To further improve product quality, Westkalk has undertaken cost-intensive repair and optimization work in recent weeks as part of its annual winter repairs. Whereas at the Warstein plant, the usual wear parts in crushers, screens, conveyors and materials chutes have been renewed, at the Kallenhardt plant more extensive measures were necessary. The rock washer has undergone a comprehensive revamp costing over 100 000 € (Fig. 1). “In this way, we can permanently strengthen our position on the market and assure environmentally compatible production,” says Dr Guido Mausbach, Technical Director at Westkalk.
Thanks to its limestone washing plant with chamber filter press and washing water recovery, Westkalk is one of the few limestone producers in the region able to supply washed limestone products. On the other hand, with the plant, Westkalk is also protecting the environment. “We’re happy to have the washer because in this way we can preserve the limestone deposit,” Mausbach explains. Up to 300 000 t pre-screened material is washed in the plant per year. If the material wasn’t washed, it would be unsaleable and most of it would land as rejected material on the waste heap. With the washing process, however, almost 90 % of the pre-screenings are processed to saleable products. The sludge produced is pressed to a filter cake and serves as a basis for replanting in recultivated areas of the quarry.
After a good 20 years of operation, a more comprehensive revamp of the limestone washing plant was necessary. The two around 6-t-heavy washing shafts, with which the rock material is moved in the water through large troughs, had become worn out. As reconditioning of the washing shafts installed in the years 2002 and 2006 no longer made any sense, two new ones were installed a few days ago, with the help of a heavy-duty crane (Fig. 2).
The important quality assurance measure had already been planned months previously. For work on the rock washer, only the frost season is available to us. In the Warstein plant we now have a short time window within which the big cement customers carry out their own winter repairs and we have to have completed any necessary work on our machines and equipment,” Dr Guido Mausbach explains (Fig. 3). During the repair period, which because of the weather conditions is traditionally in the first two months of the year, individual production lines at Westkalk’s Warstein and Kallenhardt facilities are shut down completely.