• Sustainability: Lime is naturally occurring and recyclable through carbonation, making it a relatively sustainable industrial chemical

How to Choose High-Quality Calcium Oxide: A Comprehensive Buyer's Guide

Selecting the right calcium oxide (CaO), commonly known as quicklime or burnt lime, is crucial for ensuring optimal performance in industrial, agricultural, construction, and food-grade applications. This guide provides business owners and procurement managers with a detailed breakdown of the key factors to consider when sourcing calcium oxide. By understanding purity, particle size, form, packaging, and supplier reliability, you can make informed decisions that enhance product quality, operational efficiency, and safety.

Safety Note: Calcium oxide is highly reactive with water and can cause severe burns upon contact with skin or eyes. Always handle with appropriate personal protective equipment (PPE) including gloves, goggles, and respiratory protection. Store in a cool, dry, and well-ventilated area away from moisture and acidic materials.

Key Factors in Selecting Calcium Oxide

1. Purity and Chemical Composition

   Calcium oxide is primarily derived from natural sources such as limestone (calcium carbonate) or marine shells like oyster shells. The source significantly impacts the final product’s purity:

   • Limestone-based CaO: Typically offers higher purity (often 90–98% CaO) due to lower levels of impurities like silica, iron, and magnesium. Ideal for sensitive applications including pharmaceuticals, food processing, and high-grade chemical manufacturing.
   • Oyster shell-based CaO: May contain higher levels of trace minerals and silica, which can reduce reactivity and introduce unwanted contaminants. Best suited for less critical applications such as soil amendment or wastewater treatment.
   • Industry-Specific Needs: Medical and food industries require USP or food-grade calcium oxide with documented certifications (e.g., FDA, ISO, HACCP). Always request a Certificate of Analysis (CoA) to verify composition and compliance.
2. Mesh Size and Surface Area

   The particle size, measured in mesh or specific surface area (m²/g), directly influences reactivity and application efficiency:

   • Fine powders (e.g., 200–325 mesh or ~250 m²/g) offer greater surface area, leading to faster hydration and improved performance in processes like flue gas treatment, soil stabilization, and cement production.
   • Coarser grades are suitable for applications where slower reaction rates are acceptable, such as in steelmaking slags or certain agricultural uses.
   • For maximum effectiveness in moisture absorption and chemical reactions, a mesh size of at least 250 (approximately 50 microns) is recommended. Ensure consistency in particle distribution by requesting sieve analysis reports from suppliers.
3. Form and Functional Properties

   Calcium oxide is available in several forms, each suited to specific industrial processes:

   • Calcined Lime (Quicklime): Raw CaO produced by thermal decomposition of limestone. Highly reactive and used in chemical synthesis, metallurgy, and pollution control systems.
   • Slaked Lime (Calcium Hydroxide - Ca(OH)₂): Formed by hydrating quicklime. Commonly used in construction (mortar, plaster), water treatment, and pH adjustment due to its lower reactivity and safer handling profile.
   • Hydrated Lime Powder: Pre-reacted form ideal for food processing (as a firming agent), agriculture (soil pH correction), and environmental remediation.
   • Choose the form based on your process requirements—whether you need immediate reactivity (CaO) or a more stable, manageable compound (Ca(OH)₂).
4. Packaging and Moisture Protection

   Calcium oxide is hygroscopic and reacts vigorously with atmospheric moisture, forming calcium hydroxide and reducing its shelf life and efficacy:

   • Opt for packaging with multiple moisture barriers such as plastic-lined kraft paper bags, polyethylene-lined woven polypropylene sacks, or sealed HDPE containers.
   • In humid environments or for long-term storage, rigid, airtight containers are superior to flexible bags, which may develop micro-tears or allow vapor permeation.
   • Ensure packaging is clearly labeled with batch number, production date, grade, and handling instructions. Vacuum-sealed or nitrogen-flushed packaging further enhances stability for premium-grade products.
5. Supplier Reputation and Compliance

   Partnering with a reliable supplier ensures consistent quality and regulatory compliance:

   • Prioritize suppliers with verifiable certifications (ISO 9001, GMP, FDA registration) and transparent quality control processes.
   • Evaluate their capacity for bulk supply, logistics support, and technical documentation (SDS, CoA, traceability records).
   • Avoid vendors without proper licensing or those offering unusually low prices, which may indicate adulterated or substandard products.
   • Establish long-term relationships with suppliers who offer sample testing, on-site audits, and responsive customer service.

Expert Tip: Conduct small-batch trials before committing to large orders. Test the calcium oxide in your actual process conditions to evaluate reactivity, consistency, and compatibility. This helps prevent costly errors and ensures seamless integration into your production line.

Additional Recommendations for Buyers

• Maintain a log of supplier performance, including delivery times, product consistency, and responsiveness to inquiries.
• Train staff on safe handling, storage, and emergency procedures for calcium oxide exposure.
• Rotate inventory using FIFO (First In, First Out) to minimize degradation over time.
• Stay updated on regulatory standards relevant to your industry (e.g., FDA 21 CFR for food use, OSHA guidelines for workplace safety).
• Consider sustainability: Some suppliers offer eco-friendly production methods using renewable energy or recycled raw materials.

