PDF《Combining forces》

1 C feed (product from HPGR)

2 C primary air inlets

3 C baffle plates

4 C guiding plates

5 C outer cone

6 C coarse discharge → back to HPGR

7 C guide vanes

8 C rotating cage

9 C motor

10 C inner cone

11 C middlings discharge → to ball mill

12 C feed (product from ball mill)

13 C product and air discharge Figure 5: a 2-Stage Koesep is installed at an Austrian cement plant

58 GRINDING OPTIMISATION INTERNATIONAL CEMENT REVIEW JANUARY

2017 fineness leaves the 2-Stage Koesep classifier at outlet (13) together with the separation air. For both classifying stages only one fan is necessary. This set-up is patented in Germany4 and Europe,

5 with patents pending in additional countries. While the compact 2-Stage Koesep air classifier was mainly developed for cement production with an HPGR working in semi-finish grinding circuits and a downstream ball mill, it can also be adapted to systems with only one HPGR in finish-grinding mode or even single ball mill units. Case study: grinding upgrade at Austrian cement producer An Austrian medium-sized cement manufacturer, which produces both standard cements and highly-specialised building materials, upgraded its grinding unit in

2015 with a 2-Stage Koesep system. Prior to this upgrade, an HPGR was used in pre-grinding mode with partial flake recycle in combination with a downstream ball mill in closed circuit with a dynamic air classifier. The modernisation aimed to reduce the grinding system'

s energy consumption as well as its CO2 footprint, while at the same time increasing production capacity. The operation of the HPGR was changed to semi-finish grinding using the K?ppern 2-Stage Koesep classifier (Figure 5). To maintain a high productivity rate at the cement plant during the project implementation it was important that the old grinding system continued operation. Therefore, two splitters were installed which allowed the operators to switch between the former and the upgraded system (Figure 6). Hence, most of the erection could be accomplished while production was running at full capacity on the old system. As a result the downtime of the plant during the whole upgrade totalled just 40h. The changeover of the different cement types from the former to the new grinding system went smoothly without major issues. Following a short testing period, the correct settings were determined and the same product quality was achieved, which shows that the 2-Stage Koesep classifier has a fully reproducible performance. This Figure 6: upgraded grinding system at an Austrian cement plant: HPGR in semi-finish grinding mode with the K?ppern 2-Stage Koesep (former air classifier remains available as back-up system)

1 C Polysius High-Pressure Grinding Roll (HPGR): P = 2x160kW, roller diameter = 1.0m

2 C K?ppern 2-Stage Koesep 1850-2S: rotor diameter = 1.85m

3 C Polysius two-chamber ball mill: P = 1500kW, LxW 2.8m x 15.0m

4 C Hischmann HZ 32/2: rotor diameter = 3.2m (back-up option) Figure 7: capacity increase by upgrading an HPGR in pre-grinding mode into semi-finish grinding mode with 2-Stage Koesep using the example of a cement plant in Austria One of the most efficient cement grinding technologies is an HPGR oper........