Calcium Hydroxide (Ca(OH)2)

Calcium hydroxide plays a significant role across various industries due to its strong alkaline properties and reactivity. This compound is valued for its ability to neutralize acids, relatively low solubility in water, and moderate reactivity, making it practical for construction, water treatment, agriculture, and food production applications. It serves as a key ingredient in mortar and plaster, a clarifying agent in sugar refining, and a pH adjuster in wastewater treatment. In this article, we will explore the definition of calcium hydroxide, its different grades, the production process, and the broad range of applications that make it an indispensable material in many industries.

Nobel Trading Co. is a trustworthy supplier of calcium hydroxide, recognized for its high-quality products and commitment to customer satisfaction. The company benefits from advanced production facilities, strict quality control measures, and a reliable supply of raw materials, ensuring consistent and pure calcium hydroxide for various uses. Nobel Trading Co.’s extensive global distribution network allows for efficient delivery, making them a reliable partner for clients worldwide. By offering flexible packaging, competitive pricing, and technical support, Nobel Trading Co. stands out as a preferred choice for industries seeking high-quality calcium hydroxide solutions.

 

What is Calcium Hydroxide (Ca(OH)2)?

Calcium hydroxide, also known as slaked lime or hydrated lime, is an inorganic compound with the chemical formula Ca(OH)₂. It is widely used in various industries due to its alkaline nature and reactivity. Calcium hydroxide is produced by adding water to calcium oxide (quicklime) in a process known as slaking. This chemical reaction results in a white powder or colorless crystalline substance that is only slightly soluble in water, forming what is known as lime water.

Chemical Properties

Calcium hydroxide exhibits a number of important chemical properties that are crucial for its various applications. These properties are outlined below:

  • Chemical Formula: Ca(OH)₂
  • Molecular Weight: 74.09 g/mol
  • Structure: Consists of one calcium ion (Ca²⁺) ionically bonded to two hydroxide ions (OH⁻). The calcium ion has a +2 charge, and each hydroxide ion has a -1 charge, balancing to form a neutral compound.
  • Reactivity:
    • Moderate Base: Acts as a strong base in aqueous solutions, although it is only slightly soluble in water.
      • Equation: Ca(OH)₂ → Ca²⁺ + 2OH⁻
    • Reaction with Carbon Dioxide: Reacts with CO₂ to form calcium carbonate (CaCO₃), a process known as carbonation.
      • Equation: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
    • Reaction with Acids: Neutralizes acids to form calcium salts and water.
      • General Equation: Ca(OH)₂ + 2H⁺ → Ca²⁺ + 2H₂O

Physical Properties

The physical properties of calcium hydroxide, such as appearance, density, and solubility, define its suitability for different industrial and chemical uses. These properties are detailed below:

  • Appearance: White crystalline solid or powder.
  • Crystal Structure: Hexagonal.
  • Density: Approximately 2.211 g/cm³ (solid form).
  • Melting Point: Decomposes at around 580°C (1,076°F), losing water and forming calcium oxide (CaO).
  • Solubility:
    • In Water: Slightly soluble; solubility is about 1.65 g/L at 20°C (68°F). Solubility decreases with increasing temperature.
    • In Other Solvents: Soluble in glycerol and acids. Practically insoluble in ethanol.
  • pH: A saturated aqueous solution has a pH of approximately 12.4, indicating strong basicity.
  • Hygroscopic Nature: Absorbs carbon dioxide from the air to form calcium carbonate, which can reduce its effectiveness over time.

Stability and Storage

Calcium hydroxide should be stored in airtight containers to prevent it from reacting with carbon dioxide in the air. If exposed to the atmosphere for prolonged periods, it forms a layer of calcium carbonate, which can reduce its effectiveness in many applications.

Safety Considerations

Handling calcium hydroxide requires care. It can cause skin and eye irritation, so appropriate personal protective equipment (PPE) such as gloves and safety goggles should be worn. Inhaling the dust may also lead to respiratory irritation.

In case of contact with the skin or eyes, the affected area should be rinsed with plenty of water. If irritation persists, medical attention should be sought.

