Limestone firing technology for lime production
Limestone, as a widely distributed mineral resource on Earth, is not only an important raw material in the construction industry, but also plays a crucial role in multiple fields such as chemical engineering, environmental protection, and metallurgy. The technology of firing limestone into lime has become a mature and important industrial technology after thousands of years of development.
1、 The traditional process of firing limestone into lime
The traditional process of producing lime from limestone mainly includes two processes: calcination and digestion. Calcination is the process of decomposing limestone under high temperature conditions to produce quicklime and carbon dioxide; Digestion is the process of reacting quicklime with water to produce mature lime. These two processes are interrelated and together constitute the core technology of limestone calcination.
Calcination process
The calcination process is usually carried out in a lime kiln. There are various types of lime kilns, including vertical lime kilns, rotary kilns, and annular sleeve kilns. Among them, vertical lime kiln is the most common type. In a vertical lime kiln, limestone is mixed with coke or white coal in a certain proportion and added from the top of the kiln. After three stages of preheating, calcination, and cooling, quicklime is finally generated. During the calcination process, limestone decomposes at high temperatures, producing a large amount of carbon dioxide gas (i.e. kiln gas), while also producing quicklime.
Digestive process
The digestion process involves reacting calcined quicklime with water to produce mature lime. This process is usually carried out in the ash bin. After adding quicklime to the ash tank, add an appropriate amount of water for digestion. During the digestion process, quicklime reacts with water to form calcium hydroxide (i.e. hydrated lime) and releases a large amount of heat. The digested hydrated lime can be used in various fields such as construction, chemical industry, and environmental protection.
2、 Characteristics of Limestone Burning Technology
High temperature calcination
The calcination of limestone needs to be carried out under high temperature conditions, usually reaching a calcination temperature of over 1000 ℃. High temperature calcination can ensure full decomposition of limestone, improve the yield and quality of quicklime.
Heat recovery
During the calcination process, the carbon dioxide gas (i.e. kiln gas) produced by the decomposition of limestone has a high amount of heat. By recycling and utilizing this heat, energy consumption can be reduced and energy utilization efficiency can be improved.
Digestive reactions
The digestion process is the process of reacting quicklime with water to produce mature lime. This process is an exothermic reaction, and the heat generated can be used to maintain the temperature inside the ash bin and promote the digestion reaction.
Product diversity
The products of limestone calcination include quicklime and hydrated lime. Quicklime is an alkaline substance with strong water absorption properties; Hydrated lime is a white powdery substance with strong viscosity and alkalinity. These two products have wide applications in fields such as construction, chemical engineering, and environmental protection.
3、 The Application of Limestone Burning Limestone in Modern Industry
construction industry
Hydrated lime has a wide range of applications in the construction industry. It can be used for masonry mortar, plastering, ground treatment, and other aspects. The viscosity and alkalinity of hydrated lime give it good adhesion and water resistance, which can improve the quality and service life of buildings. Chemical industry
Quicklime and hydrated lime are also widely used in the chemical industry. Quicklime can be used to manufacture chemical products such as calcium carbide and alumina; Hydrated lime can be used to manufacture bleaching agents, water treatment agents, etc.
Environmental protection industry
In the environmental protection industry, limestone fired lime technology is widely used in areas such as flue gas desulfurization and wastewater treatment. Hydrated lime can react with sulfur dioxide in flue gas to form calcium sulfate precipitate, thereby achieving flue gas desulfurization; Meanwhile, hydrated lime can also be used to neutralize acidic wastewater and reduce its acidity.
Limestone firing technology is a mature and important industrial technology. Limestone can be converted into valuable products such as quicklime and hydrated lime through processes such as high-temperature calcination and digestion reactions. These products have extensive applications in various fields such as construction, chemical engineering, and environmental protection. In the future, with the continuous progress of technology and the continuous development of industry, the technology of limestone fired lime will continue to play an important role.
