Cement Energy Environment

41 Figure 4: Primary benefits of the polysius® booster mill are improved opportunities for the production of low- clinker cements, more flexibility to upgrade the cement portfolio to high-performance cements, and opportunities to increase the production and / or save electrical energy. The current design of the mill has a capacity of roughly 20-30 t/h of clinker at a geometrical footprint of approximately 10 m x 2 m. It can be incorporated in an existing grinding system to amend the overall performance with respect to fineness, energy consumption and/or throughput. Tests and successful operation in a pilot plant on an industrial scale have shown that this mill covers a wide range of application scenarios and, thus, revealed a variety of economically interesting fields of application. The large quantities of waste are a threat to the environment and lead to social tensions between developing, emerging and industrialized countries because of sometimes inadequately controlled global disposal routes. However, due to their content of combustible materials, certain wastes can also relieve the Environment if, for example, they replace fossil fuels. In Europe, this development began as early as in the 1990s, has always been primarily characterized by questions of economic efficiency and is now gaining globally additional importance due to the principle of sustainability. One of the many restrictive boundary conditions for the use of waste is the particle size. In both primary and secondary firing systems, in principle only materials that are able to fly and burn out completely in the gas stream can be used. Thus, many wastes can only be used if they are shredded. In many cases, this makes them no longer economically viable. The polysius® prepol ® SC technology aims at the use of fuels of low qualities, in particular characterized by ultra-coarse particle sizes and high moisture contents. polysius ® Fuel Substitution Strategy - Use of Coarse Alternative Fuels Such materials can be incinerated in the combustion chamber attached to the calciner, facilitating a waste residence time of more than 1,000 seconds at high temperatures, instead of only seconds in the calciner. In addition to conserving natural resources and mitigating emissions, the overall operating costs for fuel substitution are also comparatively low. This is made possible by the use of a wide variety of waste types, low requirements on the quality of the waste and low pre-processing costs. Another factor is that 80 % of the thermal energy generated in the combustion chamber can be used directly in the process and the remaining ash is incorporated in the cement clinker (Figure 5).