The covering of the Sigmundshall tailings pile has been in progress for more than twenty years and is almost half completed. In contrast to the Friedrichshall tailings pile, where K+S Baustoffrecycling uses soil and construction waste from regional customers for covering, the covering material for the Sigmundshall tailings pile comes directly from the K+S site in the town of the same name. For this purpose, a substrate is used which is produced at the Sigmundshall site in the REKAL plant itself.

In this case, REKS makes another important contribution: the acquisition of salt slag from the secondary aluminum industry for the REKAL plant. The substrate used is produced from the recycling of these salt slags and consists of alumina, silicates and salt. In a patented process, these components are used to produce an outstandingly suitable material for the greening of the potash tailings pile. The substrate is applied to the heap in a layer of about five meters. After about two years, due to rain and weather, the salt components are flushed out and then plant and grass seeds are spread and watered. From now on, the further process is left to nature. And the results are impressive: “The Sigmundshall example shows that covering not only reduces the formation of salt water, but also makes a valuable contribution to biodiversity,” says Arne Schmeisky.