Bottle Roll Tests for Kinetic Evaluation of Nickel Ores: Capabilities, Limitations, and Misinterpretations – A Critical Review

Bottle roll testing is widely used to evaluate leaching performance due to its simplicity, low cost, and rapid execution. However, its results are often misinterpreted when extrapolated to industrial systems. This critical review examines the capabilities and limitations of bottle roll tests, with emphasis on their role in representing intrinsic chemical kinetics rather than full process behavior. Key discrepancies between laboratory and industrial conditions are analyzed, including particle-size effects, the absence of hydraulic constraints, limited representation of secondary-phase formation, and underestimation of acid consumption. Comparative analysis shows that bottle roll tests can achieve 85–95% extraction within 24–72 hours, whereas heap leaching systems typically reach 60–75% over 120–180 days, reflecting the influence of mass transfer, hydrodynamics, and time-dependent phenomena. The review highlights common scale-up pitfalls, particularly the misuse of kinetic fitting and laboratory acid consumption data for process design. A structured framework integrating bottle roll, column, and pilot testing is proposed to improve predictive capability. Data gaps are identified in coupled kinetic–transport modeling, long-term datasets, and mineralogical integration. It is concluded that bottle roll testing should be used as a screening and benchmarking tool, not as a standalone predictive method, and must be combined with scale-representative testing for reliable process evaluation.