the cement manufacturing process
Different minerals need to be mined in order to make cement. Limestone (containing the mineral calcite), clay, and gypsum make up most of it. The US Geological Survey notes that cement raw materials, especially limestone, are geologically widespread and (luckily) abundant. Domestic cement production has been increasing steadily, from 66.4 million tons in 2010 to about 80.5 million tons of Portland cement in 2014 according to the U.S. Geological Survey 2015 Cement Mineral Commodity Summary. The overall value of sales of cement was about $8.9 billion, most of which was used to make an estimated $48 billion worth of concrete. Most construction projects involve some form of concrete.
Cement manufacturing is a complex process that begins with mining and then grinding raw materials that include limestone and clay, to a fine powder, called raw meal, which is then heated to a sintering temperature as high as 1450C in a cement kiln. In this process, the chemical bonds of the raw materials are broken down and then they are recombined into new compounds.The result is called clinker, which are rounded nodules between 1mm and 25mm across. The clinker is ground to a fine powder in a cement mill and mixed with gypsum to create cement.The powdered cement is then mixed with water and aggregates to form concrete that is used in construction.
Clinker quality depends on raw material composition, which has to be closely monitored to ensure the quality of the cement. Excess free lime, for example, results in undesirable effects such as volume expansion, increased setting time or reduced strength. Several laboratory and online systems can be employed to ensure process control in each step of the cement manufacturing process, including clinker formation.
Laboratory X-Ray Fluorescence (XRF) systems are used by cement QC laboratories to determine major and minor oxides in clinker, cement and raw materials such as limestone, sand and bauxite. Read Analysis of Clinker and Cement with Thermo Scientific ARL OPTIMX WDXRF Sequential Spectrometer to learn why XRF is the technique of choice for elemental analysis in cement industry. Combination X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) systems accomplish both chemical phase analysis for a more complete characterization of the sample. Clinker phase analysis ensures consistent clinker quality. Such instrumentation can be fitted with several XRF monochromators for major oxides analysis and a compact diffraction (XRD) system which has the capability of measuring quartz in raw meal, free lime (CaO) and clinker phases as well as calcite (CaCO3) in cement.
Cross Belt Analyzers based on Prompt Gamma Neutron Activation Analysis (PGNAA) technology are installed directly on the conveyor belt to measure the entire material stream continuously and in real time to troubleshoot issues in pre-blending stockpile control and quarry management, raw mix proportioning control, and material sorting. Read PGNAA Improves Process and Quality Control in Cement Production to learn what makes PGNAA particularly suited for cement analysis.
Accurate cement production also depends on belt scale systems to monitor output and inventory or regulate product loadout, as well as tramp metal detectors to protect equipment and keep the operation running smoothly. The Cement Manufacturing Process flow chart sums up where in the process each type of technology is making a difference.
Need a Belt scale system for your bulk material handling? To help you decide which belt scale system is best for your mining operation, weve outlined the options in an easy-to-read belt scale system selection guide so you can decide which belt scale system is right for you. Click on the image, take a look at the chart, and see if it helps you decide.
re: natural gas vs. coal (above) The cost of natural gas is still around 3$ per million btu, while coal is 2$. So for a process like this that just needs heating value coal would be much preferred, and worth the cost for back end pollution control. Gas is becoming preferred for electric generation because a combined cycle plant has around 65% cycle efficiency, vs. 38% for coal-fired.
cement manufacturing process: what is cement made of
These are sedimentary, calcium carbonate rocks (CaC03). Most commonly they contain a small amount of magnesium carbonate also.Besides, usual impurities in limestones are those of iron oxides, silica, and alkalies.
The raw materials (limestone and clay) are subjected to such processes as, crushing, drying, grinding, proportioning, and blending or mixing before they are fed to the kilns for calcination or burning process.
The drying stage is typical of the Dry Process. Drying of crushed materials is essential and is achieved by heating these materials (separately) at temperatures sufficiently high to drive out uncombined water.
Each raw material is thus reduced to a required degree of fineness and is stored separately in suitable storage tanks called SILOS or bins where from it can be drawn out conveniently in requisite quantities.
The blended materials are now ready for feeding into the burning kilns. From this stage onwards, there is practically no major difference between the dry and wet processes, except in the design of the rotary kiln.
(c) Compound Formation: Lime and magnesia as formed above are combined in the next stage with silica, alumina and ferric oxide to form the basic compounds of cement, namely, the tri-calcium and di-calcium silicates, tri-calcium aluminates and tetra-calcium-alunino ferrite.
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.
cement manufacturing - components of a cement plant
This page and the linked pages below summarize the cement manufacturing process from the perspective of the individual components of a cement plant - the kiln, the cement mill etc..For information on materials, including reactions in the kiln, see the ' Clinker ' pages. For a more detailed account of the cement production process, see the Understanding Cement book.
