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 - civil engineering
The raw cement ingredients needed for cement production are limestone (calcium), sand and clay (silicon, aluminum, iron), shale, fly ash, mill scale and bauxite. The ore rocks are quarried and crushed to smaller pieces of about 6 inches. Secondary crushers or hammer mills then reduce them to even smaller size of 3 inches. After that, the ingredients are prepared for pyroprocessing.
The crushed raw ingredients are made ready for the cement making process in the kiln by combining them with additives and grinding them to ensure a fine homogenous mixture. The composition of cement is proportioned here depending on the desired properties of the cement. Generally, limestone is 80% and remaining 20% is the clay. In the cement plant, the raw mix is dried (moisture content reduced to less than 1%); heavy wheel type rollers and rotating tables blend the raw mix and then the roller crushes it to a fine powder to be stored in silos and fed to the kiln.
A pre-heating chamber consists of a series of cyclones that utilizes the hot gases produced from the kiln in order to reduce energy consumption and make the cement making process more environment-friendly. The raw materials are passed through here and turned into oxides to be burned in the kiln.
The kiln phase is the principal stage of the cement production process. Here, clinker is produced from the raw mix through a series of chemical reactions between calcium and silicon dioxide compounds. Though the process is complex, the events of the clinker production can be written in the following sequence:
The kiln is angled by 3 degrees to the horizontal to allow the material to pass through it, over a period of 20 to 30 minutes. By the time the raw-mix reaches the lower part of the kiln, clinker forms and comes out of the kiln in marble-sized nodules.
After exiting the kiln, the clinker is rapidly cooled down from 2000C to 100C-200C by passing air over it. At this stage, different additives are combined with the clinker to be ground in order to produce the final product, cement. Gypsum, added to and ground with clinker, regulates the setting time and gives the most important property of cement, compressive strength. It also prevents agglomeration and coating of the powder at the surface of balls and mill wall. Some organic substances, such as Triethanolamine (used at 0.1 wt.%), are added as grinding aids to avoid powder agglomeration. Other additives sometimes used are ethylene glycol, oleic acid and dodecyl-benzene sulphonate.
The heat produced by the clinker is circulated back to the kiln to save energy. The last stage of making cement is the final grinding process. In the cement plant, there are rotating drums fitted with steel balls. Clinker, after being cooled, is transferred to these rotating drums and ground into such a fine powder that each pound of it contains 150 billion grains. This powder is the final product, cement.
Cement is conveyed from grinding mills to silos (large storage tanks) where it is packed in 20-40 kg bags. Most of the product is shipped in bulk quantities by trucks, trains or ships, and only a small amount is packed for customers who need small quantities.
Please note that the information in Civiltoday.com is designed to provide general information on the topics presented. The information provided should not be used as a substitute for professional services.
cement euipment overview | cement making machines | cement plant
How much do you know the cement equipment? Cement equipment refers to the cement making machines that are applied to the cement manufacturing plant. Before learning the cement equipment, we learn the process of cement manufacturing process first.
In general, we can divide the cement production line into three main steps: raw material preparation of cement, clinker production, and finished cement. Each step has some cement manufacturing machines, such as raw mill, cement crusher, cement mill, cement kiln, cement cooler, cement dryer, cement silo, packing machine, etc.
As we all know, the first step of the cement production line is raw material preparation. Cement crusher is the main equipment of this step. The raw materials are fed into cement crusher by vibratory feeder; the breaking material is transported by the belt conveyor to the impact crusher for further crusher.
There are various types of cement crusher on the market, including jaw crusher, cone crusher, hammer crusher, impact crusher, and etc. AGICO Cement can provide all types of cement crusher. Our cement crusher can fully crush the raw material, reduce feed size into the mill, and increase the reaction of raw material in the following cement manufacturing process, reduce the energy consumption of the whole cement production line.
Cement mill is another necessary cement equipment of the cement plant. After raw material crushing, cement mill plays vital role in the further cement manufacturing process. Cement ball mill, vertical cement mill, and cement roller press are common types of cement grinding plant.
Cement mill has two functions of the cement production line. Firstly, cement mill is used to grind the crushed material into fine size before clinker production. A cement mill is also applied for grinding clinker into finished cement. The cement clinker grinding is the last step of the cement manufacturing process, in this step, cement mill grinds cement clinker, gelatinizing agent and other materials into the required size, which can meet the requirement of cement.
