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Engn. Analyis 2a
Lime and Cement 2
Question | Answer |
---|---|
Calcination? | Limestone(CaCo3)+Heat = Calcium oxide (Cao) +CO2.However Cao (Quicklime) is Unstable in the presence of moisture and CO2. A more stable form of lime is calcium hydroxide. |
Reaction of Slaked Lime? | Cao+H20 = Ca(OH)2 +Heat. |
How was Cement originally made? | By adding crushed volcanic ash to lime, |
What is Sintering? | Heating the cement at a high enough temperature so that a small proportion of the material melts but the bulk of it remains solid. and it produces a material called clinker. |
How is Portland Cement made? | Portland cement is made by heating suitable raw materials, typically a mixture of finely ground limestone and clay at a temp. of about 1450c to produce a dark grey nodular material called clinker. |
Highlight the main components of a cement works. | Quarry (raw materials) = Crushers and mills = Silos for raw material blending = Kiln = Clinker store = Cement Mill. |
Name the typical rock types used in cement production? | Limestone (supplies the bulk of the materials). Clay, marl or shale (supplies the bulk of the silica, alumina and ferric oxide). supplementary materials such as, fly ash or ironstone to achieve the desired bulk composition. |
What is Marl? | Marl or Marlstone is a Calcium Carbonate which contains variable amounts of clays. |
What is Shale? | Shale is a sedimentary rock that was once deposited as mud (clay and silt) and is genrally a combination of clay, silica carbonate and organic materials. it may also have thin beds of sandstone or limestone. |
What is Ironstone? | Iron-stone is a fine-grained, heavy and compact sedimentary rock. |
Explain the Cement making process! | Raw materials from excavation site, are deposited in a crusher and are turned into rough ground limestone. they are then passed unto another secondary crusher and turned into fine ground limestone. |
Explain the Cement making process Contd? | the finely grounded lilmestone is then sent to the proportioning equipment where sand and clay are added. this mix is then sent to the grinding mill which grinds all the supplements and limestone together and then sends the mix to a preheater tower. |
Explain the Cement making process Contd 3 ? | In the preheater tower, the clay, sand, and limestone are heated up and then sent to the Kiln, where clinkering occurs and clinker is produced.it is then mmoved to a clinker cooler |