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Cement industry

  1. A cement is a binder , a chemical substance used for construction that sets, hardens and adheres to other materials to bind them together. “Building material obtain by burning intimate mixture of calcarious and Argillaceous materials.”
  2. F0R EXAMPLE: Lime stone(calcium carbonate) give us CaO. Those material which provide us CaO. So it is included in calcarious material.
  3. Those material which provide us clay. FOR EXAMPLE: • Silica(SiO2) • Alumina (Al2O3)
  4.  Calcariouus materials: Marble, Lime stone, Chock, Mrine shells  Argillaceous materials Silica(SiO2), Alumina (Al2O3)  Gypsum CaSO4.H2O
  5. There are two process: Dry process Wet process
  6.  In this process lime stone broken into pieces.  Clay mixed with it and pulverised to such a fine powder.  90 to 95%of this powder passes through a 100 mesh sieve.  The mixture is made homogeneous and this mixture is known raw meal.
  7.  Crushing and grinding of raw materials by cylindrical ball and tube mills.  Lime stone (75%) and Clay(25%) mixed under compressed air and Slurry is formed.  35 to 40% water filtered and 20 to 30% left.
  8.  An heating cylindrical vessel is used.  It has 4 chambers in which four steps occurs: • Pre heating zone • Decomposition zone • Burning zone • Cooling zone
  9.  Decomposition of Clay at 500°C.  In this process we obtain: • Silica(SiO2) • Alumina (Al2O3)
  10.  Decomposition of Lime stone at 900°C.  In this process we obtain: • CO2 • CaO  CO2 is evolved and CaO left.
  11.  In this process product of previous two steps are combined together at 1500°C.  CaO ,Silica(SiO2) and Alumina (Al2O3) are combined together.
  12.  In this process we decrease the temperature till 600°C.  Then small size particles formed which are reffered as clinker(Gryish black colour).  And after this we add 2% gypsum in clinker which is third raw material.  Cement is formed after all these process.
  13. Ca.Al2O3+6H2O Ca.Al2O3.6H2O Hydration Ca.Al2O3.6H2O+CaSO4.2H2O CaO. Al2O3 +3CaSO4. .2H2O Calcium +Sulphoaluminate.
  14. 3CaO.SiO2 (Hydration) H2O 3CaO.Al2O3 Al(OH)3 H2O (Needle shaped crystals)
  15. DG(deputy general)cement is a Pakistani building material company.  It is the largest cement manufacture of Pakistan with a production capacity of 14000tons per day.  This company has 3 plants which are presents in khairpur Chakwal, Dera Ghazi khan and Hub Balochistan.
  16.  China produce the most cement globally by large margin at an estimated 2.5 billion metric tones in 2021.  60% of world cement prepared in china.  India was the second largest cement producer in world with production amount to a distance 330 million metric tones in 2021.