outline the steps of manufacturing portland cement

cement manufacturing process: step-by-step guide - cce l online news

cement manufacturing process: step-by-step guide - cce l online news

After quarrying the rock is crushed. This involves several stages. The first crushing reduces the rock to a maximum size of about 6 inches. The rock then goes to secondary crushers or hammer mills for reduction to about 3 inches or smaller.

Next in cement manufacturing process, the crushed rock is combined with other ingredients such as iron ore or fly ash and ground, mixed, and fed to a cement kiln.A kiln is a thermally insulated chamber, a type ofoven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes

The cement kiln heats all the ingredients to about 2,700 degrees Fahrenheit in huge cylindrical steel rotary kilns lined with special firebrick. Kilns are frequently as much as 12 feet in diameterlarge enough to accommodate an automobile and longer in many instances than the height of a 40-story building. The large kilns are mounted with the axis inclined slightly from the horizontal.

The finely ground raw material or the slurry is fed into the higher end. At the lower end is a roaring blast of flame, produced by precisely controlled burning of powdered coal, oil, alternative fuels, or gas under forced draft.

As the material moves through the kiln, certain elements are driven off in the form of gases. The remaining elements unite to form a new substance called clinker. Clinker comes out of the kiln as grey balls, about the size of marbles.

Clinker and gypsum for Ordinary Portland Cement(OPC) limestone for limestone cement, and slag for slag cement are all extracted from their respective hoppers and fed to the cement mills. The ball mill grinds the feed to a fine powder in two chambers, namely the first and second chambers.

The two chambers have a certain quantity of ball charge of different sizes from 17mm to 90 mm. The mill discharge is fed to a bucket elevator which takes the material to a separator which separates fine and coarse product. The latter is sent to the mill inlet for regrinding and the final product is stored in concrete silos.

how portland cement is made? manufacturing process of portland cement - bright hub engineering

how portland cement is made? manufacturing process of portland cement - bright hub engineering

The basic ingredients of both the dry and wet processes are the same. By mass, lime and silica make up approximately 85% of portland cement. The materials that are commonly used are limestone, shells, chalk, shale, clay, slate, silica sand, and iron ore.

Since limestone is the main component, often cement plants are located near limestone quarries. The first step in both manufacturing processes after quarrying is primary crushing. Crushing reduces the size of the rock to three inches or smaller. Next, the raw materials are combined in the correct amounts and fed into the kiln system. In the dry process, the materials are grounded, mixed, and introduced into the kiln system in a dry state. In the wet process, the raw materials follow all of the steps with water added and are introduced into the kiln system in a slurry state.In the kiln system, the first process is pre-heating. The combined materials are fed through a series of vertical cyclones. As the material moves through these cyclones, it comes into contact with the hot kiln exhaust gases. The exhaust gases pre-heat the material before it enters the main part of the kiln. The pre-heat process allows the chemical reactions that take place in the kiln to happen quicker and more efficiently.In the main kiln, the raw materials are then heated to approximately 2,700 degrees F. In the kiln, the initial raw ingredients combine to from clinker. Clinker is mainly made up of tri and di-calcium-silicates which are the main chemicals that bond together when water is added to cement. Unwanted gases, including carbon dioxide, are also emitted from the process. In the next state of the process, clinker is cooled in coolers. The hot air from the coolers is returned to the pre-heater in order to save fuel in the overall process.The clinker is then ground to produce portland cement. Gypsum is added during the grinding process to control the set rate of the cement. Slag and fly ash can also be added to control other properties of the final product.Both the dry and wet processes are very energy intensive. The wet process, however, uses more energy than the dry process due to the amount of water that must be evaporated before clinker can be produced. The cement industry is constantly looking for ways to make the manufacturing process more efficient. For example, alternative fuel sources are now being used extensively throughout the industry to heat the kilns to reduce the amount of natural resources used in the process.Cement Plants

In the kiln system, the first process is pre-heating. The combined materials are fed through a series of vertical cyclones. As the material moves through these cyclones, it comes into contact with the hot kiln exhaust gases. The exhaust gases pre-heat the material before it enters the main part of the kiln. The pre-heat process allows the chemical reactions that take place in the kiln to happen quicker and more efficiently.

In the main kiln, the raw materials are then heated to approximately 2,700 degrees F. In the kiln, the initial raw ingredients combine to from clinker. Clinker is mainly made up of tri and di-calcium-silicates which are the main chemicals that bond together when water is added to cement. Unwanted gases, including carbon dioxide, are also emitted from the process. In the next state of the process, clinker is cooled in coolers. The hot air from the coolers is returned to the pre-heater in order to save fuel in the overall process.The clinker is then ground to produce portland cement. Gypsum is added during the grinding process to control the set rate of the cement. Slag and fly ash can also be added to control other properties of the final product.Both the dry and wet processes are very energy intensive. The wet process, however, uses more energy than the dry process due to the amount of water that must be evaporated before clinker can be produced. The cement industry is constantly looking for ways to make the manufacturing process more efficient. For example, alternative fuel sources are now being used extensively throughout the industry to heat the kilns to reduce the amount of natural resources used in the process.Cement Plants

