Increasing separation sharpness by optimization

With the aim of further improving its product quality,
Westkalk has completed an extensive modernization of its processing machinery. In the fine-grinding plant at its Kallenhardt facility, the capability of the air classifier has been significantly improved (Fig. 1). The air classifier is now capable of performing a precise cut at 1.0 mm with a feed size of on 0–2 mm. With this increased separation sharpness, Westkalk can limit the content of fine limestone in the coarser-grained products in order to meet the customers’ increased quality requirements. The volume of the modernization work amounts to around 400 000 €. In addition to the improved separation sharpness of the air classifier, its nominal capacity has also been notably increased: instead of the maximum of 90 t rock per hour it has processed up to now, it can now handle up to 150 t rock per hour.

Before the air classifier could be fitted with the new rotor, distributor plate and wear lining, the roof structure of the processing facility had to be removed above the classifier. Only in this way was it possible for an around 55-m-high 200-tonne crane to transport the new components, which weighed up to 14 t, direct to the air classifier (Fig. 2). For the work scheduled over two weeks, Westkalk deliberately chose the beginning of the year as this tends to be quieter than the rest of the year with regard to shipping products. In this period, production at the Kallenhardt Quarry could be temporarily shut down. Customers from the construction sector tend to slow down production in the winter anyway. But this year’s unusually mild winter was clearly a boon for the modernization work.

The next big winter repair will be completed in April at Westkalk’s Warstein plant. “We try to fit in with the production breaks of our key customers. In 2012 these were not at the beginning of the year nor are they set for the end of the year, but in spring”, explains Dr. Guido Mausbach, Technical Manager at Westkalk. So when the machines are scheduled to stop at the cement works operated by HeidelbergCement AG in Ennigerloh in April, any repairs planned in the scope of previously performed maintenance are undertaken at the Warstein plant. Mainly wear parts of crushers, screens, belt conveyors and chutes are renewed. For the repairs at its Warstein plant, Westkalk estimates a low six-figure amount for the total cost.