Mineral processing test work at the “Steirischer Erzberg” shall show whether enrichment of sideroplesite by means of gravity separation using centrifugal force is possible in a size range –2.5 +0.1 mm. Necessary experimental data which computer simulations could be based on are not available and suitable pilot plants are out of reach. The objective of the thesis thus focuses on the development, design and implementation of a pilot plant for dense media separation in a cyclone of the smallest size available. In its first part this paper considers the design relevant function and interaction of all the components needed for this test rig (centrifugal pump, dense media cyclone, pump box, pipes) as well as its technical design for a looped application. The second part investigates the separation by a spiral classifier and the intergrowth characteristics of sideroplesite in its coarse fraction (>0.1 mm), which has been dumped so far. The float-and-sink analysis and an analysis on a Frantz Magnetic Separator show a sideroplesite content of 71.6 % in the fraction of 2.5/0.5 mm and 76.2 % in the fraction of 0.5/0.1 mm, with a liberation based on susceptibility analysis of 40 %. The concentrate output at the same mining effort can be increased by about 100,000 t/a, assuming a perfect separation at a density of 3.1 g/cm³. The pilot plant developed in this paper is presently being implemented within an FFG project.