The external circulation technology of raw material roller mill is a new stage in the development of roller mill system. The external circulation reform of the raw material roller mill system can save energy remarkably. After the external circulation reform, the power consumption of the raw mill system is comparable to that of the raw material final grinding system of the roller press. The reform of external circulation roller mill of raw material final grinding system can retain the equipment and foundation of the original roller mill. Compared with modification of the raw material final grinding system with the new roller press, it can save about half of the investment and reach the energy consumption index equivalent to that of the raw material final grinding system of the  roller press. In 2018, Tianjin Cement Industry Design & Research Institute Co., Ltd. carried out two projects. Practice shows that this kind of modification can improve the system output, reduce raw mill fineness, and reduce the power consumption of the raw mill system by 4kWh/t compared with that before the external circulation reform.

The stability and dispersion of graphene lamellae in cement are the key points to play the toughening role of graphene. In this paper, the graphene lamellae were transformed into aerogel to achieve uniform dispersion of graphene sheets on three dimensional scales. Subsequently, the graphene aerogels were introduced into the cement system to investigate the effect of graphene aerogels on the mechanical properties of cement composites. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, laser micro-Raman spectroscopy, scanning electron microscopy, universal testing machine and dynamic mechanical properties were used to characterize the surface chemical state, micro-morphology and mechanical properties of the materials. The results show that the graphene aerogels with relatively stable properties can be prepared by Hummers oxidation method combined with hydrothermal reaction process, and the characteristics of carbon atoms in aerogels are similar to those of graphene lamellar carbon atoms. Graphene aerogels have obvious toughening effect on cement-based materials, which shows great potential for application.