Cement is typically made from limestone and clay or shale. These raw materials are extracted from the quarry crushed to a very fine powder and then blended in the correct proportions.This blended raw material is called the 'raw feed' or 'kiln feed' and is heated in a rotary kiln where it reaches a temperature of about 1400 C to 1500 C. In its simplest form, the rotary kiln is a tube up to 200 metres long and perhaps 6 metres in diameter, with a long flame at one end. The raw feed enters the kiln at the cool end and gradually passes down to the hot end, then falls out of the kiln and cools down.The material formed in the kiln is described as 'clinker' and is typically composed of rounded nodules between 1mm and 25mm across.After cooling, the clinker may be stored temporarily in a clinker store, or it may pass directly to the cement mill.The cement mill grinds the clinker to a fine powder. A small amount of gypsum - a form of calcium sulfate - is normally ground up with the clinker. The gypsum controls the setting properties of the cement when water is added.
Articles like this one can provide a lot of useful material. However, reading an article or two is perhaps not the best way to get a clear picture of a complex process like cement production. To get a more complete and integrated understanding of how cement is made, do have a look at the Understanding Cement book or ebook. This easy-to-read and concise book also contains much more detail on concrete chemistry and deleterious processes in concrete compared with the website.
Almost everyone interested in cement is also concerned to at least some degree with concrete strength. This ebook describes ten cement-related characteristics of concrete that can potentially cause strengths to be lower than expected. Get the ebook FREE when you sign up to CEMBYTES, our Understanding Cement Newsletter - just click on the ebook image above.
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.
what is the cement manufacturing process? (with pictures)
The cement manufacturing process involves several key steps, including preparing the raw materials, grinding the materials together, heating the newly formed clinker in a kiln, and finishing the cement with fine grinding. Some of the main ingredients used to make cement include limestone, clay, shale, iron, and sand. Different manufacturing techniques will use either wet or dry grinding, but each cement manufacturing process will culminate in heating and fine grinding to finish the product.
Preparing the raw materials is often the first step in the cement manufacturing process, and involves mining the limestone or obtaining safe industrial waste products. Drilling, blasting, and crushing machinery convert mined limestone to fragments about 0.39 inches (about 1 cm) in diameter, after which it is stored until needed. Crushing practices will sometimes be used on the other materials as well, especially if they contain large or irregularly sized fragments.
Grinding is the next step in the cement manufacturing process, and it can occur in either wet or dry forms. Wet grinding involves combining all of the materials in a mill with water and grinding it into slurry. In contrast, dry grinding processes combine and grind the materials without water, creating a substance known as kiln feed. Both types of grinding will yield material that contains an average particle size of about 75 micrometers. After each process, the materials are further mixed for proper homogeneity and placed in storing units.
Heating occurs next, and it takes place in a rotary kiln that is fired at high temperatures. The kiln heats the clinker, the name for the dried material formed after the grinding process, until it reaches upwards of 2732F (about 1500C). Afterward, the material is sent to a clinker cooler where the temperature lowers to a reasonable level, at which point the material can be stored once again.
The cement manufacturing process is completed when the cooled clinker is ground once again in a rotating finishing mill. A combination of gypsum and limestone will usually be added in small amounts to the heated cement during this last grinding step, and coloring agents can also be added here. The fineness of the finished particles will vary according to individual preferences, and the cement can reach a level of fineness where it will travel through liquid sieves. Completion of the finishing step means that the cement is ready to be packaged and distributed to builders and consumers.
cement manufacturing process - chemical engineering world
Cement is a material which is used to bind other materials together. Binding means it has an effect ofgluing the substances together due to cohesive and adhesive action and then hardens and sets in order to become permanent. Cement is usually not used on its own; it is mixed with other materials called aggregates to produce a combined material of desired properties.
When it is mixed with sand, gravel then concrete is produced. If it is mixed with fine aggregates then it produces mortar. Cements are prepared by materials which have a high amount of calcium or aluminium and silicon. Calcium containing materials are called calcareous materials and aluminium and silicon containing materials are called argillaceous materials. Cement is used for constructing buildings, dams, roads, bridges etc.
These are cements which require dry conditions in order to set and harden. They lose their efficiency and durability in presence of water. It sets as it dries and reacts with carbon dioxide in air. After setting it is resistant to chemical attacks.
These are cements which can set even if its surrounded by any amount of water. In such cements, the cement reacts with aggregates to form mineral hydrates which are insoluble in water. The water can protect the cement and the aggregate from chemical attacks this helping it set and harden and become very durable. An example of this type is Portland Cement.
In wet process the calcareous and argillaceous materials are grinded to required size and stored in separately silos. Before the argillaceous materials are stored it is first washed with water. Both the materials are then channeled to mill equipment where they are intimately mixed in desired proportions to form a paste. This paste is then stored in a silo for further processing.