AGICO Cement adopts the advanced internal selection and special compartment device, add the activation device. The grinding tail has a special discharge grate plate, which greatly reduces the size of the grinding media of the grinding bin, greatly improves the grinding efficiency, and achieves the goal of high output and low energy.
Cement kiln is used to make cement clinker, and it is the core equipment of cement production line; usually, apply for dry method cement production. There are two main kinds of cement kiln to manufacture cement clinker. One is the cement rotary kiln, and it is horizontal and can rotate. Rotary kiln is widely applied to the cement clinker production. Another one is vertical and fixed kiln, so it is called as a vertical kiln.
AGICO Cement can manufacture cement rotary kiln with advantages of convenient and reliable operation, stable thermal regulation, and high operation rate. Compared to other rotary kilns on the market, our rotary kiln increase operation rate by 10%, production capacity by 5%-10%, widely apply for cement production line of different countries.
Clinker cooler and dryer are two necessary parts of cement clinker production. The dryer produced by AGICO can apply for various raw materials and easy to adjust. During the operation, the dryer supplies heat stably, ensures the drying quality and cement quality. The cement cooler is also used for clinker production. Using blower blowing cold air, quench the cement clinker that laid on the grate plate, decrease the temperature of clinker from 1200 to 100 and below, the cooling exhaust gas enters into the kiln as secondary air.
In fact, every cement plant requires different cement equipment. Except for the cement equipment we mentioned above, there are many other cement making machines applied for the cement plant. In the real application, as a professional EPC cement plant project provider, AGICO Cement always provides a solution according to clients needs, such as mini cement plant, VSK cement plant. We also provide single cement equipment with high quality and competitive price, welcome to contact!
cement making process, ielts writing task 01
The first diagram explains how the cement is produced in a cement making factory using various materials and equipment and the second diagram shows the way of making concrete using cement for buildings purposes.
Limestone and clay are used as main raw materials in the cement production. In the first step, these two materials are crushed and converted into powder form using a crusher and mixed in a huge mixer. Then, this mixed powder goes through a special rotating heater which has 45 degrees angle and a heavy flame spreads from top to bottom. The heated powder which comes out of the rotating heater is ground and make cement as the final production. Then the cement is packed and distributed throughout the country. As it is explained in the second diagram gravel (50%), sand (25%), cement (15%) are mix together with water (10%) in a concrete mixer to make concrete for buildings.
how is cement produced in cement plants | cement making process
Cement is a kind of powdery hydraulic inorganic cementitious material, which is the most basic and widely used building material in modern society. Cement can be hardened in the air or in water, and can firmly bond sand and stone together. It is widely used in civil engineering, water conservancy, national defense, and other projects.
The most commonly seen and used cement is portland cement, or ordinary portland cement (OPC). This type of cement was invented in the early 19th century by Joseph Aspdin. It is named portland cement because its property is similar to the stone quarried on the Ise of Portland, England.
The making process of portland cement in the modern industry can be divided into the wet process, dry process, and semi-dry process. Nowadays, the dry process is the most popular cement making process which is widely adopted by cement plants all over the world for its great advantages in energy saving and environmental protection.
The raw materials needed for cement production mainly include limestone (main material, providing CaO), clay materials (providing SiO2, Al2O3 and a small amount of Fe2O3), correction raw materials (to supplement some insufficient ingredients), and auxiliary raw materials (such as mineralizer, cosolvent, grinding aid), etc. Generally, the limestone accounts for 80% of cement raw materials, which is the main cement manufacturing material.
Cement plants are usually built near the quarry of limestone so the quarried limestone can be transported to the cement plant directly by belt conveyor or other conveying systems. If the distance between the quarry and the cement plant is too long to use conveyors, the limestones will have to be transported by trucks, which means higher transportation fees and inconvenience. The short distance between the cement plant and the quarry saves transportation fees and fuel costs and makes the cement making process economical.
Apart from limestone, there are also other raw materials used in the cement making process, such as clay, fly ash, iron ore, and coal. The need for these raw materials in cement production is relatively small so it is OK to just buy them from a supplier.
Before raw materials being transported to the cement plant, they are crushed into smaller size pieces by the crusher at the quarry. Compared to large pieces, raw materials in smaller pieces are easier to be loaded and transported, and more convenient for subsequent processing.
