Development of new analysis methods for the characterization and classification of wet sticky ores

• Adhesive tensile stress is mainly dependent on capillary forces.
• Adhesive tensile stress is independent on wall material.
• Based on measurement of adhesion and cohesion a threshold for problematic material can be determined.

Economic drives dictate the exploitation of formerly less attractive ore bodies located close to or even beneath the water table. These ores can cause handling problems and expensive downtime of processing equipment due to their increased adhesive characteristics and are colloquially termed as “wet and sticky” ores.In order to gain a better understanding of the causes of poor performance in the handling process, experimental test methods for adhesion and cohesion within bulk solids samples were developed and validated. The results confirmed that adhesion of bulk solid to equipment surfaces is mainly governed by capillary pressure. It can therefore be described using the Young–Laplace equation, which implies that adhesion is primarily dependent on the interfacial water between bulk material and the adhesion partner. Accordingly, the governing material parameters of adhesion are its capillarity and permeability, as these two characterize water transport to or from the interface of the adhesion partners. Furthermore a threshold for the classification of a material as wet and sticky based on the measurements of adhesion and cohesion has been proposed.

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