vanning

Vanning is a manual or mechanical process for concentrating ore by washing material across an inclined surface, typically a flat shovel or shallow pan, to exploit differences in density and particle size. Heavier minerals settle and accumulate while lighter waste material washes away with water, leaving behind a concentrate enriched in valuable ore.

In its simplest form, vanning uses a wide, shallow metal pan or shovel held at a slight angle. Ore mixed with water is swirled or rocked; gravity and the water flow separate dense minerals like gold, tin, or cassiterite from lighter silicate gangue. The operator tilts and shakes the pan rhythmically, allowing heavy particles to migrate toward the deeper end while lighter material spills over the edge with the water. This method remains effective for small-scale or artisanal operations where capital investment is minimal.

Mechanical vanners automate this principle using tables that oscillate or tilt at a controlled frequency, with water jets applied at precise points. The table surface is often corrugated or grooved to enhance stratification. Feed rates typically range from several hundred kilograms to a few tonnes per hour, depending on table size and ore characteristics. Vanners are particularly suited to fine material between approximately 0.5 and 3 millimeters; finer particles may not separate effectively due to reduced settling velocity and increased fluid drag.

Efficiency and Limitations

Vanning recovers material based on relative density, not chemical composition, so it works best on ores where the valuable mineral is significantly denser than the waste rock. Recovery efficiency depends heavily on particle size uniformity and density contrast. The process produces two streams: a heavy concentrate (the desired product) and a light overflow (tailings). Intermediate, difficult-to-separate fractions must often be retreated or discarded.

The term derives from the vessel itself, the vanner or pan, though its roots extend to the wash pan or cradle used in alluvial mining for centuries. Vanning sits at the simpler end of the concentration hierarchy, below flotation and magnetic separation in operational complexity. It remains economically attractive for operations processing small volumes, ores with very high density contrasts, or in regions where water is abundant and infrastructure sparse.