Variability of iron ore flow properties and probabilistic envelopes for the design of industrial hoppers

The flow design of silos and hoppers for iron ore is traditionally based on a single sample deemed representative, a fragile assumption for Brazilian deposits, where the lithological transition and the variation of moisture content compromise the adequate flow condition in the hopper. This work quantifies the variability of the flow properties of fourteen iron ore products (mineral provinces in northern and southeastern Brazil and port environment), based on a database of 33 Jenike shear cell tests, and presents the Geometallurgical Probabilistic Design Method (GPDM), which extracts, per consolidation stress class, the 80th percentile (P80) of the flow resistance variables and the 20th percentile (P20) of the bulk density. The unconfined yield strength increased by 25% to 31% with moisture, and the envelope covered a product excluded from the database with a conservative margin of 12% in the critical outlet dimension. The application to the Mine 1 wagon loader demonstrated the geometric conformity of the buffer and dosing hoppers. The GPDM converts geometallurgical variability into auditable design parameters from the early engineering phases onward.