Date

2011

Author

Fidan, Berkan

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The conventional cement grinding system, the ball mill, has very poor efficiencies in spite of innovative improvements. For this purpose, development of new techniques, which allow proper size reduction and uniform particle size distribution with less specific energy consumptions, have become a necessity. The aim of this study is to make a comparative analysis of the fairly new cement grinding technologies, COMFLEX® Grinding System, Roller Press and HOROMILL®, at the same cement production plant with the same raw materials. In this context, CEM I 42.5 R type cement was produced with a fixed Blaine fineness of 3600 (±100) cm2/g at three different grinding units. The same raw materials, clinker and gypsum, and identical feeding ratios, 95% and 5%, were used to produce cement. Accordingly, these different grinding techniques were inspected with respect to the microstructural properties of cement particles, and the relative chemical, physical and mechanical properties of products. It was found that the main cement grinding parameters, specific surface area and sieve residue, do not show expected relation and change with each grinding system due to differences in the size reduction technique. Moreover, strength and other hardened mortar properties are directly affected by the liberation conditions of reactive grains at grinding stages.High capacity and low specific energy consumption i.e. the breaking and cracking efficiency of the roller press and higher grinding performance of the ball mill promoted the COMFLEX® system. On the other hand, the roller press was clearly advantageous at early strength performances with moderate specific energy usages during grinding. Nonetheless, it also had drawbacks like higher water demand and earlier setting times (which mean higher hydration temperatures). When the wideness and sharpness of classification results were considered, HOROMILL® gave better results with high circulation and efficient air classification design; although there were weaknesses of the system such as lower capacity and higher specific energy consumption rate.

Subject Keywords

Cement industries., Materials of Engineering and Construction.

URI

http://etd.lib.metu.edu.tr/upload/12612997/index.pdf
https://hdl.handle.net/11511/20374

Collections

Graduate School of Natural and Applied Sciences, Thesis