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shkarA

class work 3 on cement production

What is Cement?

Cement is a hydraulic powder material, which reacts with water to produce strength-bearing lattices. The mixture of aggregates, cement and water is concrete. The strength and durability of concrete makes it one of the most useful materials developed by man. The chemistry and mineralogy of cement is complex. In simple terms, cement is a manmade mineral structure created at high temperatures, mainly comprising lime (CaO), Silica (SiO2) and oxides of aluminium and iron (Al2O3 and Fe2O3).

The cement making process can be divided; first "clinker" is made at temperatures of 1400 oC. Then the clinker is milled with other minerals to produce the powder we know as cement. Technology:

There are two basic types of cement production processes and a number of different kiln types. Cement production is either "wet" or "dry", depending on the water content of the material feedstock. The wet process was the original rotary kiln process developed at a time when material handing of slurries was more developed than those of dry powders. It is still being used to process very wet raw materials and allows for easier control of the chemistry. However, it has much higher energy requirements due to the amount of slurry water that must be evaporated before calcinations can take place. The dry process avoids the use of slurry material and as a result is far less energy intensive. Modern day kilns are much more efficient than the kilns of old.

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cohort 5