In many parts of the world, important reserves of Microscopic Biogenous Sediments or Pelagic Sediments occur which primarily consist of settled siliceous or calcareous microorganisms. Such sediments typically have zones, in which an intimate association of siliceous remains of diatoms and CaCO3 is experienced. The purity of diatomite crude ores is very important for producing the filter grade finished products by means of the conventional flux calcination procedures. Calcination of DE materials with high calcium carbonate is not economically or environmentally friendly. The prime objective of this study was to evaluate the advanced STET tribo-electrostatic separator for the beneficiation of DE having relatively high quantities of CaCO3 to produce a suitable calciner feed for the production of filter grade finished products.& para;& para;In the best operating conditions, the STET technology showed the ability to reduce the calcium carbonate content of a natural-grade DE. product from, 19.5% to 10.9% which is an acceptable quantity of CaCO3 for calciner feeds. Limitations of the DE recovery process using this technology was primarily due to superficial heterogeneity of some DE particles. The validation process of the beneficiated DE confirmed that the STET technology has the potential for upgrading natural-grade DE products having relatively high quantities of CaCO3 to produce a suitable calciner feed for the production of filter grade finished products with the exception of the brewery industry. (C) 2017 Elsevier B.V. All rights reserved.