In developing countries cassava starch is produced mostly rurally using artisan methods through wet-way processes that consume as much as 37 m³ of water per processed ton. In comparison, the little industrial production consumes 5 m³ of water per processed ton. These waste waters, highly contaminated, are usually discharged in to the rivers without any treatment. With the aim of industrializing the cassava flour production, CIAT and CLAYUCA are developing an alternative dry technology, environmentally sustainable, to produce enriched flour as a starch substitute. The intention is to separate the starch enriched flour (< 44 mum) from the fiber rich coarse flour (> 44 mum). The use of an inversely operated cyclone (related to the conventional operation) showed good potential in terms of efficiency and economy. In this paper we propose pressure drop (deltap), fines (< 44 mum) recovery efficiency (eta), and fines recovery quality (q), as main functional parameters to characterize the apparatus. Results show that deltap, eta, and q only depend on gas velocity (v g) and on the feed solid concentration (c). The h and q magnitudes, approximately 60 and 80% respectively, demonstrate the effectiveness of this technique. Potential improvements merit further exploration.