The clinker is then ground to produce portland cement. Gypsum is added during the grinding process to control the set rate of the cement. Slag and fly ash can also be added to control other properties of the final product.Both the dry and wet processes are very energy intensive. The wet process, however, uses more energy than the dry process due to the amount of water that must be evaporated before clinker can be produced. The cement industry is constantly looking for ways to make the manufacturing process more efficient. For example, alternative fuel sources are now being used extensively throughout the industry to heat the kilns to reduce the amount of natural resources used in the process.Cement Plants

Both the dry and wet processes are very energy intensive. The wet process, however, uses more energy than the dry process due to the amount of water that must be evaporated before clinker can be produced. The cement industry is constantly looking for ways to make the manufacturing process more efficient. For example, alternative fuel sources are now being used extensively throughout the industry to heat the kilns to reduce the amount of natural resources used in the process.

what is portland cement process of manufacturing,dry and wet

what is portland cement process of manufacturing,dry and wet

Portland cement is an extreme ground material having adhesive and cohesive properties, which provide a binding medium for discrete ingredients. It is hydraulic cement made by finely pulverizing the clinker produced by calcining to incipient fusion a mixture of argillaceous and calcareous materials. Cement undergoes a chemical reaction with water and sets and hardens when in contact with air or underwater.

Portland cement is a general term uses to describe hydraulic cement. The typical raw materials used for making cement are limestone (CaCo3), sand (Sio2), state clay (Sio2, Al2O3 or Fe2O3) and iron oxide (Fe2O3). Thus, the chemical components of cement are calcium (Ca), silicon (Si), aluminum (Al) and iron (Fe).

The raw materials required for the manufacture of Portland cement are calcareous materials, such as limestone or chalk and argillaceous materials, such as shale or clay. The process of manufacture of cement consists of grinding the raw materials, mixing them and then burning them in a kiln at a temperature of about 1300oC to 1500oC at, which temperature, the material sinters and partially fused to form nodular shaped clinker. The clinker cool sinters and partially fuses to form a nodular shaped clinker. The clinker cool and ground to a fine powder with the addition of about 2 to 3% of gypsum. The product formed by using this procedure is Portland cement.

Portland cement is two processes, known as wet or dry processes depending upon whether the mixing and grinding of materials done in wet or dry conditions. A wet process was popular in the early years because of the possibility of more accurate control in the mixing of raw materials. The nowadays dry process is much popular because the dry process required less fuel than the wet process because in a wet process the slurry contains 35 to 50 percent water.

In the wet process, limestone is first crushed to smaller fragments. Then, it takes to ball or tube mill where it mixes with clay and finely ground. Then, water adds to it to make a slurry. It pumps to slurry tanks, where it keep in an agitated condition by means of rotating arm or by compressed air from the bottom to prevent settling of limestone and of the flexible chain, loses moisture and becomes flakes.

These flakes drop reaction takes place and 20 to 30% of materials get the fuse. Lime, silica, and alumina get recombine The fused mass turns into to nodular form called clinker. The clinker drops into the rotary cooler where it cool under controlled conditions. The cool clinker is then ground in a ball mill with the addition of 2 to 3% of gypsum.

In this process, the raw materials dried and ground to a fine powder by grinding mill. The dry powder is then further blende and corrected for its right composition and mixed by means of compressed air. The blended powder then store in the storage silos from where. It is the pass to the granulator comprising an inclined rotating drum or dish.

A quantity of water about 12 percent by weight then add to make the blended powder into nodules. These nodules are then dry by preheater and then enter to the rotary kiln from the upper end. These nodules drop to lower end where it subject to the temperature about 1500oc Chemical reaction takes place and 20 to 30% material get the fuse. Lime silica and alumina get recombine. The fused mass turns into a nodular form called clinker.

The clinker drops into the rotary cooler, where it is cool under control conditions. The cool clinker is then ground in a ball mill with the addition of 2 to 3% of gypsum. In the ball mill, particles crush to a fine powder and filled into bags.

The equipment used in the dry process in comparatively smaller. This process is economical than the wet process. The total consumption of coal in the dry process is only about 100 kg, as compared to the requirement of about 350 kg, for producing a tonne of cement in the wet process.

opc cement | types of opc, 4 manufacturing steps

opc cement | types of opc, 4 manufacturing steps

In the proportion of about two parts of calcareous materials to one part of argillaceous materials, the ingredients are mixed and then in a dry state or mixed in wet state crushed and ground in ball mills.

Then in a rotary kiln at a temperature between 1400 degrees C to 1500 degree C the dry powder or the wet slurry is burnt and the kiln is first cooled and the clinker is obtained. Then according to the class of product gypsum is added and it is ground to the requisite fineness.

Firstly, to 550C the mix is preheated and all the moisture content is evaporated and clay is broken into silica, iron oxide, and aluminum oxide. Then the temperature is rise to 1500 degree Celsius where the oxides form silicate, ferrite, and aluminate.

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