Browsing by Subject "Staged mill float circuits"

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    Integrating Fine Grinding options in Platinum Processing Circuits
    (2026) Chottu, Dinesh; Mainza, Aubrey
    Platinum producers have invested significant capital in the pursuit of efficient operations to achieve high metal recoveries. However, studies on how various technologies can be linked together in circuits to reduce PGM losses to the final tailings have lagged. These losses may be due to insufficient liberation of PGMs, flotation inefficiencies, or a combination of both. The biggest opportunity to maximise recovery is linked to fine grinding and understanding flotation techniques to support recovery of fine PGM particles. However, the integration of fine grinding technologies such as the IsaMill™ and HIGmill™ into circuits and their combined impact on continuous flotation performance, remains underexplored. This study evaluates how different comminution configurations can be integrated into staged millfloat circuits, in a Flexi-Float Pilot concentrator plant, to improve the flotation response of PGM bearing ores. Process flows investigated were mill-float-mill-mill-float (MFM2F) and MFM2FMF. Four Flexi Float continuous pilot campaigns were conducted using combinations of ball milling, IsaMill™ tertiary milling, and HIGmill™ quaternary milling. Target grinds ranged from 80% passing 75 µm to 95% passing 53 µm, enabling a direct comparison of MF2 and MF3 type circuit behaviour under controlled conditions. Results demonstrate that PGM recovery was driven primarily by fineness of grind rather than mill selection. Increasing the grind from 80% to 90% passing 75 µm raised the overall 2E recovery from 86% to ~90% and was consistent with laboratory batch flotation. Ultrafine grinding to 95% passing 53 µm yielded a marginal additional recovery (~92.1%) but required a substantial increase in specific energy input (from 17.6–20.8 kWh/t to 45.6 kWh/t), as well as increased depressant and frother demand to manage liberated phyllosilicates and excess fines observed in the tertiary rougher flotation stage. The findings confirm that while ultrafine grinding can improve metallurgical performance, the additional cost associated with higher energy utilisation and reagent consumption outweighs the small incremental gains in recovery. For this batch of ore, the optimal trade-off between recovery, energy, and reagent use occurred at 90% passing 75 µm with two flotation stages, representing a practical and economically favourable configuration.