Advanced mineral processing for better resource efficiency
Within mineral processing different unit operations for comminution and physical separation as well as flotation are combined to multi-stage beneficiation processes in order to provide an ore concentrate or to produce an industrial mineral product of defined application properties.
In recent decades, process technologies have matured but still need to be improved. Within mineral processing, innovative processing concepts and machinery as wells as optimization are the keys to improving resource efficiency while minimizing energy consumption, auxiliaries and waste. CAMM research on advanced mineral processing is conducted in the areas of (i) comminution, (ii) separation processes, and (iii) process systems engineering:
- Dynamic models of grinding mills and mill charge are developed using multi-phase computational physics in order to optimize tumbling mill and stirred media mill performance. This involves investigation of how energy is utilized and how wear of media and liners is affected by operational and design parameters as well as particle properties.
- Mineral liberation, being crucial for the efficiency of subsequent separation processes, can be enhanced by better adjusting target particle size and breakage mechanism to ore texture and mineral associations. In a more fundamental investigation different stress modes and rates are applied to various ore types in order to identify optimal liberation conditions and develop advanced process models.
- For fine-grained, complex ores and fine tailings the combination of mineral processing and hydrometallurgical processing is considered as a promising concept that requires further investigation. Raffinate milling will result in innovative processes, e.g. leaching while grinding, and novel grinding circuits for improved resource efficiency.
- The effect of low temperatures on the efficiency of flotation separation, particularly oxide and silicate flotation, is investigated in order to identify novel flotation reagents, suitable reagent regimes and hydrodynamic concepts adapted to mineral beneficiation and tailings treatment in cold climate.
- Using dry processes wherever possible will result in lower process water consumption and smaller ecological footprint. This refers to ore sorting, dry primary comminution, dry screening instead of wet classification, dry concentration, and also dry deposition techniques. Research on extending dry processes to the sub-millimeter range is particularly needed.
- New technologies available for mineralogical analysis, as hyperspectral imaging or computer tomography, are investigated with respect to their potential for process design and control. Challenges arise from linking mineralogy to processing properties in order to make property modeling more generic. Soft-sensors for advanced process control are developed that use such models.
- Improving resource efficiency requires processes that are flexible towards variations in an ore body. Geometallurgy as a holistic approach to optimizing process design and control provides methods and tools for linking ore properties and process behavior. While ongoing research is on geometallurgical testing and modeling, a coherent methodology is developed here to integrate with sustainability and flexibility concepts.