PRECONCENTRATION AND ORE SORTING
Facilitating industry sortability
The Advanced Mineral Processing Technologies( AMR) department at RWTH Aachen University is an academic institution focusing on the processing of mineral raw materials. The group’ s overarching mission is to advance the scientific foundations and technological innovations underpinning modern mineral processing, with particular emphasis on developing efficient and sustainable processing solutions for the mining industry, including in the field of SBS.
AMR’ s research and teaching activities form an essential part of the broader field of mineral resources engineering at RWTH Aachen University, combining fundamental research with industrially oriented application projects.
At the core of the group’ s experimental work is a fullyequipped technical centre, hosting approximately 70 operational units that represent the major process stages of mineral processing. These include equipment for material characterisation and analysis, comminution, classification, and separation and sorting, as well as a flotation lab.“ This comprehensive infrastructure allows the institute not only to replicate conventional beneficiation circuits but also to design and test novel process configurations under controlled technical conditions,” Tobias Vraetz, Director of AMR, told IM.“ The technical centre thus represents a bridge between laboratory-scale research and industrial-scale implementation.”
One central research focus of the institute has been the field of SBS. Over the past years, the AMR has developed and evaluated various SBS concepts and technologies, ranging from optical and nearinfrared( NIR) sensors to X-ray-based sensor systems.“ These developments have been supported by both fundamental investigations into sensor-material interactions and extensive test campaigns designed to evaluate sorting capabilities under realistic operating conditions,” Vraetz explained.
The institute operates as an independent academic research entity, free from commercial dependence on equipment suppliers or sensor manufacturers, hence its relevance to this conversation.
This independence is crucial, Vraetz says, as it ensures objectivity, methodological credibility and the ability to conduct truly manufacturer-neutral comparisons of different technologies in the field of mineral processing.“ By maintaining this autonomy, the AMR can perform unbiased assessments and methodological studies that focus solely on the scientific and technical validity of results rather than on commercial and sales interests,” he said.
To support its SBS research activities, the institute maintains a wide range of sensor technologies such as RGB imaging, NIR spectroscopy, laser-induced fluorescence, and, of particular importance, XRT.“ This setup facilitates systematic experiments that explore how composition, grain size, liberation degree and internal material structure influence sensor response and separation outcomes,” Vraetz says.
The availability of such XRT equipment enables direct comparative studies with conventional beneficiation processes, such as density separation using jigging or other solutions, contributing to an integrated methodological understanding of sorting strategies.“ All experimental investigations are carried out independently of specific sensor types or commercial manufacturers, emphasising a purely methodological and datadriven approach,” Vraetz added.
This has set the AMR up to conduct objective studies on the sortability of minerals, including and addressing topics like techno-economical feasibility as well as a focus on sustainability.
Vraetz added:“ These studies address a wide spectrum of industrially relevant questions, including the identification of sorting limits for specific minerals, evaluation of new sensing principles, and integration of SBS into conventional processing chains and plants. The results contribute both to the academic advancement of mineral processing science and to the practical optimisation of resource recovery strategies in industrial applications.” The AMR is not alone in trying to assess industry‘ sortability’. Founded in 2024, ROKKSTA was established to address a critical need in the SBS industry: a dedicated, independent laboratory providing specialised ore characterisation and unbiased equipment performance evaluations. It intends to bridge the gap between equipment OEMs and engineering service providers by delivering transparent, data-driven insights to help stakeholders make fully informed decisions.
ROKKSTA is cooperating with RWTH Aachen University on OEM-independent XRT scanning as well as going to OEMs or other labs for testing of UV laser, hyperspectral or colour scanning.
Fabian Riedel, Managing Director of ROKKSTA, said the
Through its use of sensor technologies like XRT, the AMR can conduct objective studies on the sortability of minerals, including and addressing topics like techno-economical feasibility as well as a focus on sustainability
company is targetting the decision-making process during prefeasibility, where there are normally not enough samples available for( representative) bulk testing of SBS methods.“ Nonetheless, a preliminary equipment sizing has to be done at this stage for a conceptual flowsheet,” he told IM.“ This is where we combine the material discrimination efficiencies derived from static scans with the( physical) separation efficiency determined in our simulation tool and generate the parameters required for equipment sizing( feed rate per working width, compressed air consumption, ore recovery, separation efficiency, etc).”
The basis for any test work is determining the sorter feed heterogeneity, Riedel explains, characterising the material regarding its grade distribution.“ This is usually done at particulate level but can also be implemented at larger pod sizes up to several tonnes to determine the BOS potential of the feed stream.”
To this point, ROKKSTA’ s lab has evaluated dozens of tests on ores and industrial minerals including gold, nickel, copper, tungsten, lithium, magnesite and kimberlite. These have been conducted with various sensor-based solutions.
International Mining | MARCH 2026 71