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Resources conservation, energy saving and abatement of CO2 emissions are subjects of increasing topicality. The cement industry as an energy-intensive sector is making great efforts to save primary fuels and electrical energy. One possibility is offered by the use of clinker substitute materials such as granulated blast furnace slag. The energy consumption for finish grinding is still very high, but can be reduced by using efficient grinding systems. Grinding of blast furnace slag and cement in vertical roller mills reduces the specific power consumption efficiently. Due to the market demand for higher throughputs grinding systems with high availability and versatility are requested. In the early 1970s Loesche introduced the module system with individual grinding rollers in its mills for producing raw meal. It is possible to operate large mills for grinding cement raw materials with drive ratings of up to 7,000 kW and throughput of up to 1,000 t/h without any problems. This system has also been adapted for grinding blast furnace slag and cement. Since 1994 Loesche mills with the so-called 2+2 and 3+3 technology have been used for grinding blast furnace slag and clinker. Loesche mills are designed for a wide range of properties of feed materials. The process provides a good drying capability, particularly for the grinding of blast furnace slag, as grinding, separation and drying are taking place in the mill,. For more than 10 years these mills have proved their worth in many installations. Their high flexibility with respect to cost-effective grinding of a wide variety of mill feeds, their high level of availability as well as their energy efficiency make any grinding plant using a vertical roller mill into a cost-saving grinding system. Loesche has sold by today more than 130 mills for blast furnace slag and cement grinding worldwide. In the following paper the technology used by Loesche for grinding blast furnace slag and cement is described. A report of operating experience (plant layouts, performance data for cement and slag grinding, product quality) with different mill types is given.