The samples of limestones from the quarry are first sent to the laboratory of the cement plant, where they are tested and analyzed for proportioning. The proper proportioning of limestone and other raw materials is a necessary job before the beginning of grinding. The proportioning of cement raw materials is not all the same but should be determined according to the actual situation. The proportion of raw materials of different specifications of cement is also different. Generally, the proportion of components in cement raw materials is 67-75% limestone, 10-15% clay, 0.5-1.5% iron ore and 8.5-11% coal.
With the help of roller crushers or other types of crushers, the raw materials are blended and further ground into smaller pieces of raw meal in the cement plant. In a roller crusher, the rotating table rotates continuously under the roller and brought the raw mix in contact with the roller. Roller crushes the material to fine powders and finishes the job. The raw mix is stored in a pre-homogenization pile after it was ground to fine powders.
After being crushed by the roller crusher, the raw meal is ready to enter the preheater. The cyclone preheater is one of the core equipment for dry process cement production, which consists of a series of vertical cyclones locate on several stages. Inside the cyclones, raw meal meats with the exhaust gas emitting from the rotary kiln and performs suspension heat exchange with it. The suspension pre-heating process helps cement plants save energy and reduce environmental pollution.
The calcination is the core phase of the cement making dry process. The calcination of the preheated raw meal takes place in the rotary kiln of the cement plant. The rotary kiln is a huge rotating furnace in which the raw meal is heated up to 1450 C and turned to clinker.
The heat source of the rotary kiln is the flame from the burner locates on the kilns front end. Using natural gas or coal as fuels, the burner shoots high-temperature flames to calcine the raw meal. After calcination, the cement clinker will enter a cooler for cooling.
The hot clinker discharged from the rotary kiln is cooled in the grate cooler by forced air, which is extracted from the outer atmosphere by grate cooling fans. The temperature of the clinker after being cooled drops from 1350 1450C to around 120C. The cooled clinker is then transported to clinker silos or hoppers directly by conveyors for storage and later cement grinding process. The hot air in the cooler is recirculated back to the rotary kiln for reuse, which further saves energy consumption of the cement plant.
The cooled clinker is then fed to cement mills for final grinding. Many factories nowadays prefer to use ball mills for cement grinding, since this kind of mills has small product particle size distribution and is easy to operate.
The cement ball mill is a horizontal cylinder filled with steel balls or other grinding media. Inside the cylinder, the steel balls are rotated and tumbled and crush the clinker into very fine powders, which are product cement powders. During the grinding process, a small percentage of gypsum is added to the mix to control the setting time of cement.
The product cement discharged from the cement grinding mills is conveyed to the cement storage silos. Further, it is packed into bags or shipped to customers in bulk quantities by trucks, rail freight wagons, or ships. The most popular cement packing machines are roto-packers which can pack cement fast and in large quantities.
graph writing # 102 - stages and equipment used in the cement-making process
Sample Answer 1: The given diagram shows the process of cement production and then how this cement is used for concrete production. As is observed from the graph, cement production involves some complex processes and concrete production is done using the water, cement and sand in a concrete mixer. The first diagram depicts that, to produce cement first the limestone and clay are crushed and the produced powder from this is passed through a mixer. The power is then passed via a rotating heater where heat is supplied constantly and this process creates the raw cement materials which are passed on a grinder machine to finally produce the cement. The cement is then packed and marketed for sale. The second diagram presents how the concrete is produced for housing and building work. In the first stage, 15% cement, 10% water, 25% sand and 50% small stones are mixed in a concrete mixer machine and the machine rotates fast to have the ingredients mixed together to create the concrete.
Sample Answer 2: The two diagrams illustrate the cement-making process. We can see from the given illustration that cement is manufactured first, and then it's used in the concrete production. In the first diagram, we can see that limestone is the raw material with which clay added. Firstly, the two materials are crushed to form the powder. Then this powder passes through a mixer and a heater through which the powder is exposed to flame. The powder now is in the form of a paste. This paste is grinded to be cement to pass through the last process; packing in bags. The second diagram shows that cement can be used to produce concrete. This process is simpler than cement production; concrete is a mixture of 15% cement, 10 % water, 25% sand and 50 % small stones which are named as "Gravel". The four elements are poured in a huge mixer which rotates producing concrete. We can see that once the cement is produced by several steps and equipment, it can be used in other less complicated processes, for instance, concrete production.
