Cement, Energy and Environment

Ball mill 29% Other Vertical mill 61% with 34 per cent. Taken together, coal and slag grinding make up less than a quarter of all applications. All these figures have to be seen against the background of the order boom of the two years and particular account must be taken of the fact that vertical mills have the longest delivery times, other mills provide price advantages or have their own particular advantages and that therefore a decision in favour of vertical mills was made more difficult in specific cases. 2 Mill orders 2007/2008 according to mill types (OneStone) Raw material grinding applications and requirements than for others, and there is no universal mill. Instead, combination processes have been devised, or else certain mill types dominate individual applications. Figure 2 presents an overview of new mill orders in the cement industry worldwide from 2007 to 2008. These figures do not include local supplies by Chinese vendors as no precise data material is yet available for such cases. In the above two years, which will go down in history as boom years for mill suppliers, more than 660 mills were sold, 373 of them in 2007 and 289 in 2008. The above statistics take account of cancellations due to the impending world economic crisis. Of the more than 660 mills, 61 per cent (41 0 machines) were vertical mills. In the case of western vendors, 63 vertical mills were delivered to China (82 per cent for raw material grinding), while Chinese vendors delivered 5 units to clients outside China. During the stated period an estimated 300 vertical mills were supplied by Chinese vendors to clients within China. Aside from the 410 vertical mills in the above statistics, 189 ball mills (29%) and 63 (10%) other types of mill were sold. Of these 63 other mills types, 59 were roller presses and only 4 were horizontal mills, so that the last type of mill only had a total market share of less than 1 per cent in the period of time under consideration. Figure 3 depicts the percentages of the different applications. Clinker/cement grinding is the biggest market segment with 42 per cent, followed by raw material grinding 42% Slag 6% Raw material grinding has the objective of producing a homogenous raw meal from a number of components that are sometimes variable in themselves. The feed moisture contents are generally between 3 and 8 per cent, but sometimes also over 20 per cent by weight. Fineness requirements are usually <10% to 15% residue on the 901Jm screen (<1-2% residue on the 200 IJm screen) with feed particle sizes of 100-200 mm. Figure 4 shows that on this sector, vertical mills were installed in 80 per cent of all new grinding plants, after 84 per cent in the preceding period of time. Raw material 34% 3 Mill orders 2007/2008 according to application (OneStone) 2