Cement, Energy and Environment

Horizontal mills are suitable for use as a single-stage grinding process in cement finish grinding systems. After some teething problems, the scaled-up Horomill process is now regarded as technically mature. More than 15 years after its introduction onto the market, --~r - more than 40 Horomills are now in operation (Figure 15), most of them for cement grinding. Compared to ball mills, an energy saving of up to 50 per cent can be achieved, and compared to vertical mills the saving is up to 20 per cent. This mill type's limitation to relatively low throughput rates is regarded as the biggest hurdle for its further marketing. The biggest mill available at present allows a throughput rate of 120 tph for 80 • ...... ::t e... 6Q QJ ~- .. "' .c 40 VI 15 Twin Horomill at Cam Pha Cement in Vietnam (FCB Ciment) normal Portland Cement. A report concerning a modified horizontal mill, called the BETA mill (Figure 16). This grinding principle permits individual setting of grinding bed depth and grinding • 2000/02 . 2007/08 Sail mill Other . Mill type . • W11hout local Chioese mali<et increasing the possibility that equally high or higher efficiencies could be achieved than with roller presses. Slag grinding The grindability of 17 Types of mill for slag grinding (OneStone) granulated blast furnace slag (GBFS) is up to 30 per cent worse than that of cement clinker, while the fineness requirements of 4200 cm 2 /g to 5600 cm 2 /g are comparatively high and the moisture content can reach 20 per cent. However, with 6 per cent of all applications, slag grinding only accounts for a minor proportion of grinding systems in the cement industry. For this reason, just a few orders suffice to alter the weighting of individual mill types. After a period of high growth rates, the market share of vertical mills recently declined from 59% to the present 45 % (Figure 17). While the share of ball mills has remained almost constant, the other grinding processes have nearly doubled their market share from 19 per cent to 34 per cent. However, this is practically restricted to roller presses, because horizontal mills have so far hardly become established for slag grinding. 7