Pre-selection refers to the process of discarding surrounding rocks and inclusions using different beneficiation methods before the ore enters the grinding process. The more waste inclusions removed during pre-selection, the better the energy-saving and production-increasing effects, and the higher the economic benefits. Iron ore pre-selection methods include (weak, strong) magnetic separation or gravity separation. Weak magnetic separation is used for magnetite ore pre-selection, often employing dry magnetic pulleys and large-scale magnetic separators.

Weakly magnetic iron ore pre-selection uses heavy media or jigging gravity separation or strong magnetic separation, primarily employing gravity separation equipment and strong magnetic separation equipment. There are many types of heavy media pre-selection equipment; the most commonly used in iron ore pre-selection is the heavy media vibrating sluice. The main characteristics of a heavy medium vibrating sluice are the vibration of the sluice body and the upward flow of water within it. Therefore, it allows for the use of coarser weighting agents (suspended matter), thus reducing or eliminating limitations imposed by the viscosity of the suspension (heavy medium). It enables the preparation of suspensions with relatively high volumetric concentrations and allows the use of weighting agents with lower densities, such as hematite concentrate with a density of 4.0 g/cm³, expanding the source of weighting agents. Furthermore, the density of the prepared feed medium can be lower than that of the separation medium, further reducing the concentration and viscosity of the medium. Even with improved separation accuracy, medium recovery is relatively easy. Jigging pre-selection mainly processes weakly magnetic iron ores and mixed ores. Over the years, trapezoidal jigs, rectangular jigs, AM series large-particle jigs, and prototype jigs have been developed. These devices are widely used due to their simple structure, large processing capacity, and strong adaptability. High-intensity magnetic separators are effective separation equipment for weakly magnetic iron ores. The successful development of an electromagnetic induction roller-type high-intensity magnetic separator for processing coarse particles has made progress in the pre-selection of high-intensity magnetic separators.