What is Solvay Process?

Solvay process is an industrial process in which sodium carbonate are prepared from limestone ammonia and NaCl.

This mean, it is also define as the solvay process or (ammonia nh3) process is the major industrial process for the production of sodium carbonate. 

Yes, Sodium carbonate are manufacture by Solvay process.

The Solvay process, also known as the ammonia-soda process, is a method used for the industrial production of soda ash (sodium carbonate).

The process involves several chemical reactions that convert common raw materials into soda ash.

Here are the key steps:

  1. Brine purification: Sodium chloride (common salt) is first purified to remove impurities such as calcium and magnesium ions.
  2. Ammonia absorption: The purified brine is then mixed with ammonia (NH₃), causing the formation of ammonium chloride (NH₄Cl) and sodium chloride (NaCl).
  3. Sodium bicarbonate formation: Carbon dioxide (CO₂) is introduced into the mixture from step 2, leading to the formation of sodium bicarbonate (NaHCO₃) and ammonium chloride (NH₄Cl).
  4. Sodium carbonate formation: The sodium bicarbonate is separated from the mixture and heated to produce soda ash (sodium carbonate, Na₂CO₃) and water (H₂O).
  5. Ammonia recovery: The ammonium chloride obtained in step 3 is heated with calcium hydroxide (Ca(OH)₂), producing ammonia gas (NH₃) and calcium chloride (CaCl₂). The ammonia is then recycled back to step 2.

The soda ash produced through the Solvay process is widely used in various industries, including glass manufacturing, detergents, paper production, and chemical synthesis.


It is an important industrial chemical with a wide range of applications.

You can also follow this Mathods

There are three steps are involved to produce Na2CO3.

The Solvay process gives,

1) Soda ash (sodium carbonate, Na2CO3)

2) Brine (sodium chloride, NaCl)

3) Limestone (calcium carbonate, CaCO3 ).

How to sodium carbonate (NaCO3) are Manufacture by solvay process?

Sodium carbonate (is know as Washing soda, soda ash) manufacture by this process. the process involves following steps,

Step 1

CO2 passed through a solution of NH3, as a results NH4 HCO3 is produced.

CO2 used in step 1 is produced through heating CaCO3 as,

CaCO3 ∆ – CaO + CO2

Step 2

NH4HCO3 is then reacted with NaCl as a results, NaHCO3 + NH4Cl is forned.

Step 3

When bicarbonate are heated as a result, finally the sodium carbonate as a product are formed.

Bicarbonate ∆ – NaCO3 + H2O + CO2

Major Raw Materials Used in the Solvay Process

(1) – Sodium chloride (NaCl)

(2) – Ammonia (NH3)

(3) – limestone (for CO2)

(4) – Water (H2O)

Most of NH3 can be recovered in the process.

CaCl2 – it is only by products

The Solvay process is a method used for the production of soda ash (sodium carbonate) from sodium chloride, ammonia, and limestone.

The major raw materials used in the Solvay process are

  1. Sodium Chloride (NaCl): Commonly known as table salt or rock salt, sodium chloride is the primary raw material in the Solvay process. It provides a source of sodium ions (Na+) necessary for the production of sodium carbonate.
  2. Limestone (Calcium Carbonate, CaCO3): Limestone is a sedimentary rock primarily composed of calcium carbonate. It is used in the Solvay process as a source of calcium ions (Ca2+) and carbon dioxide (CO2). The calcium ions react with the sodium carbonate to form calcium carbonate precipitate, while the carbon dioxide is recycled in the process.
  3. Ammonia (NH3): Ammonia is an essential raw material in the Solvay process. It is used as a reactant and a catalyst in the production of sodium carbonate. Ammonia reacts with carbon dioxide and water to form ammonium bicarbonate, which further reacts with sodium chloride to produce sodium bicarbonate. The sodium bicarbonate is then converted into sodium carbonate by heating.
  4. Water (H2O): Water is used in various stages of the Solvay process, including the dissolution of sodium chloride, the reaction with ammonia to form ammonium bicarbonate, and the conversion of sodium bicarbonate to sodium carbonate.

