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Ceramic industries

Ceramic industries
Manufacturing Process of Portland Cement
Mixing wet process
Storage and packaging

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Ceramic industries

  1. 1. GUJARAT TECHNOLOGICAL UNIVERSITY Subject : Chemical Process Industries Sem-3 (Chemical) Topic : Ceramic Industries
  2. 2. Cement Cement is a powdery substance made by calcining lime and clay,mixed with water to form mortar and mixed with sand to form concrete.  Manufacturing Process of Portland Cement Raw materials:- 1.Calcareous materials:-CaO , Lime 2.Agrillaceous materials:-𝐴𝑙2 𝑂3 , 𝑆𝑖𝑂2 3.Powdered coal 4.Gypsum
  3. 3. Lime Stone Crusher Grinder Raw material Kiln Clinker Additives Grinder Cement
  4. 4.  Flowsheet of Portland Cement
  5. 5.  MANUFACTURE PROCESS It involves the following steps:- 1.Crushing 2.Mixing wet process 3.Grinding 4.Kiln 5.Grinding 6. Storage and packaging
  6. 6. 1.Crushing:- This is the first step in the manufacturing of Portland cement. Jaw crushers of various sizes are use for the crushing process. Raw materials are crushed by crushers till the size of the raw material reduces to ¾ of an inch. It is then send for either wet process or dry process. 2.Mixing wet process:- calcareous materials are crushed , powdered and stored in bins. Argillaceous materials is mixed with water and washed. Then it removes any adhering organic impurities. Powdered, calcareous and washed argillaceous materials are mixed in proper proportions to get a slurry. This slurry is then fed into a rotary kiln.
  7. 7. 3.Grinding:- Grinding can be done by the two stages. 1.Ball mill 2.Tube mill 4.Kiln:- Slurry is brunt in rotary kiln. kiln is divided into three zones 1.Drying zone – 200-500°c 2.Calcinating zone – 1000°c 3.Clinkering zone – 1400-1600°c 1.Drying Zone :- This is the upper part of the kiln. Temperature is maintained about 200-500°c. Most of water gets evaporated from the slurry by means of hot gases.
  8. 8. 2.Calcinating Zone:- This process is done in the middle portion of the kiln. The temperature is maintained about 1000°c Here in organic matter burns away and 𝐶𝑎𝐶𝑂3decomposes to quick lime and 𝐶𝑂2 escapes away. Materials forms small lumps formed. 𝐶𝑎𝐶𝑂3 CaO + 𝐶𝑂2 3.Clinkering Zone:- This is the lower portion of the kiln. The temperature is between 1400-1600°c. Here lime and clay nodules melts with chemical fusion and gives calcium aluminates and silicates. And then forms small hard stones called clinkers and then cooled to form crystals. Lime stone Quick lime
  9. 9. 2CaO + 𝑆𝑖𝑂2 𝐶𝑎2 𝑆𝑖𝑂4 3CaO+ 𝑆𝑖𝑂2 𝐶𝑎3 𝑆𝑖𝑂5 3Cao+𝐴𝑙2 𝑂3 𝐶𝑎3 𝐴𝑙2 𝑂6 4CaO+𝐴𝑙2 𝑂3 +𝐹𝑒2 𝑂3 𝐶𝑎4 𝐴𝑙2 𝐹𝑒2 𝑂12 5.Grinding:- Clinkers are finally grinded in the ball mill and tube mill to a fine powder. 6.Packing:- Cement is stored in bins from which it is fed to automatic packing machines.Each bag usually contains 50 Kg of cement. Major Engineering Problems:- 1.Grinding 2.Kiln design 3.Heat economy 4.Quality control
  10. 10.  CERAMIC INDUSTRIES Ceramic is an inorganic,nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous(e.g. glass).  The word"ceramic" comes from the Greek word Keramos means burnt stuff. Earlier the term ceramic was applied to products made from natural earth material that was not exposed to heat. But nowadays the silicate mainly used in the construction industries and prepared by burning the clay products are called as ceramics.
  11. 11.  CLASSIFICATION A broad sense classification divides the ceramic products in to two classes 1.Heavy clay products e.g. bricks, roofing tiles, drain tiles, hollow tiles, stoneware and refractories 2.Pottery products e.g. chinaware, wall tiles, electric insulation Ceramic may also be classified as 1. porous 2.non-porous  The porosity is depends on particle size, moulding pressure and temperature of vitrification.
  12. 12.  Further, ceramic may be classified based on the method of production and its uses into following classes: 1.Whiteware 2.Structural clay products 3.Refractory material 4.Special ceramic products 5.Vitreous enamel  RAW MATERIALS  The raw materials for ceramics are divided into following groups: a)Plastics material such as clay b)Fluxes such as feldspar c)Non-plastics materials such as silica
  13. 13. a)Clay:-Clay gives the main body to the ceramics. The advantage of using clay are it is plastic when mixed with water becomes hard after drying and finally it becomes irreversibly solid after firing. Clay is chosen according to the requirements of particular products and Is often blended. Impurities in common clay incorporate specific qualities as follows.  Iron oxide in common clay gives red colour to the burnt material.  Lime, magnesia, iron oxide and alkali oxides act as flux which lowers the fusion point of clay.  Silica increases its porosity and refractory nature, while decreases shrinkage.  Clay containing very little and good deals of silica known as fire clays.
  14. 14. b)Feldspar Feldspar is general name given to the group of minerals. Flux materials like feldspar (Na2OAl2O3.6SiO2) which is easily melting material decreases the melting point of sand or quartz present in the ceramic body. So, that after firing glass like material is obtained called as vitrified material, which is highly impervious and stable to the environment. Fluxes are used for adding vitrifications, reducing porosity, to increase the strength of cold articles and for bonding. Feldspar is used as fluxing constituent in ceramic formulations along with clay. The common fluxing agents which lower the temperature are borax, boric acid, soda ash, sodium nitrate, potassium carbonate, calcined bones, lead oxides, lithium & barium minerals.
  15. 15. Type of feldspar Potash feldsparK2O.Al2O3.6SiO2 Soda feldspar Na2O.Al2O3.6SiO2 Lime feldspar CaO.Al2O3.6SiO2 c)Silica or quartz The non-plastic or leading admixture like sand or quartz gives strength to the body. It is incorporated in ceramic formulation to reduce shrinkage and cracking which is occurs during drying and firing.
  16. 16. USES Ceramic is one of the oldest materials used in construction with the time quality and decoration has been added to its property and therefore they are at present used in following: 1. Construction and decoration as bricks and tiles 2. Metallurgy as construction material of furnace 3. Chemical products as stoneware and porcelain 4. In drainage of water 5. In sanitation The small uses includes pottery work, specialty ceramic like peuzo electric and insulation material in electrical connections Therefore, we conclude that ceramics deals with manufacture and technical characteristics and raw material for article building.