Sample Answer 3: These two diagrams reveal the flow diagrams of both cement and concrete production processes with necessary equipment and materials that are used. Mainly, both processes have similarities and differences. They are similar because each of them has more than one input and a single output. On the other hand, they differ in the number of production steps. In the cement production diagram, firstly, limestone and clay are gathered and passed through a crusher. Then, the powder obtained from crusher is moved to the mixer to make a homogene mixture. Next, rotating heater welcomes the material from the mixer. After heating step, resulting material flows on the grinder. Finally, cement becomes ready to be packed in bags at the end of the grinder. In the concrete production diagram, the process contains only one step to have concrete material that is mixing. Cement, water, sand and gravel which is a general name for small stones are all mixed in a rotating concrete mixer in precise proportions such as 15%, 10%, 25% and 50% respectively.
To begin with, cement is produced by combining raw materials like limestone, clay, which are processed in a tool called crusher. Those all items are mixed together to create a perfect blend. The blend, furthermore, goes into to a rotating heater. As it is in the rotating heater tube, heat is introduced from the end of the tube before the blend is actually dropped onto grinder. Then, after all the systemic process, the mixture turns into some cement which is then packed into bags.
Meanwhile, to create concrete, the main components of construction systems are gravel, cement, water, sand and a concrete mixer to blend all the materials. Gravel or small stone is the major and biggest component needed and accounts for 50% among all materials. There are, however, some other materials like the sand which is mainly used and comes in the second place and is accounted halved from gravel, followed by cement and water. The cement accounts for 15% compared to among all materials used to construct a new real construction. All the material is mixed together by a concrete mixer.
Overall, the steps of making cement are more complicated and require advanced machinery while concrete production requires mixing required components in the right proportion in a simpler machine. While heat is required to produce cement, no heat penetration during the combination period of making concrete is required.
ielts report on cement and concrete making process
Overall, the first diagram shows all the steps required for the production of cement like crushing, mixing heating, grinding, packing and the usage of the final product along with few other raw materials. Whereas, concrete production is depicted in the second diagram. Cement production involves more steps as compared to the production of concrete but the former requires less number of raw materials than the latter. Concrete is the final output which is directly used for the building process, whereas cement is a semi-finished product and needs further processing.
Firstly, limestone and clay are turned into powder by putting them in a crusher. This powder is then mixed in a mixer, after which it is put in a rotating heater. Here, this mixture is heated by applying heat externally. Then the mixture passes through a grinder, and fine cement is produced, which then is packed in a bag for further usage.
Secondly, this cement along with water, sand and gravel, as per specified proportions, is put in a concrete mixer. The concrete mixer rotates, thereby producing the final output, i.e. concrete which is directly used for building purposes.
Although the information in the sentence above is accurate, it is not presented anywhere on the diagram. You must avoid any temptation to offer any piece of information which is not mentioned in the chart.
You may observe that in case both the body paragraphs, the writer has missed the introductory statement. A simple statement, such as given below, would have been sufficient at the beginning of body paragraph 1.
You may notice that at the beginning of body paragraph 1 and 2, the two linking words used are firstly and secondly. Well, these words are not used correctly. These linking devices are used when you are listing down something.
The cement production involves five stages, a straightforward process that begins with the mixing of raw materials and reaches a finale in the packaging of new cement. Making concrete is a simple process that involves mixing four ingredients in a concrete mixer.
Overall, the first diagram shows the equipment and the process of cement making. Limestone and clay are simultaneously passed through the crusher to form powder which is then mixed before passing it through a rotating heater. Once heated, this mixture is ground through a grinder. Now that the cement has been produced, it is packed into bags.
At the same time, the second diagram shows the concrete production process. For the production, the concrete mixture needs four ingredients and a concrete mixer. The concrete mix comprises half a portion of gravel (small stones), a quarter portion of sand, 10% water and 15% cement. All of these are added together in a cylindrical drum and rotate until the concrete is produced.
ielts task 1 process- cement & concrete production - ielts advantage
The production of cement involves a 5 stage, linear process that begins with the mixing of raw materials and culminates in the packaging of new cement. Making concrete is a simpler process that involves mixing four ingredients in a concrete mixer.
Limestone and clay are crushed and the resulting powder is then mixed before being passed through a rotating heater. Once heated this mixture travels over a conveyor belt and is ground through a grinder. Now that the cement has been produced, it is packaged and transported to a building site where it can be used to make concrete.
The fourth paragraphdetails the process of concrete production. This is a much simpler process and does not require so much sequencing. There are some percentages so it does allow us to show the examiner that we can use the language of proportions instead of just repeating all of the numbers.
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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.