The process of burning is carried out in rotary kiln and the rotary kiln is lined with refractory bricks. The prepared mixture stored in the silo is fed into the rotary kiln from upper side and a burning fuel is fed from the lower side of the rotary kiln in order to produce hot flame. The fuel can be oil or powdered coal or it even can be hot gases.
There is a temperature gradient inside the rotary kiln with the lowest temperature being at the upper side and the highest temperature being at the lower side. There is a countercurrent motion between the feed mixture and the burning fuel. Due to the slow rotation of the rotary kiln the temperature of the feed mixture rises gradually as it moves from the upper end to the lower end of the rotary kiln.
The temperatures are around 1000C. This part is also known as calcination zone because lime stone decomposes in this part. Calcium carbonate decomposes to form calcium oxide and carbon oxide. After the carbon dioxide escapes remaining material forms small lumps called nodules.
The temperatures in this part are between 1500-1700C. This part is also known as clinkering zone. The calcareous and argillaceous materials react to form calcium silicates and calcium aluminates. The aluminates and silicates fuse together to form small and hard stones known as clinkers.
The clinkers which are output from the rotary kiln are very hot hence they are first cooled by air in a countercurrent fashion. The clinkers are of size of about 5-10 mm. They are fed to grinders in order to grind them to reduce their sizes. The clinkers are fed into ball mill or tube mill along with powdered gypsum.
The gypsum acts as a regarding agent so that the resulting cement does not set quickly when it comes in contact with water. The mixture fed for grinding contains tricalcium aluminates which are soluble in water. Gypsum reacts with them to produce tricalcium sulfoaluminates which is insoluble in water. They retard the rate of setting of cement thus giving time for concrete placing.
cement | definition, composition, manufacture, history, & facts | britannica
Cement, in general, adhesive substances of all kinds, but, in a narrower sense, the binding materials used in building and civil engineering construction. Cements of this kind are finely ground powders that, when mixed with water, set to a hard mass. Setting and hardening result from hydration, which is a chemical combination of the cement compounds with water that yields submicroscopic crystals or a gel-like material with a high surface area. Because of their hydrating properties, constructional cements, which will even set and harden under water, are often called hydraulic cements. The most important of these is portland cement.
This article surveys the historical development of cement, its manufacture from raw materials, its composition and properties, and the testing of those properties. The focus is on portland cement, but attention also is given to other types, such as slag-containing cement and high-alumina cement. Construction cements share certain chemical constituents and processing techniques with ceramic products such as brick and tile, abrasives, and refractories. For detailed description of one of the principal applications of cement, see the article building construction.
Cements may be used alone (i.e., neat, as grouting materials), but the normal use is in mortar and concrete in which the cement is mixed with inert material known as aggregate. Mortar is cement mixed with sand or crushed stone that must be less than approximately 5 mm (0.2 inch) in size. Concrete is a mixture of cement, sand or other fine aggregate, and a coarse aggregate that for most purposes is up to 19 to 25 mm (0.75 to 1 inch) in size, but the coarse aggregate may also be as large as 150 mm (6 inches) when concrete is placed in large masses such as dams. Mortars are used for binding bricks, blocks, and stone in walls or as surface renderings. Concrete is used for a large variety of constructional purposes. Mixtures of soil and portland cement are used as a base for roads. Portland cement also is used in the manufacture of bricks, tiles, shingles, pipes, beams, railroad ties, and various extruded products. The products are prefabricated in factories and supplied ready for installation.
wet process of cement manufacturing - cement wet process & cement dry process
Cement is a kind of powdery material. When properly mixed with water, it will turn into slurry. The slurry will gradually harden in air and glue together the granular or fibrous materials such as sand and stone firmly. It is widely used in all aspects of our lives, such as subway construction, bridge construction, and residential building construction. It is an indispensable part of our city.
The production process of silicate cement (also known as Portland cement) is representative in cement production. It usually adopts limestone and clay as main materials. After been crushed, proportioned and ground into appropriate granularity, most of the raw materials will be fed into cement kiln for calcining clinker, and then we usually add an appropriate amount of gypsum (sometimes mixed with other materials or additives) in the cement grinding process, finally obtaining the cement products with a qualified fineness. At cement plant, according to different raw materials preparation methods, cement manufacturing can be divided into the dry process (including semi-dry process) and wet process (including semi-wet process). Next, we will discuss the wet process of cement manufacturing in details.
The wet process of cement manufacturing refers to grinding raw material into slurry after mixing with water and then feeding them into the wet process kiln for drying and calcination and finally forming clinker. The slurrys water content is usually between 32%-36%. In addition, the raw material slurry can also be dehydrated into raw material blocks and put into the kiln to calcine clinker. This method is called the semi-wet process, which still belongs to the cement wet process production.
