steps of cement production process - flyer cement silo
Cement is one of the most common and important building materials. It is a very critical ingredient because only cement has the ability to increase the viscosity of concrete, which in turn provides the ability to lock sand and gravel together in concrete mixtures. But most of us may not know how cement is produced. Here are several simple steps that will help us understand the cement production process.
In cement production process, most of raw materials must be crushed, for example, limestone, clay, iron ore, coal, etc. In cement production, limestone is the main raw material whose amount is the largest in all the raw materials. After being mined, usually limestone is in large size and high hardness, it is necessary to crush it into small pieces in order to produce cement.
Pre-homogenization technology is the use of advanced stacking recovery technology in the process of raw material recycling to achieve homogenization of raw materials, so that the material field can have the function of storage and homogenization.
In the cement production process, each ton of portland cement requires the grinding of at least 3 tons of materials which include all kinds of raw materials (fuel, clinker, gypsum, mixture, etc.). According to statistics, for the dry cement production line, power consumed on the grinding takes more than 60% of the total power consumption, including more than 30% consumption used on raw material grinding and about 40% on cement powder grinding. Therefore, choosing reasonable grinding equipment and technology, optimizing process parameters, operating correctly and establishing a good operation control system are of great significance to ensure product quality and reduce energy consumption.
In the new dry process of cement production, the stability of raw material composition is the premise to ensure the stability of clinker sintering heat regulation. Raw material homogenizing system plays a final role in controlling the composition of stabilized kiln.
The length of rotary kiln can be shortened by using preheater instead of partial function of rotary kiln to preheat and partially decompose raw materials. When the air-material heat transfer process in the kiln occurs in a suspended state rather than in a stacking state, the air released in the kiln will be fully mixed with the raw material, and the contact area between the air and the material will be increased, so as to achieve high-speed heat transfer and efficient heat transfer. This improves the production efficiency of kiln system and reduces the heat consumption of clinker combustion.
When the air carrying powder enters the cyclone separator, it is forced to rotate in the annular space between the cyclone separator cylinder and the inner cylinder (exhaust flue). It rotates downward from the cylinder to the cone until the bottom of the cone, and is upturned and finally discharged from the exhaust passage.
Precalcining technology is a technological leap of cement calcining process. The calciner is innovatively set up between the preheater and rotary kiln with a newly added rising flue and a fuel injection device, which makes exothermic process of fuel combustion and endothermic process of carbonate calcining of raw materials quickly occur as a suspending or a fluid state in the calciner furnace. The calcining rate of raw materials can increase to 90%. The carbonate calcining moves from the rotary kiln to the calciner furnace, which reduces the heat load of the kiln, prolongs the life of the kiln lining and is conducive to large-scale production. Because the fuel and raw materials can mix evenly, fuel combustion heat can transfer to the materials timely, so that the combustion, heat transfer and carbonate calcining process are optimized. Thus it has a series of excellent characteristics of high quality, high efficiency, low power consumption, etc.
The rotary kiln is a huge rotating furnace as the heart of cement making process. Here, raw materials are heated up to 1450. This temperature begins a chemical reaction so called decarbonation. In this reaction materials (like limestone) release carbon dioxide. High temperature of the kiln makes slurry of the materials.
In the rotary kiln, carbonate is further decomposed rapidly with a series of solid phase reactions. With the materials temperature is up, other minerals in the materials will be dissolved into liquid phase, and generate a large amount of clinker. As cement clinker sinters, the temperature decreases, and then under the function of the cooling machine high temperature clinker will be cooled and discharge to storage.
There is a horizontal filled with steel balls. Clinker reaches in this rotating drum after cooling. Here, steel balls tumble and crush the clinker into a very fine powder. This fine powder is considered as cement. During grinding gypsum is also added to the mix in small percentage that controls the setting of cement.
Cement production plant has two methods of storing cement: bag or bulk. Cement is directly conveyed to the silos (silos are the large storage tanks of cement) from the grinding mills. Further, it is packed to about 20-40 kg bags. Only a small percent of cement is packed in the bags only for those customers whose need is very small. The remaining cement is stored in cement steel silo and waited to be transported in bulk by mean of trucks, rails or ships.
large cement plant design principles | agico cement machinery
With the continuous development of cement production technology, the production limit of cement plant is also increasing. Nowadays, cement plants with a clinker capacity of more than 5000 tons per day are gradually becoming the first choice of many cement manufacturers. As a cement plant designer and builder, AGICO has accumulated a lot of experience in large-scale cement plant construction projects, and developed 4 design principles more suitable for large cement plants.
