Metso's ACT Thickener Optimizer Improves Boliden Kevitsa's Thickening Process

Metso Oyj has successfully deployed its ACT Thickener Optimizer at Boliden's Kevitsa open-pit mine in northern Finland. The system optimizes the concentrator's thickening process, leading to substantial improvements in efficiency and stability.

The Kevitsa mine, acquired by Boliden in 2016, had faced challenges due to variations in feed ore grade and hardness. These inconsistencies affected the nickel concentrate production, impacting the feed to the thickener and complicating process control.

Traditional PI control loops proved insufficient for managing the process's complex dynamics and fluctuating feed conditions. The new, model-based ACT Thickener Optimizer effectively handles multiple variables simultaneously, including underflow density, overflow turbidity, and bed pressure. It automatically adjusts underflow pump speed and flocculant dosing.

Following the implementation, Kevitsa's underflow density variation has decreased by 24 percent. Additionally, polymer consumption has been reduced by approximately 10 percent due to the system's optimized dosing. The improved process control has significantly reduced solids carry-over to the overflow, thereby enhancing overall process stability.