Contemporary methods of manufacturing cement can be divided into two ways: dry-process cement production and wet-process cement production. The latter measure has been widely utilized in the cement industry; it is a common manufacturing method in which fuel and power consumption have been reduced to a larger extent. This paper mainly discusses the general steps during the whole production process.
1. Crushing and Prehomogenization
To turn the solid raw materials into a slurry-like substance, most of the raw materials must be crushed first, such as limestone, iron ore, coal, etc. Among them, limestone is the largest raw material used in cement production. After mining, the particle size is larger and the hardness is higher. Therefore, the crushing of limestone plays an important role in the material crushing of cement manufacturing plants. Meanwhile, the prehomogenization technology is to use scientific stacking and retrieval technology to achieve preliminary homogenization of raw materials during the storage and retrieval process of raw materials, so that the raw material yard has the functions of storage and homogenization at the same time.
2. Preparation of Raw Materials
Raw materials have been regarded as the beneficial part of cement production, in this setting, the relevant preparation is also significant. In the cement production process, at least 3 tons of materials (including various raw materials, fuels, clinkers, mixtures, and gypsum) must be ground for every ton of Portland cement produced. According to statistics, the dry cement production line grinding operation consumes Power accounts for more than 60% of the power of the whole plant, of which raw material grinding accounts for more than 30%, coal grinding accounts for about 3%, and cement grinding station account for about 40%. Therefore, cement production equipment and cement production process flow should be rationally selected to optimize process parameters, correct operation, and control of operating systems are of great significance to ensuring product quality and reducing energy consumption.
3. Preheating and Decomposition
The preheating and partial decomposition of the raw meal is completed by the cyclone preheater, replacing part of the function of the rotary kiln to shorten the length of the return kiln. At the same time, the heat exchange process of gas and material is carried out in the piled state in the kiln, and moved to the suspended state inside the preheater. It is carried out at a lower speed, so that the raw material can be fully mixed with the hot gas discharged from the kiln, which increases the contact area of the gas and material, the heat transfer speed is fast, and the heat exchange efficiency is high, thereby improving the production efficiency of the kiln system and reducing the heat consumption of clinker firing purpose.
4. Calcination of cement clinker
After the raw meal is preheated and pre-decomposed in the cyclone preheater, it then enters the rotary kiln for clinker firing. In the rotary kiln, the carbonate further rapidly decomposes and undergoes a series of solid phase reactions to generate minerals such as cement clinker. As the temperature of the material increases, the minerals will turn into a liquid phase, and the minerals dissolved in the liquid phase will react to form a large amount of (clinker). After the clinker is fired, the temperature begins to decrease. Finally, the cement clinker cooler cools the high-temperature clinker discharged from the rotary kiln to a temperature that the downstream transportation, storage and cement machinery can withstand. At the same time, the sensible heat of the high-temperature clinker is recovered to improve the thermal efficiency of the system and clinker quality.
5. Powder Grinding
Cement machinery is the final process of cement manufacturing and the process that consumes the highest power. Its main function is to grind cement clinker (and gelling agent, performance adjustment materials, etc.) to the appropriate particle size (expressed in terms of fineness, specific surface area, etc.) to form a certain particle gradation and increase its hydration area. Accelerate the hydration rate and meet the cement slurry setting and hardening requirements.
Dry process of cement production vs wet process of cement production
Dry process of cement production
The raw materials are dried and ground at the same time, or the raw materials are first dried and ground into raw meal powder and then fed into the dry kiln to be calcined into clinker. However, there is also a method of adding raw meal powder to an appropriate amount of water to make raw meal balls and sending them to the Liboer kiln to calcine the clinker. This is called the semi-dry method, which is still a type of dry production.
The new dry process cement production line refers to cement produced using a new process of decomposition outside the kiln. Its production is based on suspension preheater and external kiln decomposition technology, using new raw materials, fuel homogenization and energy-saving grinding technology and equipment, and using computer distributed control throughout the entire line to achieve automation of the cement production process and high efficiency, high quality, low consumption and environmental protection. .
Advantages: rapid heat transfer, high thermal efficiency, larger output per unit volume than wet cement, and low heat consumption (for example, the heat consumption of clinker in a dry kiln with a preheater is 3140-3768 J/kg). The disadvantages are that The material composition is not easy to be uniform, the dust in the workshop is large, and the power consumption is high.
Wet process of cement production
The raw materials are ground into raw slurry by adding water and powder, and then fed into the wet kiln to calcine the clinker. There is also a method in which the raw meal slurry prepared by the wet method is dehydrated and then made into raw meal blocks and burned into clinker in a kiln. This is called the semi-wet method, which is still a type of wet production.
Advantages: Wet production has the advantages of simple operation, easy control of raw material ingredients, good product quality, convenient slurry transportation, and less dust in the workshop. The disadvantage is high heat consumption (clinker heat consumption is usually 5234-6490 J/kg).
Through the above professional manufacturing we finally complete the wet process of producing cement. Our company has decades of experience in manufacturing cement and is proficient in the production of dry and wet cement. Contact us to perfect your business.