 

Different Grades of Calcium Hydroxide 

Calcium hydroxide is available in several grades, each designed to meet specific application requirements based on purity, regulatory standards, and intended use. Using the correct grade is essential for ensuring product safety, efficacy, and compliance with industry standards. Below, we outline the various grades of calcium hydroxide and its unique features and applications.

Technical Grade

Technical-grade calcium hydroxide is produced for general industrial use where ultra-high purity is not required. It contains permissible levels of impurities suitable for non-critical applications. The purity level is lower compared to other grades, making it suitable for less sensitive uses. Technical-grade calcium hydroxide is commonly used in construction as a key ingredient in mortar, plaster, and cement, providing binding properties that contribute to the strength and durability of these materials.

This grade is also used in water and sewage treatment, acting as a flocculant and pH adjuster to remove impurities and neutralize acidic conditions. Additionally, it plays a role in various industrial processes, including the production of chemicals and flue gas desulfurization. This grade is cost-effective and ideal for large-scale industrial operations but is not appropriate for applications involving ingestion or requiring high purity.

Food Grade

Food-grade calcium hydroxide is manufactured to meet stringent safety and purity standards for use in food production. Its purity is higher than that of technical grade, with controlled impurity levels to ensure safety for consumption. Food-grade calcium hydroxide complies with food safety standards set by agencies like the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA).

The food grade of calcium hydroxide functions in nixtamalization, a process for treating corn to enhance nutritional content and flavor, making it a key ingredient in foods like tortillas. It also plays a role in sugar refining, acting as a clarifying agent to remove impurities, and in food preservation, adjusting pH and improving texture in pickling processes. Food-grade calcium hydroxide must be used within regulated limits to prevent health risks, and products containing it must be labeled appropriately for consumer awareness.

Pharmaceutical Grade

Pharmaceutical-grade calcium hydroxide is characterized by the highest level of purity, adhering to strict standards required for medical and pharmaceutical applications. It meets pharmacopeial standards with minimal impurities and is produced to ensure compliance with specifications outlined in pharmacopeias such as the United States Pharmacopeia (USP) and European Pharmacopoeia (Ph. Eur.).

The pharmaceutical grade serves in medical and dental treatments, including root canal fillings and pulp capping, due to its antibacterial properties and ability to promote healing. It is also used as an inactive ingredient or pH adjuster in various pharmaceutical formulations. Pharmaceutical-grade calcium hydroxide undergoes rigorous quality checks and requires detailed documentation and traceability to ensure safety and effectiveness in pharmaceutical use.

Reagent Grade

Reagent-grade calcium hydroxide is designed for laboratory and analytical purposes, where extremely high purity is required. This grade has minimal impurities to prevent interference in analytical procedures. It is commonly used in laboratory settings for analytical chemistry, research, and experimental work that requires precision.

Additionally, reagent grade calcium hydroxide is used in preparing standard solutions for titrations and other quantitative analyses. A certificate of analysis typically accompanies it to verify impurity levels, ensuring its suitability for laboratory use. Due to the additional purification steps, reagent-grade calcium hydroxide is generally more expensive.

 

Calcium Hydroxide Production Process

Calcium hydroxide is produced industrially by reacting calcium oxide (quicklime) with water in a process called slaking. The entire production process involves multiple steps to ensure the quality and consistency of the final product. Below, the main stages of production are detailed:

Raw Material Preparation

High-quality limestone (calcium carbonate, CaCO₃) is carefully selected based on its purity and chemical composition. The limestone is cleaned to remove impurities such as clay and sand, and then crushed to an appropriate size to prepare it for further processing.

Calcination

The crushed limestone is subjected to high temperatures in a kiln to produce calcium oxide (quicklime) and carbon dioxide. The chemical reaction involved is:

CaCO₃ → (heated to 900–1000°C) → CaO + CO₂↑

Rotary kilns or shaft kilns are most commonly used for calcination. The temperature is maintained around 900°C to ensure effective decomposition of limestone, and the kiln atmosphere is controlled to maximize energy efficiency and enhance reaction completion.

