Where fox and hare say good night to each other on the green tailings pile
The covering of the Sigmundshall tailings pile is progressing year by year. For some time now, the large salt mountain has been surprising with green grass, colorful flowers and a great variety of animals.
Rich flora and fauna
Every nature lover is thrilled by this view. Lush greenery, lots of colorful plants as well as bumblebees and bees buzzing everywhere, butterflies and other insects flying. No, the observer is not standing in a park or a garden, but on the tailings pile at the Sigmundshall site. How successful a tailings pile cover can be is particularly visible here in the summer of 2021.
"Step by step, nature is taking the reins again," says Claudia Janák, Head of Environment and Permits at Sigmundshall, describing the positive development at the tailings pile. "Even foxes, hares and deer live in the already greened flanks of the tailings pile," says Janák. She can even watch the animals sometimes in the evening from her balcony on the nearby Tienberg. Birds of prey such as the buzzard, the kite or the kestrel have also had their nesting sites here for several years.
Step by step, nature is taking the reins again.
Covering material produced on site
The aim of the tailings pile cover is to greatly reduce the formation of saline tailings pile water caused by precipitation and therefore to avoid eternity burdens as far as possible. The tailings pile at Sigmundshall has been covered for a good 20 years. A substrate is used that is produced on site in the REKAL plant itself. It is produced by recycling salt slag from aluminum production and consists mainly of alumina, silicates, and salt. This substrate, which is ideally suited as a covering material, is applied to the tailings pile at a thickness of about 5 meters. It initially remains there for about two years, until the rain has flushed out the last salt components. Then grass or plant seed is applied to the areas. At the beginning of the greening and on the southern flanks with high sun exposure, watering is still necessary at first. After some time of growth, this is also no longer necessary, and the areas can be completely left to nature. "By covering and recultivating the tailings pile area, more than 80 percent of the resulting tailings pile water then evaporates here," explains Janák.
More than 150 plant species have now settled on the top of the tailings pile and on the vegetated flanks of the pile. That is very impressive!
Around 40 percent of the large salt mountain has been covered. The progress is already very visible from a distance, for example when approaching the plant from the direction of Wunstorf. "More than 150 plant species have now settled on the top of the tailings pile and on the vegetated flanks of the pile. That is very impressive!" says plant assistant Marco Szykora, who works in the REKAL plant at the site and frequently accompanies visitors on and around the tailings pile.
Covering a tailings pile takes decades
Despite the good progress, it will take another ten years or so before the Sigmundshall tailings pile is completely covered in vegetation. "You have to have a lot of staying power when it comes to covering a tailings pile," says Silvia Niessing, Head of Team Tailings Piles at K+S. "It usually takes several decades to completely green a large tailings pile," she explains. "At each of our sites, there are specific conditions we need to consider when covering the tailings piles," says Niessing's colleague Arne Schmeisky, who is responsible for tailings piles at the REKS joint venture. "Through the successful greening at Sigmundshall, however, we have gained a great deal of knowledge contributing to the coverage of other K+S tailings piles."
It usually takes several decades to completely green a large tailings pile.
Accordingly, over the coming years the last remaining open areas of Sigmundshall's "Monte Kali" will gradually disappear, one by one. The future of the green mountain is still unclear. However, it is already clear that the greening of the tailings pile in Sigmundshall is a success story of the renaturation of a large, former industrial area.