When selecting the construction site for a cement plant, both raw material supply and marketing should be considered. In the past, the idea of putting a complete cement production line in the same plant site is gradually changing into the idea of building clinker and cement projects separately, that is, the clinker production line is built close to limestone quarry and the grinding station is built close to the target market.
To construct the clinker production line near the quarry reduces the transportation cost of raw materials and lowers the risk caused by the supply of raw materials. The clinker production line should also be built in the location with convenient transportation, such as places near the river or port, so that the clinker produced can be transported to grinding stations or exported by cheap waterway, which greatly reduces its transportation and sales costs and enhances its market competitiveness.
To construct the grinding station near the market allows the production to quickly adapt to market fluctuations. In addition, the grinding station near the sales market helps to establish a good brand image and makes customers feel your products are safe and reliable.
In the design of large cement plants, there are always pre homogenization yards for raw materials, especially for limestone. However, due to the large daily consumption of limestone in the large cement plant, the blasting time interval is greatly shortened in the mining process, and the limestone has been consciously matched in the mine production, which naturally includes homogenization. Therefore, in large cement plants, the storage function of the limestone pre homogenization yard weighs heavier than the pre homogenization function.
Large rotary kiln has strong adaptability to raw materials, and its sensitivity to homogenization is not as high as that of small rotary kiln. So the real function of limestone pre homogenization yard is to act as buffer between the limestone crushing system and the raw meal grinding system. In general, if the time of replacing a pair of hammers of the crusher is 1d, then 3d will be enough for the designed capacity of the pre homogenization yard.
In large cement plants, the long pre homogenization yard has more advantages because of its expandability. But its track width should be controlled within 40m, otherwise the rigidity of the reclaimer girder will face serious challenges. The number of stacking layers is not necessary to design as many as 400 layers, and the speed of stacker can be slowed a little, but the storage yard must be equipped with emergency access, which can be used in the maintenance of reclaimer.
Cement plants are usually designed with raw material grinding systems with low energy consumption, especially the vertical roller mill (VRM), which is the first choice for large cement plants. Due to the large power consumption of large cement plants, the use of vertical roller mill can obtain obvious power saving effect.
In the vertical roller mill system, no matter the electric dust collector or bag dust collector is used, there must be a cyclone to pre collect the dust containing gas from the mill, so as to reduce the load of the dust collector and improve the gas emission standard.
The technology of our calcination system is very mature and has reached the international advanced level. Moreover, the new generation of the calcination system is more adaptable to raw materials and fuels. In the past, it was considered that the calorific value of raw coal should be greater than 22990kj to meet the requirements of the precalciner kiln, but now it only needs 18810kj or even lower, which greatly reduces the cost of raw fuels.
Our low-temperature waste heat power generation technology without supplementary combustion is also very mature, which provides a good technical support for the energy-saving design of cement plants. In the past, the waste gas from the calcination system was directly discharged after humidification, cooling and dust collection, and the rest heat was not recycled. Now, the application of this technology can make the waste heat power generation of one ton of clinker reach 36 ~ 40kwh.
AGICO has always been trying to improve the design scheme of large-scale cement plant project, striving to build cement plants with reliable performance, advanced technology, energy conservation and environmental protection for clients.
brief introduction of cement production line
Cement production line is the cement plant consists of a series of cement production equipment. Cement production line is mainly composed of crushing and pre-homogenization, homogenization of raw materials preparation, preheating decomposition, firing of cement clinker, cement grinding and packaging process.
Most of raw materials need be crushed in the cement production process, such as limestone, clay, iron ore and coal. Limestone is the raw materials with the largest amount on the cement production. However, the mining limestone has large size and high hardness. Therefore, the crushing of limestone in the cement plant occupies a more important position.
Pre-homogenization means that using the scientific stacking and reclaiming technology realizes the preliminary homogenization in the process of raw materials access procedure. In this way, the raw material stacking plant owns functions of storage and homogenization.
Hongxing Machinery has specialized in production line manufacture for more than 30 years and Hongxing Machinery can design and provide customers with a series of process solutions. Nowadays stone production line, cement production line, magnetic separation production line, aggregate production line, sand production line and other production lines are all available in Hongxing Machinery. To make a further understanding of cement production line, welcome to consult us via [email protected]
cement plant optimization
Online training of cement industry professionals is our mission-1 to contribute in cement plant optimization, and towards our vision of carbon neutral cement manufacturing. Our online training courses have boosted hundreds of cement plant professionals to progress in their career across the globe. We have designed these training programs to align your knowledge and skills to enhance your capacity to identify and tap optimization opportunities in your plant. Our training programs are available online 24x7 .