Slaking (Hydration)

After producing quicklime, it undergoes a slaking process where it is combined with water to form calcium hydroxide. This is an exothermic process that must be carefully controlled.

  • Dry Slaking (Dry Hydration Process)

In the dry hydration process, finely ground quicklime is mixed with just enough water for complete hydration, typically in insulated vessels or hydrators to retain the generated heat. The temperature is managed to reach between 85–110°C, which promotes efficient hydration. This process produces a fine, dry powder of calcium hydroxide with a high specific surface area and reactivity. The dry form is ideal for applications that require high reactivity, such as chemical manufacturing or flue gas treatment.

  • Wet Slaking (Wet Hydration Process)

In the wet hydration process, quicklime is mixed with an excess amount of water, forming a suspension known as “milk of lime” or lime slurry. The slurry may undergo screening or cyclone treatment to remove impurities and achieve the desired particle sizes. The resulting slurry is suitable for specific applications, such as sugar refining or wastewater treatment.

Cooling

Once hydrated, calcium hydroxide is cooled to below 50°C to stabilize it and prevent premature reaction with carbon dioxide in the air. The cooling process can be achieved using cooling belts, fluidized bed coolers, or air cooling systems. This ensures the hydrated lime retains its desired properties and quality.

Finishing

If necessary, any residual moisture is removed to achieve the desired dryness. The product is then ground to achieve specific particle sizes, and air classifiers can be used to segregate particles based on their size. The final product is packaged in moisture-resistant bags or stored in bulk for large-scale usage. Tests are performed to ensure the product meets standards for purity, particle size, and reactivity.

Advantages of the Dry Slaking Process

The dry hydration method produces calcium hydroxide with a larger surface area, significantly enhancing its chemical reactivity. Due to careful water addition and minimized contamination, the dry process results in a high-purity product. Additionally, calcium hydroxide in powder form is easier to transport, store, and handle compared to slurry.

This structured approach to calcium hydroxide production, from raw material preparation to packaging, ensures a product that meets stringent industry requirements and is suitable for various applications.

 

Calcium Hydroxide Applications

Calcium hydroxide is widely used across various industries due to its alkaline properties, calcium content, and its ability to form strong adhesives. Below are some key applications of calcium hydroxide:

Construction and Industrial Uses

Calcium hydroxide plays an essential role in the construction industry. It is a major ingredient in mortar, plaster, and cement, serving as a binder that contributes to the strength, durability, and workability of these materials. In water and sewage treatment, calcium hydroxide acts as a flocculant, aiding in the removal of impurities by causing suspended particles to coagulate and settle, thus improving water clarity.

In paper production, particularly the Kraft process, calcium hydroxide helps regenerate sodium hydroxide from sodium carbonate during the recovery phase, which is crucial for sustainable pulp production. It is also used as a neutralizing agent to adjust the pH of acidic soils in agriculture and acidic waterways in environmental applications. This neutralization improves soil quality and restores aquatic environments affected by acidification. In flue gas treatment, calcium hydroxide reacts with sulfur dioxide in industrial scrubbers, producing calcium sulfite or calcium sulfate, thereby reducing air pollution.

Food Industry

Calcium hydroxide has a significant role in the food industry. In the process of nixtamalization, corn is treated with an alkaline solution containing calcium hydroxide. This treatment improves the nutritional value, flavor, and aroma of corn-based foods such as tortillas and tamales by increasing the bioavailability of niacin. Calcium hydroxide is also used in the preservation of foods, such as century eggs and pickled vegetables, where it alters texture and pH to achieve the desired culinary qualities.

In sugar refining, calcium hydroxide is used as a clarifying agent and pH adjuster, aiding in the removal of impurities from sugar cane or beet juice through a process called carbonatation, resulting in a purer product. It is also used in the preparation of traditional Indian sweets like petha, where it helps achieve the required texture and firmness.

Agriculture

Calcium hydroxide is an active ingredient in Bordeaux mixture, a fungicide used to protect plants from fungal diseases like downy mildew. The mixture forms a protective barrier on plant surfaces, helping to prevent fungal growth. Additionally, calcium hydroxide is applied to adjust the pH of acidic soils, improving conditions for plant growth by enhancing nutrient availability and encouraging healthy microbial activity.

