The flotation process is meanwhile used at all production locations to separate potash and Kieserite from the dissolution residue.
This makes possible a considerable reduction in the liquid salt waste, which resulted from the previously common Kieserite washing process and had to be disposed of. The basic principle of the process is based on the fact that the minerals that are to be separated are suspended in a saturated salt solution, into which air is blown.
To ensure that the air bubbles only adhere to particular kinds of minerals, these are specifically "lubricated" by adding a small quantity of special flotation agents, and made water-repellent. Only these minerals will then adhere to the air bubbles. The Kieserite that is to be separated then floats to the surface as froth, and can be skimmed off.
The rock salt remains at the bottom of the flotation cells, and, after being separated from the liquid, is stockpiled or transported to large underground cavities.
The success of this sorting process depends on the fact that the minerals that are to be separated from one another are not aggregated, but are milled to a fine particle size beforehand. This process results in scarcely any surplus salt solutions that have then to be disposed of.