We deliver onsite classroom training on the subjects like, procedure of plant audit and detailed process analysis with a preliminary pyro audit as a practical exercise to enable your plant team to use portable instruments to conduct a detailed process & energy audit of any section of your plant. Short term courses on subjects like, CCR operation, Mass and Heat balance, Raw mix design can be opted to include in audit training.
Our recommended offer includes AUDIT + AUDIT TRAINING, to conduct a detailed audit [Process + Energy] of your plant and train your engineers to conduct a complete plant audit at any time you want. In this way you get an internal audit team to start and follow plant optimization process.
It is fact that cement industry has seen a sea of developments in the area of production enhancement (from 50 tons/day/kiln to 10000 tons/day/kiln) and energy consumption (from 1400 kcal/kg-clinker to 670 kcal/kg-clinker) and 160 kwh/ton-cement to 70 kwh/ton-cement). However, we are still producing about 0.8 ton of CO2 for each ton of cement, and loosing 250-400 kcal of heat per kg-clinker produced and wasting a lot of electric energy in various inefficient ways. Therefore, a huge scope of improvement is always there for optimization cement plant.
Vision: To help cement industries towards low carbon [minimum CO2 Emission] cement manufacturing through energy optimization and capacity utilization.
Mission #1: Knowledge and skill development of cement plant professionals to make them self sufficient to identify optimization opportunities in cement plant operation.
Mission #2: Visualization of present performance level and road map to achieve potential performance through process and energy audit.
Mission #3: Incorporation of future forward technology to augment plant optimization process by empowering your employees with data on real time to take decisions in advance to avoid breakdowns. #Industry 4.0
We have collaboration with technology leaders like LEAN AUTOMATION for Industry 4.0 [for mission #3] to facilitate three pillars for cement plant optimization at one window. Technology is a great enabler for optimization, But we need to update continuously the knowledge and skill set of front line action takers through capacity development training. So that the cultural transformation will take place to embrace newer possibilities and overcome skepticism.
ppc cement manufacturing process - portland pozzolana cement plant | agico
What is Portland pozzolana cement? The hydraulic cementitious materials made of Portland cement clinker, pozzolanic material, and a proper amount of gypsum are all called Portland pozzolana cement (PPC cement). It is a kind of blended cement which is manufactured by mixing and fine-grinding silicate cement clinker, pozzolanic material, and gypsum.
Pozzolanic materials contain active silica and aluminum and usually do not have any cementitious properties. But when they are mixed with water and lime at ambient temperatures, they will react with calcium hydroxide to form compounds possessing cementitious properties. The commonly used pozzolanic materials can be classified as natural or artificial:
Portland pozzolana cement shall be manufactured by mixing and inter-grinding Portland cement clinker, pozzolanic materials, and gypsum. The manufacturing process is approximately the same as ordinary Portland cement, which can be divided into four processes: raw material crushing, raw material grinding, clinker calcination, and cement grinding.
Limestone and clay are the main material for Portland cement production. After mining, these raw material stones are unloaded by trucks and sent into crushers for reducing particle size. Then they are piled in a pre-homogenization yard waiting for processing.
Fine particle size raw materials are fed into the raw mill in a desired proportion for further particle size reduction, then they are stored in silos, meanwhile completing the material blending and homogenization process.
Cement raw meals are sent into a cement rotary kiln to be calcined under a high temperature. After several chemical reactions are produced, some spherical gray particles, what we called clinker, are formed. In cement cooler, these hot clinkers will be cooled to a normal temperature.
After cooling, the clinker is mixed with pozzolanic materials and gypsum in a required proportion and then sent to the cement mill for final grinding. The cement powder is usually stored in cement silos, then bagged and stored in the warehouse.
In the Portland pozzolana cement manufacturing process, we need a variety of cement equipment. AGICO, as a cement plant supplier in China, offers different cement solutions and cement manufacturing equipment.
Portland pozzolana cement, portland slag cement, and portland fly ash cement are all made by adding active admixture and an appropriate amount of gypsum based on Portland cement clinker. They are similar in nature and scope of application, so they can be used interchangeably in most cases. However, the physical properties and characteristics of the active admixture are different, which makes the three types of cement have their unique characteristics.
Slow setting and hardening, low early strength, and high late strength. The clinker content of the three kinds of cement is small, and the secondary hydration reaction is slow, while their later strength exceeds the ordinary Portland cement of the same grade.
Sensitive to temperature and humidity, suitable for high-temperature curing. When the three types of cement are cured at high temperatures, the hydration of the active mixture and clinker will be accelerated, and the early strength is improved without affecting the development of the later strength. Ordinary Portland cement, although the use of high-temperature curing can improve the early strength, the development of later strength will be affected.
