Cement is the most important ingredient in the field of construction because of its unique property and usefulness that meet the requirement of construction of small and heavy engineering. Thus it is necessary to understand the cement production in order to know the unique characteristics and properties of cement.
Raw materials for cement production :-
The most basic raw materials required for cement production are generally the part of igneous rocks. This constituents lime stone, (which is the major components of cement) clay and marl or shale. With the technological and research advancement the ingredient comprising in the cement has seen a few additional ingredients. Some of the industrial wastes like silica fumes and fly ash has found its uses in cement production as they resembles the vary property of cement and enhances the working.
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Collection Of Raw Materials For Cement Production:-
The raw material required for cement production are generally obtained naturally apart from some of the additional ingredients which are conveyed by the cement production industries from different industries.
Lime stone :- Lime stone is the most important component of cement as it is already stated earlier. It is obtained from blasting the quarries of lime stone. The quarries of lime stone are firstly identified and blasted by using detonators and the broken blocks of lime stone are collected. This collected lime stones are then primarily crushed into 6 inches of small pieces. They are then secondarily crushed into 3 inches of lime stone pieces. This secondary pieces of lime stone are sent to the cement producing factories for the purpose of making cement.
Clay, Marl or Shale :- They are collected naturally.
Collection of additional Ingredients :-
Silica Fumes and Fly Ash
Silica Fumes :- Silica fume is a by product obtained from the smoke that are released in electric blast furnaces. These smokes are collected and sold as silica fume which act as a admixture in the cement production.
Where as fly as is a pulverized fuel ash. It is generally a residue generated by coal combustion which is so fine that it fly along with the flue gas and thus they are called so. The collection of fly ash is done by capturing it by elctro static precipitators before the flue gases reach the chimneys of coal fired power plant and further they are transported for the cement production to the factory.
Process of cement production :-
Mixing of raw materials :-
After the collection of raw materials from different sources, the processes of cement production follows the mixing of raw materials. In this step the raw materials are mixed in the required proportion for better outcome during and after the use of cement.
Kiln :- After the mixing of raw materials in its required proportions, the mix is fed to kiln. In kilns the cement mix is generally heated in different temperature zones which enables it to release various unwanted substances in the form of gasses and create a favorable condition for the various chemical reaction to undergo. The ingredients are heated to about a temperature of 2700 degree Fahrenheit. In general kilns used for the cement production are huge cylindrical chambers of steel which are inclined at a certain angle with the horizontal so that mixed ingredient fed to the can move forward continuously. with the release of unwanted substances and continuous undergoing of chemical reactions, the cement becomes more and more unified to form clinkers of cement. These clinkers of cement comes out of the kiln in red hot form from the lower end of the kiln. They are than guided through different cooling systems to bring the down the overall temperature to handling temperature.
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Grinding :- Afterwards when the clinker is cooled it is fed to grinding department of the cement production company, where it is grinded into the fine particle of the cement. But cement production does not ends up here. After grinding the grinded material carried through another process in it is mixed with a small amount of gypsum (about 4%-5%). The addition of gypsum is very important because it controls the rate of hardening of the cement. It basically controls the rate of setting, and if it is not been added to the cement than it will set immediately after mixing of the water leaving no time for placing .
Once the cement is mixed the gypsum the cement is ready for packaging and selling .