Abstract
Evolving orebody composition due to ore grade depletion at Rio Tinto Fer et Titane’s Havre-Saint-Pierre (HSP) massive hemo-ilmenite (HI) mine led to a recent interest in the use of pre-concentration strategies to optimize run-of-mine material composition. Out of the studied strategies, discrete (ie. particle by particle) sensor-based ore sorting (SBOS) of low-grade materials stood out as particularly promising. Various sensors were studied in laboratory-scale studies, and it was deemed that sorting based on atomic density, estimated via x-ray transmission (XRT), would be the best suited to the HSP orebody.
As such, in 2023, a 3 ton SBOS test was conducted in collaboration with an external laboratory on two types of low-grade materials from the HSP mine: high-grade waste (HGW) (ie. ilmenite-rich waste rock (30-60 %HI)) and low-grade ore (LGO (60 -70%HI)) (ie. ore with grade below cut-off). The main objectives of said study were to assess the upgrading potential of these two materials and evaluate the impact of the sorted fractions on product quality in downstream processes. Sorting concentrates were assayed and sent to a pilot-scale rendition of Sorel-Tracy’s metallurgical complex beneficiation processing plant. Once processed, it was possible to compare properties of the produced beneficiated ore with conventional benchmarks originating from run-of-mine material.
Metallurgical balances indicated that the XRT SBOS led to successful upgrading of HGW and LGO to conventional grades of beneficiation plant feedstocks (+80% HI). This enrichment led to significant mass reduction in both HGW and LGO (54% and 37%, respectively), while maintaining satisfactory HI recovery rates (+80%).
Results from this study were deemed promising and led to the development of an ongoing demonstration plant project. In 2024, Rio Tinto Fer et Titane acquired a sorting unit from Comex (CRX-1000) and is currently working on its implementation on the HSP mine-site (start-up planned Q3 2025). If conclusive, the demonstration plant could lead to a full-scale deployment of the technology and provide an operational step change in how value is extracted from the HSP orebody.