The challenges of rock salt sorting at the Grasleben mine
At the Grasleben mine, rock salt is extracted from a high-quality underground deposit that stretches across two Federal States. It is processed into a wide range of products, from de-icing salt for winter road services to food-grade table salts and lick stones for livestock and domestic animals. For K+S, consistently achieving certified and guaranteed high purity, compliant with the strict standards of the food industry, is a priority.
“The sorting of rock salt is complex and demanding due to its crystalline properties. This leads to strong fluctuations in the appearance of the material”, states Sven Raabe, Technische Büro Mechanik, K+S Minerals and Agriculture.
TOMRA recommended using COLOR sorting technology: “with a customized set-up of the light sources we can detect the difference in transparency of the different particles, ensuring the high quality of the rock salt,” explains Mathilde Robben, Key Account Manager at TOMRA Mining. The team also advised installing the sorter in the underground mine, so that “after an initial underground sorting stage, only the coarsely crushed rock salt undergoes further grinding and sieving above ground. Only the valuable product needs to be transported in the shaft, and the final result is high-quality, pure rock salt products in various grain sizes, which are ideal for this application. Furthermore, waste rejects can be backfilled underground, avoiding storage and emissions on the surface.”
In this project we also had to contend with the difficulties created by the Covid-19 pandemic. I am very pleased that we have been able to meet K+S's requirements and deliver on schedule.