white cement manufacturing process: 6 steps | white cement plant
In the cement manufacturing process, in order to avoid the mixing of colored impurities, calcination of white cement plant mostly use natural gas or heavy oil as fuel. Reduction slag, gypsum and white granulated slag produced by electric steelmaking can also be used to produce white cement without clinker.
Strength: strength is another typical standard, there some factors to affect the cement strength, such as constituent minerals of clinker, sintering degree, crystalline state, cement fineness, admixture activity, cement particle gradation, etc.
The white cement manufacturing process is similar to the Portland cement manufacturing process, so we introduce the factors that affect cement quality. Just like general cement manufacturing plant, the white cement manufacturing process can be generally divided into six steps:
In the white cement manufacturing process, the kiln firing system is the key to the entire cement production line, which affects the product quality and energy consumption of the entire white cement plant. Therefore, it is important to rationally design the kiln firing system. AGICO CEMENT introduces the design of the rotary kiln firing system on the white cement plant.
Because a small amount of fluorite is added as a mineralizer in the white cement raw material to reduce the firing temperature. Fluctuation or improper control of the blending amount in the cement production can cause the liquid phase to appear in advance in the preheater at all levels of the kiln, especially in the high temperature section and the decomposition furnace, which will cause the material to stick. It is especially serious in the place where a little cold wind leaks in and may occur at any time. This is also a feature that must be paid attention to in white cement manufacturing process.
Therefore, in the design of the preheater at each level (fifth stage) of the kiln tail, more attention must be paid to solving the problems of sealing the kiln end preheater system and preventing the accumulation of materials. The solutions are as follows: all the flanged parts of the preheater air pipe flanges are welded to completely prevent air leakage in this part; All levels of unloading air-locking flap valves are made of high-quality heat-resistant steel to reduce the deformation of the valve body at high temperatures to ensure the effect of air-locking; the connection between the cyclone inlet and the air duct at all levels eliminates horizontal or circular air ducts completely, the air pipe is connected with a large inclination angle (with a horizontal angle of 55 ) to avoid the accumulation of material at this part as much as possible.
The volume should meet the average residence time of the gas in the furnace is equal or more than 5.5s, because the clinker from the kiln is cooled by the water spray, which will cause the temperature of the tertiary air decrease, resulting in a corresponding increase in the fuel combustion time. It is important to ensure that the material entering the kiln has a high carbonate decomposition rate, and reduce the calcination pressure in the cement kiln.
The clinker adopts a combination of water spray quenching and grate cooler. The principle is to promote the reduction of ferric iron in the clinker to divalent iron to increase the whiteness of the clinker.
In actual cement production, the consumption of the water spray is determined by the specific whiteness and intensity control requirements that can meet the quality of the clinker. The design should ensure reasonable configuration and automatic control and operation. This kind of bleaching method can produce all high-quality white cement with a Heinz whiteness of 90 or more and a P W42.5 or more.
Due to spray bleaching, the temperature of the tertiary air will be reduced, in order to compensate and reduce its adverse effects as much as possible. It is necessary to add a layer of 40mm-60mm calcium silicate board in the lining of the tertiary air duct to enhance its thermal insulation effect.
Through the above reasonable design, it is beneficial to reduce the energy consumption on the production line, ensure the production quality of white cement, and produce cement clinker with higher whiteness and strength. AGICO CEMENT has rich experience in cement production line design and supplying cement equipment.
White Portland cement is main kind of white cement. low content of ferric oxide and other non-ferrous metal oxide of limestone, clay, silica are used as the main raw material, after high temperature calcination, quenched into cement clinker, adding suitable amount of gypsum (can also add a small amount of white limestone instead of part of the clinker) into cement grinding mill equipped with stone or wear-resistant metal plate and grinding medium.
Uses: white Portland cement is similar to ordinary Portland cement in physical properties, mainly used as decorative materials for buildings, but also for sculpture crafts. The use of white cement also includes putty powder, coating, caulking agent, binder, waterproof coating, terrazzo, artificial stone, floor tile, permeable brick, washing stone, sculpture, wear-resistant floor, color cement and so on
jk cement :: india's premier cement company
At JK White Cement Works, Gotan we use technical expertise from F.L. Smidth & Co. from Denmark and state of the art technology with continuous on-line quality control by micro processors and X-rays to ensure that only the purest White Cement is produced. We manufacture White Portland Cement through these 5 significant stages - Crushing, raw meal grinding, clinkerisation, cement grinding and packing for dispatch.
manufacturing process of white portland cement - chemistry top
White Portland cement (Royal cement) is similar to ordinary gray Portland cement in all aspect, except for its high degree of whiteness obtaining this color requires substantial modifications to the method of manufacture and because of this it is somewhat more expensive than the gray product.
