The raw material calcination process and cement production
The calcination process can be declared as following reaction (Stefanovic et al., 2010).
XCO3 + Heat XO + CO2
In this reaction X usually denoted as Ca and Mg. Therefore, the MgCO3 and CaCO3 are converted into CaO or MgO, these are the main component of clinker. In the CaCO3 burning process huge quantities of CO2 given off into the surroundings. This amount of CO2 directly proportional to the CaO quantity of the clinker. Roughly 65% of the clinker is consist with CaO or MgO (Van Oss et al., 2003). Furthermore, the quantity of CO2 emissions in cement production process depends on some other factor related to clinker / cement ratio, which is varied from 0.50 to 0.95. Thinning of this ratio desired to mitigate the emission per ton of cement. Considering of these status, an average of 0.50 – 0.53 kg of CO2 is produced per kg clinker (Hendriks et al., 2002 and Van Oss et al., 2003).
Combustion of traditional fuels
Nonrenewable energy sources such as coal, diesel, natural gas, fuel oil, or petroleum coke is traditionally used in the cement manufacturing process in worldwide. These sources, mainly used in kilns and preheater system to generate higher values of temperatures to produce clinker. Nearly 40% of the greenhouse gas emissions to the atmosphere in between the cement production (World Business Council for Sustainable Development, 2002)
Table 1.5 CO2 emissions per GJ of energy for several traditional fuels. (Source: Pardo et al., 2011)
kt of CO2/GJ
1.2 Global energy context
Because of the global sustainability trend new environmental friendly policies developed, world energy requirements go up more slowly than in the former, however, it will still amplify by 30% between today and 2040. (IEA, 2017).
Figure 1.8 nergy consumption by fuel source from 2000 to 2015, with growth rates indicated for the more recent period of 2010 to 2015 (Source: Global Carbon Budget, 2016 and Jackson et al., 2015)
Consider of energy demand side its shift in the rapidly growing and developing economic countries such as China and India, together with a slowing in overall energy growth as it is used ever more efficiently. And on the supply side, it’s moving into green energy sources dominant by renewable energy sources, as a result of sustainability trends and technological improvements (BP Statistical Review of World Energy, 2017)