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2026

The centrifugal principle of gold‑selecting centrifuges

When a suspension containing fine particles is allowed to stand still, the suspended particles gradually settle under the influence of the gravitational field.

When a suspension containing fine particles is allowed to stand still, the particles gradually settle under the influence of the gravitational field. The heavier the particles, the faster they sink; conversely, particles with a density lower than that of the liquid will rise. The rate at which particles move in a gravitational field depends on their size, shape, and density, as well as on the strength of the gravitational field and the viscosity of the liquid. Particles on the order of red blood cell size—having diameters of several micrometers—can be observed undergoing sedimentation under normal gravitational conditions.
Furthermore, as substances settle in a medium, they are accompanied by diffusion. Diffusion is unconditional and absolute; it is inversely proportional to the mass of the substance, meaning that smaller particles experience more pronounced diffusion. In contrast, sedimentation is relative and conditional, requiring an external force to occur. Sedimentation is directly proportional to the weight of the particle, so larger particles settle more rapidly. For particles smaller than a few micrometers—such as viruses or proteins—which exist in solution in a colloidal or semi‑colloidal state, gravitational settling alone cannot be observed. This is because the smaller the particles, the slower their sedimentation and the more significant the diffusive effects. Therefore, a centrifuge must be employed to generate strong centrifugal forces, enabling these particles to overcome diffusion and undergo sedimentation.
Centrifugation utilizes the powerful centrifugal force generated by the high-speed rotation of a centrifuge rotor to accelerate the sedimentation of particles in a liquid, thereby separating substances in a sample that differ in their sedimentation coefficients and buoyant densities.

Working principle of a sand-dredging vessel

The GW-type external-filter vacuum rotary drum filter is a solid–liquid separation device independently developed by our company.

Working principle of a sand-dredging vessel

The GW-type external-filter vacuum rotary drum filter is a solid–liquid separation device independently developed by our company.