These raw materials, along with the necessary heat and the Solvay process itself, enable the production of soda ash, which has numerous industrial applications in the manufacturing of glass, detergents, chemicals, and other products.

Importance of Solvay Process

The solvay process was developed in the 1860s by Ernest Solvay and has since become one of the most important industrial processes for the production of sodium carbonate.

Here are some reasons, why the Solvay process is considered important.

  1. Sodium carbonate production: The Solvay process is the primary method for producing sodium carbonate on a large scale. Sodium carbonate is widely used in industries such as glass manufacturing, paper production, detergent manufacturing, and chemical synthesis. It is a crucial raw material for these industries and serves as a precursor for the production of other chemicals.
  2. Cost-effectiveness: The Solvay process is known for its cost-effectiveness compared to alternative methods of sodium carbonate production. It utilizes readily available raw materials such as limestone (calcium carbonate) and brine (sodium chloride solution). The process operates at high efficiency, enabling large-scale production at a relatively low cost.
  3. Environmental impact: The Solvay process has certain advantages in terms of environmental impact compared to alternative methods. It produces sodium carbonate without generating substantial amounts of waste or harmful byproducts. Additionally, the process can be designed to recover and reuse chemicals, minimizing its overall environmental footprint.
  4. Energy efficiency: The Solvay process is energy-efficient, particularly when combined with modern technologies and process optimizations. By recycling and reusing certain chemicals and optimizing reaction conditions, energy consumption can be reduced. This efficiency is crucial in large-scale industrial operations, where energy costs are significant.
  5. Historical significance: The development of the Solvay process marked a significant advancement in the chemical industry. It revolutionized the production of sodium carbonate, which was previously obtained from natural sources like trona deposits. The Solvay process enabled the large-scale production of sodium carbonate, leading to its widespread availability and utilization in various industries.

The Solvay process’s importance lies in its role as a cost-effective and environmentally friendly method for producing sodium carbonate, a vital chemical used in numerous industrial applications.

Its historical significance and continued use in modern industrial operations highlight its enduring importance in the chemical industry.

Some important reaction,

(1) CO2 used in step 1 is produced through heating CaCO3 as,

CaCO3 – ∆ – CaO + CO2.

(2) Ammonia is recovered back from NH4Cl of step 2 as,

CaO + H2O – Ca(OH)2

2NH4Cl + Ca(OH) – CaCl + 2NH3 + 2H2O.

Properties of Solvay Process

Solvay process, also known as the Ammonia-soda process.

It is a method for the production of sodium carbonate (soda ash) and other chemicals such as,

Sodium bicarbonate (baking soda).

Here are some key properties and characteristics of the Solvay process:

  1. Raw Materials: The Solvay process requires three main raw materials: sodium chloride (salt), limestone (calcium carbonate), and ammonia. These materials are abundant and readily available.
  2. Reaction Steps: The Solvay process involves several chemical reactions that take place in a series of interconnected vessels or stages:a. Formation of Ammonia Solution: Ammonia gas (NH₃) reacts with water to form aqueous ammonia (NH₄OH).b. Sodium Hydrogen Carbonate Formation: Carbon dioxide (CO₂) is passed through the ammonia solution, resulting in the formation of sodium hydrogen carbonate (NaHCO₃).c. Sodium Carbonate Formation: The sodium hydrogen carbonate is then heated to produce sodium carbonate (Na₂CO₃), carbon dioxide, and water.d. Lime Recovery: The spent or used-up ammonia is regenerated by treating it with lime (calcium hydroxide, Ca(OH)₂), which produces calcium carbonate (CaCO₃) and water.e. Calcium Oxide Regeneration: The calcium carbonate is then heated to high temperatures, leading to the formation of calcium oxide (CaO) and carbon dioxide. The calcium oxide is recycled back to the lime recovery stage.
  3. Continuous Process: The Solvay process is typically operated as a continuous process, where fresh raw materials are continuously fed into the system, and the products are continuously removed. This allows for a consistent production of sodium carbonate.
  4. Energy Efficiency: The Solvay process is energy-efficient compared to older methods of sodium carbonate production. The reactions occur at moderate temperatures, and the heat generated during certain stages can be utilized in subsequent steps.
  5. Environmental Impact: The Solvay process has some environmental considerations. It produces carbon dioxide (CO₂) as a byproduct, which is a greenhouse gas contributing to climate change. Efforts are being made to capture and mitigate CO₂ emissions in Solvay plants.
  6. Versatility: Besides sodium carbonate, the Solvay process can also produce other important chemicals. By controlling the reaction conditions, sodium bicarbonate (NaHCO₃) can be obtained instead of sodium carbonate.
  7. Global Importance: The Solvay process is one of the most widely used methods for sodium carbonate production worldwide. It has played a significant role in various industries, including glass manufacturing, detergent production, papermaking, and chemical synthesis.

It’s important to note that while these properties generally apply to the Solvay process, specific details may vary depending on the plant design, technological advancements, and environmental considerations implemented in different production facilities.

Crystallizes as decahydrate

Na2CO3.10H2O – Na2CO3 . H2O + 9H2O ∆ – Na2CO3 – NO decomposition.

For example,

Fusion mixture – Na2CO3 + K2CO3 mixture – two carbonate are thermally stable in nature.

Solvay Process Application

The Solvay process, also known as the ammonia-soda process.

It is a chemical method for the production of sodium carbonate (soda ash) from sodium chloride, ammonia, and carbon dioxide.

It has several applications in various industries.

Here are some of the key applications of the Solvay process:

  1. Glass Manufacturing: Sodium carbonate is a vital ingredient in the glass industry. It is used as a flux to lower the melting point of the silica in glass manufacturing, making it easier to shape and mold glass products. The Solvay process provides a cost-effective and efficient method for producing sodium carbonate, which is essential for glass production.
  2. Detergents and Soaps: Sodium carbonate, or soda ash, is widely used in the production of detergents and soaps. It acts as a water softener and pH regulator in these products, enhancing their cleaning efficiency. The Solvay process ensures a reliable and continuous supply of sodium carbonate for the detergent industry.
  3. Paper Manufacturing: Sodium carbonate is utilized in the paper industry as a pH adjuster and sizing agent. It helps control the acidity of the pulp during papermaking, improving the quality and strength of the paper. The Solvay process provides a consistent source of sodium carbonate for paper mills.
  4. Water Treatment: Sodium carbonate is employed in water treatment processes to control pH levels and remove impurities. It is particularly useful in neutralizing acidic water and treating wastewater. The Solvay process enables the production of sodium carbonate on a large scale, ensuring its availability for water treatment applications.
  5. Chemical Manufacturing: Sodium carbonate serves as a raw material or chemical reagent in various chemical manufacturing processes. It is used in the production of sodium bicarbonate, sodium silicates, sodium phosphates, and other chemical compounds. The Solvay process plays a crucial role in the synthesis of these chemicals, providing a fundamental starting material.
  6. Food and Beverage Industry: Sodium carbonate is approved for use as a food additive and is commonly employed in the food and beverage industry. It can act as a leavening agent in baking, adjusting the pH in certain food products, and enhancing the stability of canned foods. The Solvay process ensures a consistent supply of sodium carbonate for these applications.

Other Uses

1) Long used to manufacturing of sodium bicarbonate and sodium carbonate.

2) This is industrial process in which chemicals required for cleaning formulations,

3) And many other applications.

4) Limestone is widely used in Architectural applications for walls.

5) Decorative trim and veneer


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