The characteristic greenish gray to brown color of ordinary Portland cement derives from a number of transitional elements in its chemical composition. Therefore, These are in descending order of coloring effect. For example, Chromium, manganese, iron, copper, vanadium, nickels and titanium.
The other elements are usually not a significant problem. Limestone use in ordinary cement manufacture usually contain 0.3-1% Fe2 O3 whereas levels below 0.1% are rough in limestone for white manufacture.
Typical clays use in gray cement raw mix may contain 5-15% Fe2 O3 levels below 0.5% are desirable and conventional clays are usually replace and so a large amount of sand is usually also include in mixture.
Chromium can arise notably from the wear of chrome steel grinding equipment during the production of raw mix. This wear is exacerbate by the high sand content of mix which makes it extremely abrasive. The sand must be ground to below 45 micrometer particle diameter. Often this is achieve by grinding media to reduce contamination.
In general, the rotary kiln use to chemically combine the raw materials are operate at a higher peak temperature (1450-1500) than require for gray clinker manufacture (1400-1450). This requires a higher fuel consumption (typically 20-50% more), and results in lower kiln outputs (typically 20-50% less) for a given size kiln.
The reason for this is relatively small amount of liquid produce during sintering, because of low iron content of the mixture. Therefore, The final reaction in the kiln conversion of be lite to alit, Requires the melt liquid as a solvent and is slower if the amount of melting is low.
This reduction is vigorously avoid in case of grey cement production because of deleterious effect it can have on clinker quality. But in white clinker, production where the iron content is low, this is not an issue.
To prevent the re-oxidation of iron, quenching is perform. On the other hand, This consist of rapidly lowering the clinker temperature from 1200 degree centigrade to below 600 C in a few second as it leaves the kiln. This usually involves drooping it into cold water.
The clinker is next ground to cement. Here calcium Sulphate is add to control setting in the form of a high-purity grade of gypsum or anhydride. In some specification, a small amount of titanium dioxide may be add to improve reflectance . Therefore, At all stages, great case is need to avoid contamination with color material.
white cement manufacturing process | agico white cement plant
Our company has rich experience in white cement plant design and white cement equipment manufacturing. Our design of the white cement production line is the result of our years of technical improvement and experience accumulation. AGICO white cement plant is able to produce cement clinker with high whiteness and strength, reduce the energy consumption of the production line, and ensure the quality of the white cement produced at the same time.
The manufacturing process of white cement is similar to that of Portland cement. Compared with Portland cement, white cement has higher requirements for the calcining system in the cement plant. In the production process of white cement, the calcining system is the key part of the whole process, whose quality directly affects the product quality and energy consumption of the whole production line. Therefore, to produce white cement, it is necessary to design the calcining system reasonably.
In white cement production, natural gas and heavy oil are the most commonly used fuels in the calcining process. Because they do not contain many colored impurities themselves, using them as fuels could effectively reduce the content of colored impurities in the white cement clinker and improve the whiteness of white cement.
A small amount of fluorite will be added to the raw material of white cement as mineralizers to reduce the calcining temperature. In the process of production, the fluctuation of the mixing amount may become liquid phase ahead of time in the preheater and the high-temperature section of cement kiln, which will cause the material to stick and even lead to blocking. This kind of phenomenon may occur at any time in a place where there is cold air leakage.
1. Welding all the flange connection parts of preheater air pipes to completely eliminate air leakage;2. Using high-quality heat resistant steel as the material of blanking air locking flap valves to reduce the deformation of the valve under high temperature and ensure the air locking effect;3. Using large-angle air ducts instead of horizontal or circular arc type air ducts to connect the air duct inlet at all levels to avoid material accumulation as much as possible.
In the white cement production line, the volume of the calciner of kiln needs to meet the requirements that the gas residence time in the calciner is no less than 5.5 seconds. The reason is that the clinker out of the kiln needs to be sprayed with water and fog for sudden cooling, which leads to the temperature of the tertiary air in the calciner decrease, and thus the combustion time of the fuel in the calciner is prolonged. This is a key pinot to guarantee the high Carbonate decomposition rate of the raw materials in the kiln and reduce the pressure in the kiln while calcining.
