K+S Minerals and Agriculture operates in a sector that is recording a growing trend. According to the “Global salt market size 2019-2025” report published by market and consumer data provider Statista, the global salt market was valued at about 28 billion US$ in 2019 and is forecast to exceed 32 billion US$ by 2025. The industry growth is driven by a rise in the demand for salt applied in the chemical manufacturing industry – especially in chlorine-alkali chemicals production.
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 agreed installing the sorter in the underground mine as requested, 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.”
Testing the solution at TOMRA’s Demonstration and Test Center in Wedel
TOMRA conducted a demonstration of the proposed solution at its Demonstration and Test Center in Wedel. Sven Raabe attended the test with colleagues from K+S’s technical team, Florian Lieske, Stephan Meiberg and Sven Lindner.
Seeing the technology in action was decisive: “The tests were very well prepared,” says Sven Raabe. “The on-site team quickly developed a feel for our product. The uncomplicated adaptation of the program to the different material qualities also convinced us. An important factor in our purchasing decision was the positive test result achieved with the system, using transmitted light to obtain more efficient separation. It is possible to react quickly and individually to changing situations during mining. We expect this to be more effective, and the ease of use of the system was also convincing.”
The order was placed and installation completed on schedule
Following the positive experience at the Test and Demonstration Center and the results of the test, K+S placed the order for TOMRA’s solution, with installation planned for September 2020. The negotiations were conducted via video conference due to the Covid-19 travel restrictions and lockdown. The order was entered in TOMRA’s production plan and the Factory Acceptance Test was conducted on September 23, 2020. The sorter was transported to the Grasleben mine, where it was placed in position underground on September 30, 2020 and installation was completed on schedule.