Advantages: the wet process of cement production has the characteristics of simple operation, low dust and easy conveying. Because the slurry has fluidity so that its homogeneity is good and the quality of clinker is improved. Whats more, the energy consumption of raw material grinding in the wet process is reduced by nearly 30%.
Disadvantages: the heat consumption of the wet process is too high, usually between 5234-6490 J/kg and the consumption of ball mill vulnerable parts is also large. Compared with other processing methods, the clinker manufactured by the wet process has a low temperature when it comes out of the kiln, so this method is not suitable to produce the clinker with a high silica rate and high aluminum-oxygen rate.
The dry process of cement manufacturing means that after raw materials with different particle sizes are dried, broken and ground into powders of certain fineness, they will be sent into the dry process kiln for calcining, finally forming clinker. Besides, the raw material powder can also be made into raw material balls by adding a proper amount of water and then be directly sent to the Lepol kiln for calcining. This method is called a semi-dry process, which belongs to the cement dry process production.
Advantages: as the dry process is to directly feed raw material powder into the rotary kiln for calcination, and the moisture content of raw materials is about 1% 2%, it saves the heat consumption needed for the moisture evaporation. Therefore, this method has the advantages of energy-saving, high production efficiency and stable output, which can meet the production needs of large cement plants. At the same time, there is less sewage discharged in the dry process cement production. It is conducive to environmental protection. Nowadays, we call the production line with preheater and precalciner as the new dry process cement production line, which is the development direction of dry process cement manufacturing in the future.
The procedures of the wet process are basically the same with the dry process, which can be divided into three stages: raw materials preparation, clinker calcination, and the cement grinding. All of these stages are covered in the article What You Need to Know about Portland Cement Manufacturing Process we mentioned before.
Similar to the dry process, materials also need
to undergo quarrying, primary crushing, secondary crushing, proportioning and
grinding in the raw materials preparation stage of the wet process. The biggest
difference between the two methods is that in the wet process, water is usually
required as a process media added in the raw mix to form slurry. After mixing
and blending, the slurry will be stored in the slurry tank waiting for further
processing. While in the dry method cement production line, the raw mix doesnt
In the calcination stage, the cement kiln
used by the wet process is longer in comparison to the dry process, and there
is no preheater and precalciner in front of the kiln. The temperature in cement
kiln can reach 1400-1500, slurry in it is heated and dried and finally forming
the clinker compounds, namely Di-calcium Silicate, Tricalcium Silicate,
Tri-calcium Aluminate and Tetra Calcium Alumino-Ferrite. Clinker is a kind of
particle with a variety of size and dark green color. After cooled down in the
grate cooler, they will be sent into the grinding mill for the last processing.
In the last stage, clinker will be ground
into qualified fineness in grinding mills. During this process, we usually add
some gypsum and other materials into clinker to give the final cement product
different properties and usages. For example, we add gypsum to obtain the
ordinary Portland cement and add gypsum and fly ash to obtain the Pozzolana
Wet process cement manufacturing method can be used to produce various types of Portland cement, such as ordinary Portland cement, white Portland cement, oil well cement, etc. It can help your cement plant to achieve high quality and high output cement production.
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.
the manufacturing process - hoffmann green cements
These co-products, present in abundance, are then mixed with our activators and superactivators specifically formulated by Hoffmann Green, giving rise to our three revolutionary cements: H-UKR, H-EVA and H-P2A.
Hoffmann Green has initiated a technological breakthrough based on changing the composition of cement so that it does not contain clinker, the main source of CO2 emissions in traditional cement production, as well as creating a cold and clean cement manufacturing process (no firing of raw materials).
The manufacturing process for Hoffmann Green cements is based on the systematic use of abundant co-products as a substitute for natural resources. This innovation makes it possible to produce a carbon-free cement 0% clinker while preserving natural resources, particularly without the use of quarries. Also, with the absence of a firing process, the carbon impact of Hoffmann cements is significantly reduced compared to the traditional cement manufacturing process.
Adjuventation and mixing are at the heart of our industrial process. This is followed by the packaging of our cements (big bag, bulk or bags) and then shipment to the site areas according to an optimized transport scheme (see animation above).
Far from the image of traditional cement factories, the Hoffmann Green industrial scheme allows its factories, without kilns or chimneys, to be located as close as possible to urban areas with major works.
process of manufacturing of cement - learning technology
NOTE : The crushed material are checked for content of CaCO3 ,Lime, Alumina, Silica, Fe2O3. Any compnent found short in quarried material is added separately e.g. Silica is less than crushed sandstone is separately added to raw mix and if lime is less then high grade limestone is crushed and added into raw mix.
Burning Zone: In this zone the ingredients of calcareous and argillaceous component i.e. lime, silica, alumina, iron oxide, etc. get united with each other at a very high temperature and this process is called fusion.
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