Quicklime, also known as lime, is produced by calcining natural calcium carbonate rocks at an appropriate temperature to eliminate the released carbon dioxide, resulting in a product primarily composed of calcium oxide. There are various types of natural calcium carbonate rocks, with limestone, chalk, and marl being the main ones used.
There are many kinds of equipment used in the lime production line and the production line structure is complex. The following introduces the work flow of the lime production line and the equipment that may be used in each process for your reference.
In the preparation of quicklime, the general process involves crushing and processing the limestone into particles, followed by limestone calcination. The main equipment used in quicklime plant includes a vibrating feeder, jaw crusher, belt conveyor, preheater, vertical lime kiln (or rotary kiln), and cooler.
All equipment configuration of the lime processing plant is decided by the lime manufacturing process you choose, so it’s important to introduce it first. The lime manufacturing processing steps can be summarized as follows: Initially, the coarse crushing process is performed using a jaw crusher to break down large limestone pieces into smaller limestone particles. Subsequently, the processed limestone is fed into a rotary kiln for calcination, resulting in the production of quicklime.
As we mentioned before, the lime manufacturing process can be generally divided into the following steps:
- Raw material preparation
- Lime calcination
- Lime grinding
- Lime conveying
Lime calcination equipment
The lime kiln is definitely the core equipment of the lime processing plant, and the calcination section is the most important section among all steps of the lime production line. Limestone and other rocks must be calcined into lime with certain activity in a lime kiln. How many types of lime kilns can we choose from? the answer is two, rotary lime kilns and vertical lime kilns are two types of lime kilns used in lime manufacturing plant.
Rotary lime kiln
When limestone particles enter the rotary kiln but haven’t yet reached the high-temperature zone where they come into contact with the flame, the decomposition continues due to the convective heat transfer from the waste gas heat. This stage is essentially the theoretical material decomposition phase.
After the preheated limestone particles come into contact with the flame and before they pass through the entire flame radiation zone within the rotary kiln, they undergo intense chemical reactions and are ultimately converted into lime under the high-temperature conditions of the flame. This process (stage) is generally completed within 30 to 40 minutes.
In a rotary kiln with a vertical preheater, the burning zone is usually located around 10 meters from the kiln discharge end and extends about 20 to 25 meters into the kiln (toward the feed end). The flame length is typically distributed within this area. This area is commonly referred to as the “burning zone.”
Vertical lime kiln
The vertical lime kiln is well-suited for lime production lines with modest capacities, offering affordability, safety, and environmental friendliness. It operates based on the principle of material descent due to its weight and the ascent of hot gas for heat exchange, facilitating the lime-burning process. Our selection includes twin shaft lime kilns, double beam lime kilns, annular lime kilns, and various other vertical lime kiln models.
Crushing Equipment
Some lime kilns require limestone with a particle size less than 40mm. Therefore, we need to first crush the limestone material to below 40mm and then perform screening. Limestone particles that do not meet the required particle size are sent to the crushing equipment for re-crushing, while the qualified ones are sent to the next stage. If the limestone meets the required purity, the qualified particles are directly sent to the raw material storage room. If the purity is not up to standard, they are cleaned to the required level using a sand washing machine and then sent to the raw material storage silo.
The main equipment used in this stage includes a jaw crusher, impact crusher (or cone crusher, either one of the two), circular vibrating screen, belt conveyor, sand washing machine, and storage silo.
Grinding Equipment
Lime grinding equipment is an important machine that determines the fineness of lime powder. For producing 200 mesh and 325 mesh commonly used lime powder, one of the main machine configurations for the grinding process is either the vertical lime grinding mill or the Raymond mill (pendulum grinding mill).
The Raymond mill has lower investment but requires frequent replacement of wear-resistant parts. The vertical lime grinding mill has higher investment, larger production capacity, longer lifespan for wear-resistant parts, and simpler replacement.
cooling equipment
After high-temperature lime particles enter the cooler, they undergo heat dissipation and transfer through the penetration of secondary air. They are forcibly cooled to below 100°C. The cooling process of lime clinker in the cooler is typically completed in about 40 minutes, with the main objective being to achieve the desired rapid cooling characteristic of active lime.
Common cooling equipment used in lime processing plants includes grate coolers, vertical coolers, etc.
conveying equipment
Conveying equipment is a necessary part of the lime processing plant, such as belt conveyors, bucket elevators, screw conveyors, silo, and etc. these conveying equipment is required in raw material preparation, limestone crushing, lime grinding and finished production sections. For example, after being cooled, the finished lime is transported from the cooling process to the lime storage silo using conveying equipment such as conveyor belts and bucket elevators. The equipment utilized in this process includes belt conveyors, bucket elevators, and storage silos.
Auxiliary equipment
Except for these steps, there is some auxiliary equipment required in the lime processing plant, such as baghouse dust collector, cyclone preheater, separator, fan, feeder, etc.
AGICO CEMENT is a lime calcination plant manufacturer, we offer solutions for lime processing plants, and we also supply all equipment and related parts used in lime processing plants, if you have any need, feel free to contact us!
