Rotary kiln lime kiln calcination process for lime
The rotary kiln lime kiln calcination process is an important heat treatment technology widely used in metallurgy, chemical industry, and building materials industry. This technology uses high-temperature calcination of limestone to decompose it into calcium oxide (quicklime), thereby meeting the needs of different industrial fields. This article will elaborate on the process flow, technical characteristics, and applications of rotary kiln lime calcination in various industrial fields.
technological process
Raw material preparation
The first step in the calcination process of rotary kiln lime kiln is raw material preparation. Limestone, as the main raw material, needs to be crushed and screened according to design requirements to ensure uniform particle size and suitability for calcination in the kiln. The crushed limestone is transported to the material yard for stacking and sent to the top material bin of the preheater through equipment such as loaders and feeders.
Preheating process
Preheating is one of the key steps in the calcination process of rotary kiln lime kiln. When limestone passes through the preheater, it exchanges heat with the high-temperature flue gas from the rotary kiln, causing its temperature to rapidly rise to around 900 ℃. At the same time, about 30% of the limestone undergoes decomposition reaction. Preheaters usually adopt vertical preheaters, which are equipped with multiple heating chambers inside to evenly heat limestone and improve thermal efficiency.
Calcination process
The preheated limestone is pushed into the rotary kiln for high-temperature calcination. A rotary kiln is a cylindrical device that is tilted and slowly rotates, filled with limestone and fuel inside. Fuel is sprayed into the kiln through a burner for combustion, and the high temperature generated decomposes calcium carbonate in limestone, releasing carbon dioxide and producing calcium oxide (quicklime). During the calcination process, limestone rotates clockwise in the kiln for about 20-30 minutes, and the temperature inside the furnace is usually maintained at 1300-1450 degrees Celsius.
Cooling and Collection of Finished Products
After calcination, the quicklime is sent to a cooler for cooling. The cooler usually adopts a vertical cooler, which cools the quicklime to below the ambient temperature of+60 ℃ by blowing in cold air. The cooled lime is uniformly discharged by a vibrating feeder and transported to the finished lime warehouse through equipment such as chain plate conveyors, bucket elevators, and belt conveyors. The finished lime warehouse adopts a circular storage bin, with different sizes of storage bins set up according to customer needs, in order to load lime into cars and tank trucks for external transportation.
Technical features
Efficient and energy-saving
The rotary kiln lime kiln calcination process has the characteristics of high efficiency and energy saving. The rotary kiln with preheater and cooler has uniform heat transfer and belongs to the high-temperature rapid burning and rapid cooling roasting process, so the heat transfer efficiency is high and the hourly output is large. In addition, by fully utilizing the high-temperature flue gas generated by calcination in the rotary kiln to preheat limestone and recovering the waste heat in the cooler, the energy utilization efficiency has been further improved.
Stable product quality
The quality of lime products produced by the rotary kiln lime kiln calcination process is stable. Due to the uniform rolling and advancement of materials in the kiln, the heating is uniform and sufficient, and the heat transfer is rapid, resulting in stable product quality and low rates of overheating and overburning. At the same time, the thermal system inside the kiln is stable and can calcine high activity activated lime for steelmaking, meeting the high requirements for lime quality in industrial fields such as steelmaking.
High utilization rate of raw materials
The rotary kiln lime kiln calcination process can directly calcine fine-grained limestone no larger than 50mm, which is often difficult to utilize in other kiln types. By constructing a rotary kiln production line, the limestone mining resources can be fully utilized, the utilization rate of raw materials can be improved, and it is in line with the sustainable development policy of the lime industry. Environmental emissions
The rotary kiln lime kiln calcination process also has significant advantages in environmental protection. The kiln structure is simple, the airflow is smooth, and sulfur-containing flue gas can be discharged in a timely manner. The sulfur content in the fuel is not easily attached, so the product has a low sulfur content and meets environmental protection requirements. At the same time, the flue gas discharged from the preheater has a low temperature and low dust content, which facilitates the configuration of subsequent flue gas treatment equipment and meets environmental emission standards.
High degree of automation
The rotary kiln lime kiln calcination process has a high degree of automation, and all equipment can be centrally controlled. Through PLC or DCS control systems, operators can monitor and adjust various processes such as feeding, calcination, and product transportation in the central control room, ensuring smooth and orderly production. This not only improves production efficiency, but also reduces labor costs and intensity.
application area
The lime produced by the rotary kiln lime kiln calcination process is widely used in metallurgy, chemical industry, and building materials industry. In the metallurgical industry, lime is an indispensable auxiliary material in the steelmaking process, used to remove impurities and desulfurization from molten steel; In the chemical industry, lime can be used to produce chemical products such as soda ash and caustic soda; In the building materials industry, lime can be used to prepare building materials such as cement, glass, ceramics, etc.
The rotary kiln lime kiln calcination process is known for its high efficiency, energy saving, and environmental protection. Through preheating, calcination, cooling, and other steps, limestone is converted into high-quality quicklime. This process has a high degree of automation and stable product quality, and is widely used in fields such as metallurgy, chemical engineering, and building materials. Its unique advantage lies in the ability to fully utilize raw material resources, improve production efficiency, and reduce environmental pollution, which is an important direction for the development of the lime industry.
