The challenge of tailings pile water
The crude salts underground have a certain natural composition. In Germany, up to 30 percent of the amount mined can be used for fertilizer production. The remaining residues are stored in tailings piles, as is common practice in potash production worldwide.
When precipitation falls on the tailings, it creates saline water - so-called tailings pile water - which has to be disposed of properly. This is currently done mainly by discharging it into rivers close to the site. These discharges are strictly regulated and are not possible when the rivers are low. In some cases, tailings pile water is transported by truck or rail to distant mines for discharge.
We do not consider river discharge to be a permanent disposal option as we continue to reduce our impact on water and the environment. We are also subject to regulatory requirements. Transporting the water to mines far from the site is also not a sustainable solution, as these mines can only accept limited amounts of tailings pile water. We are, therefore, constantly looking for ways to reduce and, in the long term, eliminate tailings pile water.
After decades of intensive research projects, tailings pile covering has been proven to be an efficient, practical, and sustainable way to mitigate tailings pile water.
Covering: Increased evaporation, less tailings pile water
Before
When precipitation falls on a tailings pile, saline water is generated. The amount of water varies greatly depending on the amount of precipitation. Only a small amount evaporates; most of it is collected in the tailings pile trench and later disposed of.
Without covering: little evaporation, more tailings pile water
After
Covering the tailings pile reduces contact between precipitation and the saline residue. Covering also absorbs some of the precipitation and allows it to evaporate. If the cover is vegetated, the plants absorb additional rainwater and release it at different times. This increases evaporation, reduces the volume of the tailings pile water and decreases its salt concentration.
With covering: more evaporation, less tailings pile water
Examples of covering the tailings piles
Due to the different characteristics of each tailings pile - such as surface area, height, subsurface topography and, composition of the tailings material - the tailings pile cover has to meet specific requirements. In the course of decades of research, K+S has developed, tested, and partially implemented various options. The prerequisites are materials with defined properties and long-term availability.
Each site requires its own saline water reduction concept, because each tailings pile is different. In the past, cover types were implemented in their pure form. In the future, combinations are more likely to be used in order to optimally exploit the advantages of the individual types of cover. Together with the responsible authorities, K+S is striving to relieve the environment in the long term.