Choosing the right calcium oxide is not just about cost—it's about ensuring quality, safety, and process efficiency. By focusing on purity, particle size, form, packaging integrity, and supplier credibility, businesses can optimize their operations and maintain high standards across applications. When in doubt, consult with technical experts or request product samples to validate suitability before full-scale procurement.

Calcium Oxide: Safety, Quality, and Handling – Frequently Asked Questions

Handling calcium oxide (also known as quicklime) dust requires strict safety precautions due to its highly reactive and caustic nature. While it is possible for business personnel to manage it safely, proper protective measures are essential to prevent health risks.

• Respiratory Protection: Always wear a NIOSH-approved dust mask or respirator when handling calcium oxide to avoid inhaling fine particles, which can cause severe irritation to the nose, throat, and lungs.
• Skin Protection: Use chemical-resistant gloves, long sleeves, and protective clothing. Direct contact with skin can lead to chemical burns or dermatitis, especially if the dust becomes moist and forms calcium hydroxide.
• Eye Protection: Wear safety goggles or a face shield to prevent eye exposure, which can result in serious injury or corneal damage.
• Ventilation: Work in well-ventilated areas or use local exhaust systems to minimize airborne dust concentrations.

Proper training and adherence to OSHA and MSDS (Material Safety Data Sheet) guidelines are critical for workplace safety when managing calcium oxide.

High-purity calcium oxide is crucial for industrial efficiency and safety. Businesses should evaluate several key factors to ensure they are sourcing top-grade material:

• Calcium Content: Premium calcium oxide typically contains over 95% calcium (CaO), with some grades exceeding 98%. Higher purity enhances reactivity and performance in applications like steelmaking, water treatment, and flue gas desulfurization.
• Low Moisture Absorption: High-quality quicklime absorbs less than 1% water, indicating minimal pre-hydration and better shelf life.
• Low Impurities: Look for low levels of silica, iron, aluminum, and magnesium, as these can interfere with chemical processes and reduce effectiveness.
• Proper Packaging: Reputable suppliers package calcium oxide in moisture-proof, sealed containers—such as plastic-lined paper bags, poly-lined woven sacks, or airtight drums—to prevent premature reaction with atmospheric moisture and CO₂.
• Certification: A valid certificate of analysis (COA) or ISO certification from the manufacturer is a strong indicator of consistent quality and traceability.

Purchasing from trusted suppliers with transparent quality control processes ensures reliability and compliance with industry standards.

Calcium hydroxide (slaked lime) is produced through a two-stage chemical process that begins with raw limestone (calcium carbonate, CaCO₃). The process is both energy-intensive and precisely controlled to ensure product consistency.

1. Calcination: Limestone is heated in a rotary or vertical kiln at temperatures between 900°C and 1,100°C. This thermal decomposition drives off carbon dioxide (CO₂), leaving behind calcium oxide (quicklime):
   CaCO₃ → CaO + CO₂↑
2. Hydration (Slaking): The resulting quicklime is carefully mixed with water in a controlled exothermic reaction. This process, known as slaking, produces calcium hydroxide (Ca(OH)₂) and releases significant heat:
   CaO + H₂O → Ca(OH)₂ + heat

The hydration process can yield either dry hydrated lime (powder) or lime slurry (milk of lime), depending on the water-to-lime ratio and application needs. The final product is then screened, cooled, and packaged for industrial use in construction, environmental treatment, food processing, and more.

Chronic exposure to calcium oxide, especially in dusty environments, poses significant health risks. While acute exposure causes immediate irritation, prolonged contact can lead to lasting medical conditions:

• Respiratory Issues: Long-term inhalation of calcium oxide dust may result in chronic bronchitis, reduced lung function, and potential scarring of lung tissue (pulmonary fibrosis). Workers in lime plants or construction sites are particularly at risk.
• Skin Conditions: Repeated skin contact—especially in humid conditions—can lead to dermatitis, dryness, cracking, and chemical burns due to the formation of calcium hydroxide upon contact with sweat or moisture.
• Ocular Damage: Frequent eye exposure increases the risk of conjunctivitis, corneal irritation, and in severe cases, permanent vision impairment.
• Secondary Exposure Risks: Calcium oxide reacts with moisture in the air or on the skin to form calcium hydroxide, which is also caustic and contributes to long-term tissue damage.

Employers must implement engineering controls (e.g., dust suppression systems), provide appropriate PPE, and conduct regular health monitoring to protect workers from cumulative exposure effects.

Proper storage is essential to maintain the chemical integrity and safety of calcium oxide. Because it is highly reactive with moisture and carbon dioxide, incorrect storage can lead to degradation, clumping, and hazardous reactions.

• Dry Environment: Store in a cool, dry, and well-ventilated area with low humidity. Ideal storage conditions are below 50% relative humidity.
• Airtight Containment: Use sealed, moisture-proof containers such as plastic-lined bags, poly drums, or HDPE totes. Once opened, transfer unused material to airtight secondary containers.
• Avoid Paper Bags in Humid Areas: Standard paper bags offer minimal protection. In humid climates or outdoor storage, use plastic containers or climate-controlled warehouses.
• Separation from Incompatibles: Keep away from acids, water sources, and combustible materials. Store on elevated pallets to prevent ground moisture absorption.
• First-In, First-Out (FIFO): Rotate stock regularly to prevent long-term storage and degradation.

Regular inspection of packaging and storage areas helps detect leaks or moisture intrusion early, minimizing waste and safety hazards.