Manufacturig of Cement

MANUFACTURING OF CEMENT:
  1) Early History
Cement is very important building material which was first introduces by an English Mason Joseph Aspdin. He found it when strongly heated mixture of limestone and clay was mixed with water and allowed to stand, it hardened to a stone like mass which resembled Portland rock; a famous building stone of England. Since then the name of Portland Cement is given to the mixture of lime (obtained from limestone), silica, iron oxide and alumina.
This was the start of Portland cement industry, as we know today. The cement is now low in cost, as it is applied everywhere in the construction of houses, public buildings, roads, industrial plants, dams, bridges, and many other structures.
  2) Definition
Cement is the material obtained by burning an intimate mixture of calcarious and argillaceous materials at sufficiently high temperature to produce clinkers. These clinkers are then ground to a fine powder.
The essential constituents are lime (obtained from limestone) silica and alumina (present in clay).
  3) Raw Materials
The important raw materials used for the manufacture of cement are:
  i) Calcarious material (limestone, marble, chalks, marine shell) as source of CaO.
  ii) Argillaceous material (clay, shale, slate, blast furnace slag). They provide acidic components such as aluminates and silicates.
  iii) Other raw material being used in gypsum.
  4) Manufacturing Process of Cement
The manufacturing process of cement involves either a dry process or a wet process. The choice of dry or wet process depends on the following factors.
  i) Physical condition of the raw materials.
  ii) Local climatic condition of the factory.
  iii) The price of the fuel.
In Pakistan most of the factories use wet process for the production of cement. Dry process needs excessive fine grinding and it is more suited for the hard material, Wet process, on the other hand, is free from dust, grinding is easier and the...