Good corrosion resistance. They have good corrosion resistance and are suitable for the environment containing sulfate, magnesium salt, soft water, etc. However, when the corrosion resistance requirements are high, it is not suitable for the application.
Poor frost resistance. Slag and fly ash are easy to bleed to form connected pores. As to pozzolana, it has a large water storage capacity, which will increase the internal pore number. Therefore, the frost resistance of the three types of cement is poor.
Composite Portland cement: the early strength of composite Portland cement is higher than slag (or pozzolana, fly ash) cement, closes to ordinary Portland cement. It has low hydration heat, good corrosion resistance, impermeability, and frost resistance.
AGICO Group is an integrative enterprise group. It is a Chinese company that specialized in manufacturing and exporting cement plants and cement equipment, providing the turnkey project from project design, equipment installation and equipment commissioning to equipment maintenance.
cement manufacturing process | phases | flow chart | cement | engineering intro
Cement is the basic ingredient of construction and the most widely used construction material. It is a very critical ingredient, because only cement has the ability of enhancing viscosity of concrete which in returns provides the better locking of sand and gravels together in a concrete mix.
Cement uses raw materials that cover calcium, silicon, iron and aluminum. Such raw materials are limestone, clay and sand. Limestone is for calcium. It is combined with much smaller proportions of sand and clay. Sand & clay fulfill the need of silicon, iron and aluminum.
Generally cement plants are fixed where the quarry of limestone is near bye. This saves the extra fuel cost and makes cement somehow economical. Raw materials are extracted from the quarry and by means of conveyor belt material is transported to the cement plant.
There are also various other raw materials used for cement manufacturing. For example shale, fly ash, mill scale and bauxite. These raw materials are directly brought from other sources because of small requirements.
Before transportation of raw materials to the cement plant, large size rocks are crushed into smaller size rocks with the help of crusher at quarry. Crusher reduces the size of large rocks to the size of gravels.
The raw materials from quarry are now routed in plant laboratory where, they are analyzed and proper proportioning of limestone and clay are making possible before the beginning of grinding. Generally, limestone is 80% and remaining 20% is the clay.
Now cement plant grind the raw mix with the help of heavy wheel type rollers and rotating table. Rotating table rotates continuously under the roller and brought the raw mix in contact with the roller. Roller crushes the material to a fine powder and finishes the job. Raw mix is stored in a pre-homogenization pile after grinding raw mix to fine powder.
After final grinding, the material is ready to face the pre-heating chamber. Pre-heater chamber consists of series of vertical cyclone from where the raw material passes before facing the kiln. Pre-heating chamber utilizes the emitting hot gases from kiln. Pre-heating of the material saves the energy and make plant environmental friendly.
Kiln is a huge rotating furnace also called as the heart of cement making process. Here, raw material is heated up to 1450 C. This temperature begins a chemical reaction so called decarbonation. In this reaction material (like limestone) releases the carbon dioxide. High temperature of kiln makes slurry of the material.
The series of chemical reactions between calcium and silicon dioxide compounds form the primary constituents of cement i.e., calcium silicate. Kiln is heating up from the exit side by the use of natural gas and coal. When material reaches the lower part of the kiln, it forms the shape of clinker.
After passing out from the kiln, clinkers are cooled by mean of forced air. Clinker released the absorb heat and cool down to lower temperature. Released heat by clinker is reused by recirculating it back to the kiln. This too saves energy.
Final process of 5th phase is the final grinding. There is a horizontal filled with steel balls. Clinker reach in this rotating drum after cooling. Here, steel balls tumble and crush the clinker into a very fine powder. This fine powder is considered as cement. During grinding gypsum is also added to the mix in small percentage that controls the setting of cement.
Material is directly conveyed to the silos (silos are the large storage tanks of cement) from the grinding mills. Further, it is packed to about 20-40 kg bags. Only a small percent of cement is packed in the bags only for those customers whom need is very small. The remaining cement is shipped in bulk quantities by mean of trucks, rails or ships.
Widely used in highways, utilities, construction and other industries washing, grading, cleaning, as well as fine-grained and coarse-grained materials processing and other operations, the construction and gravel roads are particularly suitable. We feel proud to present ourselves as the well renowned importer and exporter of different Optimum Quality Engineering Equipments. Each and every product, forming part of our exquisite collection, has to go through different stringent quality checks so as to ensure that only finest quality product ultimately reaches the market.
control in cement production - sciencedirect
The paper deals with control in the cement manufacturing. A short description of the technology is given first, then the control problems and applied strategies are discussed. After a short summary of the existing control systems technology the possible applications of advanced control algorithms are treated.