In our white cement plant, we use the combination of spray fog quenching and grate cooler strong wind quenching to bleach the clinker out of the kiln. The principle of this method is to reduce the trivalent iron in clinker to bivalent iron, so as to improve the whiteness of clinker.
In the actual production of white cement, the water consumption of spray fog is determined according to the specific whiteness and strength control requirements of clinker quality. Our design ensures the rational configuration and automatic control of the spray water and the cooling air volume of the grate cooler.
Because of the spray, water bleaching will reduce the temperature of the tertiary air in the calciner of the kiln. In order to minimize its adverse effects, we add a layer of 40mm-60mm calcium silicate board in the lining of the tertiary air duct to strengthen its heat preservation and insulation effect.
The recommended cement mills in white cement production are vertical roller mills or ball mills. The use of these two mills is conducive to reducing iron pollution in the white cement production process.
The color of Portland cement is mainly influenced by its ratio of iron oxide. General Portland cement contains a relatively high level (3%-4%) of iron oxide, which makes it obviously gray; when the content of iron oxide drops to 0.45% 0.7%, the color of Portland cement will turn to light green; while in white Portland cement, the content of iron oxide is only 0.35% 0.4%, in addition, there are very few coloring substances such as manganese oxide, titanium oxide, chromium oxide, cobalt oxide, etc., so its color is very close to pure white.
1. During cement clinker calcination, using weak reducing atmosphere and natural gas or liquid fuel without ash powder as fuel to improve the whiteness of white cement clinker.2. Add a certain amount of gypsum with high whiteness in the cement grinding process to improve the whiteness and fineness of white cement.3. The mill lining is made of granite, white ceramic, or high-quality wear-resistant special steel, and the grinding body is made of wear-resistant materials such as silicon pebble or artificial ceramic ball to prevent sundries from mixing during the manufacturing process.
White cement (or white Portland cement) is a kind of hydraulic cementitious material, which is made of white Portland cement clinker with less iron oxide content, an appropriate amount of gypsum and mixed materials (limestone and kiln ash).
White cement is more difficult to manufacture and has higher prices than normal Portland cement. White Portland cement clinker is made of pure raw materials, such as pure kaolin, pure quartz sand, pure lime or chalk, at a higher temperature (1500 ~ 1600 ). It is generally used for interior and exterior decoration of buildings. For example, the decoration of stairs, floors, walls, etc. It is not economical to use white cement for structural purposes.
white cement manufacturing technology course
This 6 week online training course will be suitable for employees of white cement manufacturing companies, those who are considering manufacturing white cement, and employees of companies supplying equipment, goods and services to white cement manufacturers.
Module 1 - Will cover the applications and composition of white cement. At the outset students will need to know what we are making and why. White cement is an Ordinary Portland cement, as is grey cement, but with the defining characteristic of its whiteness. It is a niche product that finds application in prestige projects where the appearance of mortar or concrete is important. In many applications it provides a surface finish as flooring, precast panels, mortar screeds or even white cement based paints, rather than structural concrete. We will talk about some of these applications in a dedicated session of this Module 1. As whiteness is the defining characteristic of white cement we will also consider whiteness and whiteness measurement in a dedicated session of module 1.Module 2 - Will consider raw materials for white cement manufacture and their processingModule 3 & 4 - will consider the pyroprocessing of white cement clinker where the key differences from grey cement manufacture are found.Module 5 - we will consider the finish grinding of white cement and also the typical organisation and management of a white cement factory.Module 6 - we will review the white cement industry and players around the world. Again we will highlight the differences with the grey cement industry. And speculate on how the white cement industry might develop in the future.
The course is open to all in the cement industry and a small fee will be charged for each student. You may also use the course in a classroom situation with multi-student involvement, although certification and course monitoring can only be arranged for the people actually registered for the course.The course is conducted on-line, allowing students flexibility (within a six-week period) to complete each module and associated assessments at work or home. Students should expect to devote around 5+ hours per week/per module plus some additional time for private reading/study. A computer with internet access (broadband recommended) and email capabilities will be necessary.Throughout the course the lectures are supplemented with exercises allowing students to relate the course material to their cement factories, or the cement factories of their clients in the case of equipment or service suppliers to the cement industry. Certification is achieved by completing a satisfactory level of exercises, and by end-of -module exams.The course is complete with downloadable transcripts of the lectures, exercises, and reading material for the training record.