How does calcium oxide manufacturing process occurs

Calcium oxide manufacturing process is a chemical process to produce calcium oxide. Calcium oxide is widely used in the production of various building materials such as Portland cement, water glass, and concrete. The main raw material required for producing calcium oxide is limestone. The steps involved in the manufacturing process are as follows:

1. Pre-heating of limestone and lime to 700-800C

This is done using the kiln. After reaching the required temperature, limestone and lime are mixed into a homogeneous mixture. Calcium oxide is produced by the reaction of limestone and lime through exothermic heat generated by high temperatures in a kiln.

2. Cooling down of slag

Slag formation is one of the problems encountered for calcium oxide production from limestone in large quantities. Slag formation separates CaO from Ca(OH)₂ after reaching temperatures of around 900℃ in the kiln, thus making it difficult to obtain CaO at low cost. This problem can be solved by adding aluminum or iron oxide to react with calcium hydroxide (Ca(OH)₂). Slag formation is reduced by increasing the lime-to-limestone ratio and decreasing the oxidant concentration.

3. Cooling down of slag and limestone mix

The deposit of slag and limestone which is at a temperature of around 900℃ is cooled down to around 350℃ in a cyclone where water sprinklers are used. At this stage, iron oxide reacts with calcium oxide to produce iron oxide (Fe₂O₃) with calcium hydroxide (Ca(OH)₂). The solution is then filtered by using vesicular diatomaceous earth filter cake. The filtrate is at a temperature below 90℃and taken out of the cyclone. The filtrate is sprayed onto the limestone and mixed. The mixture is then cooked in the kiln at temperatures of 700-850℃ to produce calcium oxide.

4. Post-heating of limestone and slag mix

The product of calcium oxide production is calcium hydroxide which changes into Ca(OH)₂ during heating in a pyrometer based calorimeter. The heating process takes place within the kiln where uniformity checks are done for both temperature and time to reach a certain temperature or for a certain time period as well as consistency. This entire process can take up to 3 days depending on how much limestone is used and how many times the product has been cooked in the kiln.

5. Cooling down of product

The final product is cooled down in the air to room temperatures. In order for the product to dry, it is spread over a flat area without any type of moisture. Once dried, it is passed through the sieve machine where it is crushed into powder form. This process can take up to a day and then prepared for transportation. This is the final step in calcium oxide manufacturing process.

Uses of calcium oxide

1. It is used in the production of Portland cement 

Portland cement is a widely used material in the production of concrete which is an essential part of buildings and other engineering constructions. Calcium oxide helps with creating strong, firm and hard cement paste.

2. It is used in the glass making industry

Calcium oxide is also widely used in manufacturing glass by reacting with silicon dioxide. The reaction between calcium oxide and silicon dioxide produces lime silicates which are responsible for giving glasses their strength, durability and transparency. It is also used as a flux for melting metallic ores for metals such as Zinc, Iron Copper and Aluminium.

3. It is used in the production of concrete

Calcium oxide is used in making concrete. It reacts with silicates such as alumina and silicates to form calcium hydroxide which is a strong binders for Portland cement. The resulting mixture (calcium hydroxide, lime and limestone) is then mixed with water to produce concrete, cement and lime plaster. Calcium oxide has been found to be an effective treatment for the degradation of Portland cement when exposed to sunlight. This problem is solved by using it in large quantities as an additive for Portland cement.

4. It is used in manufacturing water glass

Water glass or silicic acid is made by the reaction between calcium oxide, water and nitric acid. These are added in a specific ratio to form the desired product. The reaction between the compounds produces corrosive fumes which are dangerous to human life and should be handled with care. The water glass can be used to etch metal surfaces giving them a higher quality finish.

In conclusions, calcium oxide manufacturing process is a chemical process to produce calcium oxide. Calcium oxide is widely used in the production of various building materials such as Portland cement, water glass, and concrete. The main raw material required for producing calcium oxide is limestone. The steps involved in the manufacturing process are as follows: Pre-heating of limestone and lime to 700-800℃ Cooling down of slag Cooling down of slag and limestone mix Cooling down of product Post-heating of limestone and slag mix.