Settlers by Metso: Innovation for Rapid and Efficient Sedimentation
In a mineral processing plant, the particle size distribution of solids is one of the main factors to consider when selecting equipment, as it determines how solids behave in crushing, grinding, classification, and concentration processes. In flotation or magnetic separation, particles that are too fine or too coarse can negatively affect the desired separation.
Thus, the particle size distribution of solids in mining is essential to optimize production processes, improve energy efficiency, meet final product specifications, and minimize environmental impacts and operational costs.
Thickening technology allows us to achieve solid-liquid separation in the mining industry with excellent results in its different models: High Rate (HRT), High Compression (HCT), or Paste (PT), primarily in concentrates (<100 microns) or in tailings (<300 microns). However, when dealing with material with a particle size above 300 microns, the question arises whether to use the same thickening technology or to focus on a different piece of equipment.
To address this issue, Metso offers its Settlers solution as an ideal alternative for easily and rapidly settling material. Metso Settlers are elevated tanks with a steeply sloped cone at the bottom and no rake system, created 20 years ago specifically for small-diameter equipment (<5m). Currently, Metso Settlers focus on sedimenting coarse materials (>300 microns) with excellent results in both the percentage of solids in the underflow and the clarity of the overflow. The need for flocculant in the process will depend on the specific case and the mineral to be settled. However, its use is minimal since its goal is to "capture" the fine particles in the slurry.
The distribution of coarse material in the "settler" is of utmost importance, which is why Metso designed a feedwell that allows for even distribution around the entire equipment. The internal lining of the tank with special materials counteracts the impact of coarse material abrasion at the bottom of the tank.
Metso has supplied Settlers that are already operational in the Peruvian mining industry, working with minerals having a P80 greater than 300 microns, proving to be a tested solution for the market. Additionally, there are several projects with minerals of similar particle size soon to be supplied.
It is noteworthy that this technology is part of Metso's Planet Positive portfolio, focusing on environmental performance. Settlers maximize recovery rates compared to other market solutions, optimizing water usage.