The Knelson Concentrator 3-inch Lab Model (also known as KC-MD3) is a laboratory-scale centrifugal gravity concentrator designed for efficient recovery of fine free gold and other high-density minerals. It operates by applying centrifugal forces up to 60 times that of gravity, which significantly enhances the separation of particles ranging from 10 µm to 6 mm. The concentrator features a fluidized bed and a series of internal rings (riffles) that trap denser particles, while lighter particles are flushed out. This lab model has a throughput of approximately 45 kg/h dry feed and 8 L/min volumetric throughput. It is widely used in gold processing plants, for assessing gravity recoverable gold content, and for recovering precious metals like silver and platinum group metals (PGMs) from various mineral streams.