The companies technological collaboration is based at the Zielitz mine in Germany
Tomra Mining and K+S Minerals and Agriculture have reached a milestone in their technological collaboration at the Zielitz mine in Germany, with the success of their underground sorting pilot plant for rock salt pre-separation
The project's goals are to reduce both stockpiling and the bottleneck at the mineshaft and accommodate further mine expansion. The pilot plant is equipped with a Tomra XRT sorter, developed specifically for the conditions and requirements of the mine, helping to achieve K+S's objectives.
This project is the latest development in the collaboration between the two companies, which first began working together in 1998 when the first Tomra colour sorter was installed at the Braunschweig-Lüneburg site at Grasleben.
Zielitz's underground challenge
K+S initiated the project as part of its focus on identifying practical, long-term solutions to improve sustainability and productivity in its production and supply chains.
The company partnered with Tomra to find ways of removing barren waste underground, reducing stockpiling, which reduces the mine's environmental impact, and improving grade through the shaft.
Dr. Isabell Pfaffe, a co-author in a recent technical paper on the project, said, “The handling of backfill has been an important issue in mining for decades. The ever-increasing demands of deeper and more complex deposits, the economic necessity for economies of scale and increasing environmental regulations must be met. The lean manufacturing approach of removing worthless minerals from the material stream as early as possible and further processing the valuable minerals in a concentrated form promises numerous advantages.”
Installed and commissioned in 2022, the sorting plant features Tomra's XRT technology to identify and remove waste material, predominantly halite with a potassium content below 2%.
The three main challenges at Zielitz are:
- Stockpile reduction is necessary because the large quantity of stockpiled material implies a significant environmental protection effort
- The mineshafts bottleneck, the shaft hoists up to 45,000 metric tons per day, meaning there is no capacity to expand or return processed waste underground
- Resolving infrastructure constraints with future mine extension planned over 40km in mind, as there is no transport capacity or facilities to return processed waste as backfill into mined-out areas
Collaborating for a custom solution
Tomra created a solution, specifically for the Zielitz pilot project, based on a Tomra COM XRT 2.0 1200 sorter, which features a sensing system adapted with setup and algorithms specially designed to achieve the objectives K+S set.
The process starts with a feed system equipped with an adjustable flow divider at the main belt, directing the raw salt feed to a double-deck vibration screen. The material is then separated into defined size fractions, and the oversize and undersize fractions are returned to the main belt.
The screen mats are interchangeable so that operators can try various size ranges. Once screened, the material is conveyed to the XRT sorter to identify potash rocks and remove unwanted sodium salt.
The material identified as waste, containing a potassium content below 2.0%, is then diverted to a conveyor for backfill, whilst concentrate is fed back to the main belt and then to the shaft.
A vision for the future
The pilot project has achieved all of its objectives and demonstrated that the Tomra XRT sorter is capable of removing liberated halite.
The pilot plant currently processes 50 tons per hour, removing up to 50% of the feed as barren rocks underground, minimising the load to the shaft and enabling an increase in mining capacity.
Part of the barren waste is used as backfill to reduce the amount going to a stockpile, and the remaining 50% of the feed is blended into the main material stream to the shaft and hoisted to the processing plant.
Following the results achieved by the pilot plant, the next phase will explore the scaling up of capacity and integrating Tomra's AI-powered technology, Obtain.
Obtain uses Deep Learning to identify the properties of each individual particle, even when touching on the belt.
Jens Michael Bergmann, global segment manager of Industrial Minerals at Tomra Mining, said, “Our vision of what can be achieved in a further stage, introducing more sorters with OBTAIN, is to sort as many tons of ROM as possible. The sorted waste, which is about half of the sorter feed, is used for backfilling, and the remaining amount of high-grade product is conveyed to the shaft.”
“The aim is to increase further the K2O grade at the shaft, which will mean hoisting the same tonnage but at a higher grade in the future. This will automatically reduce stockpiling, and the downstream processing steps at the surface installations will be more efficient due to the higher potassium grade of the hoisted raw material. We have started testing OBTAIN to see how much we can increase the sorter capacity while maintaining the same performance. The initial trials at the TOMRA tecentreter have shown very promising results."
