Cements environmental benefits

Fly ash, as it is a large-volume industrial waste, is both cheap and abundant, so that there is an economic incentive to use fly-ash-modified cements. In addition, C02 is also produced as a waste by-product of industrial processes (power generation, cement manufacture, etc.), and its permanent sequestration into cement is an added environmental benefit. A fully carbonated Portland cement permanently sequesters about 130 L of C02 per kilogram of cement. Figure 15.8 shows the structural and chemical modifications produced in cemented fly ash microspheres as a result of the supercritical C02 treatment. As is the case with fly ash, kiln dusts are primarily siliceous, so that the same benefits can be derived from their use as modifiers in immobilization and S/S matrices. 

A further investigation dealt with the importance of the complementary process. CE/Delft has compared the environmental effect nsing a separated plas-tic/paper fraction from household waste as fuel in a coal-tired power plant, co-tiring it with biomass, using it as fnel in a cement kiln, or incinerating it in a municipal waste incineration plant. The largest environmental benefit was obtained substituting coal in a power plant [14]. 

Uitilization of FGD gypsum in cement-based material is feasible. It is not only for environmental uses, but also in construction and civil engineering. The results contribute to a greater understanding of how to sustainably and beneficially manage various industrial wastes and byproducts and suggest that there are also several important environmental and economic benefits that can be realized. 

Measurement. The need for cost-effective pollution prevention, efficiency improvements, and emissions meastmement has created a need for new types of integrated control and meastirement systems. One of the best methods to improve environmental performance initially is to maximize efficiency through optimization in their manufacturing and energy processes. Many cement kilns now use continuous NOx measurement at the kiln exit to feed back information to the process control to optimize combustion. Capital costs are usually small, especially if PEM/ optimization software systems can be included at the time of a control system u rade. The increased operator awareness of the plant is a benefit, and fuel savings, qualify control, and maintenance planning can quickly pay back initial costs. 

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