Filtered tailings – an iron ore experience

Transitioning to a green future requires the mining industry to adopt sustainable practices. Filtered tailings are become a key expectation of the communities we operate in and are growing in a number or mining commodities including bauxite, nickel, gold and iron ore. The filtration technologies required range from dewatering screens to vacuum and pressure filters. Particular challenges faced in iron ore applications include large scale which means several units of large size are often required. In addition, a high specific gravity that cause sedimentation issues and a high abrasion level make demands on achieving reliability level at above 90 per cent. This paper describes the testing, selection criteria and specific features required to provide a rational option for equipment and plant design. An example of how this has been applied in an iron ore application in Brazil is used to demonstrate a successful outcome. This project installed four overhead beam filter presses each producing around 200 t/hr utilising a recessed chamber plate, feed pressures up to 15 bar, cake thickness of 5 mm. The moisture lower than 20 per cent that was produced was considered to provide material with handling and geotechnical properties to guarantee a safe stacking. Regular high pressure washing at 100 bar was considered imperative to maintain cloth life and process performance. The correct management of the system (OPEX control) by PLC control ensures a balance between machine potentials and plant needs. With this equilibrium it is possible to limit mechanical wear preserving equipment lifetime.