Medical and Dental Applications

In dentistry, calcium hydroxide is used in root canal treatments, pulp capping, and as a dressing for avulsed teeth. It has antibacterial properties and promotes the formation of secondary dentin, assisting in the healing and regeneration of dental tissues. In pharmaceuticals, calcium hydroxide serves as an inactive ingredient or pH adjuster in certain formulations.

Other Applications

Calcium hydroxide is also employed in various other industries. In leather tanning, it is used during the liming process to remove hair, fats, and other unwanted materials from animal hides. In chemical manufacturing, calcium hydroxide is used to produce various calcium-based compounds, such as calcium stearate, a lubricant and release agent.

In paints and coatings, calcium hydroxide serves as a filler and provides adhesive properties. It is also used in fresco painting, where it reacts with carbon dioxide to form a durable calcium carbonate layer. In rubber and plastic production, calcium hydroxide acts as a filler and improves mechanical properties and heat stability. It is also found in some pesticides and hair care products, such as hair relaxers and straighteners, due to its ability to break down the protein structure in hair for reshaping.

 

About Nobel Trading Co’s Calcium Hydroxide

Based in China, Nobel Trading Co is a prominent provider of calcium hydroxide, catering to diverse industrial needs with a focus on quality and reliability. By leveraging their considerable stake in advanced production facilities and reliable raw material sourcing, they maintain a steady supply of high-quality calcium hydroxide at competitive prices for clients worldwide.

Manufacturing Excellence

Nobel Trading Co’s production facilities are outfitted with modern equipment to ensure an efficient and tightly controlled production process. Quality assurance is implemented at every stage to produce calcium hydroxide with consistent purity. A skilled team oversees the process to guarantee adherence to industry standards.

With substantial production capacity, Nobel Trading Co can meet both domestic and international demands. This ensures that the supply chain remains uninterrupted, even for customers with large-scale needs.

Cost-Effective Solutions

Nobel Trading Co’s strong partnerships with global mining enterprises ensure a stable supply of high-quality limestone, the key raw material for calcium hydroxide. The combination of effective resource sourcing and efficient manufacturing enables the company to offer its products at competitive prices, benefiting from economies of scale.

Moreover, streamlined logistics and supply chain practices help to reduce operational costs, with these savings being directly passed on to customers, ensuring both quality and affordability.

Packaging and Logistics Services

To address varying customer needs, Nobel Trading Co provides several packaging options for calcium hydroxide, including moisture-resistant bags, bulk containers, and drums. This flexibility ensures the product’s integrity is maintained during transit. Shipping options include both sea and air freight, allowing for timely and reliable delivery worldwide.

A dedicated logistics team handles every aspect of the shipment, from documentation to compliance with international regulations, ensuring a seamless process for clients.

Customer-Centered Services

Nobel Trading Co emphasizes customer satisfaction by offering technical assistance to ensure the proper use of calcium hydroxide. Each product is accompanied by comprehensive safety data sheets (SDS) and meets international standards, ensuring safe and efficient usage.

Quick and effective responses to customer inquiries are part of the company’s commitment to superior service. This customer-centric approach has helped Nobel Trading Co forge strong, enduring partnerships with its clients.

Advantages of Choosing Nobel Trading Co

  • Quality Commitment: Advanced facilities and rigorous quality control ensure consistent product standards.
  • Affordable Pricing: Cost efficiencies in production and supply provide competitive pricing.
  • Tailored Solutions: Flexible packaging and shipping options cater to specific customer requirements.
  • Reliable Availability: High production capacity and a robust supply network guarantee an uninterrupted supply.
  • Global Service: Nobel Trading Co’s extensive distribution and logistics network supports customers globally.

Nobel Trading Co’s calcium hydroxide is a preferred choice for its reliability, quality, and flexibility. With a steadfast commitment to excellence and customer satisfaction, Nobel Trading Co stands as a trusted partner for calcium hydroxide solutions across industries.