Produced from limestone, quicklime is one of the most important materials that is used in metallurgy, construction, wastewater treatment, chemical manufacturing, etc. Despite being a centuries-old material, modern quick lime manufacturing is a carefully controlled industrial operation governed by chemical principles, energy efficiency considerations, and quality standards. To make the best use of it as well as understand why it is used so much across industries, one needs to know about the process of quicklime production.

Quick Lime Manufacturing Process

In India, limestone is found in the highest amount in Rajasthan, making the state the hub of its conversion into quick lime. The manufacturing of quick lime for industrial use follows a process regulated by standards such as ASTM C51, EN 459, and BIS IS 1540. These standards define the chemical composition, reactivity, and physical properties that the quick lime produced by quick lime manufacturers in Rajasthan should take care of. 

The following are the steps followed in the entire process of quick lime manufacturing:

1. Drying and Grinding of Limestone

The process of quick lime production begins with ensuring that the lime being used is prepared to ensure uniform heat transfer and chemical conversion. This first step, drying and size reduction through grinding, helps by improving calcination efficiency and reducing fuel consumption. This step helps reduce energy losses and improve kiln throughput.

This stage typically involves:

• Drying the lime to remove surface and absorbed moisture
• Crushing the limestone into smaller fractions
• Screening to eliminate fines and oversized material
• Temporary storage to ensure feed quality

2. Calcination

The second step in the science behind lime manufactured into quicklime involves calcination. It is the central chemical process in quick lime manufacturing and involves heating the limestone, after drying and heating, in kilns at temperatures ranging from 900°C to 1,200°C. 

The optimal temperature to maintain depends on the kiln design and limestone purity. Incorrect measurements can harm the overall quicklime production process. If the temperature is too low, limestone remains partially unreacted. Additionally, if the temperature is too high, the lime becomes dead-burnt, and its reactivity is reduced.

To make the limestone undergo calcination, the common kiln types used industrially are:

• Rotary kilns
• Vertical shaft kilns (VSK)
• Regenerative kilns (PFR kilns)

3. Purification and Classification

After the second step, i.e., calcination, is completed, the quick lime must be cooled, cleaned, and classified, which forms the third step of the process. As quick lime manufactured is used by different industries, purification ensures compliance with the chemical and physical specifications required by each, making it a step that demands accuracy and attention.

Improper cooling proves to be a frequent challenge that can affect the product’s quality. This is because exposure to atmospheric moisture can partially hydrate quick lime before packaging, harming the efficiency of this entire step.  

The procedure of this step includes:

• Controlled cooling to prevent air slaking
• Magnetic separation to remove metallic contaminants
• Screening into lump, pebble, or granular forms
• Sampling and laboratory testing to check the CaO content and reactivity

Properties of Quick Lime

Quick lime is a highly alkaline, reactive material with distinct physical and chemical characteristics. Its physical and chemical properties determine how it behaves in storage, transport, and end-use applications. Other than the manufacturer, the buyer of quick lime should understand these properties to select the right material for themselves.

The key properties of quick lime are:

• Has high calcium oxide (CaO) content, typically 85–95% depending on grade
• Has strong alkalinity with a pH above 12 when reacting with water
• Shows exothermic hydration behavior
• It has a hygroscopic nature, readily absorbing moisture from the air
• Shows low solubility in water but high chemical reactivity

Applications of Quick Lime

You already know that quick lime is used across different industries. However, the reason that you don’t know about it involves its alkalinity, reactivity, and ability to bind impurities. The major applications of quick lime across different sectors include:

• Helps in impurity removal and formation of slag in the steel and metallurgy sector.
• Helps in the stabilization of soil and asphalt modification during construciton.
• Used in pH control and softening during treatment of water and wastewater.
• Used as an intermediate for calcium-based compounds during chemical manufacturing.

Conclusion

The manufacturing of quick lime is a technically complex process that requires accuracy on every step. While the chemistry of this process seems straightforward, the practical production demands careful control of temperature, quality of the raw material being used, as well as handling. Even for a buyer, understanding this process is important to select, use, and manage quick lime more effectively and safely.

To fulfill your need for quicklime, we at Rajasthan Lime stand as one of the best manufacturers and providers of the material in Rajasthan for the last 40 years. Contact us now and benefit from our top-quality quick lime, delivered quickly and in line with your requirements.

FAQs

Q. What is the raw material of quicklime?

The raw material for quick lime is limestone or calcium carbonate, which is heated to remove carbon dioxide from it, and after a long process, forms quick lime, which consists of calcium and oxygen. 

Q. What happens when limestone is calcined?

When limestone is calcined in a kiln, the heat it undergoes converts the mineral into quicklime, releasing carbon dioxide.

Q. What is another name for quick lime?

Quick lime is commonly also called calcium oxide (CaO) or burnt lime because it is produced by heating limestone.